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38–057PS 2008

NEAR-EARTH OBJECTS (NEOS)—STATUS

OF THE SURVEY PROGRAM AND REVIEW

OF NASA’S 2007 REPORT TO CONGRESS

HEARING

BEFORE THE

SUBCOMMITTEE ON SPACE AND AERONAUTICS

COMMITTEE ON SCIENCE AND

TECHNOLOGY

HOUSE OF REPRESENTATIVES

ONE HUNDRED TENTH CONGRESS

FIRST SESSION

NOVEMBER 8, 2007

Serial No. 110–72

Printed for the use of the Committee on Science and Technology

(

Available via the World Wide Web: http://www.house.gov/science

(II)

COMMITTEE ON SCIENCE AND TECHNOLOGY

HON. BART GORDON, Tennessee, Chairman

JERRY F. COSTELLO, Illinois

EDDIE BERNICE JOHNSON, Texas

LYNN C. WOOLSEY, California

MARK UDALL, Colorado

DAVID WU, Oregon

BRIAN BAIRD, Washington

BRAD MILLER, North Carolina

DANIEL LIPINSKI, Illinois

NICK LAMPSON, Texas

GABRIELLE GIFFORDS, Arizona

JERRY MCNERNEY, California

LAURA RICHARDSON, California

PAUL KANJORSKI, Pennsylvania

DARLENE HOOLEY, Oregon

STEVEN R. ROTHMAN, New Jersey

JIM MATHESON, Utah

MIKE ROSS, Arkansas

BEN CHANDLER, Kentucky

RUSS CARNAHAN, Missouri

CHARLIE MELANCON, Louisiana

BARON P. HILL, Indiana

HARRY E. MITCHELL, Arizona

CHARLES A. WILSON, Ohio

RALPH M. HALL, Texas

F. JAMES SENSENBRENNER JR.,

Wisconsin

LAMAR S. SMITH, Texas

DANA ROHRABACHER, California

ROSCOE G. BARTLETT, Maryland

VERNON J. EHLERS, Michigan

FRANK D. LUCAS, Oklahoma

JUDY BIGGERT, Illinois

W. TODD AKIN, Missouri

JO BONNER, Alabama

TOM FEENEY, Florida

RANDY NEUGEBAUER, Texas

BOB INGLIS, South Carolina

DAVID G. REICHERT, Washington

MICHAEL T. MCCAUL, Texas

MARIO DIAZ-BALART, Florida

PHIL GINGREY, Georgia

BRIAN P. BILBRAY, California

ADRIAN SMITH, Nebraska

PAUL C. BROUN, Georgia

SUBCOMMITTEE ON SPACE AND AERONAUTICS

HON. MARK UDALL, Colorado, Chairman

DAVID WU, Oregon

NICK LAMPSON, Texas

STEVEN R. ROTHMAN, New Jersey

MIKE ROSS, Arizona

BEN CHANDLER, Kentucky

CHARLIE MELANCON, Louisiana

BART GORDON, Tennessee

TOM FEENEY, Florida

DANA ROHRABACHER, California

FRANK D. LUCAS, Oklahoma

JO BONNER, Alabama

MICHAEL T. MCCAUL, Texas

RALPH M. HALL, Texas

RICHARD OBERMANN Subcommittee Staff Director

PAM WHITNEY Democratic Professional Staff Member

KEN MONROE Republican Professional Staff Member

ED FEDDEMAN Republican Professional Staff Member

DEVIN BRYANT Research Assistant

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C O N T E N T S

November 8, 2007

Page

Witness List ............................................................................................................. 2

Hearing Charter ...................................................................................................... 3

Opening Statements

Statement by Representative Mark Udall, Chairman, Subcommittee on Space

and Aeronautics, Committee on Science and Technology, U.S. House of

Representatives .................................................................................................... 11

Written Statement ............................................................................................ 12

Statement by Representative Tom Feeney, Ranking Minority Member, Subcommittee on Space and Aeronautics, Committee on Science and Technology, U.S. House of Representatives ............................................................... 13

Written Statement ............................................................................................ 15

Panel 1:

Representative Luis Fortun ̃ o, Resident Commissioner, Puerto Rico

Oral Statement ................................................................................................. 16

Written Statement ............................................................................................ 17

Discussion

Impact of Shutting Down Arecibo ....................................................................... 18

George Brown ....................................................................................................... 19

Importance of Arecibo With Regard to Cost ...................................................... 20

Visiting Arecibo .................................................................................................... 21

Panel 2:

Dr. James L. Green, Director, Planetary Science Division, Science Mission

Directorate, National Aeronautics and Space Administration (NASA)

Oral Statement ................................................................................................. 22

Written Statement ............................................................................................ 24

Biography .......................................................................................................... 27

Dr. Scott Pace, Associate Administrator, Program Analysis and Evaluation,

National Aeronautics and Space Administration (NASA)

Oral Statement ................................................................................................. 28

Written Statement ............................................................................................ 30

Biography .......................................................................................................... 34

Dr. Donald K. Yeomans, Manager, Near-Earth Object Program Office, Jet

Propulsion Laboratory

Oral Statement ................................................................................................. 34

Written Statement ............................................................................................ 37

Biography .......................................................................................................... 40

Dr. Donald B. Campbell, Professor of Astronomy, Cornell University; Former

Director, Arecibo Observatory

Oral Statement ................................................................................................. 40

Written Statement ............................................................................................ 42

Dr. J. Anthony Tyson, Professor of Physics, University of California, Davis;

Director, Large Synoptic Survey Telescope Project

Oral Statement ................................................................................................. 47

Written Statement ............................................................................................ 48

Page

IV

Dr. J. Anthony Tyson, Professor of Physics, University of California, Davis;

Director, Large Synoptic Survey Telescope Project—Continued

Biography .......................................................................................................... 54

Mr. Russell ‘‘Rusty’’ L. Schweickart, Chairman and Founder, B612 Foundation

Oral Statement ................................................................................................. 54

Written Statement ............................................................................................ 57

Biography .......................................................................................................... 94

Discussion

Importance of Surveying Objects Larger Than 140m ....................................... 95

Risk of Changing the Project Timeline .............................................................. 95

Non-U.S. NEO Characterization ......................................................................... 96

Increasing International NEO Collaboration ..................................................... 96

Public Safety ......................................................................................................... 97

NEO Deflection Technology ................................................................................. 98

Deflection of NEOs into Keyholes ....................................................................... 99

More on International Collaboration .................................................................. 100

Probability of a 10km NEO Hitting Earth in the Near Future ....................... 100

Apophis NEO ........................................................................................................ 101

Understanding the Threat Posed By NEOs ....................................................... 101

Future Responsibility .......................................................................................... 102

Potential NASA Partnerships ............................................................................. 103

NASA Funding NEO Partnerships ..................................................................... 103

Using LSST for NEO Detection .......................................................................... 105

Radar Versus Optical NEO Detection ................................................................ 106

Importance of Arecibo Radar .............................................................................. 106

Radius of NEO Surveys ....................................................................................... 106

Ramifications of an Asteroid Hitting Earth ....................................................... 107

NEO Survey Objectives ....................................................................................... 109

Planetary Defense Responsibilities ..................................................................... 109

Goldstone Antenna Upgrades ............................................................................. 111

Future Steps in NEO Detection and Deflection ................................................ 112

Orbital Determination ......................................................................................... 112

More on Detection and Deflection ....................................................................... 113

Importance of NEO Characterization ................................................................. 114

Appendix 1: Answers to Post-Hearing Questions

Dr. James L. Green, Director, Planetary Science Division, Science Mission

Directorate, National Aeronautics and Space Administration (NASA) ........... 118

Dr. Scott Pace, Associate Administrator, Program Analysis and Evaluation,

National Aeronautics and Space Administration (NASA) ................................ 127

Dr. Donald K. Yeomans, Manager, Near-Earth Object Program Office, Jet

Propulsion Laboratory ......................................................................................... 134

Dr. Donald B. Campbell, Professor of Astronomy, Cornell University; Former

Director, Arecibo Observatory ............................................................................. 142

Dr. J. Anthony Tyson, Professor of Physics, University of California, Davis;

Director, Large Synoptic Survey Telescope Project ........................................... 146

Mr. Russell ‘‘Rusty’’ L. Schweickart, Chairman and Founder, B612 Foundation ........................................................................................................................ 151

Appendix 2: Additional Material for the Record

NASA Rebuttal to remarks made by Mr. Schweickart during the November

8, 2007 hearing regarding Near-Earth Objects ................................................. 162

Statement of The Planetary Society in Support of Planetary Radar at the

Arecibo Observatory ............................................................................................. 163

Letter to The Honorable Dana Rohrabacher from John W. Meredith, President, IEEE–USA, dated 08 November 2007 ...................................................... 164

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NEAR-EARTH OBJECTS (NEOS)—STATUS OF

THE SURVEY PROGRAM AND REVIEW OF

NASA’S 2007 REPORT TO CONGRESS

THURSDAY, NOVEMBER 8, 2007

HOUSE OF REPRESENTATIVES, SUBCOMMITTEE ON SPACE AND AERONAUTICS, COMMITTEE ON SCIENCE AND TECHNOLOGY, Washington, DC.

The Subcommittee met, pursuant to call, at 10:07 a.m., in Room

2318 of the Rayburn House Office Building, Hon. Mark Udall

[Chairman of the Subcommittee] presiding.

2

3

HEARING CHARTER

SUBCOMMITTEE ON SPACE AND AERONAUTICS

COMMITTEE ON SCIENCE AND TECHNOLOGY

U.S. HOUSE OF REPRESENTATIVES

Near-Earth Objects (NEOs)—Status

of the Survey Program and Review

of NASA’s 2007 Report to Congress

THURSDAY, NOVEMBER 8, 2007

10:00 A.M.–12:00 P.M. 2318 RAYBURN HOUSE OFFICE BUILDING

Purpose

On Thursday, November 8, 2007 at 10:00 a.m., the House Committee on Science

and Technology’s Subcommittee on Space and Aeronautics will hold a hearing to examine the status of NASA’s Near-Earth Object survey program, review the findings

and recommendations of NASA’s report to Congress, Near-Earth Object Survey and

Deflection Analysis of Alternatives, and to assess NASA’s plans for complying with

the requirements of Section 321 of the NASA Authorization Act of 2005.

Witnesses

Panel 1

• The Honorable Luis G. Fortun ̃ o, Resident Commissioner, Puerto Rico

Panel 2

• Dr. James Green, Science Mission Directorate, NASA

• Dr. Scott Pace, Program Analysis and Evaluation, NASA

• Dr. Donald K. Yeomans, Jet Propulsion Laboratory

• Dr. Donald B. Campbell, Cornell University

• Dr. J. Anthony Tyson, University of California, Davis

• Mr. Russell ‘‘Rusty’’ Schweickart, B612 Foundation

Potential Issues

• What is the current status of NASA’s Near-Earth Object (NEO) search program, and how urgent is the need to move ahead with the expanded search

that was directed in the 2005 NASA Authorization Act? Is the timeline for

achieving the goal appropriate or would changes in the ‘‘deadline’’ provide

benefits in terms of technical approaches or costs?

• What are the most important priorities to address relative to detecting, characterizing, and developing the means to deflect NEOs?

• NASA submitted a 2007 report to Congress on NEO search and deflection options, but the report doesn’t provide a recommended option, as required in the

2005 NASA Authorization Act. What approach does NASA recommend for

complying with the legislated mandate and what steps has NASA taken to

begin implementing any of the options identified in the report?

• NASA’s report to Congress mentions search options that would rely on

planned ground-based telescopes that have been proposed for development

under the auspices of other agencies. What role, if any, should NASA play in

supporting the NEO-related operations of those telescopes? What alternatives

exist if those assets are not funded and developed?

• Planetary radar facilities have been cited as critical for providing more precise orbital determinations of potentially hazardous NEOs. However, the two

radar facilities currently being used to obtain data on NEOs [Arecibo and

Goldstone] may not be available in the future. What are the implications

should existing planetary radar facilities become unavailable?

4

• A NEO object, Apophis, has been identified and could pass as close as 23,100

kilometers from the Earth’s surface in 2029 and return again for a close approach in 2036. What threat does this object pose in terms of a potential impact with Earth, and what is needed to improve our understanding of the

threat?

• How much time would be required to prepare a mitigation approach if a hazardous object were discovered to be on a collision course with Earth? How

much time would likely be available?

• How well understood are the potential approaches to deflecting asteroids?

What is the confidence level in the technologies that would be required? What

information is needed to assess the various approaches, and how will decisions be made on which mitigation strategy to take?

• What is the degree of international involvement in searching for, characterizing, and studying deflection options for NEOs? What steps, if any, has

NASA taken on potential collaboration or coordination of NEO-related initiatives?

• How will policy and legal issues involved in addressing NEOs—e.g., when and

how to warn the public and whether to use nuclear explosives to deflect an

asteroid—be handled on national and international levels? What steps have

NASA and other federal agencies taken to date to address such issues?

Background

Astronomers estimate that millions of asteroids, comets, meteoroids, and other

cosmic debris orbit within the vicinity of Earth and the Sun. The Earth is continually bombarded by these remnants from the formation of the solar system. Small

objects ranging from the size of a dust particle up to a size of about 50 meters in

diameter do not pose impact threats to Earth, because they burn up and disintegrate upon entry to the Earth’s atmosphere. However, larger objects pose potentially

catastrophic threats because they would not disintegrate before impacting the

Earth. Near-Earth Objects (NEOs) are defined as asteroids and comets whose trajectories bring them within 45 million kilometers (km) of the Earth. NEOs larger than

about 140 meters, whose orbits about the Sun bring them within 7.5 million km of

the Earth’s orbit, are classified as potentially hazardous objects (PHOs). Most of

these objects are asteroids. According to NASA, there are currently 900 known Potentially Hazardous Asteroids (PHAs). NASA scientists estimate that the population

of PHOs is about 20,000 objects.

The literature on NEOs is not entirely consistent on the threats posed by various

sizes of objects. Information from NASA’s Near-Earth Object Program webpage

[http://neo.jpl.nasa.gov] and other sources indicates the following:

• Objects larger than 50 meters can survive entry through the Earth’s atmosphere, and could cause local disasters or events such as tsunamis upon impact. Estimates of the frequency of impacts of objects of this size range from

once every 100 years to once every 500 years.

• Objects larger than one km in diameter that impact Earth would cause disasters on a global scale, and ‘‘the impact debris would spread throughout the

Earth’s atmosphere so that plant life would suffer from acid rain, partial

blocking of sunlight, and from the firestorms resulting from heated impact debris raining back down upon the Earth’s surface.’’ Estimates of the frequency

of these range from once every few hundred thousand years to once every million years.

• ‘‘Extinction-class’’ objects (10 km or greater in size) are estimated to occur on

average once every 50 million to 100 million years.

Past NEO Impacts and Events

Evidence from past major NEO impacts or aerial explosions illustrates the catastrophic consequences that these objects can have:

• The impact of a NEO on the north side of Mexico’s Yucatan Peninsula some

65,000,000 years ago that is thought to have helped bring about the extinction of the dinosaurs and to have destroyed 75 percent of life on Earth. Scientists estimate the frequency of an impact event of this magnitude to be

about once every 50–100 million years.

• The Barringer Meteor Crater in Arizona is about one kilometer wide and is

estimated to be 50,000 years old. The impact was caused by a nickel-iron meteorite, weighing about 300,000 tons and whose size was roughly 45 meters

in diameter. The impact explosion was comparable to 20 million tons of TNT

5

and created a hole 174 meters deep. Scientists estimate these types of impacts to occur once every 250–1,000 years.

• The Tunguska Event took place in Siberia in 1908 when a NEO estimated

to be 50–100 meters in size disintegrated about five-ten kilometers above the

Earth’s surface. That event unleashed energy comparable to an estimated 10–

15 million tons of TNT. The explosion flattened trees and other vegetation

over an area of roughly 2,000 square kilometers [about 500,000 acres]. Scientists estimate that this scale of impact would occur about once every 250–

1,000 years.

Within the last two decades, instances of objects that passed near Earth brought

increasing interest in identifying NEOs and exploring options to protect Earth from

a potential NEO impact. For example:

• On March 23, 1989, the 1989 FC asteroid with an estimated diameter of 0.3

miles came within 430,000 miles of Earth. 1989 FC carried the energy estimated to be more than 1,000 one-megaton hydrogen bombs. The asteroid was

only discovered after it had made its closest approach to Earth.

• Asteroid 99942 Apophis, discovered in 2004, is estimated to be roughly 300

meters in diameter, and could pass as close as 29,470 km [about 18,300 miles]

from the Earth’s surface [i.e., about the altitude that geosynchronous communications satellites orbit the Earth] in 2029. Radar observations conducted at

the Arecibo Observatory in January 2005 significantly improved the understanding of the asteroid’s orbit. The probability of impact in 2036, when the

asteroid makes another close approach, is currently estimated to be 1/45,000.

Scientists hope to use Arecibo again in 2012 to further refine the orbital coordinates when the asteroid is expected to be in a favorable viewing position.

Determining the population of NEOs, including those in the PHO category, can

only be achieved by conducting a search campaign using ground-based or spacebased telescopes, or a combination of the two.

Previous Congressional Actions Related to NEOs

Congress has taken a number of steps since 1990 to promote increased understanding of NEOs and the potential threat they pose, as well as potential options

for protecting Earth from hazardous NEOs. The National Aeronautics and Space

Administration Multi-year Authorization Act of 1990 directed NASA to conduct two

workshop studies on NEO detection and interception. In 1993 the House Science

and Technology Committee held a hearing to review the results of the two reports,

and in 1994 [by means of House Report 103–654, which accompanied the National

Aeronautics and Space Administration Authorization and Space Policy Act for Fiscal

Year 1995] gave further direction to NASA to coordinate with the Department of Defense and international space partners on identifying and cataloging NEOs greater

than one kilometer in diameter that are in an orbit around the Sun that crosses

Earth’s orbit within the next decade. In 1998, NASA established a Near-Earth Object Program Office at the Jet Propulsion Laboratory and established its Spaceguard

Survey. The Survey had the goal of detecting and cataloging 90 percent of NEOs

one km or larger by the end of 2008.

NASA’s Current NEO Survey Program and Budget

The Spaceguard Survey was housed in NASA’s Exploration Systems Mission Directorate in recent years, but earlier this year it was moved to the Science Mission

Directorate. NASA’s report to Congress states that the current budget for the program is $4.1 million per year for Fiscal Years 2006–2012. NASA officials report that

the annual budget is allocated as follows: $3 million are used to support the search

teams and ground-based telescope facilities, $500,000 is allocated to JPL for studies

on near-Earth objects, $400,000 is provided to the Minor Planets Center at the

Smithsonian Center for Astrophysics to refine the orbital coordinates of NEOs that

have been detected, and the remainder is allocated to additional NASA-funded studies.

NASA’s report to Congress states that as of December 2006 the Spaceguard Survey had identified 701 of the estimated 1100 NEOs larger than one km that are believed to exist.

Recent Congressional Action on NEOs

Section 321 of the 2005 NASA Authorization Act directed NASA ‘‘to plan, develop,

and implement a Near-Earth Object Survey program to detect, track, catalogue, and

characterize the physical characteristics of near-Earth objects equal to or greater

6

than 140 meters in diameter in order to assess the threat of such near-Earth objects

to the Earth. It shall be the goal of the Survey program to achieve 90 percent completion. . .within 15 years after the date of enactment of this Act.’’ Section 321 also directed NASA to report to Congress on an analysis of ground-based and space-based

alternatives to conduct the Survey; a recommendation on which Survey option to

pursue and a proposed budget; and an analysis of options to divert an object that

threatens impact with Earth.

NASA’s Near-Earth Object Survey and Deflection Analysis of Alternatives Report to

Congress

NASA’s report, Near-Earth Object Survey and Deflection Analysis of Alternatives,

Report to Congress, prepared in response to Sec. 321 of the NASA Authorization Act

of 2005, was submitted to Congress in March 2007. The study was led and managed

by NASA’s Office of Program Analysis and Evaluation. The report is a condensed

version of a longer, un-circulated version that included the analysis on which findings of the report to Congress were based. The 2007 report to Congress provides options for meeting the Survey goals by 2020, as required in the Act, and options for

meeting the goals on a longer timeframe. However, the report does not provide Congress with NASA’s recommended option for conducting the Survey or provide a cost

estimate for that Survey.

The report’s basic conclusion is that ‘‘NASA recommends that the program continue as currently planned, and we will also take advantage of opportunities using

potential dual-use telescopes and spacecraft—and partner with other agencies as feasible—to attempt to achieve the legislated goal within 15 years. However, due to current budget constraints, NASA cannot initiate a new program at this time.’’

In addition, the report contained a number of additional findings, including:

• ‘‘The goal of the Survey Program should be modified to detect, track, catalogue, and characterize, by the end of 2020, 90 percent of all Potentially Hazardous Objects (PHOs) greater than 140m whose orbits pass within 0.05 AU

of the Earth’s orbit (as opposed to surveying for all NEOs).

• The Agency could achieve the specified goal of surveying for 90 percent of the

potentially hazardous NEOs by the end of 2020 by partnering with other government agencies on potential future optical ground-based observatories and

building a dedicated NEO survey asset assuming the partners’ potential

ground assets come online by 2010 and 2014, and a dedicated asset by 2015.

• Together, the two observatories potentially to be developed by other government

agencies could complete 83 percent of the survey by 2020 if observing time at

these observatories is shared with NASA’s NEO Survey Program.

• New space-based infrared systems, combined with ground-based assets, could

reduce the overall time to reach the 90 percent goal by at least three years.

Space systems have additional benefits as well as costs and risks compared

to ground-based alternatives.

• Radar systems cannot contribute to the search for potentially hazardous objects, but may be used to rapidly refine tracking and to determine object sizes

for a few NEOs of potentially high interest. Existing radar systems are currently oversubscribed by other missions.

• Determining a NEO’s mass and orbit is required to determine whether it represents a potential threat and to provide required information for most alternatives to mitigate such a threat. Beyond these parameters, characterization

requirements and capabilities are tied directly to the mitigation strategy selected.’’

The NASA report also describes the general advantages and disadvantages of

using ground versus space-based search systems and analyzes an approach that includes a combination of ground-based and space-based NEO search capabilities:

• Ground-based Optical Systems. Ground-based telescopes are relatively easy to

maintain and offer the flexibility for upgrades. They are limited by their

nighttime or early morning viewing periods as well as the atmosphere’s effects on observations.

• Space-Based Optical Systems. These systems can take advantage of proven

space technologies, are not restricted in viewing hours and atmospheric interference, and can observe objects in inner Earth orbits or orbits similar to

Earth’s more easily than can ground-based systems. Space-based survey approaches however require access to space, data downlinks, and replacement

spacecraft.

7

• Space-Based Infrared Systems. The technology for space-based infrared systems is less mature than space-based optical technology, however the infrared

systems would require smaller aperture telescopes and could provide greater

accuracy on the sizes of NEOs they detect.

The NASA report suggests that the goals of the Congressionally-mandated survey

could be met by acquiring shared access to a proposed ground-based NSF/DOE, telescope system, the Large Synoptic Survey Telescope (LSST) and a potential Air Force

telescope system, the Panoramic Survey Telescope and Rapid Response System

(Pan-STARRS). In addition, this exemplar search program would require an additional LSST-type telescope dedicated to the NEO survey effort.

LSST is proposed as a large-aperture, wide-field telescope. According to literature

from the LSST project, the telescope will ‘‘Conduct a survey over an enormous volume of sky; do it with a frequency that enables repeat exposures of every part of the

sky every few nights in multiple colors; and continue this mode for ten years to

achieve astronomical catalogs thousands of times larger than have ever previously

been compiled.’’ LSST was recommended as a high priority initiative in the 2001 National Academies Astronomy and Astrophysics Decadal Survey. In addition, the

2003 National Academies Solar System Exploration Survey included the following

recommendation: ‘‘The SSE [Solar System Exploration] Survey recommends that

NASA partner equally with the National Science Foundation to design, build, and

operate a survey facility, such as the Large Synoptic Survey Telescope (LSST). . .to

ensure that LSST’s prime solar system objectives are accomplished’’ LSST has not

yet been approved as new project start by the National Science Foundation.

The Director of the LSST project is expected to testify that LSST could complete

the mandated survey within 12 years from the start of the telescope operations.

This goal would involve modifications to the observing strategy and to the data processing procedures. The LSST project estimates that the cost of an LSST NEO survey

over 12 years would be about $125M.

Pan-STARRS is being developed by the University of Hawaii with funding from

the U.S. Air Force. A main goal of Pan-STARRS is to detect potentially hazardous

objects. Pan-STARRS is planned to be a system of four individual telescopes that

will survey large areas of the sky at a high degree of sensitivity. The prototype onemirror Pan-STARRS telescope is complete; a full four-telescope system has not yet

been approved.

The NASA report to Congress also indicates that by using a space-based infrared

telescope [along with the LSST and Pan-STARRS systems], NASA could exceed the

mandated requirement and detect an estimated 90 percent of the PHO population

by 2017.

An additional capability that could be brought to bear on the NEO survey task

is NASA’s Wide-field Infrared Survey Explorer (WISE), which is scheduled for

launch in 2009. The WISE spacecraft will survey the sky in the infrared band at

high sensitivity. Asteroids, which absorb solar radiation, can be observed through

the infrared band. NASA officials told Committee staff that NASA plans to use

WISE to detect NEOs, in addition to performing its science goals. NASA expects

that WISE could detect 400 NEOs [or roughly two percent of the estimated NEO

population of interest] within the spacecraft’s six month—one year mission.

It should be noted that the National Academies’ 2001 report New Frontiers in the

Solar System [the solar system exploration decadal survey] commented on the potential value of ground-based observatories for detecting near-Earth objects: ‘‘The

SSE Survey’s Primitive Bodies Panel endorses the concept of a large telescope capable of an all-sky search strategy that would reveal large numbers of near-Earth objectsalso endorses a telescope that would enable the physical study of such objects by

spectroscopic and photometric techniques. The panel heard recommendations for the

Large Synoptic Survey Telescope (LSST) and the Next Generation Lowell Telescope

(NGLT). . .Other options, including the Panoramic Optical Imager concept, should

be explored and a choice made that NASA can support in the next decade.

According to the NASA report to Congress, once a NEO is identified, further characterization of its mass and orbit are required to ‘‘assess the threat’’ as required in

the Act. Characterization involves observations that provide details on an object’s

structure, whether it is a single or binary NEO, its porosity, rotation rate, composition, and surface features. NASA’s report to Congress discusses the need to characterize an object to inform decisions on mitigation.

According to NASA officials, characterization is usually focused on those objects

that are identified as posing a potential threat. Both optical and radar ground-based

systems can be used, however radar provides precise orbital determinations more

quickly than optical systems. A dedicated in-situ mission to observe the object would

provide the greatest detail on the character of the object and, according to the NASA

8

report to Congress, help to ‘‘confirm the probability of impact and characterize the

potential threat if deflection is necessary.’’

The report presents two broad strategies for diverting asteroids from a collision

path with Earth. ‘‘Impulsive’’ options would involve the use of conventional or nuclear explosives and have immediate results. ‘‘Slow push’’ options would achieve deflection results over a period of time.

• ‘‘Impulsive’’ options include:

• Surface conventional explosive (detonating on impact)

• Subsurface conventional explosive

• Standoff nuclear explosive (detonate on flyby with proximity fuse)

• Surface nuclear explosive (detonate via impact with surface fuse)

• Delayed nuclear explosive (surface lander, detonate at chosen time)

• Subsurface nuclear explosive

• Kinetic impact (high speed impact)

• ‘‘Slow push’’ approaches include:

• Focused solar (focused beam to burn-off surface material)

• Pulsed laser (rendezvous mission that burns-off material using laser)

• Mass driver (rendezvous mission mines and ejects material)

• Gravity tractor (large rendezvous mission flies in proximity to ‘‘pull’’ object off course)

• Asteroid tug (rendezvous mission attaches to and pushes object)

• Heating of surface material

The report includes the following findings on deflection alternatives:

• ‘‘Nuclear standoff explosions are assessed to be 10-100 times more effective

than the non-nuclear alternatives. . .. Other techniques involving the surface

or subsurface of nuclear explosions may be more efficient, but they run the risk

of fracturing the target NEO. They also carry higher development and operations risks.

• Non-nuclear kinetic impactors are the most mature approach and could be

used in some deflection/mitigation scenarios, especially for NEOs that consist

of a single, small solid body.

• ‘‘Slow push’’ mitigation techniques are the most expensive, have the lowest

level of technical readiness, and their ability to both travel to and divert a

threatening NEO would be limited unless mission durations of many years to

decades are possible.

• 30–80 percent of potentially hazardous NEOs are in orbits that are beyond the

capability of current or planned launch systems. Therefore, planetary gravity

assist swing-by trajectories or on-orbit assembly of modular propulsion systems

may be needed to augment launch vehicle performance, if these objects need

to be deflected.’’

Critics of NASA’s analysis of deflection options argue that NASA’s report focuses

on atypical asteroid threats rather than the objects of size ranges that have a much

higher probability of actually impacting the Earth. They argue that NASA’s focus

on the less likely scenarios results in a set of deflection requirements that are

skewed towards nuclear explosives. If the focus would be placed on addressing the

deflection requirements of the smaller, more common PHOs, the critics of NASA’s

analysis would assert that ‘‘over 99 percent of them can be deflected using non-nuclear means.’’ One of the witnesses at the hearing, Mr. Russell ‘‘Rusty’’ Schweickart,

will discuss issues related to NASA’s analysis of deflection options, as well as identify what he believes are serious technical flaws in NASA’s report to Congress.

Planetary Radar Facilities

Arecibo Observatory

The Arecibo Observatory in Puerto Rico, which has been described as ‘‘the largest

and most sensitive’’ ground-based radar telescope on Earth, has been used to reduce

the uncertainty of NEO collision estimates and refine the time period of when a

NEO may pass near Earth. In addition, radar observations are more precise than

data from optical telescopes in identifying details on the mass, shapes, trajectories,

sizes, and on whether the NEO is a single object or part of a binary system. In 2005,

Arecibo observations improved the estimates of the trajectory for the object,

9

Apophis, which is on a path that will take it close to Earth in 2029. Research using

the Arecibo Observatory also helps improve our understanding of how solar radiation influences near-Earth objects.

Arecibo is operated by Cornell University under a cooperative agreement with the

National Science Foundation. A 2006 independent review of all NSF ground-based

astronomy facilities recommended that ‘‘The National Astronomy and Ionosphere

Center [Arecibo Observatory] . . .should seek partners who will contribute personnel

or financial support to the operation of Arecibo. . . by 2011 or else these facilities

should be closed.’’ At present, the planetary radar facility at Arecibo is funded

through FY 2008. Funding beyond that date is uncertain.

NASA’s Goldstone Deep Space Tracking Station

The only planetary radar facility other than Arecibo is NASA’s Goldstone Deep

Space Tracking Station in Goldstone, California. Goldstone is less sensitive than

Arecibo, however its steerable antenna allows it to see a larger portion of the sky.

NASA is planning to replace the current Deep Space Network antennas and is looking at a number of options, including phased array antennas. The current replacement options do not appear to provide a planetary radar capability comparable to

that of the existing Goldstone facility.

The 2003 National Academies Solar System Exploration Survey report contained

the following recommendation: ‘‘In addition, NASA should continue to support

ground-based observatories for planetary science, including the planetary radar capabilities at the Arecibo Observatory in Puerto Rico and the Deep Space Network’s

Goldstone facility in California. . .as long as they continue to be critical to missions

and/or scientifically productive. . .’’

NEO Contributions to Science, Human Exploration, and Resource Utilization

The NASA report notes that an increased search for and characterization of NEOs

will benefit scientific discovery and study of Kuiper Belt Objects, as well as in determining whether certain comets originated in the Kuiper Belt. Further data on NEOs

could also provide information that could be used to consider extracting and using

asteroid resources and for considering a potential human mission to an asteroid. A

1998 National Academies Report on The Exploration of Near-Earth Objects notes

that:

‘‘Although it would be difficult to justify human exploration of NEOs on the

basis of cost-benefit analysis of scientific results alone, a strong case can be made

for starting with NEOs if the decision to carry out human exploration beyond

low Earth orbit is made for other reasons. Some NEOs are especially attractive

targets for astronaut missions because of their orbital accessibility and short

flight duration. Because they represent deep space exploration at an intermediate

level of technical challenge, these missions would also serve as stepping stones

for human missions to Mars. Human exploration of NEOs would provide significant advances in observational and sampling capabilities.’’

NEO-Related Activities at the United Nations

The United Nation’s Committee on the Peaceful Uses of Outer Space (COPUOS),

Scientific and Technical Subcommittee has discussed and considered the issue of

NEOs. In 2006, the subcommittee established a Working Group on Near-Earth Objects to focus on the issue over the 2006–2007 timeframe and also formed an Action

Team. Over the next one to two years, the subcommittee plans to continue to obtain

reports on NEO activities and to address the need for more international coordination on observations and follow-up studies. The subcommittee also plans to work on

international procedures for handling NEO threats.

Space Science Missions to Comets and Asteroids

In addition to its ground-based Spaceguard Survey program, NASA and non-U.S.

space agencies have launched, or are planning to undertake a number of space

science missions to study asteroids and comets. NASA’s report to Congress notes

that information gained from these missions benefits the agency’s current NEO program. A number of past, current, and future missions of note include:

• NASA’s Near-Earth Asteroid Rendezvous (NEAR) mission, launched in 1996,

flew by two asteroids and studied one, Eros;

• The Stardust mission collected dust samples from comet Wild 2;

• Deep Impact, launched in 2004, penetrated comet Tempel 1;

10

• The Dawn mission, launched in late September 2007 is en route to study,

Ceres and Vesta, two of the largest known asteroids located in the main asteroid belt between Mars and Jupiter;

• Japan’s Hayabusa mission had the objective of collecting a sample from the

near-Earth asteroid Itokawa, and the sample carrier is en route back to

Earth; and

• The European Space Agency’s Rosetta mission to comet ChurymovGerasimenko in late 2014 will rendezvous with and land on the comet.

• In addition, the European Space Agency has conducted studies on a potential

space mission that could test and validate technologies for deflecting an asteroid.

11

Chairman UDALL. Good morning. This hearing will come to

order. I would like to extend a particular welcome to our witnesses,

and in particular, recognize Congressman Luis Fortun ̃ o’s presence

here with us today.

As many of you may recall, today’s hearing on Near-Earth Objects was originally scheduled for October 11, but we postponed it

in the wake of our good friend Rep. Jo Ann Davis’ untimely death.

Thus, before we proceed any further, I would like to express my

appreciation to each of the witnesses for your willingness to accommodate that postponement, and appear before us today. Your testimony will be invaluable to us as we consider how best to proceed

in getting a better understanding of the potential threats of NearEarth Objects, NEOs, as well as options for dealing with them.

Today’s hearing is the latest in a series that stretches back to the

early 1990s. We have come a long way since the late George

Brown, former Chairman of the Science and Technology Committee, led the first efforts to focus Congressional attention on the

potential threat posed by Near-Earth asteroids and comets.

It has been a bipartisan effort over the intervening years, and a

lot has been accomplished. In that regard, I want in particular to

salute the dedication of Mr. Rohrabacher in pushing for continued

federal initiatives to detect, track, and catalog NEOs, as well as to

examine ways to deflect them if necessary. He has been an effective

catalyst for action, and I look forward to continuing to work with

him on this issue.

As we will hear from our witnesses, much progress has been

made in detecting and cataloging the largest NEOs over the last

decade. However, as we will also hear, much more remains to be

done. In particular, we need to survey potentially hazardous asteroids that are smaller than the ones cataloged to date, but which

could do significant damage if they impact or explode above the

Earth’s surface near populated areas.

That is why Congress directed NASA to ‘‘plan, develop, and implement’’ a NEO survey program for objects as small as 140 meters

in size, in the NASA Authorization Act of 2005. As a result, I am

disappointed and concerned that NASA’s report to Congress failed

to provide a recommended option and budget plan for such a survey, as directed by the Act. In fact, the report says NASA has no

plans to do anything beyond the current Spaceguard program at

this time.

Equally troubling, one of the NASA witnesses will testify that

‘‘NASA would be pleased to implement a more aggressive NEO program, if so directed by the President and Congress,’’ with the implication that Congress has not yet done so. I believe section 321 of

the NASA Authorization Act, which I quoted earlier, is unambiguous. Congress, in fact, has directed NASA to ‘‘plan, develop, and

implement’’ such a program, and we would hope that the President

would send over a NASA budget request that reflects that Congressional direction.

Today, I want to focus on where we go from here. Given the lack

of a clear plan in NASA’s report to Congress, I hope that our witnesses today will be able to provide some guidance to the Committee on the best and most cost-effective path forward for meeting

the goal of surveying NEOs down to 140 meters in size. In that reVerDate 11-MAY-2000 18:21 Feb 21, 2008 Jkt 038057 PO 00000 Frm 00015 Fmt 6633 Sfmt 6601 C:\WORKD\SA07\110807\38057 SCIENCE1 PsN: SCIENCE1
12

gard, there are a number of related questions that need to be addressed.

First, I would like to hear from each of the witnesses about the

planetary radar capabilities at Arecibo and Goldstone. How important are they to addressing the NEO task? Second, how can we

make the most effective use of capabilities being planned or developed by other federal agencies, such as LSST and Pan-STARRS,

and what role should NASA play in supporting them?

NASA’s testimony indicates that it has been providing funds to

the Air Force’s Pan-STARRS project, so that it will be capable of

providing data on NEO detections. That is an interesting development, and it raises the question of whether NASA should also be

providing funds to other facilities, such as Arecibo, and the proposed LSST project, if doing so will materially contribute to meeting the NEO survey objectives in a responsible, cost-effective manner.

Third, I would like to know if there are adjustments to either the

timetable or scope of the NEO survey called out in the NASA Authorization Act that would make sense, either by allowing more

cost-effective approaches on a slightly longer timetable, or by focusing on just potentially hazardous objects, rather than on all NEOs.

Fourth, surveying NEOs is just part of the task. If we find one

that is headed towards Earth, we will need to have good options

for deflecting it. What priorities should be given to developing deflection technologies versus NEO survey systems in the coming

years?

And finally, the potential threat posed by Near-Earth Objects is

not isolated to the United States. What contributions are other national and international bodies making to the effort? Should more

be done?

Well, as you can see, we have a lot to consider today. Fortunately, we have a very distinguished set of witnesses to assist us

in our oversight task, and I again want to welcome all of you, and

I look forward to your testimony.

At this point, the Chair now recognizes my friend, the Ranking

Member, Mr. Feeney from Florida, for his opening remarks.

[The prepared statement of Chairman Udall follows:]

PREPARED STATEMENT OF CHAIRMAN MARK UDALL

Good morning. I’d like to extend a welcome to our witnesses and in particular recognize Congressman Luis Fortun ̃ o’s presence here with us today.

As many of you may recall, today’s hearing on Near-Earth Objects was originally

scheduled for October 11th, but we postponed it in the wake of Rep. Jo Ann Davis’s

untimely death. Thus, before we proceed any further, I’d like to express my appreciation to each of the witnesses for your willingness to accommodate that postponement and appear before us today.

Your testimony will be invaluable to us as we consider how best to proceed in getting a better understanding of the potential threats posed by Near-Earth Objects—

NEOs, as well as options for dealing with them.

Today’s hearing is the latest in a series that stretches back to the early 1990s.

We have come along way since the late George Brown—former Chairman of the

Science and Technology Committee—led the first efforts to focus congressional attention on the potential threat posed by Near Earth asteroids and comets. It has

been a bipartisan effort over the intervening years, and a lot has been accomplished.

In that regard, I in particular want to salute the dedication of Mr. Rohrabacher

in pushing for continued federal initiatives to detect, track, and catalog NEOs, as

well as to examine ways to deflect them if necessary. He has been an effective catalyst for action, and I look forward to continuing to work with him on this issue.

13

As we will hear from our witnesses, much progress has been made in detecting

and cataloging the largest NEOs over the last decade. However—as we will also

hear—much more remains to be done.

In particular, we need to survey potentially hazardous asteroids that are smaller

than the ones cataloged to date, but which could do significant damage if they impact or explode above the Earth’s surface near populated areas. That is why Congress directed NASA to ‘‘plan, develop, and implement’’ a NEO survey program for

objects as small as 140 meters in size in the NASA Authorization Act of 2005.

As a result, I’m disappointed and concerned that NASA’s report to Congress failed

to provide a recommended option and budget plan for such a survey, as directed by

the Act. In fact, the report says NASA has no plans to do anything beyond the current Spaceguard program at this time.

Equally troubling, one of the NASA witnesses will testify that ‘‘NASA would be

pleased to implement a more aggressive NEO program if so directed by the President

and Congress,’’—with the implication that Congress has not yet done so. I think Sec.

321 of the NASA Authorization Act, which I quoted earlier, is unambiguous—Congress has in fact directed NASA to ‘‘plan, develop, and implement’’ such a program.

And we would hope that the President would send over a NASA budget request that

reflects that congressional direction.

Today, I want to focus on where we go from here. Given the lack of a clear plan

in NASA’s report to Congress, I hope that our witnesses today will be able provide

some guidance to this committee on the best and most cost-effective path forward

for meeting the goal of surveying NEOs down to 140 meters in size.

In that regard, there are a number of related questions that need to be addressed.

First, I’d like to hear from each of the witnesses about the planetary radar capabilities at Arecibo and Goldstone. How important are they to addressing the NEO task?

Second, how can we make the most effective use of capabilities being planned or

developed by other federal agencies, such as LSST and Pan-STARRS, and what role

should NASA play in supporting them? NASA’s testimony indicates that it has

begun providing funds to the Air Force’s Pan-STARRS project ‘‘so that it will be capable of providing data on NEO detections. . .’’

That’s an interesting development, and it raises the question of whether NASA

should also be providing funds to other facilities such as Arecibo and the proposed

LSST project if doing so will materially contribute to meeting the NEO survey objectives in a responsible, cost-effective manner.

Third, I’d like to know if there are adjustments to either the timetable or scope

of the NEO survey called out in the NASA Authorization Act of 2005 that would

make sense—either by allowing more cost-effective approaches on a slightly longer

timetable or by focusing on just potentially hazardous objects rather than on all

NEOs.

Fourth, surveying NEOs is just part of the task. If we find one that it is headed

towards Earth, we will need to have good options for deflecting it. What priority

should be given to developing deflection technologies versus NEO survey systems in

the coming years?

Finally, the potential threat posed by Near-earth objects is not isolated to the

United States. What contributions are other national and international bodies making to the effort? Should more be done?

Well, as you can see, we have a lot to consider today. Fortunately, we have a very

distinguished set of witnesses to assist us in our oversight task.

I again want to welcome all of you, and I look forward to your testimony.

Mr. FEENEY. Well, thank you, Mr. Chairman, and I appreciate

you calling this morning’s hearing, although I did tell you as I

greeted you this morning that this is just one more thing for us to

worry about, that hadn’t been on my list until a couple weeks ago,

when I saw the original notice of hearing.

And I want to echo your remarks. We are very grateful to the

witnesses, because we had to reschedule the hearing on short notice, and we thank you, and we are very appreciative that you are

here today, so that we can accommodate that emergency change.

NASA’s Near-Earth Object program, though very modest in scale

compared to many of the agency’s multi-billion dollar endeavors, is

vitally important, and NASA has been doing an exemplary job

standing up an office and managing the Nation’s and world’s only

survey for potentially hazardous Earth-crossing asteroids and comVerDate 11-MAY-2000 18:21 Feb 21, 2008 Jkt 038057 PO 00000 Frm 00017 Fmt 6633 Sfmt 6601 C:\WORKD\SA07\110807\38057 SCIENCE1 PsN: SCIENCE1
14

ets. I find it distressing that other nations haven’t, to date, taken

a more active role, and I note that we have some visitors from Germany here today. We are very grateful for their interest.

NASA began the NEO survey, called the Spaceguard program, in

1998, and I note that my colleague, Dana Rohrabacher, who is

here, was instrumental in advocating that, with the goal of detecting and cataloging 90 percent of all potentially hazardous asteroids

and comets larger than one kilometer in diameter within a decade,

and it appears to be relatively on track to meet that target. Subsequently, a 2003 NASA-chartered team of scientists recommended

that the survey seek all NEOs of 140 meters in diameter or larger,

reasoning that the smallest of these could still inflict large regional

impacts if they struck the Earth.

Their recommendations were made part of the 2005 NASA authorization legislation, directing NASA to ‘‘plan, develop, and implement a Near-Earth Object survey program to detect, track, catalog, and categorize Near-Earth Objects equal to or greater than 140

meters in diameter.’’

The goal was to get 90 percent completion within 15 years. This

change in mission is no small matter. As the universe of potentially

hazardous objects, PHOs, to be detected and cataloged increased by

a factor of 20, from 1,000 to approximately 20,000. The bill also required NASA to complete an analysis of alternatives to meet this

ambitious goal, and to report back with a recommended option.

NASA provided such a report earlier this year, but did not indicate

a preferred choice, instead urging the current Spaceguard program

be allowed to continue its survey for one kilometer and larger

Near-Earth Objects, that will allow the agency to take advantage

of opportunities using potential dual use telescopes and spacecraft

to achieve the goals outlined in the 2005 authorization.

Although the 15-year timeline may not be met in all cases,

NASA’s rationale is purely budget-driven, arguing that current resources are too constrained. While disappointed, I certainly can’t

disagree or argue with their reasoning.

At this morning’s hearing, it is my hope that we get a clearer understanding of NASA’s plans to proceed with utilizing dual use

telescopes and spacecraft, their potential costs and schedules, and

other facilities that may be utilized, including the Arecibo Observatory.

I hope to hear concrete steps taken by NASA to develop cooperative relationships necessary to ensure the requirements laid out in

the 2005 NASA authorization are met. We will also hear about the

future of the Arecibo Radio Observatory in Puerto Rico, the largest

and most powerful such facility in the world. Arecibo is operated

by the Cornell University under a contract with the National

Science Foundation (NSF). It appears very likely that NSF will significantly reduce its financial support, such that Arecibo will have

to shut down its radar facility. This, I think, would be a mistake.

Arecibo has the capability of making very precise orbital calculations in a short amount of time, a critical feature that optical telescopes simply cannot match. And the sum of money at stake is on

the order of several million dollars a year, an investment I think

is well worth the return. While NSF may be outside the purview

15

of this subcommittee, the ramifications of Arecibo’s loss to the NEO

program begs the discussion.

I want to first welcome my good friend, Luis Fortun ̃ o, to today’s

hearing. I want to also thank all of our guests once again, express

my appreciation for changing their schedule to accommodate our

schedule, and I want to thank my Chairman, Mr. Udall, and with

that, look forward to the discussion.

[The prepared statement of Mr. Feeney follows:]

PREPARED STATEMENT OF REPRESENTATIVE TOM FEENEY

Thank you, Mr. Chairman, for calling this morning’s hearing. And I want to echo

Mr. Udall’s comments, acknowledging that our originally scheduled hearing was

postponed on very short notice. I greatly appreciate that all of our scheduled witnesses were able to accommodate the date change, and I hope notice got out quickly

enough to save you from unnecessary travel.

NASA’s Near-Earth Object (NEO) program, though very modest in scale compared

to many of the agency’s multi-billion dollar endeavors, is vitally important, and

NASA has been doing an exemplary job standing-up an office and managing the Nation’s—and world’s—only survey for potentially hazardous Earth-crossing asteroids

and comets. I find it distressing that other nations haven’t, to date, taken a more

active role.

NASA began the NEO survey, called the ‘‘Spaceguard’’ program, in 1998 with the

goal of detecting and cataloguing 90 percent of all potentially hazardous asteroids

and comets larger than one kilometer in diameter within a decade, and it appears

to be on track to meet that target.

Subsequently, in 2003 a NASA-chartered team of scientists recommended that the

survey seek all NEOs of 140 meters in diameter or larger, reasoning that the smallest of these could still inflict large regional impacts if they struck Earth. Their recommendations were made part of the 2005 NASA authorization legislation, directing

NASA to ‘‘plan, develop and implement a Near-Earth Object Survey program to detect, track, catalogue, and characterize. . .near-Earth objects equal to or greater

than 140 meters in diameter. . .,’’ with the goal of 90 percent completion within 15

years. This change in mission is no small matter, as the universe of potentially hazardous objects (PHOs) to be detected and catalogued increased by a factor of twenty

(from 1000 to 20,000). The bill also required NASA to complete an analysis of alternatives to meet this ambitious goal and to report back with a recommended option.

NASA provided such a report earlier this year but did not indicate a preferred

choice, instead urging the current ‘‘Spaceguard’’ program be allowed to continue its

survey for 1 kilometer and larger near-Earth objects, and to allow the agency to

take advantage of opportunities using potential dual-use telescopes and spacecraft

to achieve the goals outlined in the 2005 authorization, although the 15 year

timeline may not be met in all cases. NASA’s rationale is purely budget driven, arguing that current resources are too constrained. While disappointed, I certainly

can’t disagree with their reasoning.

At this morning’s hearing, it is my hope that we get a clearer understanding of

NASA’s plans to proceed with utilizing dual-use telescopes and spacecraft, their potential costs and schedules, and other facilities that may be utilized, including the

Arecibo Observatory. I hope to hear of concrete steps being taken by NASA to develop cooperative relationships necessary to ensure the requirements laid out in the

2005 NASA authorization are met.

We’ll also hear about the future of the Arecibo Radio Observatory in Puerto Rico,

the largest and most powerful such facility in the world. Arecibo is operated by Cornell University under a contract with the National Science Foundation (NSF). It appears very likely NSF will significantly reduce its financial support such that Arecibo will have to shut down its radar facility. This, I think, would be a mistake. Arecibo has the capability of making very precise orbital calculations in a short amount

of time, a critical feature that optical telescopes cannot match. And the sum of

money at stake is on the order of about $2 million a year, an investment that I

think is well worth the return. While NSF may be outside the purview of this subcommittee, the ramifications of Arecibo’s loss to the NEO program begs the discussion.

I want to welcome my friend, Rep. Fortun ̃ o, to today’s hearing. I also want again

to say thanks to our excellent panel of expert witnesses for taking time from their

busy schedules to be here.

Thank you, Mr. Chairman.

16

Chairman UDALL. Thank you, Congressman Feeney. If there are

Members who wish to submit additional opening statements, your

statements will be added to the record. Without objection, so ordered.

And in addition, I would also like to include a statement for the

record from the Planetary Society into today’s hearing. Without objection, so ordered. [See Appendix 2: Additional Material for the

Record.]

At this time, I would like to go ahead and recognize our first

panel. And we are delighted to have Representative Luis Fortun ̃ o,

the Resident Commissioner of Puerto Rico, with us here today, who

will be testifying, I think, before the Committee for the first time.

Congressman Fortun ̃ o, the floor is yours.

Panel 1

STATEMENT OF REPRESENTATIVE LUIS FORTUN ̃ O, RESIDENT

COMMISSIONER, PUERTO RICO

Mr. FORTUN ̃ O. Thank you. Thank you, Mr. Chairman. Chairman

Udall, Ranking Member Feeney, distinguished Members of this

subcommittee.

Every day, an enormous quantity of cosmic material falls to the

Earth. Most burn up on reentry in a harmless way. However,

NASA predicts that more than 20,000 large, potentially dangerous

objects pass by the Earth in close proximity, and given the proper

circumstance, could threaten or severely impact our existence. Although the chances of a major impact are slim, the consequences

are too great to disregard.

I believe we should continue to advance our knowledge of NearEarth Objects and their potential consequences for life on Earth. I

commend Congressman Rohrabacher on his effort to continue funding for Near-Earth Objects surveillance programs. Since 1992, the

Spaceguard program’s goal was to discover 90 percent of the NEOs

with one kilometer diameter potential by 2008. Although the success of this program will be substantial, there will still be thousands of objects, ranging from 200 to 500 meters in diameter, that

will be overlooked. We must enhance our understanding of this

phenomenon by studying and assessing the threats posed to our environment and to our national security.

According to Director Michael Griffin, NASA does not have the

funds to carry out a more extensive program. There have been suggestions that NASA and the National Science Foundation should

cooperate to fund the construction of a new ground-based telescope

to perform tracking functions of Near-Earth Objects and other astronomy surveys. I do not think we need to take on such a burden,

when there is still a great deal of information to be gained by utilizing the unique capabilities of the Arecibo Observatory in Puerto

Rico.

As the world’s largest and most powerful radio telescope, the

Arecibo Observatory is essential to monitoring and surveying

NEOs. However, the National Science Foundation has threatened

to close the observatory in 2011, and NASA has, so far, been unwilling to assume funding of the radar required for tracking NEOs.

17

Closing the observatory will severely limit our ability to quickly

and accurately refine the orbits of newly emerging threats, and reduce our monitoring capabilities.

This is why I have introduced H.R. 3737, which directs the National Science Foundation and NASA to work together to ensure

continued full funding of the Arecibo Observatory, and in particular, the radar. It is my recommendation and the recommendation of 19 of my colleagues, that these agencies start working in

collaboration and reconsider how they allocate their funding.

Mr. Chairman and Ranking Member Feeney, the Arecibo Observatory’s radar is the world’s most powerful instrument for post-discovery characterization and orbital refinement of Near-Earth asteroids. Observations performed with the radar are critical for identifying asteroids that might be on a collision course with Earth.

I respectfully urge the Committee to consider continuing the important work performed by the Arecibo observatory, and consider,

as well, H.R. 3737, as one potential solution to this challenge. The

unique capabilities of radar are critically important as we work towards fulfilling the 2005 Congressional mandate of detecting and

characterizing 90 percent of NEOs down to 140 meters in diameter.

A potentially dangerous collision of an asteroid or comet is a very

real threat. We must take action now to enhance our awareness to

prevent a catastrophe. A better understanding of our skies will not

only help us to comprehend the wonders of the Earth’s environment, but is essential to assessing the dangers that may threaten

our society.

The world’s most sensitive radio telescope at Arecibo Observatory

must not be closed. By the way, we don’t have final numbers, but

NSF is determining the cost of dismantling this facility and bringing the area back to a greenfield, but it is around $200 million. We

are dealing with a $4 million gap a year, so the numbers are certainly there as well.

Mr. Chairman and Ranking Member Feeney, thank you for the

opportunity to provide my views on this issue. I will now ask permission to show, in the Committee’s flatscreen, some images of the

Arecibo Observatory, that would help understand the size and magnitude of this extraordinary science resource.

Chairman UDALL. Please proceed.

Mr. FORTUN ̃ O. Thank you.

That is an aerial picture of the radio telescope. As you see, it is

embedded in a number of mountains. That is another angle. It is

a massive facility. It really is.

It is visited every year by 300,000 people, 25,000 of them are K–

12 students. That is it.

Thank you again, Mr. Chairman.

[The prepared statement of Mr. Fortun ̃ o follows:]

PREPARED STATEMENT OF CONGRESSMAN LUIS G. FORTUN ̃ O

Chairman Udall and Ranking Member Feeney,

Every day an enormous quantity of cosmic material falls to the Earth. Most burns

up on re-entry in a harmless way, however NASA predicts that more than 20,000

large, potentially dangerous objects pass by the Earth in close proximity and, given

the proper circumstance could threaten or severely impact our existence. Although

the chances of a major impact are slim, the consequences are too great to disregard.

18

I believe we should continue to advance our knowledge of Near-Earth Objects and

the potential consequences for our life on Earth.

I commend Congressman Rohrabacher on his efforts to continue funding for NearEarth Objects surveillance programs. Since 1992, the Spaceguard program’s goal

was to discover 90 percent of the NEOs with one kilometer diameter potential by

2008. Although the success of this program will be substantial, there will still be

thousands of objects—ranging from 200 to 500 meters in diameter—that will be

overlooked. We must enhance our understanding of this phenomenon by studying

and assessing the threats posed to our environment and to our national security.

According to Director Michael Griffin, NASA does not have the funds to carry out

a more extensive program. There have been suggestions that NASA and the National Science Foundation should cooperate to fund the construction of a new

ground-based telescope to perform tracking functions of Near-Earth Objects and

other astronomy surveys. I do not think we need to take on such a burden, as there

is still a great deal of information to be gained by utilizing the unique capabilities

of the Arecibo Observatory in Puerto Rico. As the world’s largest and most powerful

radio telescope, the Arecibo Observatory is essential to monitoring and surveying

Near-Earth Objects. However, the National Science Foundation has threatened to

close the Observatory in 2011 and NASA has so far been unwilling to assume funding of the radar required for tracking NEOs. Closing the Observatory will severely

limit our ability to quickly and accurately refine the orbits of newly emerging

threats, and reduce our monitoring capabilities.

This is why I have introduced H.R. 3737, which directs the National Science

Foundation and NASA to work together to ensure continued full funding of the Arecibo Observatory and in particular, the radar. It is my recommendation that these

agencies start working collaboratively and reconsider how they allocate their funding.

Mr. Chairman and Ranking Member Feeney, the Arecibo Observatory’s radar is

the world’s most powerful instrument for post-discovery characterization and orbital

refinement of near-Earth asteroids. The observations performed with the radar are

critical for identifying asteroids that might be on a collision course with Earth. I

respectfully urge the Committee to consider continuing the important work performed by the Arecibo Observatory and consider, as well, H.R. 3737 as one potential

solution to this challenge. The unique capabilities of radar are critically important

as we work towards fulfilling the 2005 congressional mandate of detecting and characterizing 90 percent of near-Earth Objects down to 140 meters in diameter.

A potentially dangerous collision of an asteroid or comet is a very real threat. We

must take action now to enhance our awareness to prevent a catastrophe. A better

understanding of our skies will not only help us to comprehend the wonders of the

Earth’s environment, but is essential to assessing the dangers that may threaten

our society. The world’s most sensitive radio/radar telescope at Arecibo Observatory

must not be closed.

Mr. Chairman and Ranking Member Feeney, thanks for the opportunity to provide my views on this issue.

DISCUSSION

Chairman UDALL. Thank you, Resident Commissioner Fortun ̃ o.

This testimony has been very helpful, and I want to pay particular

note to the costs that might be involved in decommissioning this

site, and we look forward to getting firmer numbers, because the

obvious argument would be you would take the money that would

be used in decommissioning the site, and actually operate it for a

certain number of years or even decades into the future.

At this time, I would be happy to recognize Mr. Feeney, if he has

any questions for his colleague, Mr. Fortun ̃ o.

IMPACT OF SHUTTING DOWN ARECIBO

Mr. FEENEY. Well, thank you, Mr. Chairman, and thank you for

your testimony, Congressman. You know, as I read through the

materials and the different NSF and NASA projections, and discussion of this important issue, all of them suggest that Arecibo is

very important to our capabilities.

19

Any decision to close it down seems to be purely budget-driven,

and so that I hope, as we get the numbers and the estimates for

what it would cost, and what the impact would be of shutting it

down, that you will immediately provide this committee, and also,

the Committee with jurisdiction over NSF, with those numbers. Because if this is entirely cost-driven, then we need to, as we are understanding the advantages that everybody acknowledges, we also

need to know that the, of keeping it open, that the disadvantages

of closing it also will have a significant cost many, many times

what it costs on an annual basis to keep it alive.

Our next panel includes some very distinguished witnesses. One

of them, for example, Mr. Yeomans’ testimony will tell us that Arecibo and Goldstone complement one another and provide two very

different functions. That is very important, because while the one

telescope is capable of identifying Near-Earth Objects that may be

a threat, it is Arecibo that helps us determine the exact threat to

the Earth. And the fascinating thing is that we have the capability

with Arecibo, at least with the large objects that we have now proceeded to catalog, and we are very near our goal, or at least we are

on track. Mr. Yeomans will testify that once we find the vast majority of them, they can be tracked, cataloged, and then ruled out

or in as threats during the next 100 years or so.

I think the people of the world would be very grateful to know,

especially with 100 years notice, that there may be a catastrophe,

driven by a Near-Earth Object. But most importantly, we have the

technological capabilities to actually deflect or to eliminate the

damage with that type of notice, and again, Mr. Yeomans and our

other witnesses will testify to that.

So, Mr. Fortun ̃ o, I know that Congressman Rohrabacher had a

question. I wanted to yield a few minutes to him, but if you could

tell us the impact, because probably uniquely you are able to tell

us this question, the impact on Puerto Rico if we shut Arecibo

down, in the next year or two, what the local impact would be. We

will get to the technical experts. I had assumed you are not an astrophysicist. Neither am I. Don’t feel bad about that. Go ahead and

tell us the impact on Puerto Rico.

Mr. FORTUN ̃ O. Thank you, and thank you for your comments. Certainly. The impact, we are estimating that it will be about $50

million for the Arecibo area, actually. On top of that, the impact

on those kids that may have an interest in science and technology,

that will not be able, otherwise, to visit a facility like this one. If

I may add, the Arecibo radio astronomy led to the first discovery

of a planet outside of our own solar system, to the first discovery

of a binary pulsar, resulting in a Nobel Prize, and the first detailed, three dimensional mapping of how galaxies are distributed

in the universe.

So, it is really, from the scientific point of view, it will be priceless to our young students, that have an interest in this area.

GEORGE BROWN

Mr. FEENEY. Any remaining time, I would be pleased to yield to

Congressman Rohrabacher.

Mr. ROHRABACHER. Thank you very much. And thank you, Mr.

Chairman, for your kind words, and bipartisan words, and holding

20

the hearing. I can’t help but notice George Brown’s picture right

back there. I don’t know how many people in this room knew

George Brown. I knew him. He was the Chairman here when I

came here 20 years ago, and he was a wonderful human being. He

was a man of integrity, and I am very pleased that some of the

work that I have done in this area actually bore the name of

George Brown, because he was just a fine person, and had that

very same bipartisan spirit that Mr. Udall has been trying to demonstrate here today.

And hopefully, when we are talking about things that might

threaten the entire planet, that may well motivate Congress to be

bipartisan, if nothing else does. I mean, after all, it is just the entire planet that may be destroyed. But George Brown really gave

me personal guidance, and his integrity was very much appreciated.

IMPORTANCE OF ARECIBO WITH REGARD TO COST

When we are talking about Arecibo, I want to, of course, recognize the hard work that Congressman Fortun ̃ o is actually putting

into this effort. It is a heroic effort. I am very pleased to be assisting him. But of course, we are not trying to do anybody any favors

here. This isn’t an issue of doing anyone a favor.

First and foremost, the Arecibo telescope is doing work currently

that would cost us more, even outside of the area of Near-Earth

Objects. Even outside the area of Near-Earth Objects, the Arecibo

telescope is doing work that would be more costly to do if, for example, we would send satellites. I understand we sent a mission

to Venus that cost a certain amount of money, but the actual images that we got back from Arecibo were better than sending the

probe up to Venus. Now, how much did that cost us? I mean, it

probably cost us enough to keep Arecibo going for a decade.

And clearly, also, when you look at the shutdown costs, which

has been mentioned here, if you take all of that together, well, you

could probably put that in the bank, and the interest on that

money would probably keep the Arecibo telescope going. And this

exemplifies sort of the screwball nature of the way we do business

up here on Capitol Hill sometimes. And if we let this asset be set

aside and closed down, it would be a tragedy, but also, as I say,

very symbolic of the fact that we can’t even do our job in Capitol

Hill enough to take a very cost-effective asset, and something that

is doing a mission that is vitally important to our security, that we

can’t even get ourselves together enough to get a limited amount

of money to keep that project going. So, I think this is very symbolic, and that we should all be working together on this, and we

are working on this.

Just a question. Now, you mentioned the kids that there are, and

you mentioned how this would affect your economy. Tell me, if we

didn’t know that a Near-Earth Object was coming, and thus, one

snuck by and landed in the Caribbean, would it be possible that

Puerto Rico would be wiped out?

Mr. FORTUN ̃ O. Well, actually, anything can happen, but certainly,

you could have the East Coast of the United States, not just the

Caribbean, affected by something like that. And again, the cost-effectiveness of this facility has to be highlighted, and I thank you,

21

Mr. Rohrabacher, for your leadership on this issue, not just on Arecibo, the issue in general.

I think it is an issue that we need to devote resources and time

to it, and again, I thank the Chairman and all the Members of this

subcommittee.

Mr. ROHRABACHER. Shutting down Arecibo means that we are intentionally putting ourselves in a position of ignorance of potential

threats, and with that ignorance may come bliss for a while. However, let us note it also not only gives us ignorance, but it also prevents us from having any chance of deflection if there is a threat.

So, we are putting ourselves in a position of being ignorant of a potential threat, and also, making ourselves incapable of responding

to the potential threat. And Arecibo is in the middle of this. No one

should take us seriously about watching out for the long-term interests if we let this asset go.

So, I thank you very much, and I am looking forward to working

with you, working with the Ranking Member, and working with

the Chairman. We need to work on this, and show that we can actually—if we can’t get this done, we can’t get anything done. I

mean, it is as simple as that.

Mr. FORTUN ̃ O. Thank you.

Mr. ROHRABACHER. And thank you for your hard work.

VISITING ARECIBO

Chairman UDALL. I thank the gentleman from California. I

would note, for the record, that my colleague from Texas, Mr.

Lampson, is here. There is nobody more passionate an advocate for

NASA and all that NASA does. I do believe he does not have a

question——

Mr. LAMPSON. No, I don’t.

Chairman UDALL.—for his colleague from Puerto Rico. Resident

Commissioner, if you——

Mr. LAMPSON. I do look forward to visiting, however.

Chairman UDALL. I am sorry, you——

Mr. LAMPSON. I do look forward to visiting the facility some time.

Chairman UDALL. That is an open offer, I am sure.

Mr. FORTUN ̃ O. It is a beautiful facility, but actually, some time

between December and March is the best time to visit.

Chairman UDALL. Well, I again want to thank the Resident Commissioner, and at this time, would be pleased to excuse you. I know

you have other responsibilities and a busy schedule. Thank you

again for joining us.

Mr. FORTUN ̃ O. Thank you, Mr. Chairman.

Chairman UDALL. At this time, as the Resident Commissioner

departs, we will pause, while the second panel can take your seats

and get comfortable, and then, we will begin the presentations from

the second panel in a few minutes.

I want to welcome the panel, and at this time, it seems appropriate to introduce all of the witnesses that have joined us. I would,

before I do so, just let the panel know, and the others who are here

with us, that there are votes pending at some point in the next 25

to 30 minutes. We will, I think, have a series of at least two votes,

and we will do all we can to move the testimony forward, and then

we will recess for 40 minutes, and then reconvene the hearing.

22

Let me begin here, on my left to the audience’s right, with Dr.

James Green, who is the Director of the Planetary Science Division

at NASA. Next to him is, moving from left to right again, is Dr.

Scott Pace, who is the Associate Administrator of the Office of Program Analysis and Evaluation at NASA. Third on the panel, Dr.

Donald Yeomans, who is the manager of the Jet Propulsion Laboratory’s Near-Earth Object Program Office. Proceeding down the line,

Dr. Campbell, Dr. Donald Campbell, who is a Professor of Astronomy at Cornell University, and a former Director of the Arecibo

Observatory. Next to Dr. Campbell, Dr. J. Anthony Tyson, who is

a Professor of Physics at the University of California, Davis, and

a Director of the Large Synoptic Survey Telescope Project. And our

last witness on the second panel, we have Mr. Russell ‘‘Rusty’’

Schweickart, former Apollo astronaut, Lunar Module pilot on Apollo IX, and the Chairman and Founder of the B612 Foundation.

Welcome, gentlemen, to all of you. We are really pleased to have

you here today. I think all of you know, I think many of you have

been before the Committee before, that your spoken testimony is

limited to five minutes each, after which the Members of the Subcommittee will have five minutes each to ask questions.

So, Dr. Green, we will begin with you. The floor is yours.

Panel 2

STATEMENT OF DR. JAMES L. GREEN, DIRECTOR, PLANETARY

SCIENCE DIVISION, SCIENCE MISSION DIRECTORATE, NATIONAL AERONAUTICS AND SPACE ADMINISTRATION (NASA)

Dr. GREEN. Thank you, Mr. Chairman and Members of the Committee, for the opportunity to present information on NASA’s important efforts to find Near-Earth Objects or NEOs.

At the request of Congress, NASA currently conducts a very successful NEO search program designed to find 90 percent of the

NEOs greater than one kilometer in diameter. Since the program

started in 1998, NASA has funded over $30 million in NEO search

efforts. During this time period, NASA has found, as of Monday,

I checked, 727 one kilometer or larger Near-Earth asteroids and 65

Earth-approaching comets, as well as 4,198 smaller NEOs.

At the current discovery rate, we will have discovered more than

50 large NEOs by the end of 2008, bringing us very close to achieving our 90 percent discovery goal, according to our current estimate

of roughly 940 greater than one kilometer size NEOs.

NASA currently funds four teams that operate eight groundbased telescopes, of mostly one meter class, dedicated to searching

the skies and detecting NEOs. All NEO observations that are collected are sent to an international clearinghouse for small bodies.

This organization is called the Minor Planet Center. The Minor

Planet Center determines the initial orbit for any newly discovered

NEO, so that observatories worldwide may observe the object and

confirm its existence. Once an NEO’s orbit has been determined, its

potential for impacting the Earth is assessed. Over 99 percent of

the objects discovered by our search efforts so far have no potential

for Earth impacts over many millennia, but a smaller number,

which do, are tagged potentially hazardous objects.

23

Now, more detailed and refined analysis of potentially hazardous

objects’ orbits is then conducted by NASA’s NEO Program Office at

the Jet Propulsion Laboratory. Observations on potentially hazardous objects are also automatically received, their orbits updated

to determine the level of probability of impacting the Earth in the

next 100 to 200 years. The results of this analysis is constantly updated and published on our NEO program website.

Now, the National Science Foundation’s Arecibo Radio Telescope,

although it has no use in detecting NEOs, does indeed provide us

important observations for NEOs that pass within 20 million miles

of the Earth. Arecibo plays that important role in refining the

orbit, allowing us to obtain information about the object’s size, its

shape, and its spin rate. The only other facility currently being

used by NASA for routine planetary radar is NASA’s own

Goldstone facility, which is part of our Deep Space Network. To

date, no international facilities are capable of performing this feat

on a regular basis.

Previous planetary spacecraft missions have not contributed directly to detecting NEOs. NASA missions, such as the Near-Earth

Asteroid Rendezvous, Stardust, Deep Impact, and the Japanese

Hayabusa 1 missions, have all brought us fascinating information

on NEO composition, origin, and migration into the inner solar system. The recently launched Dawn mission will travel past the orbit

of Mars and into the main asteroid belt, observing both Vesta and

Ceres, which are the largest objects in that region. The asteroid

belt has been shown to be the most probable region where these

objects are coming from, that we now classify as NEOs.

In our report to Congress, requested by the 2005 Act, NASA recommended that the current program be continued, and that we

would look at opportunities for potential dual use ground-based

telescopes, spacecraft, and also, partner with other agencies as feasible. For example, we are actively planning to use the Air Force

Panoramic Survey Telescope and Rapid Response System, also referred to as Pan-STARRS, after it becomes operational with its

very first telescope next year. When Pan-STARRS is completed,

and with its intended four telescope configuration, by 2011, this

system alone could discover up to 70 percent of the potentially hazardous objects larger than 140 meters by 2020.

It is important to note that no significant NEO detection efforts

are currently conducted outside of NASA. However, there is growing interest in international communities to contribute. Most recently, the United Nations Committee on the Peaceful Uses of

Outer Space recently established a working group on NEOs, to encourage more international work on the issue.

Other opportunities are beginning to materialize; that can help

us in these detection efforts. NASA’s own Wide-Field Infrared Survey Explorer, which is being developed for a late 2009 launch, is

an astrophysics mission designed to map the infrared sky. However, it is also capable of detecting many asteroids, in which a portion will indeed be NEOs.

We have also been discussing with the Canadian Space Agency

how their upcoming Near-Earth Orbit Surveillance Satellite

(NEOSSat) mission would be able to contribute to NEO research

and detection, and other important missions like these are being

24

planned by the European Space Agency, the Japanese Aerospace

Exploration Agency, and for which we are in close communications

with.

In closing, let me again thank you for the opportunity to appear

at this hearing, and I would be happy to respond to any of your

questions.

[The prepared statement of Dr. Green follows:]

PREPARED STATEMENT OF JAMES L. GREEN

Mr. Chairman and Members of the Subcommittee, thank you for the opportunity

to appear today to discuss the goals and accomplishments of NASA’s Near-Earth

Objects (NEOs) Observation Program. The Subcommittee’s invitation to testify identified a series of six questions, and I have structured my testimony around your specific concerns.

Question 1: Please describe NASA’s NEO Program and the infrastructure and operations in place to support the ongoing Survey (e.g., use of observatories, survey processing and NEO databases, analysis of identified objects, research, and sensor development)?

To achieve NASA’s stated goal of finding over 90 percent of the NEOs greater

than one kilometer in diameter, the Agency’s NEO Observation Program currently

funds four survey teams that operate eight ground-based telescopes of mostly one

meter class apertures essentially dedicated to the NEO search effort. Two of the

teams are sponsored by the University of Arizona Lunar and Planetary Laboratory,

Tucson, Arizona, one by Lowell Observatory in Flagstaff, Arizona, and one by the

Massachusetts Institute of Technology Lincoln Laboratory. Each team conducts

independent operations for 14 to 20 nights per month, as weather permits, avoiding

approximately a week on either side of the full moon when the sky is too bright

to detect these extremely dim objects from the ground.

All collected observations believed to be of known or previously unknown NEOs

are sent to the international ‘‘clearinghouse’’ for small body observation data, the

Minor Planet Center (MPC). The MPC maintains the database of observations and

orbits on all known small bodies (asteroids, comets, dwarf planets, Kuiper Belt Objects (KBO), etc.) in the Solar System under the sanction of the International Astronomical Union. It is hosted by the Smithsonian Astrophysical Observatory’s Center

for Astrophysics in Cambridge, Massachusetts, but is largely funded by NASA. The

MPC verifies and validates the observations by determining if they are of an already

known object (by comparing them to the known orbits), or are indeed a new discovery. The MPC then determines and publishes an initial orbit for the new discovery so that observatories world-wide may look for the object and confirm its existence. Sometimes it takes a few nights of additional observations to adequately determine, or ‘‘secure,’’ the orbit of a new object so that it may be regularly observed.

Once a new object’s orbit is secured, its potential for impacting the Earth is assessed. Well over 99 percent of all objects discovered (which also include Main Belt

Asteroids, comets, Trojans, Centaurs and KBOs) have no potential for Earth impact

even over many millennia, but the small fraction which do are tagged as Potentially

Hazardous Objects (PHOs). More detailed and refined analysis of a PHO’s orbit is

conducted by NASA’s NEO Program Office at the Jet Propulsion Laboratory in

Pasadena, California, which also aids in coordinating the activities and operations

of NASA’s NEO projects. Observations on PHOs are automatically forwarded to JPL

and their orbits updated with high precision analysis to determine a level of probability of the object impacting the Earth in the next 100 to 200 years. The results

of this analysis is constantly updated and published on the NEO Program website

at http://neo.jpl.nasa.gov.

Since the program’s inception in 1998, NASA has funded over $30M in NEO

search efforts using funds from the Science Mission Directorate’s Research and

Analysis program. To date, these efforts have found the vast majority of the 724

one-kilometer Near Earth Asteroids and 64 Earth approaching comets now known,

as well as the 4,128 known smaller NEOs. At the current discovery rate, we will

have found about 50 more NEOs larger than one kilometer by the end of 2008,

bringing us very close to achieving our 90 percent goal, measured against the current estimate of about 940 total one-kilometer objects. This work has retired the majority of the risk that Earth could be struck by a large asteroid in the foreseeable

future.

25

Question 2: What roles do other U.S. Government institutions, universities, private

and not-for-profit organizations, and international entities play in contributing to the

NEO Survey and how is NASA coordinating with these institutions?

As discussed above, NASA does not directly own or operate any of the NEO Survey assets, but fully or partially funds several universities and private institutions

to conduct the necessary elements of the survey using existing ground-based astronomical facilities. The University of Arizona (UofA) operates most of the search telescopes, either directly or in partnership with others. Two telescopes are operated at

Kitt Peak by the UofA Spacewatch project, while the UofA Catalina Sky Survey operates two telescopes at Mt. Lemmon Observatory and one in partnership with the

Australian National Observatory at Siding Spring Observatory in New South Wales,

Australia, which is currently our only southern hemisphere survey site. Lowell Observatory, a private institution, operates a smaller search telescope outside Flagstaff, Arizona. The remaining search team, funded by NASA at MIT/Lincoln Laboratory, operates on two U.S. Air Force-owned one-meter class telescopes at the Stallion Air Force Station on White Sands Missile Range near Socorro, New Mexico. The

Minor Planet Center is operated by the Smithsonian Astrophysical Observatory

using mostly NASA funding, and the NEO Program Office is at the Jet Propulsion

Laboratory, managed by the California Institute of Technology.

No significant NEO detection efforts are currently conducted by the international

community. Less than two percent of NEOs detected in the last ten years were

found by systems other than those funded by NASA.

Currently, the only organized work in the international community that is significant to the NEO Survey is the NEO Dynamics Site (NEODyS), operated by the University of Pisa in Italy. NEODyS conducts independent analysis on NEO orbits similar to that performed by NASA’s NEO Program Office at JPL. JPL and NEODyS

constantly compare results they obtain for PHO orbits and predicted impact probabilities. If the results from one vary significantly from the other, they redo their

analyses until they can resolve the discrepancy. This work offers a completely independent check of impact prediction results prior to an announcement of any significant threat.

Also worth noting is the current significant role for new discovery follow-up observations conducted world-wide by a dedicated amateur astronomer community.

Through its website, the MPC supplies position information on newly discovered objects and solicits observations needed to improve the orbit from anyone who may

26

want to attempt the work. Much of these follow-up observations are obtained by

amateur astronomer individuals or clubs with relatively sophisticated but smaller

telescope systems. However, once NASA moves the search to objects much smaller

than one kilometer, this work quickly becomes beyond the capabilities of these amateur systems.

Coordination of efforts is largely voluntary through the use of information published on the MPC and NEO Program Office websites. The competitive nature of

the grant program used to finance the search teams has encouraged them to make

improvements in their systems and data processing to maintain their detection

rates. This community meets either in the U.S. or internationally annually, on average, to discuss progress and improvements to the survey effort. In addition, last

year the United Nations Committee on the Peaceful uses of Outer Space (COPUOS)

established an Action Team on NEOs within its Scientific and Technical Subcommittee to encourage more international work on this issue. The Action Team is

focused on identifying gaps in efforts and coordination within the international community, as well as recommending improvements. NASA is charter member of this

new group.

Question 3: How do spacecraft missions to comets and asteroids, as well as other

scientific spacecraft, contribute to the NEO program?

Currently, spacecraft missions do not contribute to the detection of NEOs. However, space missions do provide the most significant and detailed information on

what we know about the character and composition of them. NASA Discovery missions such as the Near-Earth Asteroid Rendezvous (NEAR), Stardust, Deep Impact,

and the Japanese Hyabusa mission have contributed important information to our

understanding of the origin of comets and asteroids, providing insight on their evolution into the inner Solar System near the Earth, their structure and physical

properties, and their composition. The recently launched Dawn mission will travel

to the two largest objects in the Main Belt of Asteroids—Vesta and the dwarf planet

Ceres. This area of the Solar System has been shown to be the region of origin for

most of the objects that now are near Earth, and the Dawn mission will tell us

many things about their nature. Other significant contributions by spacecraft include studies by the Hubble Space Telescope, Spitzer, Galileo, and other asteroid

and comet flybys performed by several Solar System exploration missions.

Not only are these data important to the development of concepts to deal with

any impact threat an NEO may pose, but they are also critical to an understanding

of the nature NEOs for possible destinations and resources in our future exploration

of the Solar System.

While NASA does not have any formal responsibility for the task of mitigation,

scientific missions such as Deep Impact and the current Dawn mission to Vesta and

Ceres provide information that may be critical to planning an asteroid deflection.

Likewise, many of the systems and technologies that are being developed for exploration missions are directly applicable to mitigation missions. These capabilities are

the hallmarks of a robust, space-faring nation.

Question 4: What is the Arecibo facility’s role in the detection, tracking, and characterization of Near-Earth Objects, and what alternatives, if any, exist to carry out its

role if the facility is shut down? How do the capabilities of those alternatives compare

to those of the Arecibo facility?

The National Science Foundation’s Arecibo Radio Telescope facility has had no

useful role in the detection of NEOs—its technical characteristics make it incapable

of conducting searches for these relatively small and distant objects. However, once

we know the position of an object is accessible by a focused radar beam, Arecibo

plays an important role in the quick refinement of the orbit to a precision not obtainable by other means, and for understanding the object’s size, shape and spin

rate. Arecibo also aids in the detection of possible binary objects, (∼15 percent of

NEOs), which in turn provides data that can be used to determine their mass. When

an object passes close enough to the Earth to achieve a measurable radar return

(about 20 million miles depending on the size), the use of radar is one of several

valuable tools for obtaining additional information about these objects.

The only other facility currently being used by NASA for routine planetary radar

is NASA’s own Goldstone facility, part of our Deep Space Network (DSN) for communication with spacecraft on missions beyond Earth’s orbit. No international facility is capable of performing this feat on a regular basis.

There are significant differences with the planetary radar capability at Arecibo

compared to Goldstone. The Goldstone radar is a 70-meter steerable dish, allowing

it to access objects significantly lower to the horizon than the more limited sky area

accessible to the limited pointing capability of the Arecibo radar. However, Arecibo

27

is twice as powerful as Goldstone and has a much larger (304 meter) collection dish,

which allows it to observe objects significantly farther away than Goldstone.

Question 5: Will NASA’s current NEO program satisfy the requirement established

in Sec. 321(d)(1) of the NASA Authorization Act of 2005, and if not, what is NASA’s

plan for satisfying that requirement?

Although the current systems funded by NASA are capable of detecting objects

smaller than one kilometer in size, the objects must come significantly closer to the

Earth than a one kilometer object needs to in order to be detected. It would take

timescales much longer than 15 years to observe 90 percent of these objects with

the systems we currently use.

As outlined in the report NASA submitted to Congress on March 7, 2007, pursuant to direction in section 321 of the NASA Authorization Act of 2005 (P.L. 109–

155), the Agency recommended that the current survey program, funded at approximately $4M annually, be continued. In addition, NASA indicated that the Agency

would look for opportunities using potential dual-use telescopes and spacecraft—and

to partner with other agencies as feasible—to attempt to achieve the legislated goal

within 15 years. Several alternatives as to how this might be accomplished were

presented and analyzed in the March 7 report. However, due to current budget constraints, it is not possible for NASA to initiate a new program. The costs for the

alternative programs ranged from $470M to in excess of $1.0B over 10 to 19 years,

depending on how aggressive of a timeline would be pursued.

The current NEO program is fully funded through 2012. In addition, NASA is initiating plans to use other survey systems to increase the survey’s detection sensitivity and rates. For example, NASA has begun providing funds to the Air Force

Panoramic Survey Telescope and Rapid Response System (Pan-STARRS) project so

that it will be capable of providing data on NEO detections after it starts operations

on its first telescope in the next year. If the Air Force continues to fund this project

to its intended four telescope configuration by 2010, this system alone could discover

over 70 percent of the potentially hazardous objects larger than 140 meters by 2020.

NASA is also assessing the upgrades that must be instituted at the Minor Planet

Center to absorb the substantial increase in new detection data that this system

will provide.

Finally, NASA is also assessing what already planned spacecraft might contribute

to the detection effort. A leading example for possible dual-use is the Wide-field Infrared Survey Explorer (WISE). Currently being developed for a late 2009 launch

for a six-month astrophysics mission to map the infrared sky, the WISE instrument

is also capable of detecting many asteroids, of which a portion will be NEOs. We

are investigating improvements to the timeliness of the spacecraft’s data down-link

and archival plans to increase its utility for NEO detections, as well as a possible

extended mission to double the time available to detect these objects. The science

community may propose a NEO survey mission under the competitively-selected

Discovery program.

Question 6: What plans, policies, or protocols does NASA have in place in the event

that a previously unknown object on a near-term impact trajectory is detected?

NASA has an NEO contingency notification plan to be utilized in the very unlikely event an object is detected with significant probability of impacting the Earth.

The plan establishes procedures between the detection sites, the Minor Planet Center, the NASA NEO Program Office at JPL, and NASA Headquarters to first quickly

verify and validate the data and orbit on the object of interest, and then up-channel

confirmed information in a timely manner to the NASA Administrator. These procedures were first exercised with the discovery of the object now known as Apophis,

which was found in December 2004 in a hazardous orbit but determined to not have

a significant probability of impacting the Earth in the near-term. NASA will continue to refine this internal contingency plan, and begin work with other U.S. Government agencies and institutions when directed.

Again, thank you for the opportunity to testify today, and I look forward to responding to any questions you may have.

BIOGRAPHY FOR JAMES L. GREEN

Dr. Green received his Ph.D. in Space Physics from the University of Iowa in 1979

and began working in the Magnetospheric Physics Branch at NASA’s Marshall

Space Flight Center (MSFC) in 1980. At Marshall, Dr. Green developed and managed the Space Physics Analysis Network, which provided many scientists, all over

the world, with rapid access to data, other scientists, and specific NASA computer

28

and information resources. In addition, Dr. Green was a safety diver in the Neutral

Buoyancy tank making over 250 dives until he left MSFC in 1985.

From 1985 to 1992 he was the Head of the National Space Science Data Center

(NSSDC) at Goddard Space Flight Center (GSFC). The NSSDC is NASA’s largest

space science data archive. In 1992 he became the Chief of the Space Science Data

Operations Office until 2005 when he became the Chief of the Science Proposal Support Office. While at GSFC, Dr. Green was a co-investigator and the Deputy Project

Scientist on the Imager for Magnetopause-to-Aurora Global Exploration (IMAGE)

mission. From 1992 to 2000 he was also the Deputy Project Scientist for Mission

Operations and Data Analysis for the Global Geospace Science Missions WIND and

POLAR. He has written over 110 scientific articles in referred journals involving

various aspects of the Earth’s and Jupiter’s magnetospheres and over 50 technical

articles on various aspects of data systems and computer networks.

In August 2006, Dr. Green became the Director of the Planetary Science Division

at NASA Headquarters. Over his career, Dr. Green has received a number of

awards. In 1988 he received the Arthur S. Flemming award given for outstanding

individual performance in the federal government and was awarded Japan’s Kotani

Prize in 1996 in recognition of his international science data management activities.

Chairman UDALL. Thank you, Dr. Green. Dr. Pace.

STATEMENT OF DR. SCOTT PACE, ASSOCIATE ADMINISTRATOR, PROGRAM ANALYSIS AND EVALUATION, NATIONAL

AERONAUTICS AND SPACE ADMINISTRATION (NASA)

Dr. PACE. Thank you, Mr. Chairman. Members of the Committee,

thank you for the opportunity.

I would like to review some of the findings and recommendations

of the report that we provided to the Congress in response to the

Authorization Act of 2005. The principal findings of the report to

Congress were the result of a study led by my Office. The Study

Team conducted an analysis of alternatives, with inputs from several government agencies, international organizations, and representatives of private organizations. I think that we covered a

wide spectrum of views of the scientific and technical community

in the effort.

NASA recommended that the existing Spaceguard survey program continue, as currently planned. NASA would also take advantage of opportunities using potential telescopes, such as the Large

Synoptic Survey Telescope, and the proposed Panoramic Survey

Telescope, otherwise known as Pan-STARRS, that you heard mentioned, along with potential dual use spacecraft, some partnerships

with other agencies, as feasible, to make progress toward achieving

the legislative goal.

However, I have to say that due to budget constraints, NASA

cannot initiate a new program beyond Spaceguard at this time, and

however, as also was noted, that NASA, it is fair to say, would be

pleased to implement a more aggressive Near-Earth Object program if, in fact, so directed by the President and Congress. Given

the constrained resources and strategic objectives that the agency

has already been tasked with, I would have to say that NASA cannot place a new NEO program above current scientific and exploration missions. But I imagine that will be the subject of dialog and

discussion with you, and see how we can move forward.

The goal of finding 90 percent of potentially hazardous objects

140 meters in diameter and larger is one to two orders of magnitude more technically challenging than the existing Spaceguard

mission. To reach the goal within 10 to 15 years would require at

least one new dedicated ground or space observatory, and we can

29

share with other folks, but to really hit the goal, you need a dedicated facility.

Cataloging the number of total objects, say 100,000, at the rate

they would be discovered, around 30 to 50 a day, would require a

new tracking and data management infrastructure, whose ongoing

operation may constitute a sizable portion of the total cost. A delay

of five to 10 years in achieving the legislation goal, we think, carries little additional risk when the impact interval for 140 meter

objects is about once every 5,000 years. We think there is time to

do the survey right. This rate of impact indicates the system may

need to operate, conducting searches, tracking objects, for an extended period of time before identifying a credible threat, and I

would like to describe really three periods in that process.

Today, we know where a few 140 meter objects are, but we know

little about when or if they will impact. We are ignorant. For the

initial 10 to 20 years the survey is progressing, the average warning time will rise, the unwarned impact risk will gradually decline,

and during this period, potentially decades of warning will become

likely.

After 10 to 20 years of the survey, a steady state period will be

reached, where unwarned impacts of potentially hazardous objects

would be highly unlikely. Centuries of warning time become possible in a steady state period.

The NASA identified, in its report, an exemplar NEO survey program, with estimates for its architectural costs that, if funded,

could achieve the specified goal of surveying 90 percent of potentially hazardous objects by the end of 2020. This would occur by

constructing or funding a dedicated survey asset, combined with

NASA partnerships with other agencies on future optical groundbased observatories. Details of the exemplar program were provided in our report, and again, we would be happy to discuss them.

I want to caution, however, that the budget estimates in the report are what we call architecture costs, and a lot more rigorous

analysis would be needed before a program to be assessed for implementation. So, more work needs to be done on those cost estimates.

Finally, the current NEO Spaceguard survey program, really

without any augmentation, would not be able to satisfy the requirements of the Authorization Act. In the Act right now, the requirements of the survey program are to find only NEOs greater than

a kilometer in diameter, and therefore, if we focused on things

smaller than that, 140 meters, it would require additional effort.

Without major augmentation, NASA estimates that we could detect

14 percent of the 140 meter or larger potentially hazardous objects

by 2020.

In our cooperative efforts with Air Force, the Pan-STARRS program, it would be capable of providing data on NEO detections

after operations start. We think that this system alone could discover about 70 percent of potentially hazardous objects larger than

140 meters by 2020. So, we think there are some promising approaches.

While NASA does not have any formal responsibility for the task

of NEO mitigation, as mentioned, scientific missions such as Deep

Impact and Dawn provide information that may be critical to planVerDate 11-MAY-2000 18:21 Feb 21, 2008 Jkt 038057 PO 00000 Frm 00033 Fmt 6633 Sfmt 6601 C:\WORKD\SA07\110807\38057 SCIENCE1 PsN: SCIENCE1
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1The proposed Large Synoptic Survey Telescope (LSST) and Panoramic Survey Telescope And

the Rapid Response System (Pan-STARRS) present possible future opportunities, if they are

funded by other agencies. Another possible opportunity would be the Lowell Discovery Channel

Telescope (DCT), but its contribution would be less than LSST or Pan-STARRS.

ning and asteroid deflection, and likewise, many of the systems and

technologies that are being developed for exploration are directly

applicable to mitigation missions. These capabilities are the hallmarks of a robust and spacefaring nation, capable of the many

tasks that may be assigned to it.

Thank you, Mr. Chairman. I would be pleased to respond to any

questions.

[The prepared statement of Dr. Pace follows:]

PREPARED STATEMENT OF SCOTT PACE

Mr. Chairman and Members of the Subcommittee, thank you for the opportunity

to appear today to review the findings and recommendations of NASA’s report to

Congress in response to the NASA Authorization Act of 2005 (P.L. 109–155). Below,

I have addressed the questions posed by this Subcommittee in your invitation to testify.

Question #1: What were the principal findings and recommendations of NASA’s

Near-Earth Object Survey and Deflection Analysis of Alternatives: Report to Congress, March 2007, and what was the basis for those findings and recommendations?

The principal findings were the result of a study team, led by NASA’s Office of

Program Analysis and Evaluation (PA&E) that conducted an analysis of alternatives

with inputs from several other U.S. Government agencies, international organizations, and representatives of private organizations. The team developed a range of

possible options from public and private sources and then analyzed their capabilities

and levels of performance including costs, development schedules, and technical

risks. In order to meet the congressional goal of completing the survey by 2020, the

study team assumed primary project elements would have started their development by October 1, 2007.

NASA recommended that the existing ‘‘Spaceguard Survey’’ program continue as

currently planned, and that NASA would also take advantage of opportunities using

potential dual-use telescopes1 and spacecraft—and partner with other agencies as

feasible—to make progress toward achieving the legislative goal of discovering 90

percent of all potentially hazardous objects 140 meters in mean diameter and greater. However, due to budget constraints, NASA cannot initiate a new program beyond the Spaceguard Survey program at this time.

NASA would be pleased to implement a more aggressive NEO program if so directed by the President and Congress. However, given the constrained resources and

strategic objectives the Agency has already been tasked with, NASA cannot place

a new NEO program above current scientific and exploration missions.

For ease of following the findings and recommendations, simplified definitions are

as follows:

• ‘‘Detection’’ is the act of finding the objects;

• ‘‘Tracking’’ is the act of determining their orbits;

• ‘‘Characterization’’ is the act of determining their physical properties;

• ‘‘Cataloging’’ is the act of maintaining a data base of the orbits and physical

properties of known objects and predicting potential impacts with the Earth;

and

• ‘‘Mitigation’’ is the act of deflecting, destroying, or reducing the impact consequences of a specific object that is predicted to strike the Earth.

Key Findings for the Survey Program

• The goal of the Survey Program should be modified to detect, track, catalogue, and characterize, by the end of 2020, 90 percent of all Potentially Hazardous Objects (PHOs) greater than 140 meters whose orbits pass within 0.05

AU (Astronomical Units) of the Earth’s orbit (as opposed to surveying for all

NEOs).

• The Agency could achieve the specified goal of surveying for 90 percent of the

potentially hazardous NEOs by the end of 2020 by partnering with other govVerDate 11-MAY-2000 18:21 Feb 21, 2008 Jkt 038057 PO 00000 Frm 00034 Fmt 6633 Sfmt 6621 C:\WORKD\SA07\110807\38057 SCIENCE1 PsN: SCIENCE1
31

ernment agencies on potential future optical ground-based observatories and

building a dedicated NE0 survey asset, assuming the partners’ potential

ground assets come online by 2010 and 2014, and a dedicated asset by 2015.

• Together, the two observatories potentially to be developed by other government agencies could complete 83 percent of the survey by 2020 if observing

time at these observatories is shared with NASA’s NE0 Survey Program.

• New space-based infrared systems, combined with shared ground-based assets, could reduce the overall time to reach the 90 percent goal by at least

three years. Space systems have additional benefits as well as costs and risks

compared to ground-based alternatives.

• Radar systems cannot contribute to the search for potentially hazardous objects, but may be used to rapidly refine tracking and to determine object sizes

for a few NEOs of potentially high interest.

• Determining a NEO’s mass and orbit is required to determine whether it represents a potential threat and to provide required information for most alternatives to mitigate such a threat. Beyond these parameters, characterization

requirements and capabilities are tied directly to the mitigation strategy selected.

Key Findings for Diverting a Potentially Hazardous Object (PHO)

The study team assessed a series of approaches that could be used to divert a

NEO potentially on a collision course with Earth. Nuclear explosives, as well as

non-nuclear options, were assessed.

• Nuclear standoff explosions are assessed to be 10–100 times more effective

than the non-nuclear alternatives analyzed in this study. Other techniques

involving the surface or subsurface use of nuclear explosives may be more efficient, but they run an increased risk of fracturing the target NEO. They also

carry higher development and operations risks.

• Non-nuclear kinetic impactors are the most mature approach and could be

used in some deflection/mitigation scenarios, especially for NEOs that consist

of a single small, solid body.

• ‘‘Slow push’’ mitigation techniques are the most expensive, have the lowest

level of technical readiness, and their ability to both travel to and divert a

threatening NEO would be limited unless mission durations of many years

to decades are possible.

• 30–80 percent of potentially hazardous NEOs are in orbits that are beyond

the capability of current or planned launch systems. Therefore, planetary

gravity assist swing-by trajectories or on-orbit assembly of modular propulsion systems may be needed to augment launch vehicle performance, if these

objects need to be deflected.

Question #2: How were the cost estimates and technical options contained in the report arrived at, and was any independent assessment of the cost estimates and technical options conducted?

Technical Options

The technical options contained in the report were developed through a systematic

exploration of the trade space for feasible alternatives, followed by a conceptual design of selected options. Concepts were selected to represent the available range of

cost, performance, and acceptable technical risk to complete the detection, tracking,

cataloguing, and characterization missions. Concepts were based on historical and

existing projects and on white papers presented at a NASA-sponsored workshop of

national experts.

Trade trees were developed to describe the technical options. The detection and

tracking trade tree consisted of existing and new ground-and space-based observatories operating in the visible and infrared spectra; ground based radars were considered for tracking. The characterization trade tree contained existing, proposed,

and new remote and in-situ observing assets. Cataloguing considered a range of operations and data management options based on historical, proposed, and new information systems.

Cost Estimates

Life cycle costs were calculated as the total architecture cost in fiscal year 2006

billions of dollars including development, production, deployment, and operation of

the alternatives. Life cycle costs for the detection, tracking, and data management

options were calculated both for a fixed period (through 2020) and until the objective

32

2The proposed Large Synoptic Survey Telescope (LSST) and Panoramic Survey Telescope And

the Rapid Response System (Pan-STARRS) represent possible future opportunities, if they are

funded by other agencies. Another possible opportunity would be the Lowell Discovery Channel

Telescope (DCT), but its contribution would be less than LSST or Pan-STARRS.

of cataloguing 90 percent of specified threats was complete. For some options that

rely on existing systems or available technology, operational costs were much higher

than the development costs over the 15–20 year life cycle. In order to meet the Congressional goal of completing the survey by 2020, the study team assumed primary

project elements would have started their development by October 1, 2007.

For space-based systems, the total life cycle costs included estimated costs for program management, systems engineering, mission assurance, launch vehicle, spacecraft, scientific instruments, mission specific ground data systems, mission operations, and data analysis. Ground-based systems included the cost of development,

production, and operations. Operations costs were calculated over either the survey

period for detection, tracking, and cataloguing missions or the predicted duration of

characterization missions.

The cost estimates for the space vehicles relied on multiple methods including historical analogies and prior cost-estimating experience. Cost-risk analyses were performed using these data as inputs and assumed that every cost element could be

represented by statistical characteristics such as mean, standard deviation, and

mode. A cumulative probability distribution of total cost was generated for this analysis by combining cost distributions from the different cost elements, and costs were

estimated at the 65 percent cost confidence level when applicable. Programmatic

costs were based on historical actual costs and applied as a percentage of the space

vehicle costs. Launch vehicle costs were based on recent, publicly released estimates

for commercial launch vehicles.

Ground-based observatory costs were based on reported expenses for currently operating systems or based on estimates for systems currently in development. For

several ground based options, concepts of operations postulated utilizing (sharing)

data that would be collected on existing or planned systems without materially affecting the primary mission of these systems. For these systems, it was assumed

that the NEO program would fund only a small portion (or none) of the development

costs, but that an equitable portion of the annual operations costs would be funded

by NASA. In cases where the ground based systems were expected to be copies of

systems that are currently in development, only the production and operation costs

of the NASA-acquired systems were considered—substantially reducing their development costs and cost-risk.

Although multiple cost-estimating methodologies, databases, and organizations

were used, truly independent cost estimates were not generated as these are typically not within the scope of a conceptual, architecture-level study. Likewise, assessments of the technical options were carried out using an experienced team of personnel from several organizations, but fully separate evaluations of the concepts

were not performed.

Question #3: What is the ‘‘recommended option and proposed budget to carry out the

Survey program pursuant to the recommended option,’’ as called for in Sec.

321(d)(2)?

NASA recommended that the existing ‘‘Spaceguard Survey’’ program continue as

currently planned, and that NASA would also take advantage of opportunities using

potential dual-use telescopes2 and spacecraft-and partner with other agencies as feasible-to make progress toward achieving the legislative goal of discovering 90 percent of all potentially hazardous objects 140 meters and greater.

The goal of finding 90 percent of potentially hazardous objects 140 meters and

larger is one to two orders of magnitude more technically challenging than the

Spaceguard mission. To reach this goal within 10–15 years requires at least one new

dedicated ground or space observatory.

Cataloging the number of total number of objects—approximately 100,000—at the

rate they would be discovered, which is between 30 and 50 per day, requires a new

tracking and data management infrastructure whose ongoing operations may constitute a sizable portion of total costs.

A delay (e.g., 5–10 years) in achieving the legislative goal carries little additional

risk when the impact interval for 140m objects is about once every 5,000 years. This

rate of impacts also indicates that the system may need to operate (searching and

tracking) for an extended period before identifying a credible threat. There are three

epochs to the problem of detection and tracking:

• Now: We know where few 140m objects are and when/if they will impact.

33

• Initial 10–20 years of the survey: Average warning time will rise, unwarned

impact risk gradually decline. Decades of warning become likely.

• Steady-state: After 10–20 years of the survey, unwarned impacts of 140m objects would be highly unlikely. Centuries of warning become possible.

Currently, NASA carries out the ‘‘Spaceguard Survey’’ to find NEOs greater than

1 kilometer in diameter, and this program is currently budgeted at $4.1 million per

year for FY 2006 through FY 2012. We also have benefited from knowledge gained

in our Discovery space mission series, such as the Near-Earth Asteroid Rendezvous

(NEAR), Deep Impact, and Stardust missions that have expanded our knowledge of

near-Earth asteroids and comets. Participation by NASA in international collaborations such as Japan’s Hayabusa mission to the NEO ‘‘Itokawa’’ also greatly benefited our understanding of these objects. NASA’s Dawn mission, launched on September 27, 2007, will increase our understanding of the two largest known main

belt asteroids, Ceres and Vesta, between the planets Mars and Jupiter. NASA conducts survey programs on many celestial objects—the existing Spaceguard program

for NEOs, surveys for Kuiper Belt Objects, the search for extra-solar planets, and

other objects of interest such as black holes to understand the origins of our universe. The science community could propose such a NEO survey mission under the

competitively-selected Discovery program.

NASA also identified an exemplar NEO Survey Program and estimates for its architectural costs that, if funded, could have achieved the specified goal of surveying

90 percent of the PHOs by the end of 2020 by constructing or funding a dedicated

survey asset combined with NASA partnerships with other government agencies on

potential future optical ground-based observatories: the Panoramic Survey Telescope

and Rapid Response System (Pan-STARRS–4 or PS4) and the Large Synoptic Survey Telescope (LSST). Details of the exemplar program were provided in NASA’s report. Note that budget estimates in the report are rough ‘‘architecture costs’’ and

would require more rigorous analysis before a program could be assessed for implementation.

Question #4: Will NASA’s current NEO program satisfy the requirement established

in Sec. 321(d)(1) of the NASA Authorization Act of 2005, and if not, what is NASA’s

plan for satisfying that requirement?

The current NASA NEO ‘‘Spaceguard Survey’’ program, without any augmentation, would not be able to satisfy the requirements outlined in section 321(d)(1) of

the NASA Authorization Act for 2005. The requirements for the Spaceguard Survey

program are to find only NEOs greater than one kilometer in diameter, and its

funding is currently budgeted at $4.1 million per year. NASA estimates that the

current program, if continued without major augmentation, would detect 14 percent

of the 140 meters or larger potentially hazardous objects by the end of 2020. However, NASA is initiating plans to use other survey systems to increase the survey’s

detection sensitivity and rates. For example, NASA has begun providing funds to

the Air Force Panoramic Survey Telescope and Rapid Response System (PanSTARRS) project so that it will be capable of providing data on NEO detections after

it starts operations on its first telescope in the next year. If the Air Force continues

to fund this project to its intended four telescope configuration by 2010, this system

alone could discover over 70 percent of the potentially hazardous objects larger than

140 meters by 2020.

NASA recommended that the existing ‘‘Spaceguard Survey’’ program continue as

currently planned, and that NASA would also take advantage of opportunities using

potential dual-use telescopes and spacecraft—and partner with other agencies as

feasible—to make progress toward achieving the legislative goal of discovering 90

percent of all potentially hazardous objects 140 meters and greater.

NASA would be pleased to implement a more aggressive NEO program, if so directed by the President and Congress. However, given the constrained resources and

strategic objectives the Agency has already been tasked with, NASA cannot place

a new NEO program above current scientific and exploration missions.

Question #5: How is progress on meeting the requirements of Section 321 being measured and monitored?

Survey performance is tracked continuously by the NEO Program Office at JPL,

and reported monthly on NASA’s NEO Program website at http://neo.jpl.nasa.gov/

stats. This database shows the performance of each survey team and reports the

number of NEOs, including Earth approaching comets, found each month by orbit

and size (larger or smaller than one kilometer) class. It also breaks out the objects

which are potentially hazardous by size class. Specific orbit and estimated size inforVerDate 11-MAY-2000 18:21 Feb 21, 2008 Jkt 038057 PO 00000 Frm 00037 Fmt 6633 Sfmt 6621 C:\WORKD\SA07\110807\38057 SCIENCE1 PsN: SCIENCE1
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mation for each discovered NEO can also been found on the website, as well as probability of impact statistics for Potentially Hazardous Objects.

The discovery statistics information is rolled up each year and reported by the

Science Mission Directorate as part of our Government Performance Reporting Act

(GPRA) submittal.

In closing, NASA recommends that the existing ‘‘Safeguard Survey’’ program continue, as planned, and that the Agency take advantage of opportunities using potential dual-use telescopes and spacecraft, as well as partner with other agencies, to

make progress toward achieving the legislative goal.

Mr. Chairman, I would be pleased to respond to any questions you or the other

Members of the Subcommittee may have.

BIOGRAPHY FOR SCOTT PACE

Scott Pace is the Associate Administrator for Program Analysis and Evaluation

at NASA. In this capacity, he is responsible for providing objective studies and analyses in support of policy, program, and budget decisions by the NASA Administrator. He previously served as Chief Technologist for Space Communications in

NASA’s Office of Space Operations where he was responsible for advising senior

NASA management on issues related to space-based information systems. He participated in the negotiations that resulted in the 2004 GPS–Galileo Agreement between the United States and the European Commission. Pace also previously served

as the Deputy Chief of Staff to NASA Administrator Sean O’Keefe. His primary

areas of responsibility included oversight of the President’s Management Agenda in

Human Capital, Competitive Sourcing, Expanding e-Government, Financial Management, and Integrating Budget and Performance.

Prior to NASA, Pace was the Assistant Director for Space and Aeronautics in the

White House Office of Science and Technology Policy (OSTP). There he was responsible for space and aviation-related issues and coordination of civil and commercial

space issues through the Space Policy Coordinating Committee of the National Security Council. Pace served on the Bush-Cheney Transition Team for NASA and the

National Science Foundation.

Prior to his White House appointment, Pace worked for the RAND Corporation’s

Science and Technology Policy Institute (STPI)—a federally funded research and development center for the Office of Science and Technology Policy. In addition to his

extensive research into space policy, technology policy, and international competitiveness at RAND, Pace also was a key member of a successful international effort

to preserve radio navigation satellite spectrum at the 1997 World

Radiocommunication Conference (WRC97) and the addition of new spectrum for satellite navigation at WRC–2000. He also was a member of the Department of Defense

Senior Review Group on Commercial Remote Sensing and the National Research

Council’s Committee on Earth Sciences.

From 1990 to 1993, Pace served as the Deputy Director and Acting Director of

the Office of Space Commerce (OSC), in the Office of the Deputy Secretary of the

Department of Commerce. Among his many responsibilities at OSC, Pace coordinated space policy issues across the Department and participated in efforts affecting

export controls for space technologies; space trade negotiations with Japan, Russia,

China, and Europe; the licensing process for private remote sensing systems; missile

proliferation; and the U.S. space industrial base.

Pace received a Bachelor of science degree in physics from Harvey Mudd College

in 1980; Master of science degrees in aeronautics and astronautics and technology

and policy from the Massachusetts Institute of Technology in 1982; and a doctorate

in policy analysis from the RAND Graduate School in 1989. His dissertation was

entitled ‘‘U.S. Access to Space: Launch Vehicle Choices for 1990–2010.’’

Chairman UDALL. Thank you, Dr. Pace. Dr. Yeomans.

STATEMENT OF DR. DONALD K. YEOMANS, MANAGER, NEAREARTH OBJECT PROGRAM OFFICE, JET PROPULSION LABORATORY

Dr. YEOMANS. Mr. Chairman and Members of the Subcommittee,

thank you for the opportunity to appear today.

Chairman UDALL. Dr. Yeomans, I think you should turn on your

microphone, if you can.

35

Dr. YEOMANS. Thank you for the opportunity to appear today to

discuss the potential threats of Near-Earth Objects, progress toward meeting the discovery goal articulated in the NASA Authorization Act of 2005, the role of the Arecibo Planetary Radar within

the Near-Earth Object Program, and the response options available

if a Near-Earth Object is found to be on an Earth-threatening trajectory.

Near-Earth objects are comets and asteroids that can pass within

about 45 million kilometers of the Earth’s orbit. While some showy

naked eye comets may occasionally pass close to Earth, it is the difficult to find, but the far more numerous asteroids are of the most

concern in near-Earth space today. About one-fifth of the nearEarth asteroids can approach the Earth’s orbit even closer, to within seven and a half million kilometers, and these so-called potentially hazardous asteroids are of most concern for near-term hazard

avoidance.

As part of the NASA Authorization Act of 2005, NASA was asked

to consider options for extending the search down to objects as

small as 140 meters in diameter, and to find and catalog them

within 15 years of the Act becoming law. By finding and cataloging

90 percent of this population of potentially hazardous asteroids, the

statistical or actuarial risk to Earth from potentially hazardous asteroids of all sizes would be reduced by 99 percent from pre-survey

levels. We can speak of risk reduction in this case, because once an

object is discovered and cataloged, its future motion can accurately

be predicted, and in the unlikely case where it does threaten Earth,

there would be sufficient time to deflect it, thus saving the enormous costs due to fatalities and/or infrastructure damage.

According to a 2003 NASA Near-Earth Object science definition

team study that undertook a cost-benefit analysis for the discovery

of potentially hazardous asteroids, the risk reduction accruing from

this next generation potentially hazardous asteroid search would

pay for itself in the first year of operations.

While an impact by a 140 meter sized object would not generate

global physical consequences, its impact energy would still be about

100 megatons of TNT explosive, and the likelihood of one of these

impacts is 100 times greater than an impact by one of the less numerous one kilometer size potentially hazardous asteroids.

With regard to the uncertainty associated with threats from potentially hazardous asteroids, the largest factor, by far, is the large

number of undiscovered objects in the size ranges that are small

enough to be very numerous, yet large enough to easily penetrate

the Earth’s atmosphere. For example, we have only discovered

about four percent of the 20,000 potentially hazardous asteroids

larger than 140 meters, and less than one percent of the 200,000

objects larger than 50 meters.

The solution to this uncertainty is to continue and hopefully accelerate the search for potentially hazardous asteroids. Once we

find the vast majority of them, they can be tracked, cataloged, and

then ruled out or in as threats during the next 100 years or so.

The current NASA Near-Earth Object goal is focused upon the

discovery and tracking of objects one kilometer in diameter and

larger. It is not realistic to expect the current survey program, with

its modestly sized telescopes, to efficiently find 140 meter sized obVerDate 11-MAY-2000 18:21 Feb 21, 2008 Jkt 038057 PO 00000 Frm 00039 Fmt 6633 Sfmt 6601 C:\WORKD\SA07\110807\38057 SCIENCE1 PsN: SCIENCE1
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jects that are nearly 50 times fainter compared to the one kilometer sized objects at the same distance and with the same reflectivity.

Because all potentially hazardous asteroids do eventually come

very close to the Earth, the current ongoing surveys could complete

the goal outlined in the 2005 NASA Authorization Act, but it would

likely take over a century to do so. We simply cannot afford to wait

that long.

At least two next generation ground-based wide-field search telescope surveys are in development. Pan-STARRS is under development at the University of Hawaii, with Air Force funding, and will

have one of its 1.8 meter telescopes operational in Hawaii in early

2008. If the planned four telescope version of Pan-STARRS is completed by 2010, it could help reach the goal by about 2040.

Likewise, the 8.4 meter aperture LSST telescope that is under

development with funding from NSF, DOE, and other partners,

could help reach the goal by about 2034, if it began operation in

2014.

If we assume that both the Pan-STARRS four telescope system

and the LSST operate in their planned shared mode, which includes many observations unrelated to potentially hazardous asteroids, then the goal could be reached by about 2026. The potentially

hazardous asteroid discovery rate could be increased beyond the results shown in the NASA report, if the observing times and sequences of Pan-STARRS and LSST were optimized for potentially

hazardous asteroid observations.

Both positional data for potentially hazardous asteroid orbit determination and trajectory predictions are based upon optical,

plane-of-sky observations. Because the radars provide line of sight,

velocity, and range information to about one millimeter per second

and 10 meter accuracy levels, this data, when used in conjunction

with the optical data, provide a secure orbit and trajectory far more

rapidly than if only optical data are available. With only a limited

amount of optical data to work with, the orbit of a newly discovered

potentially hazardous asteroid is often not accurate enough to immediately rule out a future Earth impact.

However, with radar data in hand, the orbit of a newly discovered potentially hazardous asteroid can be quickly and more precisely determined, its motion accurately projected far into the future, and future impact possibilities can usually be quickly ruled

out. Likewise, in the rare situation when an object is actually on

an Earth-impacting trajectory, radar observations will be critical in

quickly identifying this case.

A number of existing technologies can deflect an Earth-threatening asteroid if there is time. The primary goal of the potentially

hazardous asteroid survey programs is to discover them early and

provide the necessary time. An asteroid that is predicted to hit

Earth would require a change in its velocity of only three millimeters per second, if this impulse were applied 20 years in advance

of the impact itself. The key to a successful deflection is having sufficient time to carry it out, whether it is a slow, gentle drag of a

gravity tractor, or the more impulsive shove from an impacting

spacecraft or explosive device. In either case, the verification process will be required to ensure the deflection maneuver was successVerDate 11-MAY-2000 18:21 Feb 21, 2008 Jkt 038057 PO 00000 Frm 00040 Fmt 6633 Sfmt 6601 C:\WORKD\SA07\110807\38057 SCIENCE1 PsN: SCIENCE1
37

ful, and to ensure the object’s subsequent motion would not put it

on yet another Earth-impacting trajectory.

While suitable deflection technologies exist, none of them can be

effective if we are taken by surprise. It is the aggressive survey efforts and robust radar systems that must ensure that the vast majority of potentially hazardous objects are discovered and tracked

well in advance of any Earth-threatening encounters.

The first three steps in any asteroid mitigation process are find

them early, find them early, and find them early.

Thank you.

[The prepared statement of Dr. Yeomans follows:]

PREPARED STATEMENT OF DONALD K. YEOMANS

Mr. Chairman and Members of the Subcommittee, thank you for the opportunity

to appear today to discuss the potential threats of near-Earth objects (NEOs), our

progress toward meeting the discovery goal articulated in the NASA Authorization

Act of 2005, the role of the Arecibo planetary radar within the NEO program and

the response options available if a NEO is found to be on an Earth impacting trajectory.

The Near-Earth Object Population: When the Earth was young, frequent collisions of comets and asteroids likely delivered much of the water and carbon-based

molecules that allowed life to form, and once life did form, subsequent collisions may

have punctuated the evolutionary process and allowed only the most adaptable species to progress further. We may owe our very existence atop the world’s food chain

to these objects. As the Earth’s closest neighbors (some pass within the Moon’s distance), these icy comets and rocky asteroids have been termed near-Earth objects.

Their proximity to Earth presents an opportunity to utilize their vast metal, mineral

and water ice resources for future space structures and habitats. Their water resources can be broken down into hydrogen and oxygen—the most efficient form of

rocket fuel. These near-Earth objects may one day be the resources, fueling stations

and watering holes for human interplanetary exploration. While these objects are

of extraordinary scientific interest, likely enabled the origin of life itself, and may

loom large for the future development of space exploration, their proximity to Earth

also presents a potential horrific threat should a relatively large near-Earth object

once again strike Earth without warning.

Potentially Hazardous Asteroids: Near-Earth objects are comets and asteroids

that can pass within 45 million kilometers of the Earth’s orbit. While some showy,

naked-eye comets may occasionally pass close to Earth, it is the difficult to find (but

far more numerous asteroids) that are of most concern in near-Earth space today.

About one fifth of the near-Earth asteroids can approach the Earth’s orbit even closer (to within 7.5 million kilometers), and these so-called potentially hazardous asteroids (PHAs) are of most concern for near-term hazard avoidance.

Celestial debris hits the Earth all the time, but the vast majority of it is so small

that it does not survive passage through the Earth’s atmosphere. The debris is created over millions of years, as asteroids inevitably run into each other, producing

smaller fragments, which themselves collide yielding even more debris. Over time,

the fragments and debris spread out, and some of it migrates into Earth approaching orbits. The Earth is pummeled with more than 100 tons of impacting material

each day but almost all of it is far too small to cause anything other than a harmless meteor, or shooting star, or the occasional fireball event. Larger objects are less

numerous than smaller objects and hit the Earth less often. While a basketball-sized

object strikes the Earth’s atmosphere daily, larger car-sized impactors hit only a few

times each year, and even these generally break up into smaller pieces as they

streak through the atmosphere. Occasionally a fragment of a larger impactor will

reach the Earth’s surface—one such hit may have occurred less than two months

ago when a reported asteroid fragment perhaps one meter in diameter struck in

southern Peru creating a 13-meter crater near Lake Titicaca.

Larger impactors with diameters in the 50 to 140 meter range, while they do not

usually impact the ground, can result in damaging air blasts that cause significant

destruction. For example, on June 30, 1908, an impactor with a diameter of about

50 meters detonated over the Tunguska region of Siberia and leveled trees for 2,000

square kilometers. Its impact energy has been estimated at about 10 million tons

of TNT explosives (10 megatons or 10 MT), comparable in energy with a modern

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nuclear weapon. Roughly speaking, PHAs that have diameters larger than 140m can

punch through the Earth’s atmosphere and cause regional damage if they strike

land or create a harmful tsunami should they impact into an ocean. There are

thought to be about 20,000 PHAs in this size range, each with a potential impact

energy of 100 MT or more. On average, one of these objects would be expected to

strike Earth every 5,000 years and therefore would have a one percent probability

of impact in the next 50 years. Although their mean impact frequency would be

about once every 500,000 years, PHAs larger than a kilometer in diameter could

cause global consequences due to not only the extraordinary blast itself (50,000 MT)

but also the dust and debris thrown into the air, and the subsequent firestorms and

acid rain. The extinction of the dinosaurs and a sizable fraction of the Earth’s other

species some 65 million years ago is thought to be due to an impactor with a diameter of about 10 kilometers that created an impact energy of as much as 50 million

MT. Over very long time intervals, PHAs with diameters greater than one kilometer

are statistically the most dangerous objects because their impacts would cause global consequences.

NASA Responses to the PHA Issues: In 1998, before the Subcommittee on Space

and Aeronautics, a NASA representative outlined the goal to discover and catalog

90 percent of the NEOs larger than one kilometer by the end of 2008. There are

currently thought to be over 900 of these objects, and about 80 percent of them have

already been found and cataloged. Roughly the same percentage of PHAs in this size

range has also been found. When this goal has been reached, 90 percent of the global risk from PHAs would be retired. Almost all of these discoveries have come by

way of NASA supported search programs.

As part of the NASA Authorization Act of 2005, NASA was asked to consider options for extending the search down to objects as small as 140 meters in diameter,

and to find and catalog them within 15 years of the Act becoming law (i.e., by the

end of 2020). By finding and cataloging 90 percent of this population of PHAs, the

statistical or actuarial risk to Earth from PHAs of all sizes would be reduced by 99

percent from pre-survey levels. We can speak of risk reduction in this case because

once an object is discovered and cataloged, its future motion can accurately be predicted and, in the unlikely case where it does threaten Earth, there would be sufficient time to deflect it, thus saving the enormous costs due to fatalities and/or infrastructure damage. According to a 2003 NASA NEO Science Definition Team study

that undertook a cost/benefit analysis for the discovery of PHAs, the risk reduction

accruing from this next generation PHA search would pay for itself in the first year

of operations. While an impact by a 140 meter-sized object would not generate global physical consequences, its impact energy would still be about 100 MT, and the

likelihood of one of these impacts is 100 times greater than an impact by one of the

less numerous one kilometer-sized PHAs.

With regard to the uncertainty associated with threats from PHAs, the largest

factor, by far, is the large number of undiscovered objects in the size ranges that

are small enough to be very numerous but large enough to easily penetrate the

Earth’s atmosphere. For example, we have discovered only about four percent of the

20,000 PHAs larger than 140 meters and less than one percent of the 200,000 objects larger than 50 meters. The solution to this uncertainty is to continue and hopefully accelerate the search for PHAs. Once we find the vast majority of them, they

can be tracked, cataloged and then ruled out (or in) as threats during the next 100

years or so. This process can continue year after year so the window of safety is

always at least 100 years. There are other, less significant, uncertainties dealing

with the refinement of a particular object’s size, mass and structure as well as the

dynamical model that is used to accurately predict the object’s motion over 100 year

time scales. For example, over long time intervals, the minute pressure of sunlight

and its thermal re-radiation can significantly affect a PHA’s motion. For a select

number of Earth approaching objects, we will need the use of the planetary radars,

or possibly rendezvous spacecraft missions, to better understand their sizes, shapes,

masses, surface properties, and possible binary natures.

The Next Generation of Search: As noted, the current NASA NEO goal is focused upon the discovery and tracking of objects one kilometer in diameter and larger. It is not realistic to expect the current survey program, with its modestly sized

telescopes, to efficiently find the 140 meter-sized objects that are nearly 50 times

fainter compared to a one kilometer-sized object at the same distance and with the

same reflectivity. Because all PHAs do eventually come very close to the Earth, the

current ongoing surveys could complete the goal outlined in the 2005 NASA Authorization Act but it would likely take over a century to do so. We cannot afford to wait

that long.

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In the report to Congress requested by the 2005 NASA Authorization Act, several

options were outlined, both ground-based and space-based, that could meet the goal

of finding 90 percent of the PHAs larger than 140 meters by the end of 2020. For

example, a one-meter aperture infrared telescope in a heliocentric orbit near Venus

could do the job three years early. Within this report, NASA noted that it did not

have the resources to carry out a survey option that would meet the 2020 deadline

set by the 2005 Act and that, in an attempt to achieve the legislative goal by the

end of 2020, it would seek to continue the current survey programs and look for opportunities to use dual use telescope facilities and spacecraft along with partnering

with other agencies as feasible.

At least two next-generation, ground-based, wide-field search telescope surveys

are in development. The Panoramic Survey Telescope and Rapid Response System

(Pan-STARRS), under development at the University of Hawaii with Air Force funding, will have one of its four 1.8 meter telescopes operational in Hawaii in early

2008. If the planned, four telescope version of Pan-STARRS is completed by 2010,

it could help reach the goal by about 2040. Likewise the 8.4 meter aperture Large

Synoptic Survey Telescope (LSST) that is under development with funding from

NSF, DOE and other partners, could help reach the goal by about 2034 if it began

operation in 2014. If we assume that both the Pan-STARRS four telescope system

and the LSST operate in their planned shared modes, which includes many observations unrelated to PHAs, then the goal could be reached by about 2026. The PHA

discovery rate could be increased beyond the results shown in the NASA response

to the 2005 Act if the observing time and sequences of Pan-STARRS and LSST were

optimized for PHA observations.

In terms of actual discoveries of new PHAs, there has been little success beyond

the survey programs supported by NASA. However, the international community,

including many sophisticated amateur astronomers, is very active in providing the

follow-up observations necessary to secure an object’s orbit once it has been found.

The NEODyS program in Pisa, Italy works closely with, but independent of, the

NEO Program Office at JPL to compute impact probabilities for predicted Earth

close approaches for at least 100 years into the future. It is also encouraging to note

the activities of a NEO Action Team within the UN Committee on the Peaceful Uses

of Outer Space (COPUOS) includes an effort to encourage more international efforts

on the NEO issues.

The importance of Radar Observations: There are only two planetary radars in

existence (and no alternatives) that can routinely observe close Earth approaching

asteroids, and both of them are critically important for investigating the nature of

these objects and for rapidly refining their trajectories. The 70-meter Goldstone antenna in California’s Mojave desert is fully steerable, can track an asteroid and can

cover large regions of sky while the larger 305-meter Arecibo antenna in Puerto Rico

has twice the range but only observes within a 40-degree zone centered on the overhead position (20 degrees on either side of zenith). The capabilities of these two telescope complement one another and often a significantly better and longer set of observations can be achieved using both radars on a close approaching target asteroid.

Most positional data for PHA orbit determination and trajectory predictions are

based upon optical, plane-of-sky observations. Because the radars provide line-ofsight velocity and range information accurate to about the one mm/s and 10 meter

levels, these data when used in conjunction with the optical data provide a secure

orbit and trajectory far more rapidly than if only optical data are available. With

only a limited amount of optical data to work with, the orbit of a newly discovered

PHA is often not accurate enough to immediately rule out a future Earth impact.

However, with radar data in hand, the orbit of a newly discovered PHA can be

quickly and more precisely determined, its motion accurately projected far into the

future and future impact possibilities can usually be quickly ruled out. Likewise, in

the rare situation when an object is actually on an Earth threatening trajectory,

radar observations will be critical in quickly identifying this case.

Unfortunately the Arecibo radar program is not funded by the NSF beyond FY

2007 and the planetary science community is in danger of losing one of its instrumental crown jewels. As a measure of this radar facility’s importance, note that 65

percent of all radar experiments to characterize near-Earth asteroids were performed at Arecibo, 47 percent of all binary near-Earth asteroids were discovered at

Arecibo and 85 percent of the near-Earth asteroids with the critical astrometric

radar data for orbit improvement have data from Arecibo. All of this was accomplished with only five percent of this instrument’s time. The superior sensitivity of

the giant Arecibo radar can determine the sizes, shapes, rotation characteristics,

surface characteristics and binary nature for many PHAs. All of these physical characteristics are important criteria to understand before a deflection mission is considVerDate 11-MAY-2000 18:21 Feb 21, 2008 Jkt 038057 PO 00000 Frm 00043 Fmt 6633 Sfmt 6621 C:\WORKD\SA07\110807\38057 SCIENCE1 PsN: SCIENCE1
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ered. Radar observations are responsible for the best physical characterization of

any PHA as large as a kilometer (i.e., the binary asteroid 1999 KW4). Radar observations reduce a PHA’s orbit uncertainties quickly and dramatically so that future

impact possibilities can be quickly knocked down thus reducing the odds that we

will need to invest in a spacecraft investigation to characterize the PHA’s nature

in preparation for a precautionary deflection mission. Thus the relatively modest

costs of maintaining the Arecibo radar in a robust state could prevent the future

need for 100’s of millions of dollars per case for spacecraft reconnaissance of an object to determine whether or not it is an actual threat.

What Should be Done in the Event of an identified NEO Threat? A number

of existing technologies can deflect an Earth threatening asteroid—if there is time.

The primary goal of the PHA survey programs is to discover them early and provide

the necessary time. An asteroid that is predicted to hit Earth might require a

change in its velocity of only three millimeters per second if this impulse were applied twenty years in advance of the impact. The key to a successful deflection is

having sufficient time to carry it out, whether it is the slow, gentle drag of a gravity

tractor or a more impulsive shove from an impacting spacecraft or explosive device.

In either case, a verification process would be required to ensure the deflection maneuver was successful and to ensure the object’s subsequent motion would not put

it on yet another Earth impacting trajectory. While suitable deflection technologies

exist, none of them can be effective if we are taken by surprise. It is the aggressive

survey efforts and robust planetary radars that must ensure that the vast majority

of potentially hazardous objects are discovered and tracked well in advance of any

Earth threatening encounters. The first three steps in any asteroid mitigation process are: Find them early, find them early, and find them early!

BIOGRAPHY FOR DONALD K. YEOMANS

At the Jet Propulsion Laboratory in Pasadena California, Donald K. Yeomans is

a Senior Research Scientist, supervisor of the Solar System Dynamics Group, and

manager of NASA’s Near-Earth Object Program Office. His group is responsible for

providing position predictions for the solar system’s planets, natural satellites, comets and asteroids. For the comets and asteroids that can approach the Earth, his

group monitors their motions and provides predictions and impact probabilities for

future Earth encounters.

Dr. Yeomans was the Radio Science team chief for NASA’s Near-Earth Asteroid

Rendezvous (NEAR) mission. He is currently the NASA Project Scientist for the

Joint Japanese and U.S. mission to land upon, and return a sample from, a nearEarth asteroid (Hayabusa) and he was a scientific investigator on NASA’s Deep Impact mission that successfully impacted comet Tempel 1 in July 2005. He provided

the accurate predictions that led to the recovery of comet Halley at Palomar Observatory on October 16, 1982 and allowed the discovery of 164 BC Babylonian observations of comet Halley on clay tablets in the British Museum.

He is a graduate of Middlebury College in Vermont and received his doctorate degree in astronomy from the University of Maryland in 1970. He has written numerous technical papers and four books on comets and asteroids. He has been awarded

15 significant achievement awards by NASA including an Exceptional Service Medal

and a Space Act Award. To honor his work in planetary science, asteroid 2956 was

renamed 2956 YEOMANS.

Chairman UDALL. Thank you, Dr. Yeomans. You all heard the

bells ringing. One vote has been called on the Floor of the House,

so we are going to continue the hearing. Congressman Lampson

will come back and relieve me, so we can make the best use of your

time and the Committee’s time.

So, thank you, Dr. Yeomans. We will move to Dr. Campbell.

Looking forward to your testimony, sir.

STATEMENT OF DR. DONALD B. CAMPBELL, PROFESSOR OF

ASTRONOMY, CORNELL UNIVERSITY; FORMER DIRECTOR,

ARECIBO OBSERVATORY

Dr. CAMPBELL. Mr. Chairman and Members of the Committee,

thank you for this opportunity to address you on the role of radar,

and specifically, the radar system on the giant Arecibo Telescope

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in Puerto Rico, in the tracking and characterization of NEOs, and

the current state of funding of this National Science Foundation facility.

Dr. Yeomans has just described the importance of precision radar

measurements in predicting the future orbits of NEOs, and determining which NEOs are really hazardous to Earth. For these hazardous objects, additional precision radar measurements are extremely important to assess the impact probability and the need to

take action to mitigate the threat.

Near-Earth asteroids form a very diverse population, encompassing a large range of sizes, shapes, rotation states, densities, internal structure, and binary nature. It is important to understand

the range of these characteristics in order to design suitable mitigation strategies. While a very small number of NEOs have been

visited by spacecraft, radar provides by far the best means to survey these characteristics for a large number of objects. For an object that we know poses a direct threat to Earth, radar can provide

vital input to mitigation planning.

As you have heard, there are only two very high powered radars

in the world capable of studying solar system bodies including

NEOs. One is on the NSF’s Arecibo Telescope, and the other is on

NASA’s Deep Space Network 70 meter antenna in California. The

Arecibo radar is over 20 times more sensitive than the one on the

Goldstone antenna, and has been the dominant contributor to nearEarth asteroid characterization and orbit prediction. However, the

Goldstone antenna can look at more of the sky than Arecibo, making the two systems very complementary. They should both be preserved.

In 2005 and 2006, the NSF Division of Astronomical Sciences undertook a Senior Review to examine the balance of its investments

in various astronomical facilities the Division supports, including

the Cornell University-based National Astronomy and Ionosphere

Center, which operates the Arecibo Observatory for the NSF. The

report was submitted to the NSF in November 2006. Despite considerable input to the Committee from both the National Astronomy and Ionosphere Center and the planetary community, the Arecibo Planetary NEO Radar Program is essentially ignored in the

Committee’s report.

The report recommended that NAIC’s operating funds provided

by the NSF’s Division of Astronomical Sciences be reduced over the

following three years from approximately $10.5 million to $8 million, and then in Financial Year 2011, be halved again to $4 million. At the $8 million level, budgetary pressures are likely to make

the termination of the radar and NEO program unavoidable, unless

additional funding is found. In the slightly longer-term, if Cornell

cannot find the additional funding needed to keep the Observatory

open, then, in the report’s words, ‘‘The Senior Review recommends

closure after 2011 if the necessary support is not forthcoming.’’

If the Arecibo radar system is decommissioned, it would leave

the lower sensitivity NASA Goldstone system as the only radar in

the world capable of precise orbit determination for NEOs and

measurements characterizing their physical properties. It will probably be unable to fill the void, especially with the large number of

NEOs likely to be detected over the next decade or more.

42

Replacing the Arecibo Telescope and radar system with a mission-specific facility of equal sensitivity would cost several hundred

million dollars. Given its contributions to the NEO program and

other research areas, and the relatively small budget needed to

keep it operating, closing Arecibo does not make sense.

In answer to the question as to how much it would cost to support Arecibo for NEO activities, independent of any other use of the

telescope, the budget would probably need to be very roughly the

same as the Observatory’s current budget, about $10 million per

year. Most of the operating costs of large telescopes are fixed costs,

relating to such things as maintenance, independent of the science

mission.

In summary, Earth-based radar provides critical information related to NEO orbit prediction and characterization. Arecibo is the

primary radar involved in this activity, and will remain so for at

least the next 10 years provided that both the Observatory and its

radar system are adequately funded.

If the Arecibo Observatory is closed, a unique research capability

will be lost that makes valuable contributions not only to the study

of Near-Earth Objects, but in other areas of astronomy and atmospheric science. One of Puerto Rico’s main research facilities, and a

spectacular structure as you saw earlier, the Arecibo Telescope is

important to local education and tourism. Its closing would be a

major loss to both science and the island.

Thank you for your attention.

[The prepared statement of Dr. Campbell follows:]

PREPARED STATEMENT OF DONALD B. CAMPBELL

Mr Chairman and Members of the Committee, thank you for this opportunity to

address you on the important issue of near-Earth objects and their potential threat

to Earth.

I have been asked to address issues related to the use of radar systems to track

and characterize near-Earth objects (NEOs) and, specifically, to address the role of

the radar system on the giant Arecibo telescope in Puerto Rico in this activity and

the current state of funding for this National Science Foundation facility. I will address these questions in turn.

• What role do Earth based radars play in the tracking and characterization of Near

Earth Objects (NEOs)? What role, if any, do they play in providing information

about specific hazardous objects?

Radar plays an important role in predicting the future orbits of NEOs and measuring many of their physical characteristics such as size, shape, rotation state and,

in the case of binary objects, their mass and density. Radar can measure distances

to NEOs to an accuracy of about 10m (30 ft) and their line-of-sight velocity to an

accuracy of about one mm per second (12 ft per hour), orders of magnitude better

than the equivalent optical measurements. For potentially hazardous objects

(PHOs), optical observations based on measuring their changing position on the sky

over days or weeks in many instances cannot rule out a possible future impact with

the Earth. To do so can require optical positional measurements spanning years or

decades. For future searches, radar astrometry, the measurement of distance and

line-of-sight velocity, can be used to help cull the number of PHOs—not all the

newly detected NEOs will be observable with radar—so that we can concentrate on

the few that really are potentially hazardous. For these objects, additional precision

radar measurements are extremely important to assess the impact probability and

the need to take action to mitigate the threat.

The more we know about NEOs in general and about specific ones that pose a

threat to Earth, the easier it will be to design effective mitigation strategies. ‘‘Know

your enemy’’ would seem to be good advice in this instance. NEOs form a very diverse population encompassing a large range of sizes, shapes, rotation states, densities, internal structure and binary nature. While a very small number of NEOs

have been visited by spacecraft, radar provides by far the best means to survey

43

these characteristics for a large number of objects. Knowing the range of characteristics facilitates the design of effective mitigation techniques that can be applied to

an object with any of these characteristics. For an object that we know poses a direct threat to Earth, radar can provide vital input to mitigation planning including

planning for any precursor space mission.

Over the past few years, the accuracy of the Earth impact prediction based on

precision radar astrometry for a few PHOs has been limited not by the accuracy of

the radar measurements but by the inability to accurately model all of the very

small forces on these objects in addition to that due to the Sun’s gravity. One of

these forces, the Yarkovsky effect, is related to sunlight absorbed by the body and

its re-emission as heat. Precision radar astrometry over several years of a small asteroid, Golevka, demonstrated in 2003 that this effect can modify the orbits of small

asteroids over very long periods of time. This has revolutionized our understanding

of how small asteroids in the main asteroid belt between Mars and Jupiter are

transported into the inner solar system to become NEOs and, some, PHOs. This new

understanding resulting from a basic science driven project will also help in refining

PHO Earth impact probabilities for the few objects that may be of real concern.

• What role has the Arecibo Observatory played in surveying NEOs and what are

the impacts to the NEO program should Arecibo be decommissioned?

The radar system on the NSF’s Arecibo Telescope in Puerto Rico is one of only

two very high powered radars in the world that are used for studying solar system

bodies including NEOs. The other one is on NASA’s Deep Space Network 70m antenna at Goldstone in California’s Mojave desert. With its 300m (1,000 ft) diameter

telescope and radiated power of one megawatt, the Arecibo radar is over 20 times

more sensitive than the one on the Goldstone antenna. However, because of its limited steerability, Arecibo can only observe about half the sky observable with the

Goldstone antenna making the two systems very complementary.

Because of its greater sensitivity and availability, the Arecibo radar system has

carried out 65 percent of all radar observations characterizing NEOs, 47 percent of

the known binary NEOs were discovered with Arecibo (most of the rest were discovered with optical telescopes), and data from Arecibo was used for 85 percent of the

NEOs for which precision radar distance and velocity astrometric measurements

have been made for orbit determination.

If the Arecibo radar system is decommissioned it would leave the lower sensitivity

radar system on the NASA 70m Goldstone antenna as the only radar system in the

world capable of precise astrometry of NEOs and measurements characterizing their

physical properties. A tremendous amount of basic science related to NEOs and

other solar system bodies would be lost and the highest sensitivity radar would no

longer be available to provide precision astrometry and characterization data just

as the NEO search programs are ramping to a new level. Given the pressures on

the 70m Goldstone antenna in carrying out its prime mission, its lower sensitivity

and the large number of NEOs likely to be detected over the next decade or more,

it seems unlikely that this system could come close to filling the void. Replacing the

Arecibo telescope and radar system with a mission specific facility of equal sensitivity would cost several hundred million dollars. Given its contributions to the NEO

program and other research areas in radio astronomy and ionospheric physics and

the relatively small budget needed to keep it operating, closing Arecibo does not

make sense. In the words of Bill H.R. 3737, recently submitted by Congressman

Fortun ̃ o on behalf of himself, Congressman Rohrabacher and other Members of the

House of Representatives, ‘‘The Arecibo Observatory is an invaluable and unique

asset in warning and mitigating potential hazards posed by near-Earth objects.’’

• Did the recent National Science Foundation (NSF) Senior Review of Arecibo evaluate the facility’s role in surveying NEOs and the impact of Arecibo’s potential decommissioning on the NEO survey program? If not, why not?

The National Astronomy and Ionosphere Center (NAIC), the formal name for the

Arecibo Observatory located in Puerto Rico, is one of the four National Astronomy

Centers plus the U.S. component of the international Gemini observatory, funded

through the Division of Astronomical Sciences at the NSF and is operated by Cornell University under a Cooperative Agreement with the NSF. NAIC is unique

among the Centers in that it supports research in three diverse areas, radio astronomy, planetary radar astronomy including the study of NEOs, and ionospheric physics. The first two are supported through funding from the Division of Astronomical

Sciences at the NSF while the ionospheric program, about 15 percent of the budget,

is funded through the Division of Atmospheric Sciences at the NSF. NAIC has about

120 people working at the Arecibo Observatory in Puerto Rico. In addition to providing research facilities for its scientific user community, it operates a visitor cenVerDate 11-MAY-2000 18:21 Feb 21, 2008 Jkt 038057 PO 00000 Frm 00047 Fmt 6633 Sfmt 6621 C:\WORKD\SA07\110807\38057 SCIENCE1 PsN: SCIENCE1
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ter that attracts about 120,000 visitors a year most from Puerto Rico including

about 25,000 school children.

In 2005–2006 the Division of Astronomical Sciences of the National Science Foundation (NSF) undertook a ‘‘Senior Review’’ to examine the balance of its investments

in the various astronomical facilities that the Division supports. The review was motivated by a combination of the budget outlook at that time for the Foundation and

the ambitions of the astronomical community to invest in new facilities to address

fundamental questions as recommended in the previous Astronomy Decadal Survey

and other reports such as ‘‘Connecting Quarks with the Cosmos.’’ The Senior Review

committee submitted its report to the NSF in November, 2006.

The aims of the Senior Review were widely supported by the astronomical community and it is not my intention to criticize its major findings. However, its charge

was to look at the ‘‘big picture’’ and in such a process small, high quality programs

that are not central to the priorities of the committee or the NSF can end up becoming a casualty on the way to the main goal. Such seems to be the case for the planetary/NEO radar program at the Arecibo Observatory. During the review process,

Cornell University and NAIC provided considerable input to the committee about

the Observatory’s research programs including the planetary/NEO radar program.

Many planetary astronomers, especially those interested in NEOs, wrote to the

Committee strongly supporting the Arecibo radar program. However, the Arecibo

planetary/NEO radar program was essentially ignored in the committee’s report

with the only explanation I have heard being that the program was too small in

funding terms to be individually considered. There were no planetary astronomers

on the committee.

I should emphasize that the Senior Review report did not recommend that the

Arecibo planetary/NEO radar program be canceled but that is likely to be the outcome of its budgetary recommendations vis-a`-vis NAIC. It recommended that

NAIC’s operating funds provided by the NSF Division of Astronomical Sciences,

about 85 percent of its yearly budget with the rest coming from the NSF Division

of Atmospheric Sciences, be reduced over the following three years from approximately $10.5M to $8M and then, in FY 2011, be halved again to $4M. By early 2009

Cornell is required to have definite commitments from other entities for the additional operating funds needed to keep the observatory open. If it cannot get these

commitments then, in the Senior Review report’s words ‘‘The Senior Review recommends closure after 2011 if the necessary support is not forthcoming.’’

The planetary/NEO radar program is scheduled to continue in operation at a reduced level of activity through FY 2008 compared with its normal use of about 400

hours of telescope time per year. If the NSF implements the Senior Review’s recommendations to reduce NAIC’s budget for astronomical research to the $8M level,

budgetary pressures and deferred maintenance are then likely to make termination

of the radar/NEO program unavoidable unless additional funding is found. Since the

planetary/NEO radar system has significant operational and maintenance costs associated with the transmitting system, terminating it is the only identifiable way

to save about $1M in operating costs short of canceling the observatory’s entire

radio astronomy program. The NSF has said that they will not augment NAIC’s

budget to provide support for the planetary radar/NEO program and has indicated

that this area of research should be supported by NASA. Until a few years ago,

NASA did provide partial support for the Arecibo radar program. In the slightly

longer-term, if additional operating funds are not found well before the projected FY

2011 NSF/AST reduction to $4M then the Arecibo Observatory will possibly be

closed definitely terminating its contributions to the tracking and characterization

of NEOs.

• What level of funding and technical support would be required to carry out the

NEO-related activities of Arecibo, independent of any other astronomy-related activities? Will any upgrades to the facility or its instruments be required?

The current yearly cost for operating Arecibo’s planetary radar system for about

400 hours a year is close to $1M. About 60 percent of this time is devoted to NEO

research. This covers the cost of the operation and maintenance of the high powered

transmitting capability plus several engineers and a small scientific staff. It does

not cover major maintenance items for the transmitting system. It also does not

cover the cost for the operation and maintenance of the telescope and the general

support for grounds, buildings, etc., needed to keep the observatory operating as a

facility. Prorating these costs based on the observing hours used would raise the

current costs of the planetary radar program to close to $2M/yr.

No study has yet been done of the precise role of the Arecibo radar and how many

hours of NEO observations will be needed when the new, high sensitivity searches

commence starting with Pan-STARRS. This needs to be done. The demand for the

45

use of the Arecibo radar will undoubtedly increase significantly but whether by a

factor of two or five is uncertain. While maintaining the observatory’s multi-disciplinary program, some increase in the use of the radar system for NEO observations

can certainly be accommodated. A program using about 500 hours a year for NEO

observations and, perhaps, 100 hours for radar studies of other solar system bodies

would cost $2M to $3M including its share of general observatory support costs. The

costs would prorate roughly with observing time.

In answer to the question as to how much it would cost to support Arecibo for

NEO activities independent of any other use of the telescope, the budget would need

to be very roughly the same as the observatory’s current budget, about $10M per

year. Most of the operating costs of large telescopes are fixed costs related to maintenance, etc., independent of the science mission. However, I want to emphasize

that any NEO radar program is unlikely to utilize all, or even a majority, of the

observing time available on the telescope.

The Arecibo telescope and radar system underwent a major NSF and NASA funded upgrading about ten years ago. At this time some major components of the transmitting system need refurbishment or replacement and some of the data handling

equipment used for the NEO program needs updating. Total costs of this are estimated to be about $2M.

• What are your perspectives on NASA’s Near-Earth Object Survey and Deflection

Analysis of Alternatives Report to Congress?

NASA’s report was a comprehensive discussion of the issues related to the detection of 90 percent of all NEOs larger than 140m by 2020, the requirement to determine their orbits, understand the broad characteristics of different classes of asteroids in order to be able to design mitigation strategies, and, of course, the range

of possible mitigation strategies. Staying within my area of expertise, the report’s

discussion on the usefulness of determining orbits with radar versus with optical

means and the best means to characterize these objects to, in the report’s words,

‘‘inform mitigation’’ should be revisited. For orbit determination the issue is whether

a relatively quick refinement of at least some percentage of the orbits of newly discovered PHOs is preferable to waiting the 10 to 20 years that optical means require

for orbit determinations that will as stated in the report ‘‘nearly match the accuracy

of radar-improved orbits.’’

The role of the radar systems in surveying the broad range of NEO types could

also have been given more emphasis in the report. Radar is currently the only Earth

or Earth-orbit based technique that has the resolution needed to provide information about a wide range of physical properties important to mitigation planning. The

images below show the detailed shape model of the main component of the binary

NEO 1999 KW4 and a simulation of the binary system, results obtained by Steven

Ostro of JPL and colleagues from observations using the Arecibo and Goldstone radars. The work was described in the cover article of Science magazine last November. We now know KW4’s size, about 1.5 km (one mile) for the main body, shape,

rotation rate, mass, density and that it is a binary object. The low density of the

main body, about twice that of water, tells us that it is rubble pile rather than a

single large ‘‘rock.’’ This is all information that is critical to ‘‘informing mitigation.’’

46

47

Chairman UDALL. Thank you, Dr. Campbell.

Next on the panel is Dr. Tyson, and I would, as a preface to his

remarks, mention that as a Member of the Armed Services Committee, I am used to many, many acronyms, and I used one earlier

in my comments to begin the hearing, about the LSST, which is the

Large Synoptic Survey Telescope Project, and Dr. Tyson is a key

part of that effort.

So, Dr. Tyson, welcome, and the floor is yours.

STATEMENT OF DR. J. ANTHONY TYSON, PROFESSOR OF

PHYSICS, UNIVERSITY OF CALIFORNIA, DAVIS; DIRECTOR,

LARGE SYNOPTIC SURVEY TELESCOPE PROJECT

Dr. TYSON. Thank you, Mr. Chairman and Members of the Committee. It is an honor to be asked to testify before you today on this

important subject.

The House Committee on Science has been a leader, on a bipartisan basis, over two decades, in focusing attention on the need to

detect, characterize, and catalog near-Earth asteroids. The passage

of the George E. Brown Near-Earth Object Survey Act was a landmark piece of legislation that sets a goal of cataloging 90 percent

of NEOs of 140 meters in diameter and larger within 15 years.

The Committee is properly looking at the existing and future capabilities of carrying out this goal and expanding the existing

Spaceguard program. LSST adopted the goal of surveying NEOs at

the outset as one of its major science capabilities. I have attached

to the statement a nine page summary of the capabilities of LSST

for detecting NEOs and obtaining their orbits.

Until recently, the discussion of risk associated with an impact

of NEOs has been statistical. In other words, what is the probability? This is similar to considerations of risk in many other

areas, such as weather and traffic accidents. What if it were feasible to deploy a system that would alert me of an impending traffic accident well in advance? That would change the very nature

of that risk from a probabilistic worry to a deterministic, actionable

situation. The ability to detect virtually every potentially hazardous near-Earth object and determine its orbit with precision

transforms that statistical threat into a deterministic prediction.

We face many threats, and virtually all of them are either so complex or unpredictable that they are treated probabilistically, even

though the social and financial consequences are legion. With a

comparatively small investment, the NEO risk can be transformed

from a probabilistic one to a deterministic one, enabling mitigation.

Ground-based optical surveys are the most cost-effective tool for

comprehensive NEO detection, determination of their orbits, and

subsequent tracking. Radar, as we have heard, also plays an important role once the threatening NEO has been found, in refining

its orbit when the NEO is near. The first job is to find the NEOs

which are potentially hazardous, so-called potentially hazardous

objects, or potentially hazardous asteroids, actually, from among

the swarm of 10 million other asteroids.

A survey capable of extending these tasks to NEOs with diameters as small as 140 meters, as mandated by Congress, requires a

large telescope, a large camera, and a sophisticated data acquisition, processing, and dissemination system. This Congressional

48

mandate drives the requirement for an eight meter class telescope

with a 3,000 megapixel camera and a sophisticated and robust data

processing system. These requirements are met by the LSST.

The LSST is currently, by far, the most ambitious proposed survey of the sky. With initial funding from the National Science

Foundation, Department of Energy laboratories, and private sponsors, the design and development efforts are well underway at

many institutions.

Fortunately, the same hardware and software requirements are

driven by science unrelated to NEOs. LSST reaches the threshold

where different science drivers, and therefore, different agencies,

NSF, DOE, and NASA, can work together to efficiently achieve

seemingly disjoint but deeply connected goals. This broad range of

science has earned LSST the endorsement of a number of committees commissioned by the National Academy of Sciences. Because

of this synergy, the Congressional mandate can be reached at only

a fraction of the cost of a mission dedicated exclusively to NEO

search.

We have carried out over 100 computer simulations of the LSST

operations for a variety of NEO optimized scenarios. The planned

LSST baseline survey cadence on the sky, that is to say, the way

you tile the sky with time, during the night, is capable of providing

orbits for 82 percent of potentially hazardous asteroids larger than

140 meters after 10 years of operation, and is 90 percent complete

for objects larger than 230 meters. This baseline cadence assumes

that five percent of the total observing time is spent on NEO specialized observing. This is what is currently planned.

By increasing this fraction of NEO specialized surveying to 15

percent, that is to say, from five to 15 percent, and by running the

survey longer, the Congressional mandate of 90 percent completeness for potentially hazardous asteroids of 140 meters and greater

size, can be fulfilled after 12 years of operation, with 60 percent

completeness level reached after only three years. These specialized

observations would be of limited use to other science programs, and

they require 15 percent of the observing time. The current cost estimate for LSST in 2006 dollars is $389 million for construction, and $37 million per year for operations. For

a 12-year long survey, 15 percent of this total cost is $125 million.

Thus, we could deliver the performance of a full NEO dedicated

LSST to NASA and to the world at a small fraction of the total cost

to build and operate such a system. This cost is equivalent to 30

percent of operations, which would commence in 2014.

Note that by operating LSST in this special NEO optimized

mode, we would have the performance equivalent of an LSST fully

dedicated to NEO serving. By supporting only 15 percent of the

total cost, NASA would be essentially getting an NEO dedicated

LSST. This is a key new insight, relative to the costing model in

the 2007 NASA NEO report to Congress.

Thank you.

[The prepared statement of Dr. Tyson follows:]

PREPARED STATEMENT OF J. ANTHONY TYSON

Mr. Chairman and Members of the Committee. It is an honor to be asked to testify before you today on this important subject. By way of identification, I am an

astrophysicist and Professor of Physics at the University of California, Davis, and

49

Director of the Large Synoptic Survey Telescope (LSST) project; before coming to

UC–Davis four years ago I did research and development at Bell Labs for 34 years.

The House Committee on Science has been a leader on a bipartisan basis for over

two decades in focusing attention on the need to detect, characterize, and catalog

near-Earth asteroids. The passage of the ‘‘George E. Brown Jr. Near-Earth Object

Survey Act’’ was a landmark piece of legislation that sets a goal of cataloging 90

percent of NEOs of 140 meters in diameter and larger within 15 years. The Committee is properly looking at the existing and future capabilities for carrying out

this goal and expanding the existing Spaceguard program. LSST adopted the goal

of surveying NEOs at the outset as one of its major science capabilities.

Until recently, the discussion of risk associated with an impact of a NEO has been

statistical; what is the probability? This is similar to considerations of risk in many

other areas such as weather and traffic accidents. What if it were feasible to deploy

a system that would alert me of an impending traffic accident well in advance? That

would change the very nature of that risk from a probabilistic worry to a deterministic actionable situation. The ability to detect virtually every potentially hazardous Near-Earth object and determine its orbit with precision transforms that statistical threat into a deterministic prediction. We face many threats, and virtually

all of them are either so complex or unpredictable that they are treated

probabilistically even though the social and financial consequences are legion. With

a comparatively small investment the NEO risk can be transformed from a probabilistic one to a deterministic one, enabling mitigation.

The First Job: Finding the NEOs

Ground-based optical surveys are the most efficient tool for comprehensive NEO

detection, determination of their orbits and subsequent tracking. (Radar also plays

an important role once a threatening NEO has been found, in refining its orbit

when the NEO is near.) The first job is to find the NEOs which are potentially hazardous (so-called Potentially Hazardous Asteroids) from among the swarm of ten

million other asteroids. A survey capable of extending these tasks to NEOs with diameters as small as 140m, as mandated by Congress, requires a large telescope, a

large camera, and a sophisticated data acquisition, processing and dissemination

system. The Congressional mandate drives the requirement for an eight-meter class

telescope with a 3000 Megapixel camera and a sophisticated and robust data processing system. These requirements are met by the LSST.

Why is a large telescope required? A typical 140-meter NEO appears very faint

(visual magnitude of 25). Multiple NEO detections in a single night are required to

estimate its motion, so that its future or past detections can be linked together. This

linkage has to be done exceedingly robustly because the near-Earth objects will be

outnumbered nearly a thousand to one by main-belt asteroids (between Mars and

Jupiter) which present no threat to Earth. By reliably linking detections on multiple

nights, the NEO’s orbit can be reconstructed and used to compute its impact probability with Earth. Despite their name, NEOs are typically found far from Earth.

In principle, very faint objects can be detected using long exposures, but for objects

moving as fast as typical NEOs, the so-called trailing losses limit the exposure time

to about 30 seconds. In order to detect 140-meter NEOs in 30 seconds, an eightmeter class telescope is required.

Why is a large camera required? The need for a very large field of view comes

from the requirement that the whole observable sky should be observed at least

every four to five nights. For comparison, we need a field of view thousands of times

larger than the Hubble Space Telescope’s Advanced Camera for Surveys. With its

10 square degree field of view, LSST will be able to reach the mandated high NEO

completeness.

Finding Near-Earth Objects with Ground-based Surveys

Ground-based optical surveys are a very cost effective tool for comprehensive NEO

detection, determination of orbits, and subsequent tracking. A survey capable of extending these tasks to NEOs with diameters as small as 140m, as mandated by

Congress, drives the requirement for a large telescope, a large camera, and a sophisticated data acquisition, processing and dissemination system.

To find a significant fraction of the faint NEOs one must essentially make a movie

of the deep sky. Each faint asteroid must be captured in many separate exposures

in order for computers to distinguish it from the numerous other asteroids and then

piece together its orbit. A large area of the sky (ideally all the sky visible from some

location on Earth, at least 20,000 square degrees) must be surveyed rapidly and

deeply in order to survey a large volume for these faint asteroids. The ability of a

telescope and camera to take rapid deep repeated images of the entire sky is proportional its ‘‘throughput.’’ Throughput (sometimes called etendue) is simply the prodVerDate 11-MAY-2000 18:21 Feb 21, 2008 Jkt 038057 PO 00000 Frm 00053 Fmt 6633 Sfmt 6621 C:\WORKD\SA07\110807\38057 SCIENCE1 PsN: SCIENCE1
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uct of the telescope light collection area (units: square meters) times the camera

field of view in a single snapshot (units: square degrees). Thus throughput of a survey facility is measured in units of square meters square degrees. The throughput

of LSST is 320 square meters square degrees. High throughput is a necessary condition for such a facility to carry out its mission, but not a sufficient condition: one

must also arrange to have high observing efficiency (access to the sky) and highly

efficient optics and imaging detectors in the camera, as well as superb image quality.

For an efficient NEO survey, the whole observable sky should be observed at least

every four to five nights, with multiple observations per night. In order to do so with

exposure time of about 30 seconds per observation, a 10 square degree large field

of view is required. Such a large field of view, with pixel size sufficiently small to

fully sample the image at a good observing site, implies a multi-billion pixel camera.

Indeed, at the time of its completion, the 3.2 billion pixel LSST camera will be the

largest astronomical camera in the world.

With a 3.2 billion pixel camera obtaining images every 15 seconds (individual 30

second exposures are split into two 15 second exposures for technical reasons), the

data rate will be about 20 thousand gigabytes per night. Not only is this a huge

data rate, but the data have to be processed and disseminated in real time, and

with exquisite accuracy. It is estimated that the LSST data system will incorporate

several million lines of state-of-the-art custom computer code.

State of the LSST project

The Large Synoptic Survey Telescope (LSST) is currently by far the most ambitious proposed survey of the sky. With initial funding from the U.S. National

Science Foundation (NSF), Department of Energy (DOE) laboratories and private

sponsors, the design and development efforts are well underway at many institutions, including top universities and leading national laboratories. The main science

themes that drive the LSST system design are Dark Energy and Dark Matter, the

Solar System Inventory, Transient Optical Sky and the Milky Way Mapping. It is

this diverse array of science goals that has generated the widespread excitement of

scientists ranging from high-energy physicists to astronomers and planetary scientists, and earned LSST the endorsement of a number of committees commissioned

by the National Academy of Sciences.

Fortunately, the same hardware and software requirements are driven by science

unrelated to NEOs: LSST reaches the threshold where different science drivers and

different agencies (NSF, DOE and NASA) can work together to efficiently achieve

seemingly disjoint, but deeply connected, goals. Because of this synergy the Congressional mandate can be reached at only a fraction of the cost of a mission dedicated

exclusively to NEO search.

The scientific priority for constructing a large aperture ground based survey telescope was recommended in the astronomy and astrophysics Decadal Survey 2000 report entitled Astronomy and Astrophysics in the New Millennium. Since then, LSST

has reached a high state of design maturity. LSST has recently passed the NSF

Conceptual Design Review for construction, which puts it on track for transition to

Readiness in spring 2008. LSST is a public-private project. To date $44M in private

funding has been raised. Twenty two institutions have joined the effort and have

contributed significant in-kind technical labor. LSST R&D continues for another

three years under NSF support along with in-kind contributions. The project is on

track for first light in 2014. It is proposed that the DOE (because of the importance

of LSST for addressing the mystery of dark energy) support the $80M cost of constructing the camera. Foreign support now appears likely, and this in-kind would

offset the camera cost.

Method of Study: the LSST Operations Simulator

The LSST Operations Simulator was developed to be able to do just the sort of

assessment described in this document. It contains detailed models of site conditions, hardware and software performance, and an algorithm for scheduling observations which will, eventually, drive the robotic LSST observatory. The resulting sky

coverage for the LSST baseline cadence is shown in Figure 1.

For the currently planned LSST baseline cadence, objects counted as cataloged are

observed on 20 different nights on average. A more stringent requirement could decrease the completeness by up to three percent. The completeness is also a function

of the assumed size distribution: the flatter the distribution, the higher the completeness. If the latest results for the NEO size distribution by A. Harris are taken

into account, the completeness increases by one to two percent. Due to these issues,

the completeness estimates have a systematic uncertainty of two percent. Our analVerDate 11-MAY-2000 18:21 Feb 21, 2008 Jkt 038057 PO 00000 Frm 00054 Fmt 6633 Sfmt 6621 C:\WORKD\SA07\110807\38057 SCIENCE1 PsN: SCIENCE1
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ysis assumes that no NEOs are known prior to LSST. Current surveys make a negligible contribution to the 90 percent completeness for NEOs of 140m and up.

The NEO survey completeness achievable with LSST

The LSST system is the only proposed astronomical facility that can detect 140-

meter objects in the main asteroid belt in less than a minute. The LSST system will

be sited at Cerro Pachon in northern Chile, with first light scheduled for 2014. In

a continuous observing campaign, LSST will cover the entire available sky every

four nights, with at least two observations of an NEO per night. Over the baseline

survey lifetime of 10 years, each sky location would be observed over 800 times. Two

NEO detections in a single night are required to estimate its motion, so that its future or past detections can be linked together. This linkage has to be done exceedingly robustly because the near-Earth objects will be outnumbered a hundred to one

by main-belt asteroids which present no threat to Earth. By reliably linking detections on multiple nights, the NEO’s orbit can be reconstructed and used to compute

its impact probability with Earth.

The currently planned LSST baseline observing cadence on the sky, described in

the Major Research Equipment and Facilities Construction proposal submitted to

NSF, is simultaneously optimized for all four main science drivers: Characterizing

Dark Energy and Dark Matter, the Solar System Inventory, Transient Optical Sky,

and the Milky Way Mapping (see Figure 1). Computer simulations of LSST observing show that the data stream resulting from this baseline cadence on the sky is

capable of providing orbits for 82 percent of Potentially Hazardous Asteroids (PHA)

larger than 140 meters after 10 years of operations. The completeness curve as a

function of time since the start of the survey is shown in Figure 2 (second curve

from top). This baseline cadence spends five percent of the total observing time on

NEO-optimized observations in the north region of the ecliptic (plane of the solar

system).

Various adjustments to this baseline cadence can boost the completeness for 140m

and larger PHAs to 90 percent. Based on about 100 different simulations, we find

that such adjustments to the baseline cadence or filter choices can have unacceptably large impact on other science programs, if the 90 percent completeness is to

be reached within 10 years from the beginning of the survey. However, with a minor

adjustment of the baseline cadence and additional specialized observing for NEOs,

this completeness level can be reached with a 12-year long survey, and with a negligible effect on the rest of science goals.

These specialized observations would be of limited use to other science programs,

and they require 15 percent of the observing time. The dependence of completeness

for 140m and larger objects on time is shown in Figure 2. For LSST, Figure 2 shows

the baseline survey and the special NEO-optimized survey. In addition, we also

show completeness curves for the same observing cadence and under the same assumptions regarding seeing and efficiency for smaller versions of LSST of less

throughput. The lowest curve (black line) in Figure 2 shows the completeness for

current NEO assets (ca. 2014–) for comparison.

Conclusions

The ability of LSST to reach the mandated 90 percent completeness for 140m and

larger PHAs in 10 years by the so-called ‘‘dedicated’’ option described in the 2007

NASA NEO report is supported by our detailed and realistic simulations. An important additional insight from these simulations is that we can deliver the performance of a ‘‘dedicated’’ system by spending 85 percent of the total observing time on

a general survey useful for all LSST science programs, and by specializing only

about 15 percent of the total observing time for NEO surveying. If such an NEOoptimized program is executed for 12 years, the 90 percent completeness for 140m

and larger PHAs can be reached without a significant negative impact on other

science programs. The current cost estimate for LSST in 2006 dollars is $389M for construction and

$37M per year for operations. For a 12-year long survey, 15 percent of the total cost

is $125M. Thus, we could deliver the performance of a full NEO-dedicated LSST to

NASA at a small fraction of the total cost to build and operate such a system. This

cost is equivalent to 30 percent of operations, which would commence in 2014. To

assure LSST keeps on schedule, about $5M should be spent on optimized NEO orbit

software pipeline development in the last phase of R&D and the construction phase,

2009–2014.

Executive Summary

In December 2005 Congress directed NASA to implement a near-Earth object

(NEO) survey that would catalog 90 percent of NEOs larger than 140 meters in 15

years. In order to fulfill the Congressional mandate using a ground-based facility,

52

an eight-meter class telescope equipped with a 3200 Megapixel camera, and a sophisticated and robust data processing system are required. These criteria are met

by the Large Synoptic Survey Telescope (LSST). We have carried out over 100 simulations of the LSST operations for a variety of NEO-optimized scenarios. The

planned LSST baseline survey cadence on the sky, simultaneously optimized for all

main science drivers, is capable of providing orbits for 82 percent of PHAs larger

than 140 meters after 10 years of operation, and is 90 percent complete for objects

larger than 230 meters. This baseline cadence assumes that five percent of the total

observing time is spent on NEO-specialized observing. This is what is currently

planned. By increasing this fraction to 15 percent and by running the survey longer,

the Congressional mandate of 90 percent completeness for NEOs of 140m and greater size can be fulfilled after 12 years of operation, with 60 percent completeness

level reached after only three years.

Note that by operating LSST in this special NEO-enhanced mode we would have

the performance equivalent of an LSST fully dedicated to NEO surveying. By supporting only 15 percent of the total cost, NASA would be essentially getting a NEOdedicated LSST. This is a key new insight relative to the costing model in the 2007

NASA NEO report to Congress.

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54

BIOGRAPHY FOR J. ANTHONY TYSON

J. Anthony ‘‘Tony’’ Tyson, distinguished Professor of Physics at University of California, Davis, is an experimentalist interested in gravitational physics. His current

research is in cosmology: dark matter distribution, gravitational lens effects, cosmic

shear, and the nature of dark energy. These investigations involve software for pattern recognition, detection of transients in images, large database handling and

processing, and new instrumentation for optical astronomy. He directs a national effort to build a new kind of telescope/camera called the Large Synoptic Survey telescope (LSST). With its large aperture and wide field of view, LSST promises to shed

light on the mysterious ‘‘dark energy’’ that is considered to be the most urgent problem in the physics of our universe.

Tony Tyson received his B.S. in Physics from Stanford in l962 and a Ph.D. from

University of Wisconsin at Madison in 1967, and a postdoctoral fellowship at the

University of Chicago. He is a Fellow of the American Physical Society and the

American Academy of Arts and Sciences, and a member of the National Academy

of Sciences and the American Philosophical Society.

Mr. LAMPSON. [Presiding] Thank you, Dr. Tyson. Mr.

Schweickart.

STATEMENT OF MR. RUSSELL ‘‘RUSTY’’ L. SCHWEICKART,

CHAIRMAN AND FOUNDER, B612 FOUNDATION

Mr. SCHWEICKART. Mr. Chairman, Mr. Ranking Member Feeney,

and Members of the Committee, Mr. Lampson, I thank you for givVerDate 11-MAY-2000 18:21 Feb 21, 2008 Jkt 038057 PO 00000 Frm 00058 Fmt 6633 Sfmt 6601 C:\WORKD\SA07\110807\38057 SCIENCE1 PsN: SCIENCE1
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ing me the opportunity here to testify on the Near-Earth Object situation, on NASA’s report to Congress on the matter, and on where

we need to go from here.

With very limited time, I will jump right into the four questions

I was asked to address, and our six specific recommendations pertaining to it. We were asked first to provide our perspectives on

NASA’s report to Congress, and whether we agree or disagree with

the report’s findings and recommendations.

The first two elements of the Congress’ directive related to analyzing ways of meeting the new goal, as we have heard, and a specific directive to recommend a program and a budget to support it.

NASA completely ignored Congress’ direction to recommend a

search program and supporting budget. I want to emphasize here,

picking up on Chairman Udall’s earlier comment that not only did

the Congress direct NASA to make a recommendation and a budget

to support it, but the President signed that into law, so it is in law

by both the President and the Congress.

So, our first recommendation is that Congress should again direct NASA, in the clearest language possible, to comply with the

law, and recommend a search program and supporting budget.

With regard to Congress’ directive, the third task of NASA, that

they analyze possible alternatives that could be employed to divert

an object on a likely collision course with Earth, we highlight only

two of the many technical flaws in NASA’s report to Congress. The

first of those, NASA misinterpreted the Congressional intent, and

elected to consider forward deflection, to look at what would be required, only a set of very large, very improbable Near-Earth Objects, rather than the far more frequent but still devastating impacts which we are much more likely to encounter.

Assuming, therefore, this extraordinary demand, NASA naturally

came up with an extraordinary response, namely, the use of nuclear explosives. In fact, 99 percent of the NEOs most likely to trigger a call for deflection can be diverted by non-nuclear kinetic impacts, that is, simply running into the Near-Earth Object with a

spacecraft, similar to what was done by NASA on July 4, 2005, in

the Deep Impact crash into Comet Tempel 1.

In a letter clarifying the Congressional intent, Congressman

Dana Rohrabacher stated that: ‘‘The first order of business is to ensure that we have a clear understanding of what the options are

for the situations we are most likely to encounter.’’ When shown

this letter, NASA’s comment to us, in a June 18, 2007 meeting was,

to paraphrase it: ‘‘If we had seen this letter at the time we began

the study, we might have come out with a different report.’’ Bottom

line, nukes are not necessary, except in extremely rare and unusual circumstances.

The second serious flaw in NASA’s report is that NASA failed to

understand and address the fact that whenever an asteroid passes

near the Earth, for example, as the result of a deflection, it passes

through a region in which are scattered hundreds of impact keyholes, small areas through which, if the asteroid passes, it will return in a few years to impact the Earth. Any deflection which

causes an impacting asteroid to avoid hitting the Earth will end

up, instead, passing through this minefield of impact keyholes. A

successful deflection, therefore, depends upon the use of both a priVerDate 11-MAY-2000 18:21 Feb 21, 2008 Jkt 038057 PO 00000 Frm 00059 Fmt 6633 Sfmt 6601 C:\WORKD\SA07\110807\38057 SCIENCE1 PsN: SCIENCE1
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mary deflection, that is, to miss the Earth, using an appropriate

impulsive technique, that is, a kinetic impact, or in exceptional

cases, a nuclear explosion, and a potential secondary deflection, if

it is headed for a keyhole, using a slow push capability, to ensure

that the NEO both misses the Earth and misses the keyholes,

therefore avoiding placing it on a return trajectory with an impact

in a few years.

Again, in our meeting on June 18, 2007 with NASA, they acknowledged that at the time the analysis was done, it did not understand the importance of this issue. Bottom line, both strength

and precision are necessary for a successful deflection.

Moving on, the second question I was asked to address was

which relevant factors, data, or options are not addressed in the report, and how should NASA investigate those areas. Given the two

serious flaws in NASA’s report, which I just cited, as well as many

others that are outlined in detail in my written testimony, we recommend, number two, that NASA should produce a supplement to

its report to Congress, based on new knowledge which has come to

light since it began its analysis.

The third question Congress asked me to respond to was what

does NASA need to do now to understand and mitigate the risks

of potential NEO impact? Absent someone in NASA going beyond

the search and discovery challenge, and thinking through the complex issues of NEO deflection, we stand justly accused of focusing

on numeric goals for the sake of meeting an abstract quota, that

is, 90 percent of so many objects, et cetera, et cetera. We therefore

recommend that NASA, our third recommendation, that NASA

should assign someone in its NEO program to the specific task of

thinking through, analyzing, and understanding the NEO deflection challenge.

And in addition, our fourth recommendation, based on this question, is that NASA should validate the basic NEO deflection capability, through the execution of a demonstration asteroid deflection

mission. That is, we should not be put in the position of doing a

deflection mission for the first time when lives actually count on

it.

Finally, we were asked what governance structure should be established to address potential NEO threats. This is, by far, the

most important question that I was asked by the Congress. NASA,

as the U.S., and arguably the world’s premier space agency, should

have the responsibility for both fully understanding the NEO deflection challenge and developing and testing deflection technology.

It does not have that responsibility now.

Therefore, our fifth recommendation is that the Congress expressly assign to NASA the technical development elements of protecting the Earth from NEO impacts as a public safety responsibility. That is, without NASA having the specific responsibility assigned to it to develop the technical means of protecting the Earth

from NEO impacts, it will not be done. They must be assigned this

responsibility. Otherwise, there will not be action in this regard.

The larger question, however, is to which agency of government

should the overall responsibility for protecting the Earth from NEO

impacts be assigned, not just the technical development aspects,

but the policy and political responsibility. This inherently interVerDate 11-MAY-2000 18:21 Feb 21, 2008 Jkt 038057 PO 00000 Frm 00060 Fmt 6633 Sfmt 6601 C:\WORKD\SA07\110807\38057 SCIENCE1 PsN: SCIENCE1
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national issue will involve complex and very sensitive coordination

and negotiation, and the U.S. involvement will place in the hands

of the agency responsible the lives and property of potentially the

entire population.

We, therefore, recommend as our final and sixth recommendation

that the Congress study the issue of overall governmental responsibility for protection of the Earth from NEO impacts, perhaps with

the assistance of specialized policy entities, and ultimately, to hold

public hearings to engage a wide perspective on this issue.

The logical candidates, obviously, for this overall responsibility

are the Department of Homeland Security, the Department of Defense, and of course, NASA itself.

This has been, of necessity, a very cursory review of a very important set of issues and questions. I thank you for the opportunity

to discuss them with you, and I look forward to responding to any

questions you may have.

[The prepared statement of Mr. Schweickart follows:]

PREPARED STATEMENT OF RUSSELL L. SCHWEICKART

Mr. Chairman and Members of the Committee:

Thank you for the opportunity to testify on this important subject; an issue of increasing interest regarding the protection of life and property around the planet.

I represent B612 Foundation (B612), a private non-profit corporation founded in

2002 by a group of astronauts, astronomers, planetary scientists and engineers to

advocate and develop the means of diverting a near-Earth object (NEO) threatening

an impact with Earth. B612 has developed several alternative concepts for deflecting NEOs and we have actively urged NASA, the Congress, and others to pursue

the NEO challenge beyond search and discovery and into mitigation and prevention.

I will start by commending the Committee for its efforts since the early 1990s in

seeing that this public safety issue is responsibly addressed. The impact of nearEarth objects with the Earth is properly described as a cosmic natural hazard of

potentially unprecedented dimension, threatening both life and property. Unlike

other natural hazards, however, we can in this instance, using current space technology, both predict and prevent the occurrence of such a disaster.

No other natural hazard presents such a wide range of potential destruction, but

in no other case are we fortunate enough to have at hand the advanced technology

and creative imagination to mitigate such a catastrophic event. The range of explosive impacts we may be called on to prevent extend from the ‘‘Tunguska Event’’ of

1908, approximately a five megaton (MT) explosion over Siberia (equivalent to over

300 Hiroshima bombs) up to impacts 100,000 times larger—large enough to destroy

civilization and threaten the survival of humanity. We intend to prevent such infrequent but devastating events by slightly and precisely modifying the orbit of a

threatening NEO, causing it to pass harmlessly by the Earth. Stated differently, we

intend, using available space technology, to slightly alter the workings of the solar

system in order to enhance human survival on planet Earth.

To realize such a bold claim we must put in place three critical components of

a response system. They are: advanced notice (i.e., an early warning system), a demonstrated deflection capability, and a standing decision process to enable timely action.

The Congress, NASA, and other key global players are to be congratulated for

their excellent work in implementing the first phase of the early warning system,

the Spaceguard Survey, which has been in operation since 1998. The Congress is

to be further commended for its vision in mandating that NASA take the next critical steps as expressed in the George E. Brown, Jr. Near-Earth Object Survey Act

of 2005 (the Act). The Act extends the Spaceguard Survey goal, directing NASA to

‘‘detect, track, catalogue, and characterize . . . near-Earth objects equal to or greater than 140 meters in diameter. . .’’ and to ‘‘achieve 90 percent completion of [the

survey] within 15 years after the date of enactment of this Act.’’

The Congress also directed that ‘‘The Administrator shall transmit to Congress

not later than one year after the date of enactment of this Act an initial report that

provides the following:

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(A) An analysis of possible alternatives that NASA may employ to carry out the

Survey program, including ground-based and space-based alternatives with

technical descriptions.

(B) A recommended option and proposed budget to carry out the Survey program pursuant to the recommended option.

(C) Analysis of possible alternatives that NASA could employ to divert an object

on a likely collision course with Earth.’’

It is NASA’s mixed response to these three directives which prompts my testimony here today.

I have been specifically requested to address the following four questions;

1. What are your perspectives on NASA’s Near-Earth Object Survey and Deflection Analysis of Alternatives Report to Congress? Do you agree or disagree

with the report’s findings and recommendations?

2. Which, if any, relevant factors, data, or options are not addressed in the report and how should NASA investigate those areas?

3. What does NASA need to do now to understand and mitigate the risks of

potential NEO impacts?

4. What governance structures should be established to address potential NEO

threats?

1. Perspectives on the NASA Report

My response to the first question is in three parts, corresponding to the three

components of the Congressional direction to NASA.

a) Analysis of Survey Program Alternatives:

I believe that NASA did a very good job (with the exception of the NASA life cycle

cost estimation for the several survey alternatives) in developing and comparing a

set of alternative Survey designs to meet the 140-meter goal. While I am not personally qualified to comment on the NASA costing I note that knowledgeable PanSTARRS and LSST personnel challenge the NASA figures used. These experts claim

that the actual costs for both cooperative and dedicated use of such telescopic facilities are considerably lower than those projected by NASA.

One factor not addressed in NASA’s analysis of options to meet the revised Survey

goal was the capability of various search system options for NEO tracking vice NEO

discovery. While all of us in the NEO community strongly support moving aggressively to meet Congress’s 140-meter discovery goal the fundamental intent of this

enterprise is to protect the Earth from NEO impacts. This ultimate purpose is

achieved by both the discovery of NEOs which might pose a threat AND also by

tracking them accurately to determine whether or not a deflection campaign is necessary.

It is an unfortunate reality that ground-based telescopic tracking produces, for

many challenging NEOs, discontinuous information; data dropouts may last for several years at a time. Should such a critical data dropout occur just as a NEO is

found to threaten an impact, the decision on mounting a deflection campaign may

well have to be made on the basis of uncomfortably ‘‘stale’’ tracking data. The wellknown NEO Apophis, which currently has a one in 45,000 probability of collision

with the Earth in 2036, is in such a data dropout period at this time. We were last

able to see Apophis in August 2006 and we will not see it again until 2011–2012.

For Apophis this data interruption is uncomfortable, but not critical since we will

see it again before we need to decide on a deflection campaign. This is, however,

simply a matter of chance and in many instances in the future we will not be so

fortunate.

The orbital phasing responsible for this interrupted tracking can be eliminated by

selecting any of several space-based search options in NASA’s analysis to augment

the ground-based systems. While NASA reports that overall costs for space and

ground tracking are comparable (a controversial claim), the tracking quality provided by a telescope in a Venus-like orbit, in particular, is vastly superior. The dualband IR telescope is especially preferable since it also improves greatly our estimates of NEO mass (and thus impact energy).

In summary, NEO search and discovery is extremely important. NEO tracking,

however, is equally important for deciding whether and when to mount a deflection

campaign. The dual-band IR telescope in a Venus-like orbit offers both discovery

and tracking advantages at a cost comparable to the best ground-based telescopic

options.

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b) Recommended Program and Supporting Budget:

With respect to the second Congressional charge to recommend a program to meet

the 140-meter search goal and a budget to support it, NASA failed to respond.

NASA opted instead to state the obvious, that ‘‘. . . due to current budget constraints, NASA cannot initiate a new program at this time.’’ Of course NASA’s tight

fiscal situation is precisely why the Congress requested not only a recommended

program but also a proposed budget necessary to carry it out.

One can sympathize with NASA’s fear of the dreaded ‘‘unfunded mandate’’ from

Congress while decrying the Agency’s decision to defy the Congressional directive

and to delay the initiation of this critical search program. Congress, however, must

also recognize and confront the dilemma it imposes on NASA (and other agencies)

when it directs action without the specific identification of funds to support the

work. Yet given that Congress explicitly directed in its mandate that NASA provide

it with a proposed budget to support the program NASA cannot be excused.

I can only urge that the Congress should again direct NASA in the clearest

language possible to comply with the law and recommend a search program and supporting budget. (Recommendation 1) It is time for the Nation

to aggressively pursue this urgent NEO program.

c) Analysis of Deflection Alternatives:

B612 Foundation believes that NASA’s analysis of deflection alternatives, as reported to the Congress, has serious technical flaws. NASA’s findings and recommendations misunderstand, mischaracterize, and misrepresent many of the critical issues and options involved in the diversion of a threatening NEO. Furthermore

the NASA Report fails to address a number of crucial issues which lie at the very

heart of the deflection challenge.

An analysis of the errors of both commission and omission are too numerous and

detailed to include in this testimony. I have therefore attached to this written testimony, and urge the Members and their staff to read, several documents which address these errors in depth. These documents include:

1. An exchange of correspondence with Congressman Dana Rohrabacher regarding clarification of the intent of the Congress in the nature of the NEOs

to be considered for diversion (attachments 1 & 2),

2. An ‘‘Independent Analysis of Alternatives that could be employed to divert a

NEO on a likely collision course with Earth.’’ (attachment 3; also available

at http://www.b612foundation.org/press/press.html, #15), and

3. Two detailed critiques of the NASA Report addressing on a point-by-point

basis specific errors in the NASA analysis. (attachments 4 & 5; also available

at http://www.b612foundation.org/press/press.html, #16).

To appreciate the depth of the technical errors in the Report, I strongly urge that

these appended documents be reviewed in detail. I will summarize here a few of the

key points.

Size matters

In examining the technical alternatives for diverting threatening NEOs, NASA selected ‘‘. . . a set of five [note: there were actually 7] scenarios representing the likely range of threats.’’ In fact, the set of impact scenarios NASA chose as ‘‘typical’’

were extraordinarily challenging, resulting in a preference for a deflection concept

delivering extraordinary capability, i.e., nuclear explosives.

The least challenging of the NEOs NASA considered in its analysis is part of a

group that comprises just two percent of the potential impact cases. The impact frequency of such an object is once every 35,000 years. The remaining objects considered by NASA range upward to a one kilometer asteroid (one impact per million

years) and a one-kilometer, long-period comet (even more rare).

In fact, objects which hit much more frequently and yet deliver considerable impact energy make up 98 percent of the likely impact threat. The most likely of these

objects to impact is comparable to the Tunguska event of 1908 in Siberian Russia.

That event is estimated to have exploded with the force of about five megatons of

TNT equivalent, or over 300 Hiroshima bombs. Had the Tunguska event been instead the ‘‘London event,’’ or ‘‘Moscow event,’’ it would have destroyed not just 800

square miles of forest and a few reindeer but an entire city and its population.

As Congressman Dana Rohrabacher stated in his clarification letter to B612 on

this subject, ‘‘While it is important to understand what technology exists or needs

to be developed to divert the larger and more devastating NEOs the first order of

business is to insure that we have a clear understanding of that the options are for

the situations we are most likely to encounter.’’

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A random impact occurring directly over a major city is, of course, highly unlikely.

Yet when the possibility of such an event and the means of preventing it from occurring are known to exist by the general population it is reasonable to conclude that

public pressure on the international community will successfully demand that we

initiate a deflection.

Given then a cohort of ‘‘most likely NEOs to be deflected’’ ranging from a

Tunguska-like object at the smallest and most frequent end of the scale up to events

100 times less frequent, we find that over 99 percent of them can be deflected using

non-nuclear means.

The need for the availability of nuclear explosions for deflection in extreme cases

cannot currently be ruled out, but the likelihood of such a demand materializing

over the next several decades is extremely small. Furthermore our search efforts

will make the need for such a solution increasingly unlikely over time.

Precision matters

NASA uses the word ‘‘effectiveness’’ in its Report purely as a measure of how

much momentum change can be imparted to the asteroid. e.g., in its ‘‘Key Findings

for Diverting a Potentially Hazardous Object,’’ the first sentence of the first finding

states ‘‘Nuclear standoff explosions are assessed to be 10-100 times more effective

than the non-nuclear alternatives analyzed in this study.’’ The technical term for

NASA’s undefined word ‘‘effectiveness’’ in this instance is ‘‘total impulse,’’ i.e., the

amount of momentum imparted to the asteroid in the process of the deflection.

Without doubt the total impulse available is a key measure of any deflection concept. However all of the impulsive (i.e., relatively instantaneous as juxtaposed with

slow) deflection techniques evaluated are, while quite powerful, highly uncertain

with regard to predicting the precise total impulse delivered. Experts in the field

estimate uncertainties ranging from factors of two to five or even higher in the resulting total impulse delivered by either the nuclear or kinetic impact deflection concepts.

Certainly ‘‘strength’’ may well be needed in the deflection of an object on an impact trajectory. The first order of business is, without question, to ensure that the

NEO is deflected sufficiently that it miss the planet.

What NASA totally missed however is that whenever an asteroid passes near the

Earth (or any planet) it passes through a region in which are scattered hundreds

of small impact ‘‘keyholes,’’ small areas in Earth’s proximity through which if the

asteroid passes it will return within a few years and impact the Earth. Any deflected asteroid which misses the Earth must transit this minefield of impact keyholes.

Because the percentage of space taken up by such keyholes is small compared

with the space between them the probability of the NEO passing through one is

fairly low. However the consequences of passing through such a keyhole are severe.

Thus, whether or not a deflected NEO misses the keyholes cannot be left to chance.

A successful deflection must therefore be defined as one which causes the potentially impacting asteroid to not only to miss the Earth but also to miss all impact

keyholes. Without this constraint any deflecting agency would be limited to declaring, ‘‘we successfully deflected the asteroid away from an impact with Earth. . . and

it is unlikely that it will return for an impact any time soon.’’

A successful deflection requires both adequate strength and high precision. Immediately following an impulsive deflection the new orbit of the asteroid must be precisely determined and examined for a future keyhole transit. if headed for a keyhole

then a small ‘‘trim’’ maneuver can be executed using a weak but precise ‘‘slow push’’

(as NASA refers to it) deflection to avoid that critical passage.

This combination of imprecise strength and precise adjustment is both necessary

and sufficient to declare to the world that a fully successful deflection has been

achieved. NASA completely missed this essential point in its analysis.

These two key flaws are illustrative of the quality of the analysis on deflection

alternatives in the NASA Report. I again refer you to the attachments for greater

detail.

2. How should NASA now proceed on these issues?

I believe that NASA should produce a supplement to its Report to Congress based on new knowledge which has come to light since it began its

analysis. (Recommendation 2) The state of knowledge of the NEO deflection

challenge is increasing very rapidly and NASA has not stayed abreast of recent developments. This is not entirely NASA’s fault since it has no assigned responsibility

in this critical area. Nevertheless given the Congressional request for an analysis

of alternatives, and the urgent need for a legitimate understanding of these options,

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I urge that NASA revisit this matter. I list below, inter alia, a few suggestions in

this regard.

a) NASA should re-examine the NEO deflection challenge utilizing the most

likely set of threatening NEOs that we will likely confront. The lower bound

of this cohort should lie in the range of the 1908 Tunguska event. (Note: This

does not imply a change in the 140 meter search goal. In meeting the 140-

meter goal NASA will discover a large fraction of the Tunguska sized NEO

cohort as well.)

b) NASA should examine the need for precision and control in the deflection

process taking particular account of the role impact keyholes play during a

deflection.

c) NASA should further review and analyze its current (and future) database

of NEOs to determine the frequency with which close gravitational encounters occur between the time of NEO discovery and the time of potential impact. In the case where such encounters occur (e.g., Apophis, the most threatening NEO in the current database) analysis shows that a single mission can

often be employed to both determine if an impact is indeed threatened and

take ‘‘slow push’’ preventive action if necessary. We must understand this

class of prospective impacts and capitalize on the potential for a simple and

less costly deflection mission.

d) NASA should fully assess the value of a dual-band IR telescope in a Venuslike orbit for search and tracking purposes. NASA has already analyzed this

instrument’s search capability, but it should extend its thinking to evaluate

how to use such an instrument to support our impact prevention capability.

e) NASA should correct its faulty analysis of the cost and technological readiness of the Gravity Tractor.

3. What needs to be done to mitigate the risks of potential NEO impacts?

There are two key actions to be taken that would make significant progress toward protecting the Earth from the potential devastation of NEO impacts. Neither

of them is expensive yet both of them are extremely important, even urgent, in light

of the anticipated rapid rise in the NEO discovery rate in the near future.

a) NASA should assign someone in its NEO Program to the specific task

of thinking through, analyzing and understanding the NEO deflection challenge. (Recommendation 3) So long as the NASA effort, and

therefore thinking, is restricted to the NEO discovery process only, the government will lack the critical information and understanding needed to protect the Earth from NEO impacts. There is critical linkage between the upstream process of NEO search and orbit analysis and the downstream information needed to deflect NEOs. Absent someone explicitly thinking this

through we stand justly accused of focusing on numeric goals for the sake

of meeting an abstract quota. I hasten to point out that NASA cannot make

such an assignment without being given the explicit responsibility for this

critical function.

b) NASA should validate a basic NEO deflection capability through the

execution of a demonstration mission. (Recommendation 4) While deflection concepts can and indeed must first be worked out conceptually, in

an endeavor as critical to public safety as deflecting an asteroid bound for

an impact, our ultimate success in such a vital undertaking cannot depend

solely on a paper analysis. A demonstration program can be performed on

a non-threatening asteroid at a cost no more than that of a typical small scientific mission. This effort need not, and perhaps should not, be undertaken

as a U.S. mission per se. The European Space Agency (ESA) has already performed the initial feasibility and design phase of such a mission (though it

should be modified to validate the ‘‘slow push’’ component). Were an international partnership agreement negotiated a reasonable cost estimate for a

complete NEO deflection demonstration campaign could be performed for

about the cost of a single scientific mission.

4. What governance structures should be established to address potential

NEO threats?

I believe this to be the single most important question of this hearing. Until and

unless an explicit assignment of responsibility within government is made to protect

the Earth from NEO impacts, no significant advances in our capability will be made,

and the US public, and indeed the world public, will remain unnecessarily at risk.

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Ironically and somewhat counter intuitively, the full cost of assigning such responsibility and paying for its operations is almost vanishingly small. It is, nevertheless, a sobering responsibility, and an historic one. The very concept of being able

to slightly alter the workings of the cosmos to enhance the survival of life on Earth

is staggeringly bold. Yet this very capability lies within our technical means today.

The missing element, the fatal missing element, is a governmental assignment of

responsibility.

I would break this charge into two logical pieces.

a) First it seems to me that there exists today a single logical entity that

should be responsible for the analysis, design, manufacturing and testing of

a NEO deflection capability. That entity is NASA. NASA is our national

space agency and is clearly charged with the development of our national

space capability. This is, I believe, a clear and obvious choice.

NEO work in NASA is, however, administratively in an orphaned status.

Protecting the Earth from NEO impacts is neither space science nor exploration, although there are elements of both involved. Protecting the Earth

from NEO impacts is a public safety activity. Yet today within NASA and

its supporting space science and exploration communities the strong perception is that a dollar spent on NEO work is a dollar taken from space science

or exploration. This ‘‘zero-sum game’’ presumption cannot be allowed to persist. Yet until explicit responsibility and funding for NEO research, as a

public safety responsibility, is assigned to NASA by the Congress, this terrible conflict will persist. I therefore recommend that the Congress expressly assign to NASA the technical development elements of protecting the Earth from NEO impacts as a public safety responsibility. (Recommendation 5)

b) The second element is considerably more challenging and controversial. That

is, to which agency of government should fall the overall responsibility for

protecting the Earth from this infrequent, but devastating natural hazard?

This responsibility is greater than and somewhat separate from the technical

issues discussed above.

While we have not addressed this matter above I will simply state unequivocally that the NEO mitigation decision process and the policies embedded

within it are inherently international. Any NEO deflection will necessarily

shift risk, however temporarily, between people and property across the

planet. As we move a NEO away from an Earth impact, we necessarily shift

its impact point from one region to another until we complete the deflection.

Given this characteristic, and I ask that you grant this arguendo, the response to a threatening NEO will involve complex and very sensitive international coordination and probably negotiation. This is a planetary challenge, not a national one. The policies, procedures, criteria, thresholds, and

agreements which must be addressed are international political challenges

and the U.S. involvement will place in the hands of the agency responsible

the lives and property of the world’s entire population.

It would frankly be presumptuous of me to make a specific recommendation

here. Obvious candidates for such a responsibility include the Department

of Homeland Security (DHS), the Department of Defense (DOD), and of

course NASA. Many other agencies will clearly need to be involved in the

decision processes given the potential of evacuation, migration (including

cross border), and potentially unprecedented property destruction.

I therefore recommend that the Congress study the issue of overall

governmental responsibility for protection of the Earth from NEO

impacts, perhaps with the assistance of specialized policy entities,

and ultimately hold public hearings to engage a wide perspective on

the issue. (Recommendation 6)

In closing I would suggest a personal perspective based on having spent the last

six years of my life studying this issue. NEOs are part of nature. A NEO impact

is a natural hazard in much the same way as are hurricanes, tsunamis, floods, etc.

NEO impacts are deceptively infrequent, yet devastating at potentially unimaginable levels. NEOs are however not our enemies. We do not need to ‘‘defend’’

against NEOs, we need to protect ourselves from their occasional impact, as we do

with other natural hazards.

Unlike other natural hazards, however, NEO impacts can be predicted well ahead

of time and actually prevented from occurring. If we live up to our responsibility,

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if we wisely use our amazing technology, and if we are mature enough, as a nation

and as a community of nations, there may never again be a substantially damaging

asteroid impact on the Earth. We have the ability to make ourselves safe from cosmic extinction. If we cannot manage to meet this challenge, we will, in my opinion,

have failed to meet our evolutionary responsibility.

Thank you.

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BIOGRAPHY FOR RUSSELL L. SCHWEICKART

Russell L. (Rusty) Schweickart is a retired business and government executive

and serves today as Chairman of the Board of the B612 Foundation. The organization, a non-profit private foundation, advocates the development of a space system

to protect the Earth from future asteroid impacts. The Foundation’s goal is ‘‘to significantly alter the orbit of an asteroid, in a controlled manner, by 2015.’’

Schweickart is the founder and past president of the Association of Space Explorers (ASE), the international professional society of astronauts and cosmonauts. .He

currently serves as Chairman of the ASE’s Committee on Near-Earth Objects. The

organization promotes the cooperative exploration and development of space and the

use of space technology for human benefit. The ASE has a current membership of

over 390 astronauts and cosmonauts from 31 nations. The Association’s first book,

The Home Planet, with a preface by Schweickart, was published simultaneously in

10 nations in the Fall of 1988 and was an immediate international best seller.

In 1987–88, Schweickart chaired the United States Antarctic Program Safety Review Panel for the Director of the National Science Foundation (NSF) in Washington, DC. The resulting report, Safety in Antarctica, a comprehensive on-site review of all U.S. activities in Antarctica, led to a restructuring of the program, increasing the safety of operations in that hazardous environment. At the request of

the National Science Foundation, Schweickart also served on the 1997–1998 United

States Antarctic Program Outside Review Panel, which reported to the White House

(OSTP) and Congress on the future of U.S. facilities in Antarctica. The U.S.’

Amundson-Scott South Pole station is currently being fully rebuilt as a result of this

work.

In 1977 Schweickart joined the staff of Governor Jerry Brown of California, and

served in the Governor’s office for two years as his assistant for science and technology. In 1979 Schweickart was appointed to the post of Commissioner of Energy

for the State of California and served on the Commission for five and a half years.

The Commission, which was chaired by Schweickart for three and a half years, was

responsible for all aspects of energy regulation in the state other than rate setting,

including energy demand forecasting, alternative energy development, power plant

siting and energy performance regulation for appliances and buildings.

Schweickart joined NASA as one of 14 astronauts named in October 1963, the

third group of astronauts selected. He served as lunar module pilot for Apollo 9,

March 3–13, 1969, logging 241 hours in space. This was the third manned flight of

the Apollo series and the first manned flight of the lunar module. During a 46

minute EVA Schweickart tested the portable life support backpack which was subsequently used on the lunar surface explorations. On the mission with Schweickart

were commander James A. McDivitt and command module pilot David R. Scott.

Schweickart served as backup commander for the first Skylab mission which flew

in the Spring of 1973. Following the loss of the thermal shield during the launch

of the Skylab vehicle, he assumed responsibility for the development of hardware

and procedures associated with erecting the emergency solar shade and deployment

of the jammed solar array wing, operations which transformed Skylab from an imminent disaster to a highly successful program.

After the Skylab program, Schweickart went to NASA Headquarters in Washington, DC as Director of User Affairs in the Office of Applications. In this position

he was responsible for transferring NASA technology to the outside world and working with technology users to bring an understanding of their needs into NASA.

Prior to joining NASA, Schweickart was a research scientist at the Experimental

Astronomy Laboratory of the Massachusetts Institute of Technology (MIT). His work

at MIT involved research in upper atmospheric physics, star tracking and the stabilization of stellar images. His thesis for a master’s degree at MIT was an experimental validation of theoretical models of stratospheric radiance.

Schweickart served as a fighter pilot in the U.S. Air Force and the Massachusetts

Air National Guard from 1956 to 1963. He has logged over 4000 hours of flight time,

including 3500 hours in high performance jet aircraft.

Schweickart was awarded the NASA Distinguished Service Medal (1969) and the

Federation Aeronautique Internationale De La Vaux Medal (1970) for his Apollo 9

flight. He also received the National Academy of Television Arts and Sciences Special Trustees Award (Emmy) in 1969 for transmitting the first live TV pictures from

space. In 1973 Schweickart was awarded the NASA Exceptional Service Medal for

his leadership role in the Skylab rescue efforts.

He is a Fellow of the American Astronautical Society and the International Academy of Astronautics, and an Associate Fellow of the American Institute of Aeronautics and Astronautics. Schweickart is a Trustee and a Fellow of the California

Academy of Sciences.

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Schweickart was born on 25 October 1935 in Neptune, NJ. He is married to

Nancy Ramsey of West Hartford, CT. He has seven children and eleven grandchildren. He graduated from Manasquan High School, NJ; received his Bachelor of

Science degree in 1956 and his Master of Science degree in 1963, both from the

Massachusetts Institute of Technology.

His hobbies include golf, bicycling, and hiking.

DISCUSSION

Mr. LAMPSON. Thank you, sir, very much. Thank all of you, the

whole panel. It is really been a pretty fascinating topic for us to

be taking up.

At this time, each Member will be given five minutes to question

the panel, and I will yield myself, as Chairman, the first five minutes.

IMPORTANCE OF SURVEYING OBJECTS LARGER THAN 140M

And Dr. Yeomans, is it correct that you pretty much agree with

the importance of surveying all potentially hazardous objects, down

to 140 meters in size?

Dr. YEOMANS. Yes. I think that is the next step. By doing so, by

finding 90 percent of these objects, we would effectively reduce the

risk of all Near-Earth Objects to Earth by 99 percent. Now, Rusty

mentioned the smaller objects still, but that could be the subject of

a third generation search. But the 140 meter and larger objects are

primarily, necessarily the focus of the next survey.

Mr. LAMPSON. Well, the Authorization Act of 2005 directs NASA

to implement a program to catalog 90 percent of all the 140 meter

or larger NEOs by the end of 2020. Is that still a realistic goal, or

should the scope or timetable be adjusted, and if so, what would

you recommend that new goal to be?

Dr. YEOMANS. Well, I think the 2020 timeline was selected because we needed some sort of a metric to judge progress by, but

it has been pointed out that the impact interval for a 140 meter

sized object is about 5,000 years, so my personal opinion would be

that we could afford to wait another couple of years, and perhaps

do the survey by the end of 2030 or thereabouts, and explore some

options that would be easier and less expensive to carry out within

that timeframe.

RISK OF CHANGING THE PROJECT TIMELINE

Mr. LAMPSON. Maybe our technology even would have grown

more, and we will be able to do it more effectively, or at a lesser

cost.

Dr. Tyson indicates that the LSST could meet the 90 percent

goal by 2026, at an average cost to NASA of about $10 million a

year for 12 years. From a risk reduction standpoint, how serious

would a 6-year delay in meeting that Congressional goal be, and

would anybody else after that, after your comment, would anybody

else like to make a comment on it?

Dr. TYSON. I think that the risk reduction is significant, if one

is able to go down to these small sizes. In 12 years, as opposed to

10 years, my personal opinion is the same as Don’s. I think that

one has to just get on with it and do these surveys, and if it takes

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12 years instead of 10 years to reach 90 percent, then we should

just do that.

Mr. LAMPSON. Dr. Yeomans, would you comment also, please?

Dr. YEOMANS. I agree with what Tony said. I would like to see,

perhaps, an extension of our report to Congress, whereby a few options are looked at in far more detail, in a more rigorous fashion,

and costing is done in a more rigorous fashion. And perhaps one

of the options, one of the few options that would be examined,

would be the LSST, working in cooperation with Pan-STARRS, and

also one, perhaps two space-based options. Infrared surveys are

still very effective, but that would be my suggestion.

NON-U.S. NEO CHARACTERIZATION

Mr. LAMPSON. Anybody else want to make a comment on that before I ask my next question? Okay, let me go on, because we are

going to get to all of you.

Dr. Yeomans, what if any contributions are non-U.S. organizations or agencies providing to the detection, tracking, and characterization of NEOs?

Dr. YEOMANS. Well, as was pointed out, in terms of discovering

them, NASA is doing the lion’s share of the work, certainly more

than 98 percent of all discoveries are by NASA-supported facilities.

But there are international efforts underway to characterize these

objects. Our colleagues in ESA, the European Space Agency, are

making strides. The Japanese have a mission currently underway

to visit a Near-Earth asteroid and bring a sample back, so that is

important.

We have a group at Pisa, Italy, that is also working with us very

closely to determine independently impact probabilities for various

objects, and so, we are constantly in touch with those folks to verify

our results, and they are doing the same, and verifying their results with us, and if we come up with interesting objects like

Apophis, for example, the object that will get very close to the

Earth in 2029, we wait until we have verified our results with our

colleagues in Italy before we make any formal announcements. So,

that is working very well.

INCREASING INTERNATIONAL NEO COLLABORATION

Mr. LAMPSON. Is there more that should be done? And if so, what

steps ought to be being taken? Can we build greater relationships,

obviously through science we can, but is this one of those areas?

Dr. YEOMANS. I think it is. We should continue to encourage our

international colleagues to participate more in the discovery area,

more in the characterization area. And those activities are ongoing,

through the Action Team that was mentioned, the UN Action Team

14, for the Peaceful Uses of Outer Space. So, those international

discussions are going on. We certainly would appreciate more international efforts in these areas.

Mr. LAMPSON. Dr. Green, what if any plans does NASA have to

engage other nations or international entities in efforts to direct

and characterize NEOs?

Dr. GREEN. Currently, through our bilateral discussions with

many of the other space agencies, such as ESA, such as the CanaVerDate 11-MAY-2000 18:21 Feb 21, 2008 Jkt 038057 PO 00000 Frm 00100 Fmt 6633 Sfmt 6601 C:\WORKD\SA07\110807\38057 SCIENCE1 PsN: SCIENCE1
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dian Space Agency, this is, indeed, a topic that comes up on every

agenda. And indeed, we do see, as I mentioned in my testimony,

growing international interest in this area. There are several missions that ESA has been studying, and most recently, in what they

call Cosmic Visions, there is another mission called Marco Polo,

that does have a much better chance now of making it through

their budgetary process, that will also add information that is important for us.

The Canadians will be launching a spacecraft called NEOSSat.

We have been discussing about how it can be utilized, and making

the data more available. So, indeed, in summary, that interest now

is becoming more international. It is getting into the plans, future

plans of our space agency partners. And as I mentioned, it is, indeed, a topic that we will continue to discuss and promote.

Mr. LAMPSON. Anyone else want to—Mr. Schweickart.

PUBLIC SAFETY

Mr. SCHWEICKART. Yes, Mr. Lampson. Let me simply second

what has been said, but go a bit beyond it. I think one of the most

important things that can come out of this hearing is to explicitly

recognize that what we are discussing here is not science. What we

are talking about here is public safety. This is not a subject in

which relatively small amounts of money, frankly, should be traded

off with the scientific research that goes on in NASA and elsewhere.

We are talking here about two separate things, and they should

not be mingled and seen as a zero-sum game, which is the way in

which expenditures for issues related to Near-Earth Objects are

seen by many people today. This is not a zero-sum game. We are

talking about two things. One is science and exploration. Another

is public safety. And we should not sacrifice public safety for

science. These things are very important.

I think when you go to the international community for additional support, it would be very helpful if the U.S., in its presentations in COPUOS, in the United Nations, were to appeal for additional support, on the basis that we are talking about, public

safety on a worldwide basis. I think that may make a real difference.

Thank you.

Mr. LAMPSON. Thank you very much for your comments. Anyone

else? Thank you very much. I will yield the next five minutes to

Mr. Feeney, the Ranking Member.

Mr. FEENEY. Well, thank you, Mr. Chairman, and I am struck by

your remark, Mr. Schweickart, that the way to appeal for international support on this is through safety and security, and I happen to agree with that. I mean, a lot of exploration, especially space

exploration, is not a zero-sum game, but there are winners and losers. There are property rights issues. There are capabilities, in

terms of geopolitics. But certainly, when you are talking about the

potential to deflect a threat to the entire Earth, it seems to me that

had the dinosaurs had the capability to deflect these things 65 million years ago, they might still be around. And maybe we can convince some of our international partners to bear some of the load;

this is a win-win for everybody involved.

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NEO DEFLECTION TECHNOLOGY

So, because there are so many fascinating parts of this, Dr. Yeomans, your remarks did not specifically talk about the technology

that Mr. Schweickart did. You said that existing technologies can

deflect an Earth-threatening asteroid if there is time. Can you describe those technologies, and can you give us your assessment of

Mr. Schweickart’s discussion of nuclear versus kinetic and the size

of the objects?

Dr. YEOMANS. Well, there is basically two groups of mitigation

techniques. There is the fast, flyby, or impacting techniques. You

run into it, as we did with the Deep Impact mission, back in July

of 2005, and simply slow the object down, if it is small enough to

do that, and you have time enough, so that in 20 or 30 years time,

when it was predicted to hit the Earth, its orbit would have been

changed, so that it wouldn’t hit. So, there is the fast or impulsive

techniques, where you run into it, or if it is a large object, you

would use nuclear explosives, perhaps.

And then, there is the slow push techniques, where you rendezvous with the object, fly alongside it, and you do a number of

techniques, possibly. A gravity tug has been suggested, where you

just take your spacecraft, and put it up next to your asteroid, and

just use the gravitational attraction between the two to move them

just a little bit. Now, that is a technique that, as Rusty pointed out,

can be used for so-called trim maneuvers. That is not what you

would do primarily, but you would use that as a secondary device

to alter the orbit of the object, in the event that your primary technique, the impulsive technique, perhaps didn’t do the job, or

knocked it into one of these subsequent keyholes that he talked

about, where a subsequent impact would be likely.

So, in any event, you need a spacecraft nearby to verify the result. That is clear, so—or that would be the optimal technique. So,

again, you have to find them early to allow that to happen.

Mr. FEENEY. Mr. Schweickart, staying on the deflection capabilities for a second. You know, NASA says the slow push mitigation

techniques are the most expensive, and we are furthest behind in

technological capabilities. You seem to have a very different view

from NASA’s preference for a nuclear device.

In terms of whether we use the slow push versus nuclear, in

terms of where we could intercept a Near-Earth Object, is there a

difference, in terms of when we can intercept the object in the two

techniques, and what are the relative advantages and disadvantages, depending on size of the NEO?

Mr. SCHWEICKART. Yes, thank you very much for the question.

First, let me endorse everything that Don just said in response

to your earlier question. I don’t think we have any daylight between us, frankly. I think the daylight is between what Don just

said and what I also believe, and what the NASA report to Congress said. There is quite a bit of difference in there.

Mr. FEENEY. Let me say that NASA knows we have nuclear capabilities, and they know that they had a mission with one kilometer NEOs. What they did was to take the limited number of

threats that they knew how to deal with very comfortably, but they

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avoided the more complex and more numerous problems. Is that

maybe——

Mr. SCHWEICKART. Yes, I think that is a fairly good representation. Let me give you an idea that the nuclear, I would not, our

organization would not suggest that nuclear can be ruled out. However, statistically, if you look at the probability of needing to use

nuclear, as opposed to nonnuclear means, the frequency of that occurrence would become necessary about once every 100,000 years.

So, you are talking about a very improbable frequency of need, and

it is that issue which we have with what appeared in the NASA

report.

And let me emphasize, again, that as I stated in my report, that

NASA in our discussions with them after they submitted their report, acknowledged that they did not fully understand this issue at

the time the report was written. Don has now reflected, in fact, a

current, and I believe a view which we totally support and agree

with.

Let me go to something which you mentioned, which is an extremely important, let me say misperception, and that is that in

some way, what we are talking about is a slow push technique

versus nuclear or kinetic impact. The thrust of my, no pun, the

thrust of my testimony is to point out that both strength and precision are needed for a successful deflection when an asteroid is

headed, let me say, for a direct impact with the Earth. You need

the strength of a kinetic impact, in general or under exceptional

conditions, a nuclear explosion, but you need to follow that up, potentially, if in fact, the deflection has now caused the asteroid to

head for a keyhole which will cause it to come back, you need now

this trim capability of the slow technique, gravity tractor or other

slow technique, which can make a precision correction, to ensure

that you don’t have that asteroid coming back and hitting. Those

two things are necessary for a successful deflection.

Now, the one final thing which you mentioned, and we have not

addressed it yet, but it is very important, and that is that NASA

did not, in completing its report on the deflection capabilities, understand that the precision deflection that we are talking about

could be done with existing space hardware. They used, for their

analysis, the assumption of a very large, very complex spacecraft

for a gravitational tractor, and that was incorrect. It was a misunderstanding, and in fact, that error should be corrected. Existing

ordinary technology can be used, it is very mature, and it is very

inexpensive, in fact.

DEFLECTION OF NEOS INTO KEYHOLES

Mr. FEENEY. Just very briefly, with my colleagues’ indulgence. I

am fascinated by these keyholes. So we are successful with the deflection for the time being, we miss, and it, for whatever reason,

it comes into a keyhole. Don’t we get a second shot to play ping

pong with the thing?

Mr. SCHWEICKART. The basic sequence, which Don outlined, and

which we advocate, is that any, first of all, we don’t talk about a

deflection mission. We should be talking about a deflection campaign, because one of the things that you need to have in place at

the asteroid that you intend to deflect is a transponder, a spaceVerDate 11-MAY-2000 18:21 Feb 21, 2008 Jkt 038057 PO 00000 Frm 00103 Fmt 6633 Sfmt 6601 C:\WORKD\SA07\110807\38057 SCIENCE1 PsN: SCIENCE1
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craft that has rendezvoused with it that has a transponder, so that

we can do precise radio tracking. Number one, we need to determine, in fact, is that asteroid headed for an impact with the Earth.

Number two, if it is, then you send up a deflection mission, a

strong one, a kinetic impact, to make the primary deflection so that

it misses the Earth.

The next thing you do is go over to it with that same spacecraft

which has now been observing that impact, to again precisely determine the success of that primary deflection, and very important,

is it now going to pass through one of these nearby keyholes. If,

and it is improbable, but if it is heading now for a keyhole, then

you need to make a small adjustment in the deflection, using that

same spacecraft with the transponder that has a gravity tractor capability, to make a small adjustment to make it miss that keyhole.

Now, you have missed the Earth and all return keyholes, and

therefore, you have a successful mission.

That is a deflection campaign, involving basically two spacecraft.

MORE ON INTERNATIONAL COLLABORATION

Mr. FEENEY. Mr. Rohrabacher.

Mr. ROHRABACHER. Thank you very much, and I have certainly

found this hearing to be fascinating, as I expected it to be, and I

would hope that we attract enough attention from the general public and from decision-makers, to understand that there are some

things that we have to do, and I certainly agree with Rusty when

he suggests that this is a safety issue and not a science issue. I

would call it planetary defense, for lack of a better description, and

I would hope that as we do enlist others, our European allies and

the Japanese and others, I would hope that we also include the

Russians in this equation as well. No one mentioned the Russians.

I think a Russian-American partnership in this endeavor, I think

they have a lot to contribute, and I think it would go a long way

towards establishing the type of cooperation we need in space with

the Russians.

PROBABILITY OF A 10KM NEO HITTING EARTH IN THE NEAR

FUTURE

And with that, I see Arecibo, when we talked about, is a shortterm issue in what we are talking about here. I mean, Arecibo is

step number one, and we’ve got to get that done, and then, we are

talking about this further threat. I understand that the object that

hit the Earth and now is being credited with eliminating the dinosaurs happened about 65 million years ago, but I understand that

they say that an object like that, odds-wise, would be about every

50 million years. So, are we not now in a cycle that would put us

in the probability that there is another such object that may head

to the Earth, not in the near future in terms of our lifetime, but

in terms of the lifetime of the planet? Is that accurate to say?

Dr. YEOMANS. If I may respond. Statistically, the likelihood of an

object that size happening, first of all, that was a 10 kilometer

sized object, and there currently are no potentially hazardous asteroids that are that size. The largest is Toutatis, which is 5.4 kilometers, so we are not likely to see another dinosaur-like event.

101

And the probabilities are such that an impact of an object of a

particular size could happen tomorrow. It could happen in 5,000

years. So, they are not really on cycles, as such.

Mr. ROHRABACHER. Well, but we are just talking about the levels

of probability or likelihood, and people chart out what these objects

are, you know, every so many thousand years, you can expect

something to happen, just with the likelihood of the objects that

are out. I think we are just talking about mathematical likelihood,

and not necessarily anything else.

APOPHIS NEO

I would like to note that just a few years ago, there was a NearEarth Object that passed between, or at least as close to the Earth

as would have been between the Earth and the Moon, it was that

close, and we didn’t actually see it until it was actually past. And

when you are talking about Apophis, it is a Near-Earth Object,

that as we say, and I think Rusty mentioned it, in 2029 is when

it will come close to the Earth.

Is it true that we do not know if that object will, after it goes

past the Earth the first time, that we do not know if the Earth’s

gravity will actually impact its trajectory to the point that it then

becomes a threat? Is that correct?

Dr. YEOMANS. That is correct. Apophis will make a close approach on April 13, 2029, Friday the 13th.

Mr. ROHRABACHER. Friday the 13th.

Dr. YEOMANS. It is within 4.5 Earth radii of the surface, well

within the geosynchronous altitude of our satellites.

Mr. ROHRABACHER. So, it is actually closer than some of our satellites.

Dr. YEOMANS. It is.

Mr. ROHRABACHER. And we don’t know what the Earth’s gravity

will do to that trajectory, and so, it may, 10 years later, we may,

as Rusty is talking about a campaign, we may be facing a second

onslaught that may be even more dangerous 10 years later.

Dr. YEOMANS. Well, it has a one in 45,000 chance of passing

through one of these keyholes that Rusty mentioned, and hitting

us in April 13, 2036, but with the help of radar, Arecibo and

Goldstone in 2013, we have a 95 percent chance of eliminating that

threat altogether. So, it is a very unlikely situation, and one that

we can drive to zero, probably.

UNDERSTANDING THE THREAT POSED BY NEOS

Mr. ROHRABACHER. Now, I will tell you that unlikely is, I remember the very first hearing we had on this, and I keep remembering,

maybe it was one of you, we suggested the chances of anyone ever

being hurt on this planet by a Near-Earth Object is, you know,

about the same chance as you getting a royal straight flush in Las

Vegas, and it just happens that I had gone to Las Vegas and got

a royal straight flush once, and so, that is really actually what

made it real for me, is when someone said that. And also, now, I

have three children at home that are three years and three and

one-half years old. We are not just talking about my lifetime or

your lifetime, we are talking about their lifetime as well.

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So, I think that Rusty calculated right. However, let me just

note, from what you said, Rusty, that you know, this is, when we

are dealing with people, we have got to deal with this as a safety

issue. It shouldn’t be a tradeoff for science. That works internationally, maybe, and it may not work, in terms of getting the job done

here. But that may be the only type of trading game that we can

do here on Capitol Hill and still get the job done.

And this issue is a priority for me. As far as I can see, we need

to understand the threat, and that is what we are talking about

right now. We don’t even fully understand the threat yet. Then we

need to know what we should do, which is a matter of discussion,

and we have not even come close to that yet.

FUTURE RESPONSIBILITY

And finally, we need to know who is going to be in charge of

doing what needs to be done. And so we need a lot of discussion

on this, and make those determinations. We are just now at the

‘‘should we even take the steps necessary to understand the threat’’

stage, and I think there is no question about that.

Rusty, do you want to comment?

Mr. SCHWEICKART. Yes. I think it is very important, your last

point, Congressman Rohrabacher. What we know now is that

NASA is responsible. NASA is in charge of discovering, tracking,

cataloging, et cetera, Near-Earth Objects. What we also know, but

we don’t seem to acknowledge, is that no one is in charge of protecting the Earth from impacts.

Mr. ROHRABACHER. Right.

Mr. SCHWEICKART. So, that next step is extremely important. At

the moment, NASA has not yet adequately thought through the deflection issues. They have not, because they have not been told to.

They do not have that responsibility. Until NASA or someone is

given the responsibility to think through all of the implications and

decisions and international cooperation, et cetera, for protecting the

Earth from impacts, not just finding them, that job will not be

done.

So, this is extremely important.

Mr. ROHRABACHER. All right. Mr. Chairman, I would suggest

that that is our job, that is our job as Congress, is to designate who

is going to be responsible for that, what Rusty was just talking

about, and we should do that in this session of Congress. It is that

important an issue, and if another Near-Earth Object sneaks up on

us, and we don’t even know who we are going to, what procedure

we are going to use to try to thwart the threat, then we haven’t

done our job.

Thank you very much, and I appreciate you, Mr. Chairman, and

yield back.

Chairman UDALL. Thank you, Mr. Rohrabacher. We, as you all

know, have another vote underway. I am going to recess the Committee for a very short period of time, given it is one vote, and we

will return as quickly as we can, and continue the questioning. We

will have another round. I know Mr. Feeney intends to return, and

I will see if Rohrabacher wants to ask another round of questions

when we reconvene the Committee.

So, the Committee stands in recess.

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[Whereupon, at 11:40 a.m., the Subcommittee was recessed, to

reconvene at 12:08 p.m.]

Chairman UDALL. The hearing will reconvene. Again, I want to

thank the panel for your forbearance with all the votes. We do, I

believe, have another vote in an hour, so I understand that we can

probably conclude the hearing in the hour we have left to us.

POTENTIAL NASA PARTNERSHIPS

At this time, the Chairman will yield himself five minutes. And

I would like to focus, Dr. Green, on the testimony, as delivered by

you and Dr. Pace, recommends that NASA continue the existing

Spaceguard survey and also take advantage of opportunities using

potential dual use telescopes and aircraft, and partner with other

agencies, as feasible, to make progress toward achieving the legislative goal.

We have heard today at least two examples of potential partnerships with other agencies supporting the planetary radar at Arecibo and funding the NEO operations of the LSST, that would

make significant progress toward achieving the legislative goal for

NEO detection and tracking at, I believe, a modest annual cost to

NASA.

What, specifically, is NASA doing to take advantage of either of

these two potential partnership opportunities?

Dr. GREEN. Indeed, we do want to continue on with our discussions with NSF for the use of the LSST. We have, certainly, an infrastructure in place with the Minor Planet Center, and our ability

to utilize that data for NEO detection and orbit determination.

Also, I had mentioned in my testimony the importance of using

the Pan-STARRS system that the Air Force is currently putting

into place, and in fact, we have provided them with a small amount

of funds to be able to upgrade their software such that they are

able to do some tracking, which is extremely important, and they

have been very receptive. And that relationship is also quite

strong.

So, our intent is, indeed, to leverage these two important facilities as they are available, and as they come online.

NASA FUNDING NEO PARTNERSHIPS

Chairman UDALL. Thank you, Dr. Green. To follow on, I wanted

to ask if you have entered into any concrete discussions with NSF

or DOE on potential partnerships addressing this Congressionally

directed NEO survey task, and if not, why not?

Dr. GREEN. Okay. Indeed, as I mentioned, we have concrete discussions with the Air Force, utilizing the Pan-STARRS system, and

they are fully aware of what our intent is. NSF, indeed, is aware

of our interest in using the LSST, and I anticipate that within this

next year, that those discussions will become more firm, as we do

understand how the funding becomes available for them to be able

to actually build that system.

Chairman UDALL. Thank you, Dr. Green. To continue this line of

inquiry, you mentioned that you are providing funding to the Air

Force for Pan-STARRS. Did NASA do an analysis of the relative

merits of providing NASA funding for Pan-STARRS, versus funding

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for the LSST or the Arecibo Planetary Radar, before deciding to

give these resources to the Air Force? And if not, why not, and how

much money is being provided, and where is it coming from in

NASA?

Dr. GREEN. The funding that we are utilizing to support small

upgrades in the software for Pan-STARRS is a fairly modest

amount. I would have to come back to the record to give you the

exact amount, but it is within the $100,000 to $200,000 range.

[The information follows:]

MATERIAL REQUESTED FOR THE RECORD

The NASA Near Earth Objects (NEO) Program started limited funding to the

Pan-STARRS project in 2007 with a partial award to a proposal submitted to the

program by the University of Hawaii, who manages the Pan-STARRS development

for the Air Force. This partial award was a one-year grant to the University of Hawaii of $450,000. Any future funding will depend on the success of pending and future proposals Pan-STARRS submits to competitive opportunities of the NEO Program that NASA announces through its annual Research Opportunities in Space

and Earth Sciences.

Indeed, what we have arranged, with time, has been utilizing the

funding for our NEO search opportunities with NSF, as Arecibo’s

telescope, by allowing us to increase the number of observers on

utilizing that facility, with time. And then NSF taking over more

of the operational activities. And then, we are following the National Academy report that did, indeed, suggest that NSF should

support their ground-based facilities, and that allows us to better

utilize the funding that we have available.

Chairman UDALL. Is NASA prepared to consider providing funding to Arecibo or the LSST project, as is being done with PanSTARRS? And again, if not, why not, and if I can add a comment,

why wouldn’t it be logical to support those other activities, if you

are prepared to support Pan-STARRS?

Dr. GREEN. Well, currently, our arrangement with NSF has been

to follow the NRC report that came out in 2001, which delineated

roles and responsibilities for the funding of infrastructure. Indeed,

we have worked with NSF in the past to be able to develop Arecibo

capability for its radar use, and therefore, we leveraged that, as the

rest of the community does, for that kind of research.

So, with respect to that, I believe we have a working relationship

is what it boils down to. NSF is funding their infrastructure capability. We are able to, with time, as I mentioned with Arecibo and

also with the Pan-STARRS system, that the Air Force provide incrementally small amounts of funds to be able to meet and satisfy

our requirements and needs, and that has worked extremely well,

and we will continue to pursue that approach in the future.

The LSST activity, of course, is one that needs to be resolved, in

terms of whether they will have sufficient funding, and be able to

put together the capability before we can begin to figure out how

to work with them and leverage that system.

Chairman UDALL. Dr. Yeomans or anybody else on the panel,

would you care to comment?

Dr. YEOMANS. I would just like to add that the modest funding

to Pan-STARRS was done under a peer review process. They submitted a proposal to the Near-Earth Object Observations Program

in NASA Headquarters, which is a modest program in and of itself,

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and it was thought at the time that their proposal was of sufficient

merit that it should be awarded this modest sum. So, that was the

process by which Pan-STARRS was funded at a modest level.

Chairman UDALL. Anybody else on the panel would like to comment? Dr. Campbell.

Dr. CAMPBELL. If I may, I would, just on the Arecibo situation,

like to comment that perhaps the NSF hasn’t read the NRC report,

but it is my understanding they feel strongly that the solar system

research, and especially research related to the NEO issue, is a

NASA responsibility, and that they are very reluctant to provide

additional funding to carry out that activity.

Their plans to act on the recommendations of the Senior Review

to reduce Arecibo’s operating budget to $8 million, the concern, as

Dr. Green just pointed out, is that NASA feels that they shouldn’t

really be supporting the operations of a National Science Foundation facility, as opposed to supporting some of the science which

makes use of it. And what we are talking about here are the operational costs of the radar system at Arecibo.

Chairman UDALL. Dr. Tyson.

USING LSST FOR NEO DETECTION

Dr. TYSON. Yes, thank you. I would like to make a couple of comments. First of all, the progress, we are on schedule on LSST towards a first light in 2014. We have a grant already from the National Science Foundation for R&D. We are about two-thirds of the

way through that. We have put in, earlier this year, a construction

grant, a construction proposal to the NSF. We just had this review,

a very good positive result from that, and we are going towards

readiness, into the National Science Board. So, we are on schedule,

actually, for a 2014 first light.

What is needed here to address this modified mission, beyond

what we intend to do, this extra 15 percent of Near-Earth asteroid

observing, is some extra support, starting now, with the collaborating with the computer science community on new ways of linking the small tracklets that one has when you take multiple images. Each one of these, LSST will see about 150, each one of these

small asteroids, about 150 times. You have to link all of these little

tracks together.

The problem is, the challenge is this. I just wish we had special

glasses that we could put on when we look out at the night sky,

and we only see the nearby Earth-threatening asteroids. Unfortunately, when you look out deeply in the night sky for things that

are moving, you are confusion limited by this huge cloud of 10 million main belt asteroids, and you actually have to track all of those

guys. You actually have to know each one of those orbits in order

to separate out the Earth-threatening ones. So, that is the challenge, and that takes a lot of, millions of lines of computer code.

There are some clever computer scientists out there that think they

have a solution to some of those problems, and we need to get on

with it. That is about $1 million a year, starting in next year or

the year after, four or five years, and then we will have the software in place. And then, that extra 15 percent effort would cost us

somewhere around $12 million a year during operations.

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RADAR VERSUS OPTICAL NEO DETECTION

I wanted to make a comment, if I may, about radar versus optical. I think you need both. One is not the replacement for the

other. Radar is not a method of discovering all of these things, and

winnowing down this 10 million objects into the few that are

threatening. But once you have done that with optical, then radar

is absolutely critical on the ones that you are really concerned

with, to refine the orbit.

IMPORTANCE OF ARECIBO RADAR

Chairman UDALL. Mr. Schweickart.

Mr. SCHWEICKART. Yes, Chairman Udall. I would like to just pick

up on where Tony left off, and give slightly different language, perhaps, or perspective on the Arecibo radar and its criticality.

As Tony said, these two are not, I mean the Arecibo radar is not

simply another thing to look for asteroids with. Number one, radar

is not a good instrument to find or discover, to meet the quota that

you guys have essentially dumped on NASA, you know, a certain

number by a certain year. However, when what you are looking at

or thinking about is protecting the Earth from impacts, picture

yourself with a few hundred baseballs headed for your head. If you

willingly take your pen and poke out one eye, you are now left with

monocular vision. You don’t have binocular vision. And if you want

to get depth perception, you need both eyes. And yet, what we are

doing is we are about to head into a serious decision-making process over the next 15 years on do we or do we not have to deflect

something, and what you have done is, if you eliminate Arecibo, is

you wiped out, willingly, your binocular vision.

Now, that is extremely important. It is a little different way of

thinking about the essential nature of Arecibo. It complements the

optical view, and the most critical decisions we are going to make,

or the most frequent ones, are the relatively small objects, which

are numerous, which we are going to have to make decisions about.

Those are the very ones that you get the least amount of data on,

and where the Arecibo contribution is extremely critical. Because

the next time you see that asteroid, it may be on final approach,

and that first vision you get of it needs both optical and radar, you

need both eyes.

So, that is a different take on it. But it is not meeting the search

goal which NASA has been assigned. It doesn’t help in that, but

it does help if what you are interested in is protecting the Earth.

Chairman UDALL. Thank you. That is very, very helpful to get

that perspective.

The Chair now recognizes, as we begin another round, the Ranking Member, Mr. Feeney.

Mr. FEENEY. Thank you, Mr. Chairman.

RADIUS OF NEO SURVEYS

This first question is for Dr. Tyson, Mr. Schweickart, Dr. Yeomans, and Dr. Campbell. The NASA recommendations are that we

survey objects that come within .05 AU of Earth’s orbit, instead of

1.3 AU, as required by the 2005 authorization. Do you agree or disagree with that recommendation, and why don’t you give us some

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comments? If we need to change our recommendation, this is a

place to start discussing it.

Dr. TYSON. Congressman, I do agree with that. If you are calculating, if you are interested in, as I think we are, completeness in

a survey of Earth-threatening objects, then you should have a survey of Earth-threatening objects, and those are the ones that come

within——

Mr. FEENEY. Is .05 the number? Do you think that is a reasonable number?

Dr. TYSON. That is right.

Mr. FEENEY. Okay.

Dr. TYSON. I agree with that.

RAMIFICATIONS OF AN ASTEROID HITTING EARTH

Mr. FEENEY. Okay. And no dissension? Okay. If anybody has an

opinion, they agree with you, Dr. Tyson. I want to get an idea of

the potential ramifications from a strike of Earth. A couple of

months ago, we had a one meter object strike in Peru, roughly. We

think it created about a 13 meter crater. Is that impact, I mean,

if I am looking at a 100 meter object, am I looking at, you know,

1.3 kilometer crater? If I am looking at a kilometer object, am I

looking at, you know, 13 kilometers?

And outside the actual kinetic strike, and the damage done by

things being broken apart by the actual collision, are there other

things, like radiation or heat, or damages that would impact the

environment or humans? This is for anybody who wishes to——

Mr. SCHWEICKART. Mr. Feeney, a relatively easy number is a 100

meter object is about 100 megatons of explosive energy, or picture

it as 100 one megaton nuclear bombs going off in one place without

the radiation, without the nuclear radiation issue. But the explosive force is tremendous. Now, the other effects, I mean, the detailed effects of shock and that sort of thing, or even if there is a

crater in the ground, are not as significant. When you talk about

an explosion in the low atmosphere equivalent to 100 megatons,

the impact on the ground is tremendous. The Tunguska event is

thought today to have been about a five megaton explosion.

Mr. FEENEY. That was in 1908?

Mr. SCHWEICKART. 1908. We are celebrating the hundredth anniversary of that event next year, celebrating——

Mr. FEENEY. We are very familiar with floods and hurricanes in

Florida. We refer to things as a 10 year event, a 20 year event, a

100 year event. What was the 1908 event, in your estimate? Is that

one in 5,000 years, one in 100?

Mr. SCHWEICKART. Well, it is about a one in 600 to 800 year

event, something like that. The size estimates have recently come

down, so the frequency at which it occurs has gone up slightly. But

I think the point is that that explosion, which flattened 2,000

square kilometers of forest and set them afire in Siberia. Luckily,

it didn’t kill anyone, maybe one person, that was only about a five

megaton event, and it never got to the ground, there is no crater.

But the impact would have wiped out all of London or Moscow or

Washington, D.C., or any other city, had it unfortunately come, or

exploded over one of those cities.

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So, the impact of these things does not necessitate a crater in the

ground, but they are extremely powerful, even down to objects as

small as, say, 40, 45 meters in diameter.

Mr. FEENEY. Dr. Tyson.

Dr. TYSON. Yes. I would like to point out that it certainly would

ruin my afternoon if one of these things hit close to my house. But

most of the Earth’s surface is covered by water, and studies of the

actual physical damage from objects that are less than about a few

hundred meters in size come really from the tidal waves that are

set off when these objects would hit the ocean. There is much more

danger that all coastal cities would experience a huge tsunami

from such objects.

The actual physics of what happens with larger objects is different. They are so large, these several kilometer size rocks are so

large that they actually go down to the bottom, all the way through

the water, and punch a hole into the ocean floor, and put all of that

mud up into the stratosphere, creating nuclear winter. It is a very

different scenario. So, for these smaller objects, it is a different and

a somewhat scarier scenario, because there are so many more of

them. As somebody pointed out, there is a factor of 100 more of

these things. And there is a problem with, you know, I have a problem with probability. You know, you can say——

Mr. FEENEY. Probably.

Dr. TYSON. Well, most likely. You can say that, well, actually,

maybe we should spend $1 million on something else, because actually, the probability of this is rather low. But if a 100 meter object

could be on its way towards Earth right now, and hit next week,

for example, even though its probability, the probability per unit

time is very low. So, I think what we need to do is to get on with

these discovery surveys, which find virtually all of the Earththreatening asteroids, and find their orbits, and then it changes the

whole equation.

Mr. FEENEY. Thank you, Mr. Chairman. I yield back.

Chairman UDALL. Thank you. I am not sure, Dr. Tyson, you ruined my afternoon with that image, but that is a very powerful

image and very compelling reason to do the work we are talking

about here today.

The Chairman recognizes the gentleman from California, Mr.

Rohrabacher.

Mr. ROHRABACHER. Let us see. It is going to create a huge wave.

I think I am the only surfer on this panel. One hand, we got another one here. All right.

Now, let me see if I have got this right, Rusty, that the one, the

object that exploded over this, was it Tunguska?

Mr. SCHWEICKART. Tunguska, yes, sir.

Mr. ROHRABACHER. Okay, was only the equivalent of a five megaton? And the one——

Mr. SCHWEICKART. Yes, sir. The most recent analytic work at Los

Alamos indicates it was about five megatons, about 45 meters.

Mr. ROHRABACHER. And you are saying the ones we are looking

for are 140, would be the equivalent of 140 megatons, if it is a 140

meter object. Is that right?

Mr. SCHWEICKART. Approximately, yes, sir.

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NEO SURVEY OBJECTIVES

Mr. ROHRABACHER. So, you are talking about something that

would be 100 times more powerful than the one at Tunguska, is

what we are just trying to observe?

Mr. SCHWEICKART. Yes, sir. That is correct. But let me emphasize, sir, that the 140 meter search goal is, in fact, at this time, the

correct goal. Because, among other things, it is extremely difficult

to find things as you get smaller and smaller. So 140 meters is a

good goal, and in the process of finding 90 percent of the 140 meter

objects, we are also going to find something on the order of 40 to

50 percent of the objects down to 45 or 50 meters. So, we will not

have, let me say, a complete survey of those things which can do

serious damage on the ground, but we will learn a great deal about

them in the process of meeting this appropriate goal.

Mr. ROHRABACHER. Right. From what you said, we are talking

about a huge potential destructive power. I mean, we are talking

about something beyond, I think, the imagination of any of us here.

What is the estimate of the number of undiscovered asteroids that

are of 140 meter range? How many have we yet to discover? What

are we talking about?

Mr. SCHWEICKART. Don has probably got the best number,

but——

Dr. YEOMANS. The 140 meter sized objects, we think there is approximately 20,000 that are in the category of potentially hazardous asteroids, and we have discovered less than four percent of

them.

Mr. ROHRABACHER. So, there are 20,000, and we have actually

charted only about four percent of them? And it is 100 times

stronger than what flattened all of that territory up in Russia?

Dr. YEOMANS. It is like your statement, sir, ignorance is bliss.

Mr. ROHRABACHER. Yes, sir. Dr. Tyson.

Dr. TYSON. Just to add a data point. It is hard to comprehend

the destructive force of something like this, but a 300 meter asteroid, of which there are many, has the potential to wipe out entire

countries.

Mr. ROHRABACHER. Well, obviously, there is a need for us to be

prepared to try to do what we could. If we could mitigate that, we

are talking about minimal expense, as compared to what, the cost

of actually having to absorb this type of damage.

PLANETARY DEFENSE RESPONSIBILITIES

I would like to talk a little bit about that. Who should be in

charge? NASA is obviously involved with the efforts of identifying

this, and with the Jet Propulsion Laboratory, and the assets that

we are talking about. And NASA has been tasked with this. Once

we determine that there is a threat, Rusty is suggesting that this

is no longer a science issue. This is a defense issue at that point.

Should the Defense Department be the ones who are then tasked

with immediately taking over responsibility? Do you have some

ideas as to who should, then, be the entity that is responsible for

planetary defense? To start with NASA, and then work our way

down.

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Dr. PACE. Thank you, sir. Well, as you probably know, there is

no one who is tasked specifically with that responsibility right now.

That is not a settled policy question. And I think it is also fair to

say that it would be something that would take the resources and

capabilities of multiple federal agencies, if they were to be so

tasked.

So, as Mr. Schweickart says about, these things are safety issues

versus sort of science issues, I would also submit this is really a

policy question as to where you want to assign policy responsibilities for this, and what sort of importance you want to give to it.

I think NASA’s traditional role certainly is stronger in the

science and in the technology side of it, and therefore, you know,

it wouldn’t be obvious that we would be the lead agency for something like that, although if so directed, we would certainly participate with other federal agencies who were assigned.

Mr. ROHRABACHER. Does anyone else have a thought on that?

Dr. TYSON. Mr. Rohrabacher, I would like to comment just a bit,

and I thank you very much for highlighting that issue, because as

I said, I believe this is really the most important single issue before

the world, frankly. It is not only the United States, the Congress,

and the Administration, but every, this is a global issue. It is not

a national issue.

Mr. ROHRABACHER. Well, the first part of it is, are we going to

do what is necessary to identify the threat, and then, the issue is

who is going to do it?

Dr. TYSON. Right. And I think that the identification of the

threat has been relatively well dealt with. NASA has explicit responsibility, in terms of discovering. The identification of a threat

comes right up to the point of warning, and issuing warnings has

not been assigned to anyone, including NASA. So, that assignment

has not been made.

And I think that, in fact, it probably was avoided at the time,

several years ago, because of this fundamental policy question.

Who is to make these large international policy decisions, and I

think that it is important that we look at the logic of it, and who

should be involved? NASA clearly is the world’s premier agency for

developing and testing and demonstrating space capability, and

space capability is the sine qua non of protecting the Earth against

asteroid impacts.

However, the policy issues are a larger issue, which involves cooperation between nations, agreements, tradeoffs of risk and many,

many other things. And so, the policy issue is somewhat separable.

Now, the Department of Homeland Security, it would seem, on

plain reading of the language, might be one logical agency. The Department of Defense is clearly another potential agency, and NASA

itself has many international responsibilities, for example, the

International Space Station, in which it makes policy decisions on

behalf of the Nation. So, to me, those three agencies are the prime

candidates.

I, frankly, because of the need for international cooperation and

worldwide public confidence, would argue against the Department

of Defense being the principal agency. The Department of Homeland Security certainly has a large responsibility, but it seems to

me that the Congress needs to hold hearings to allow many, many

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people and perspectives and issues to be openly aired in this regard. But it is extremely important, because these international decisions are being forced on us by the very search programs that we

have been talking about.

In the next 10 to 15 years, we are going to discover hundreds of

thousands of asteroids, and some of them, probably in the hundreds, will look as though they are headed for an impact. And

somebody is going to have to make a decision, within the next 15

years, of do we or do we not take protective action?

Now, those decisions are going to involve tradeoffs between nations and national policy issues, and it seems to me we need to get

on with this critical decision, so that we are in a place to contribute.

Mr. ROHRABACHER. Thank you very much, and Mr. Chairman, I

appreciate your holding this hearing, and I would like to personally

thank the witnesses. This has been very illuminating, if not hairraising. Thank you.

Chairman UDALL. I thank the gentleman from California, and I

know within his political party and his circles, there is a lot of debate about the prefix NEO, and to which words you then apply it,

but since Mr. Rohrabacher may be more of a neo-internationalist

now than he perhaps has been in the past, when it comes to supporting a worldwide effort to make sure that the planet doesn’t suffer from one of these impacts.

GOLDSTONE ANTENNA UPGRADES

We are approaching another vote. I would like to ask a couple

of additional questions of the panel, and then, we will, my questions will conclude the hearing. And I wanted to start with Dr.

Green. NASA is planning to replace the existing deep space antennas at Goldstone with an upgraded system. Will NASA maintain

the current planetary radar capability at Goldstone as part of the

upgrade, and if not, why not?

Dr. GREEN. Indeed, the organization in NASA that manages the

Deep Space Network is the Space Operations Mission Directorate.

They have the responsibility for developing an evolutionary plan

for that system. It is used for communications, in addition to the

science that we utilize that system for, and our radar requirements

have been given to that organization as they develop their plan. In

the near future, we anticipate seeing those requirements met in

the newly redesigned Deep Space Network.

Chairman UDALL. Dr. Yeomans, how important is it?

Dr. YEOMANS. How important is it to maintain the radar with

the DSN? I think it is very important. As was mentioned by a number of folks on the panel here, the Goldstone radar and the Arecibo

radar are the only two we have, in terms of planetary observations,

and they are very complementary. Goldstone covers a large area of

sky. It can actually track the objects, whereas Arecibo is fixed, and

can track 20 degrees on either side of directly overhead, so very

often, an object will come into the Arecibo window, pass out of it,

and pass into the Goldstone window and vice versa. So, it is important to keep both of these facilities robust.

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FUTURE STEPS IN NEO DETECTION AND DEFLECTION

Chairman UDALL. I would like to follow another line of questioning, but start with Dr. Yeomans again, and just give the panel

a heads-up, and invite each one of you to comment before we conclude the hearing. And the focus will be where do we go from here?

NASA submitted its report to Congress on options for the expanded

NEO program for approaches to deflect NEOs.

What do you believe, Dr. Yeomans, the relative priority for resources should be between NEO detection, tracking, cataloging,

characterizing, and development of deflection approaches? In other

words, what is most important to do next, and what specifically

should NASA do next? Easy question, I know.

Dr. YEOMANS. Well, I am a bit biased. We have to find them

early was my first, second, and third priority. And I do think finding them is the first priority. Obviously, we can’t mitigate if we

don’t find them. We can’t characterize if we don’t find them.

Having said that, we do need to characterize, because there is an

enormous diversity amongst Near-Earth asteroids. They range all

the way from a fluffy, wimpy, ex-cometary fluff ball to a rubble

pile, to a slab of solid rock, to a slab of solid iron. So, you wouldn’t

mitigate each of those objects with the same technique, perhaps.

So, we do need to characterize these objects, and we do need to at

least study techniques for mitigation. There is computer simulation

work that needs to be done to understand how an impact or an explosion would interact with a rubble pile, with a slab of iron. So,

we do need to understand the mitigation and the characterization,

but I think discovery is still the most important.

ORBITAL DETERMINATION

Chairman UDALL. Dr. Campbell, Dr. Tyson, Mr. Schweickart in

turn, would you each like to comment on the question of priorities?

Dr. CAMPBELL. I think there is little doubt that discovery is the

most important thing. If you haven’t found them, you certainly

can’t track them and characterize them. It is clear, though, that

there is little point in just making a catalog of a lot of objects in

the sky, with poorly defined orbits. And therefore, I think that the

two, orbit determination and discovery have to go hand-in-hand.

And it seems to me the most important thing to do is to cull the

number of objects that you have found as quickly as possible, so

that you can actually concentrate on the ones that actually do pose

a threat. We have already got thousands of potential objects here,

we are going to be finding tens of thousands. We need to know

which ones of these are a potential threat to Earth, and for the

very smallest objects, we have potentially very little time to do

that, in terms of the fact that they will be rather close to the Earth

in orbits, and pass rather quickly, and not be detectable in the future.

Chairman UDALL. Dr. Tyson.

Dr. TYSON. Thank you, Chairman. Discovery involves obtaining

orbits. You can find a rock that is in the sky and then lose it, and

it is of no use, and that doesn’t count as a discovery. So, with

LSST, one sees each one of these asteroids 100 to 200 times, even

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more. So, it is possible to derive a pretty good orbit for those, and

distinguish them from the background.

So, that facility would get orbits for the Earth-threatening, socalled potentially hazardous asteroids. What is not widely known

is that we observe the whole sky every several nights. We just repeat the whole sky every several nights, often in a different color

band. So, we have a huge amount of color information in a six color

system on each one of these Earth-threatening asteroids, and that,

it turns out, as you might imagine, tells you a fair amount of information about the character of its surface and what it is made out

of. So, we will gain some knowledge for characterization as well

from this data.

But I think we need, actually, the bottom line, I think, is we

need to start this process of discovery. I agree with Don that one

has to actually discover these things and get their orbits first, and

that involves a multi-agency cooperation in these new facilities. I

am thinking of the Department of Energy Office of Science, NASA,

and the National Science Foundation.

Chairman UDALL. Mr. Schweickart.

MORE ON DETECTION AND DEFLECTION

Mr. SCHWEICKART. Yes, Mr. Chairman. Thank you.

I would like to suggest that your, the way in which you have

posed the question is somewhat purist, I guess I would use the

word. Like most things in life, we are confronted with things which

are, they can be posited as either/or, but the reality is that they

are usually not, and I would suggest that this is the case here.

There is absolutely no question that finding them is absolutely

the highest priority. Finding them early is very critical. At the

same time, the most important thing to keep in mind is that we

are finding them in order to protect the Earth from impacts, and

so, I would also suggest that at the same time that we are spending money on finding them, we can also direct JPL or NASA to put

one or two people to thinking about and working through and understanding the ultimate issue of protecting the Earth, mitigating

ones that would be coming at us. And right now, unfortunately,

that additional task of thinking through the deflection issue is not

there.

And all that takes is a clever person, which JPL has lots of,

frankly, thinking about it. But right now, no one is assigned to

that, because their job is to find them. And so, I suggest that we

do both. And I don’t think it’s either/or.

Chairman UDALL. Knowing your history, and also having viewed

with Mr. Feeney the movie Armageddon, I am sure you would be

willing to volunteer for one of those missions, because the spirit is

still willing.

Thank you.

Mr. SCHWEICKART. Well, luckily, we don’t have to have a human

mission to one of these things.

Chairman UDALL. Thank you again for your testimony, for appearing here today. I want to turn to the representatives of NASA

and Dr. Green and Dr. Pace. Would you care to comment as well,

and well, you will have the final word today.

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Dr. PACE. Yes, I just wanted to address a point that any of these

sort of mitigation techniques that one would want to use, of course,

depends on the situation. As I said, many, many of these different

objects have different technical characteristics, and different mitigation techniques may be appropriate.

And so, in that regard, I just, I wanted to go back and clarify one

point, that our report, I hope, did not give the impression that we

had a preference for use of nuclear explosives. So, those are simply

one of the items in the toolkit, and people can disagree over whether it is appropriate or not, depending on the situation. I just want

to stress that we did not want to express a preference.

The second thing is that we are trying to not only find objects,

and obviously, more can be done, but that characterizing these objects is really also part of our science program. The missions, such

as Dawn, that are being done, our international cooperation, what

we learn about these objects with our science missions, we think

is also directly helpful, should and if a mitigation mission ever be

necessary.

And then, finally, I wanted to agree with Dr. Tyson’s point about

the importance of turning a probabilistic threat into a deterministic

one. That is, with a survey effort, and one can go faster or slower,

depending on available resources, that one can get to a point where

you know where these things are, and whether or not you have

thousands of threats, hundreds of threats, one, or none. And that

is also achievable. Progress is being made in ground-based optical

telescopes at an amazing rate. LSST is one particularly notable

one. And that if we simply proceed on the path we are on, we will,

in fact, get good survey information. We will get good characterization of objects with our existing science program, and make

progress, you know, toward the legislative goal.

Thank you.

Chairman UDALL. Dr. Green, did you have anything else to add?

IMPORTANCE OF NEO CHARACTERIZATION

Dr. GREEN. I certainly would echo a number of things that have

been stated here. We know enough about the asteroids to know

that not all are created equal. They are very heterogeneous, not

only in composition in size, but also in their structure. Some are

rubble piles. Some are, indeed, irons and quite different in shapes.

And therefore, that characterization aspects, which is important

from the scientific point of view, understanding their origin and

their evolution, is extremely important for any, the next step,

which would be consideration of mitigation, provided we understand that they are potentially hazardous objects, and when they

might pose an important threat to us.

So, I believe we have started that first baby step. We are moving

out with existing assets. And we are excited about the near-term

future, with new assets coming online. We will definitely step up

our effort, in terms of utilizing those, and I believe, as we learn

more about them, both from in situ observations, but continuing to

utilize our radar facilities, not only in NASA, but we sincerely hope

that NSF will continue to support the Arecibo radar, that that will

enable us to then take more of those steps, which will lead up to

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some sort of mitigation information necessary to avoid these hazards in the future.

Chairman UDALL. Thank you, Dr. Green. I think I speak on behalf of Congressman Feeney, the Ranking Member, in offering my

thanks to all of you for taking your valuable time today to appear

before us, both panels, including Congressman Fortun ̃ o, have been

very, very useful to the Committee.

I would like to make note if there is no objection, the record will

remain open for additional statements from the Members, for answers to any followup questions the Subcommittee may ask of you

all on the panel. Without objection, so ordered.

The hearing is now adjourned.

[Whereupon, at 12:50 p.m., the Subcommittee was adjourned.]

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Appendix 1:

ANSWERS TO POST-HEARING QUESTIONS

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ANSWERS TO POST-HEARING QUESTIONS

Responses by James L. Green, Director, Planetary Science Division, Science Mission

Directorate, National Aeronautics and Space Administration (NASA)

Questions submitted by Chairman Mark Udall

Q1. NASA submitted a 2007 report to Congress on NEO search and deflection options, but the report doesn’t provide a recommended option, as required in the

2005 NASA Authorization Act. What approach does NASA recommend that

complies with the legislated mandate and what steps have NASA taken to begin

implementing any of the options identified in the report?

A1. NASA will look for opportunities using potential dual-use telescopes and spacecraft—and partner with other agencies as feasible—to attempt to achieve the Congressional goal outlined in Section 321 of the NASA Authorization Act of 2005 (P.L.

109–155). The Agency has already begun work with Pan-STARRS to ensure its capability for use in the NEO survey effort, and is beginning work to assess what

might be done with the Wide-field Infrared Survey Explorer (WISE), and to upgrade

the capabilities of the Minor Planet Center (MPC).

Q1a. NASA’s report to Congress mentions search options that would rely on planned

ground-based telescopes that have been proposed for development under the

auspices of other agencies. What role, if any, should NASA play in supporting

the NEO-related operations of those telescopes? What alternatives exist if those

assets are not funded and developed?

A1a. Maximizing use of the Pan-STARRS and eventually the LSST, if they are developed by other agencies, may be a very cost-effective way for NASA (though perhaps not the Federal Government as a whole) to meet the 90 percent goal, though

not on the timeline outlined in Section 321 of the NASA Authorization Act of 2005

(P.L. 109–155). At the present time NASA does not have a commitment from the

sponsoring agencies that the assets will be developed. However, the Agency has

begun discussions with the University of Hawaii regarding use of the Pan-STARRS

prototype telescope and will continue to monitor its further development, as well as

the possible eventual support of LSST by the National Science Foundation, in order

to insert at the appropriate time capabilities and commitments for their use in the

NEO survey effort. In fact, LSST (or a generic equivalent) is expected to be

reprioritized by the National Academies in its upcoming astronomy and astrophysics

decadal survey process, and this report will play a significant role in future prospects for LSST within the Foundation’s broader set of priorities.

Q2. Dr. Yeomans testified that optical observations alone are often not ‘‘accurate

enough to immediately rule out a future Earth impact’’ once a potentially hazardous asteroid is detected. Dr. Campbell testified that the Goldstone antenna

alone would be unlikely to fill the void if Arecibo were to be shut down. What

specifically are NASA’s plans for calculating the risk of potentially hazardous

objects in a timely fashion, especially given the expected increase in NEOs detected from an expanded survey with Pan-STARRS or LSST? Do those plans involve either Arecibo or Goldstone?

A2. The Spaceguard System, which was setup and supported by NASA, will continue to process NEO observations for impact prediction analysis by the Agency’s

NEO Program Office in a near real-time manner through the established procedures

with the Minor Planet Center of obtaining timely follow-up optical observations and

reviewing archived data and photographic records for ‘‘pre-discovery observations.’’

As the proposed expanded survey efforts (potentially with assets like Pan-STARRS

and LSST) come on line to detect significantly fainter (i.e., smaller) NEOs, these

types of instruments will have the coverage capacity to essentially be responsible

for obtaining their own optical follow-up observations.

Although the radar capabilities of both Arecibo and Goldstone are able to provide

precise refinement of NEO orbits, their observations are only available on a limited

subset of NEOs—those that happen to be passing close enough to Earth to be within

their range. NASA will use these observations when available, but by far the majority of NEOs orbits must still be determined via optical observations. Once a NEO

has been initially detected and its approximate position determined, a whole host

of other optical assets can be brought to bear on that NEO’s location to determine

the orbit as precisely as our orbit models allow. Over time periods significantly

smaller than the average impact rate (a few years versus hundreds of years between

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significant impacts) a collection of optical observations will approach the accuracy

that can be obtained via radar observations.

Q3. What are the requirements for data management to support the expanded Survey? How big a job is it likely to be?

A3. Data throughput required as an expanded Survey reaches peak discovery productivity is estimated to reach as much as 100 times the current discovery and observation rates, with the associated needs for expanded data archives. The current

Minor Planet Center computer systems are at least two generations obsolete, and

will therefore need to be upgraded. However, the anticipated capabilities needed are

well within the capabilities of modern desktop computer network systems.

Q3a. Your testimony indicates that NASA has started to evaluate the needs of the

Minor Planet Center to accommodate the increase in detection that will result

from an expanded survey. What, in specific terms, are NASA’s plans for the

Minor Planet Center and any changes that may be required to support the expanded survey? What, if any, costs are associated with those plans? How do

those plans relate to options on data management presented in the report to

Congress?

A3a. In 2008, NASA’s Science Mission Directorate plans to solicit for proposals from

the small Solar System bodies community for management and operations of the

Minor Planet Center—first to modernize the current computer systems and operations, and then to accommodate expanded data throughput for an anticipated expansion of the Survey effort. Costs will be determined based on the proposals received, but NASA does not anticipate costs beyond $1.0 million per year initially.

Later options may look at back-up facility needs. This approach most closely relates

to the ‘‘Scale Existing Data Management Systems’’ alternative outlined in the NASA

report on NEOs submitted to Congress in March 2007.

Q3b. Does NASA have any plans to compete the data management task for the expanded search?

A3b. The Minor Planet Center solicitation will be a full and open competition.

Q4. The European Space Agency (ESA) has conducted a study for a mission (Don

Quixote) that would test NEO deflection technologies. Has ESA expressed any

interest in international cooperation on a mission, if it were to go forward? If

so, has NASA explored the possibility of contributing?

A4. The Don Quixote mission concept has been discussed at bilateral meetings with

ESA as a potential area for cooperation. However, NASA understands that further

development of this mission has been placed on hold by ESA.

Q4a. Your testimony noted that ‘‘ESA has been studying . . . another mission called

Marco Polo, that does have a much better chance now of making it through

their budgetary process, that will also add information that is important for

us.’’ Could you please describe the potential Marco Polo mission and how it

would benefit NASA’s NEO search and/or the characterization of NEO’s? What

is the status of any discussions between NASA and ESA on collaboration or

access to data from this potential mission?

A4a. Marco Polo is a proposed near-Earth object sample return mission to a primitive asteroid whose objective is to return samples that are otherwise not available

among known meteorites. Primitive bodies are leftover building blocks from the earliest era of Solar System formation and may have contributed water and organics

to Earth, thereby providing a foundation for life. Primitive meteorites are among the

least frequently sampled by falling to Earth and all samples received are biased by

their ability to survive atmospheric passage. Direct investigation of both the fresh

regolith and fresh lithospheric fragments is also impossible by any means other

than sample return. Marco Polo will conduct a broad in situ analysis of the target

and the geologic context for the samples prior to their acquisition. Sample return

enables the power of the Earth’s laboratories to identify major chronological events

in solar system history, to search for pre-solar material yet unknown in meteorite

samples, and to characterize in depth the nature of organic compounds that may

be present. Thus, Marco Polo will provide extensive information for the characterization of NEOs. A participating scientist proposal has been submitted by a team

of U.S. scientists to the ESA Cosmic Vision solicitation for this mission and we are

in the preliminary stages of the process to award to this proposal.

Q4b. You also testified that ‘‘The Canadians will be launching a spacecraft called

NEOSSat. We have been discussing about how it can be utilized and making

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the data more available.’’ Could you please describe the NEOSSat mission and

how the data would benefit NASA’s NEO search and/or characterization effort? What is the status of any discussions between NASA and the Canadian

Space Agency on collaboration or access to data from this potential mission?

A4b. The Canadian Space Agency (CSA) Near Earth Object Surveillance Satellite

(NEOSSat) is a small satellite with a 0.15 meter aperture visible sensor which we

understand will be launched sometime in 2009. The small aperture of the sensor

means it will have little advantage over current ground based capabilities to detect

and track NEOs. However, the continuous access offered by a space-based asset may

provide some advantage to augment our capabilities, perhaps in the area of obtaining follow-up observations. NASA is in preliminary discussions with the CSA about

collaboration or access to the data.

Q5. Dr. Tyson testified that the estimated the cost for a 12-year long survey would be $125 million. You testified that ‘‘The LSST activity, of course, is one that

needs to be resolved, in terms of whether they will have sufficient funding, and

be able to put together the capability before we can begin to figure out how to

work with them and leverage that system.’’ Is NASA ruling-out partial support

for development, even though such support could help ensure the availability of

a system that could complete the expanded Survey at a considerably lower estimated cost than the options provided in NASA’s report to Congress?

A5. Maximizing use of the proposed LSST is probably part of the most cost-effective

way for NASA to meet the 90 percent goal, though not on the timeline specified in

the NASA Authorization Act of 2005 (P.L. 109–155). LSST (or a generic equivalent)

is expected to be reprioritized by the National Academies in its upcoming astronomy

and astrophysics decadal survey process, and this report will play a significant role

in future prospects for LSST within the Foundation’s broader set of priorities. NASA

will continue to monitor its further development in order to insert at the appropriate time capabilities and commitments for its use in the NEO survey effort.

Q6. NASA Ames recently hosted a workshop on the potential of low-cost spacecraft

to characterize NEOs. What, if any, plans does NASA have to pursue such missions?

A6. NASA held a workshop on low-cost missions to NEOs at Ames Research Center

on October 20–21, 2007. The workshop agenda blended three major themes: (1) the

importance of characterizing small NEOs and the kinds of science measurements

that need to be made; (2) how to get to the targets (i.e., target populations, orbital

dynamics, direct vs. gravity-assist trajectories, opportunities for secondary payloads

and missions of opportunity); and (3) options for low-cost missions (i.e., small spacecraft, instruments, proximity operations, propulsion, landers, and impactors).

A primary conclusion from the workshop is that low-cost missions to NEOs can

play a role in exploring and characterizing these objects. Since a major objective is

to explore the diversity of the NEO population and characterize their physical properties, launching multiple small missions could be cost-effective if the technology

can be sufficiently matured. NASA already plans numerous ‘‘mission of opportunity’’

solicitations for which such proposals could be submitted.

Questions submitted by Representative Tom Feeney

Q1. NASA’s Near-Earth Object (NEO) report, delivered this March, provides several

options for meeting the goal of achieving 90 percent detection, tracking and characterization of Potentially Hazardous Objects (PHOs), and the report establishes

a clear relationship between resources invested and the time needed to achieve

90 percent coverage. In essence, the report shows that for an additional investment of approximately $536 million, we could buy-down a decade of time to

complete the survey. In your view, is that additional investment necessary? Does

the threat posed by PHOs compel faster completion of the survey?

A1. NASA’s analysis shows that not completing the NEO survey down to 140 meters until the 2025–2030 timeframe does not statistically carry a level of risk that

requires costly actions.

Q2. What are the most difficult types of NEOs to detect? Is there, for instance, a portion of the sky that won’t be covered by ground-based facilities? Are there certain

types of orbits that make it difficult to detect and track asteroids and comets?

A2. Small NEOs composed of dark, carbonaceous materials are difficult to detect because they are intrinsically faint. NEOs of any size and composition on very Earthlike orbits can be potentially difficult to detect because they may spend a considerVerDate 11-MAY-2000 18:21 Feb 21, 2008 Jkt 038057 PO 00000 Frm 00124 Fmt 6601 Sfmt 6621 C:\WORKD\SA07\110807\38057 SCIENCE1 PsN: SCIENCE1
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able number of years far from Earth on the other side of the Sun. Such objects may

spend many years being effectively unobservable to ground- or Earth-based telescopes because of their apparent faintness or apparent proximity to the Sun.

In general, the present bias toward NEO survey programs being located in the

northern hemisphere does not significantly affect progress in completing the

Spaceguard Survey for kilometer and larger NEOs; objects not detected during a

southern-hemisphere-visible close approach will most likely be detected on a subsequent northern-hemisphere close pass. The present baseline survey plan for the

Large Synoptic Survey Telescope (LSST) as developed by the project’s proponents,

which will, if funded, be based in the southern hemisphere and be a significant contributor to a follow-on survey for 140m and larger NEOs, conversely leaves some

time gap in northern hemisphere NEO detection capabilities. The LSST project proponents are, however, actively exploring options for modifications to their baseline

observing plan to include a portion of the northern ecliptic (the central plane of the

solar system—where most NEOs spend most of their time) in order to increase their

detection rate of NEOs.

In any case, all surveys able to find 90 percent of potentially hazardous objects

reduce the actuarial risk by the same amount, even if some small percentage of the

objects is more difficult to detect by a specific system.

Q3. Once the LSST and Pan-STARRS telescopes are operating, and surveys for

PHOs that are 140 meters or larger has commenced, what is the business and

public safety case for expanding the search to detect and track smaller PHOs—

or instance, down to a size of 50 meters? What are the cost and schedule implications?

A3. An object of about 50 meters and average density would not be expected to survive all the way through the Earth’s atmosphere and strike the surface, but this

depends on the object’s composition and structure. It could be expected to cause an

explosion a few kilometers above the Earth’s surface and may therefore cause some

blast damage at ground level.

The number of objects and frequency of impact increases as threshold size decreases, roughly based on the following figure, which is also Figure 2 in the report

on NEO’s NASA submitted to Congress in March 2007.

Therefore, it is estimated that, while there may be about 20,000 Potentially Hazardous Object (PHO)s 140 meters and larger, there are estimated to be about

100,000 PHOs 50 meters and larger and impacts by these smaller objects will therefore be more frequent.

Simulations suggest that a next generation search for potentially hazardous objects (PHOs) down to 140 meters that includes only Pan-STARRS (assumed 2010

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start) and LSST (assumed 2014 start) would discover roughly 42 percent of the

PHOs larger than 50 meters by the end of 2020 and 59 percent by the end of 2029.

Using a one-meter infrared telescope in a Venus-like orbit (assumed 2014 operations

start) in addition to the ground-based Pan-STARRS and LSST surveys, the discovered population of 50 meters and larger sized objects would be complete to the level

of 78 percent at the end of 2020 and 92 percent complete by the end of 2029. This

assumed timeline would require that these systems operate for over a decade, and

therefore might require multiple advanced spacecraft to be built (depending on design life), and would also require an even more capable operational data management infrastructure.

Although no estimated costs for such a program are available, it is likely that

such a search would require significantly more resources than necessary for the

Congressional goal of 90 percent of 140 meters objects outlined in the NASA Authorization Act of 2005 (P.L. 109–155). The completion of the Congressional goal alone

would retire 99 percent of the actuarial risk from PHOs of all sizes. Once significant

progress has been made toward the Congressional goal, more consideration may be

given to finding and tracking all potentially hazardous objects.

Q4. During the hearing several witnesses mentioned the Air Force’s funding of the

Pan-STARRS telescope facility in Hawaii as a possible new ground observatory

that would be very adept at detecting NEOs. What is the status of Pan-STARRS

and the likelihood that all four telescopes will be built? Would the Air Force be

willing to make available a portion of the telescope’s time to NEO surveys if less

than four telescopes are built?

A4. NASA understands that the Pan-STARRS Project Office acts as the Air Force’s

agent for discussion of capabilities related to NEO detection and survey, so all discussions have been directly with that project office at the University of Hawaii. PanSTARRS currently is in check-out of its first prototype telescope at the Air Force

facility on Haleakala, Maui. NASA cannot speculate on the future funding that will

be made available by the Air Force to this project. However, the Pan-STARRS

Project Office has already begun discussions with our NEO Program on how the single prototype telescope could be used to complete our currently ongoing one kilometer NEO survey, so it is likely they will work with the survey effort at whatever

level of capability they are able to achieve.

Q5. How adaptable are current and proposed space-based infrared satellites to the

role of NEO detection, tracking, and characterization? For instance, can Spitzer

be used, even if its cryogenic coolant is depleted? And what about WISE (Widefield Infrared Survey Explorer), due to be launched in 2009?

A5. The majority of existing astronomical telescopes are designed with limited fields

of view so they can focus on a specific object of interest. The fewer number of telescopes designed for survey work has relatively large fields of view (FOV) so that

they can cover more sky more quickly. For instance, the Spitzer telescope’s largest

FOV is only five arc minutes by five arc minutes, or less than 10 percent of the

area size that would be useful for a survey effort, usually considered to be at least

one by one degree FOV. In ‘‘back of the envelope’’ terms, this means it would take

Spitzer more than ten times longer to conduct the survey effort than a telescope designed for it, even if it were dedicated to the effort full-time. This of course is not

possible.

Of greater potential is the Wide-field Infrared Survey Explorer (WISE) since, as

its name implies, it has a wide FOV instrument. Currently being developed for a

late 2009 launch for a six month astrophysics mission to map the infrared sky, the

WISE instrument is also capable of detecting many asteroids, of which a portion will

be NEOs. NASA is evaluating what it will take to make its operations useful to the

NEO survey effort. However, the limitations of WISE relative to what it takes to

do the NEO survey will limit the results NASA can get from it. Those limitations

are its static pointing capability, because it only points along the plane of its orbit

so a NEO must pass through that plane at some time to be detected by WISE, and

its limited lifetime of only six months—although NASA is exploring what it would

take to double that lifetime. If a spacecraft with the capability of WISE could operate for 10 years, it could go a long way towards completing the survey effort, but

in only six months it may detect only about 400 previously unknown NEOs.

The NASA study looked at all known spacecraft, including those operated and

planned by the Air Force, and although several of these projects provided potential

technology that could be used in a NEO survey spacecraft, no others had the right

combination of capability and operational application that would be useful to the effort.

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Q6. The NEO Survey Analysis indicates that a space-based observatory has certain

advantages over ground-based telescopes. How seriously is NASA giving consideration to building and launching a space-based observatory?

A6. The space-based alternatives have both benefits and risks when compared with

ground-based assets. However, both types of systems can meet the Congressional

goal of surveying 90 percent of 140 meters objects outlined in the NASA Authorization Act of 2005 (P.L. 109–155). If a system is built, the benefits and risks would

be weighed against cost differences to make a selection. NASA does not have plans

for building either a ground or space-based asset for NEO detection within its budgeted program. However, there are a few programmed space flight opportunities for

competitive selection to which a capability might be proposed by the external community.

Q7. One deflection solution, suggested by NASA, is to detonate a nuclear device in

the vicinity of a PHO. What are the advantages and disadvantages of using this

approach? What circumstances would argue against using a nuclear device in

lieu of alternative approaches?

A7. The report on NEOs NASA submitted to the Congress in March 2007 did not

recommend any one specific deflection solution—different scenarios might require

completely different combinations of systems and solutions. However, the alternatives analysis for this report found:

• Deflection systems using nuclear explosives carry the highest deflection capability per kg of payload launched of the alternatives studied, therefore significantly reducing launch costs and increasing launch opportunities.

• Deflection systems using nuclear explosives were evaluated to be applicable

to the widest range of threats (size, composition, shape, spin rate, etc.), although other alternatives may have advantages in certain scenarios.

• Nuclear explosives were evaluated to be among the most reliable and repeatable of the deflection techniques evaluated, with the highest level of technology readiness relative to alternatives.

• Impulsive methods, including nuclear explosives and kinetic impactors, provide their deflection instantaneously. This improves performance in ‘‘quick response’’ scenarios and permits multiple successive attempts that are likely to

be necessary to achieve desired levels of deflection campaign reliability.

• Deflection systems using nuclear explosives are likely to be among the lowest

cost due to significantly lower launch costs, lower payload development costs,

and lower operations costs than slow push methods.

• Deflection systems using nuclear explosives carry unique operations and

launch safety risks, all of which must be evaluated in the event a credible

threat to the Earth is actually detected.

• Possible deflection scenarios cover a wide range of threat characteristics including size, mass, composition, spin rate, shape, cohesion, and number of

gravitationally bound objects. As the NASA study indicated, the alternatives

studied provide a ‘‘tool kit’’ of options to a decision-maker when an actual

threat becomes apparent.

Nuclear deflection is possibly the most effective option when cost, schedule, technology readiness, operational issues, and the need for characterization are considered, but it does have unique political, policy, and safety considerations. A series

of one or more standoff nuclear devices may be the only option as the mass of the

threat grows, but there are some instances (e.g., when the risk of fragmentation is

high) where they may not be the primary selection.

To achieve the level of reliability likely to be required to mitigate a potential

threat, it is likely that multiple deflection techniques would need to be pursued as

part of a deflection campaign such that no technology or system is a single point

of failure. The use of nuclear explosives is evaluated to be very effective for many

threat scenarios, and it is one of many options in the tool kit of defection alternatives.

Questions submitted by Representative Dana Rohrabacher

Q1. The need for a comprehensive potentially hazardous Near-Earth Objects (NEO)

program seems to require expertise of several agencies. How do you suggest coordination be handled?

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A1. At present, no department or agency of the United States is assigned the responsibility for a NEO contingency notification plan or the responsibility to mitigate

threats posed by potentially hazardous near Earth asteroids and comets. As with

other major natural disasters, a coordinated approach involving multiple federal

agencies would clearly be required. NASA has not developed a position on how responsibilities should be assigned among U.S. departments and agencies.

Q2. Describe some of the proposed mitigation techniques and their trade offs.

A2. The report on NEOs NASA submitted to the Congress in March 2007 examined

a number of techniques for deflecting a Potentially Hazardous Objects (PHO) that

have been categorized as either ‘‘impulsive’’ or ‘‘slow push.’’ The tables below provide

an overview of the impulsive methods and the slow push techniques, where the velocity change results from the continuous application of a small force, considered in

the report. Each of these concepts is developed further in the report.

In the impulsive category, the use of a nuclear device was found to be the most

effective means to deflect a PHO. Because of the large amount of energy delivered,

nuclear devices would require the least amount of detailed information about the

threatening object, reducing the need for detailed characterization. While detonation

of a nuclear device on or below the surface of a threatening object was found to be

10–100 times more efficient than detonating a nuclear device above the surface, the

standoff detonation would be less likely to fragment the target. A nuclear standoff

mission could be designed knowing only the orbit and approximate mass of the

threat, and missions could be carried out incrementally to reach the required

amount of deflection. Additional information about the object’s mass and physical

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properties would perhaps increase the effectiveness, but likely would not be required

to accomplish the goal.

Non-nuclear kinetic impact alternatives are the most effective non-nuclear option,

transferring 10–100 times less momentum than nuclear options for a fixed launch

mass. Impact velocities, varying from 10–50 km/s, produced a factor-of-three variation in deflection performance. In addition, kinetic impacts are also sensitive to the

porosity, elasticity, and composition of the target and may require large performance margins if these characteristics are not well determined.

Slow push techniques analyzed in this study included a gravity tractor, which

could alter the course of an object using the gravitational attraction of a massive

spacecraft flying in close proximity, and a space tug, which could attach itself to a

PHO and move it using high-efficiency propulsion systems. An attached space tug

has generally 10–100 times more performance than the gravity tractor, but it requires more detailed characterization data and more robust guidance and control

and surface attachment technologies. This technique could be effective in instances

where small increments of velocity (less than one mm/s) could be applied to relatively small objects (less than 200 meters in diameter) over many decades. In general, the slow push systems were found to be at a very low technology readiness

level (with the exception of the gravity tractor, which was medium) and would require significant development efforts.

Q3. What is your assessment of the need for a nuclear deflection capability?

A3. There is no need for any deflection capability at this time. No impact threat

has yet been identified. If a timely detection capability is fielded, there will most

likely be significant warning time in which to develop other parts of the system such

as sufficiently capable characterization and deflection spacecraft.

Q4. What are the weakest links in the ‘‘system’’ considering the overall goal to protect

Earth from asteroid impacts?

A4. Finding any potential threats so that their orbits can be determined is the

weakest link by far. Unless we find threats, we will be unable to react. If we do

find threats in a timely manner, there will very likely be significant warning time

in which to develop other parts of the system such as sufficient characterization and

deflection spacecraft.

Q5. Dr. Donald Yeomans stated that the highest priority regarding NEOs is to ‘‘find

them early, find them early, find them early.’’ Yet NASA refused to recommend

a program to find them (140 meters and larger) early as directed by law. Why?

How does NASA justify this refusal?

A5. NASA recommended an approach commensurate with the resources the Agency

has been appropriated to accomplish its task.

Q6. What is your estimate on the number of undiscovered asteroids in the 140 meter

and above range? Describe the potential damage that an asteroid in the 140

meter range could cause striking an ocean within, say, 500 miles from a U.S.

coast.

A6. The latest estimate of the total number of near-Earth asteroids (NEAs) larger

than 140 meters in diameter is at least 20,000, but could be higher. However, the

mean time between impacts of an object 140 meters in size anywhere on the Earth’s

surface is estimated as about 5,000 years; larger objects would be even less frequent. Objects striking the ocean within about 500 miles of a U.S. coast would be

very infrequent, considerably longer than 100,000 years between events.

The impact of a 140-meter-size object, striking at a typical impact speed of about

20 km/s, would deliver and explosive energy equivalent of some 170 megatons. Estimates of the tsunami effects from asteroid impact vary from researcher to researcher, but recent analyses, based on studies of waves generated by underwater

explosions, indicate that the risk of impact tsunami from asteroid impacts in this

size range has previously been overstated. Assuming precisely where an ocean impact might occur and then extrapolating potential damage from a related tsunami

event lends to analysis of a ‘‘worst on worst’’ scenario that couples one highly improbable event to another and biases any resulting assessment. However, the recent

studies have indicated the deepwater tsunami wave height at a point 1000 km (∼600

miles) from the impact of a 140-meter diameter stony asteroid might be on the order

of only a few meters, but this deepwater wave height can increase dramatically

when the waves reach the shoreline because the waves slow in shallow water and

concentrate the wave energy. Based on recent assessments of tsunami risks for various locations, estimates are that the typical run-up factor (the ratio of the vertical

height above sea level of the tsunami at its furthest point inland to its deepwater

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wave height) for impact tsunamis is only two to three, but this can vary considerably, depending on local topography and the direction of travel of the wave. All this

suggests that one might expect a run up tsunami wave height of up to 10 meters

or so from an ocean impact of a 140-meter diameter stony asteroid. This is roughly

comparable to the measured run-ups from the tsunami that accompanied the Sumatra earthquake of December 26, 2004.

Q7. Asteroids are more easily detected in the infrared spectrum. An asset such as

the Wide-field Infrared Survey Explorer (WISE) satellite has an effective capability for searching for NEO’s infrared output. Is WISE being tasked for this

role? What other infrared detection devices can or will be used to detect NEOs?

A7. WISE is not currently tasked for this role, but NASA is beginning to investigate

what might be done with the WISE spacecraft that could be useful to the NEO survey effort. However, because of the limited duration of the WISE mission, its usefulness to the survey effort will be limited.

NASA continues to look at other infrared capabilities in development or planning,

but no other possibilities have yet been identified.

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ANSWERS TO POST-HEARING QUESTIONS

Responses by Scott Pace, Associate Administrator, Program Analysis and Evaluation,

National Aeronautics and Space Administration (NASA)

Questions submitted by Chairman Mark Udall

Q1. Dr. Green’s testimony notes that ‘‘The science community may propose a Near

Earth Object (NEO) survey mission under the competitively-selected Discovery

program.’’ While some space science missions may offer the potential to contribute to NEO detection, in addition to their scientific investigations, a NEO

survey mission is not a science mission if its purpose is primarily to detect

NEOs. Does NASA have any plans to consider developing a dedicated Discoveryclass space-based NEO survey mission to respond to the directive in the NASA

Authorization Act of 2005? If so, how would NASA carry out such a development-what organization within NASA would have responsibility for it?

A1. A great deal of science can be learned about the history and evolution of the

Solar System by inventory of all the pieces of mass that exist in it, including those

as small as a few 100 meter sized objects, and understanding how they evolved to

their current positions. Exciting theories about the repositioning of the outer planets

have recently come to light based on studies of the dynamics of the small body population.

Although a small body survey mission has not yet be selected in the Discovery

program, there have been a few missions proposed to accomplish this type of work.

There are no plans to ‘‘dedicate’’ a Discovery mission to an NEO survey effort, but

NASA solicitations will remain open to these types of proposals. If the selection

process determines that such a mission is the best option, considering many technical feasibility factors in addition to the science, it will also be managed under the

highly successful structure that has been instituted by NASA’s Science Mission Directorate in the Planetary Science Division’s Discovery Program.

Q2. NASA is planning to replace the existing Deep Space Network (DSN) antennas

at Goldstone with an upgraded system. Will NASA maintain the current planetary radar capability at Goldstone as part of the upgrade? When, in concrete

terms, will NASA know the specifics of plans for the DSN upgrade and planetary radar capability at Goldstone?

A2. NASA is in the process of evaluating the driving requirements for capabilities

provided by the DSN. These requirements, which include planetary radar capability

at Goldstone, are being worked jointly among three Mission Directorates—Space

Operations, Exploration Systems, and Science. This collaboration will drive the decision on the needed capabilities and will formulate the options for maintaining or

upgrading the DSN assets. NASA expects to complete these plans by May 2008.

Q3. NASA is providing funding to the Air Force’s Pan-STARRS project.

Q3a. When did NASA start funding the project and how much funding is being provided on an annual basis? Is the funding provided through a grant, contract,

or other type of agreement? How much funding does NASA plan to provide in

total? Is the funding being provided to the Air Force or the University of Hawaii?

A3a. The NASA NEO Program started limited funding to the Pan-STARRS project

in 2007 with a partial award to a proposal submitted to the program by the University of Hawaii, who manages the Pan-STARRS development for the Air Force. This

partial award was a one-year grant to the University of Hawaii of $450,000. Any

future funding will depend on the success of pending and future proposals PanSTARRS submits to competitive opportunities of the NEO Program that NASA announces through its annual Research Opportunities in Space and Earth Sciences.

Q3b. What, specifically, is the funding being used for and what will be provided to

NASA in return?

A3b. The funding is largely being used to adapt existing ‘‘moving object detection’’

software from a current Spaceguard project for use by the Pan-STARRS data processing system. This allows the option for NASA to make use of Pan-STARRS for

NEO detection in the future.

Q3c. Who made the decision to fund Pan-STARRS—and did NASA approach the Air

Force or did the Air Force approach NASA?

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A3c. The decision to fund a part of the proposal submitted by the University of Hawaii to the NEO Program was made through NASA’s Research and Analysis peer

review process. The final selecting official was Dr. James Green, Planetary Science

Division Director.

Q3d. Has NASA discussed with the Air Force or University of Hawaii any changes

to the observing times and sequences of Pan-STARRS to optimize the telescope

for an expanded NEO search? If so, what is the status of those discussions?

A3d. As Pan-STARRS nears operational capability, there have been preliminary

discussions with the project office about what observing techniques and cadences

could be used to best optimize the Pan-STARRS operations to achieve all its requirements, to include NEO detection. NASA has not had any direct discussions with the

Air Force, as the Agency understands that the Pan-STARRS Project Office acts as

its agent for these matters.

Q4. Dr. Green’s testimony described NASA’s NEO contingency notification plan,

which lays out the procedures for notification up through the NASA Administrator if a NEO is detected with a significant probability of impacting Earth.

Q4a. Does a notification or warning system exist beyond NASA for informing the

public and federal and State disaster and emergency response agencies? If not,

what should be done?

A4a. At present, no department or agency of the United States is assigned the responsibility for a contingency notification plan regarding threats posed by potentially hazardous near Earth asteroids and comets. As with other major natural disasters, a coordinated approach involving multiple federal agencies would clearly be

required. NASA has not developed a position on how responsibilities should be assigned among U.S. departments and agencies.

Q4b. How will policy and legal issues involved in addressing NEOs—e.g., when and

how to warn the public and whether to use nuclear explosives to deflect an asteroid—be handled on national and international levels? What steps have

NASA and other federal agencies taken to date to address such issues?

A4b. At present, no department or agency of the United States is assigned the responsibility to mitigate threats posed by potentially hazardous near Earth asteroids

and comets. As with other major natural disasters, a coordinated approach involving

multiple federal agencies would clearly be required. NASA has not developed a position on both the policy and legal issues addressing NEOs or how responsibilities

should be assigned among U.S. departments and agencies. NASA would defer to the

Department of State to assess the best approaches to international cooperation on

this issue.

Questions submitted by Representative Tom Feeney

Q1. Once the LSST and Pan-STARRS telescopes are operating, and surveys for potentially hazardous objects (PHOs) that are 140 meters or larger has commenced, what is the business and public safety case for expanding the search

to detect and track smaller PHOs—for instance, down to a size of 50 meters?

What are the cost and schedule implications?

A1. An object of about 50 meters and average density would not be expected to survive all the way through the Earth’s atmosphere and strike the surface, but this

depends on the object’s composition and structure. It could be expected to cause an

explosion a few kilometers above the Earth’s surface and may therefore cause some

blast damage at ground level.

The number of objects and frequency of impact increases as threshold size decreases, roughly based on the following figure, which is also Figure 2 in the report

on NEO’s NASA submitted to Congress in March 2007.

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Therefore, it is estimated that, while there may be about 20,000 PHOs 140 meters

and larger, there are estimated to be about 100,000 PHOs 50 meters and larger and

impacts by these smaller objects will therefore be more frequent.

Simulations suggest that a next generation search for potentially hazardous objects (PHOs) down to 140 meters that includes only Pan-STARRS (assumed 2010

start) and LSST (assumed 2014 start) would discover roughly 42 percent of the

PHOs larger than 50 meters by the end of 2020 and 59 percent by the end of 2029.

Using a one-meter infrared telescope in a Venus-like orbit (assumed 2014 operations

start) in addition to the ground-based Pan-STARRS and LSST surveys, the discovered population of 50 meters and larger sized objects would be complete to the level

of 78 percent at the end of 2020 and 92 percent complete by the end of 2029. This

assumed timeline would require that these systems operate for over a decade, and

therefore might require multiple advanced spacecraft to be built (depending on design life), and would also require an even more capable operational data management infrastructure.

Although no estimated costs for such a program are available, it is likely that

such a search would require significantly more resources than necessary for the

Congressional goal of 90 percent of 140 meters objects outlined in the NASA Authorization Act of 2005 (P.L. 109–155). The completion of the Congressional goal alone

would retire 99 percent of the actuarial risk from PHOs of all sizes. Once significant

progress has been made toward the Congressional goal, more consideration may be

given to finding and tracking all potentially hazardous objects.

Q2. How adaptable are current and proposed space-based infrared satellites to the

role of NEO detection, tracking, and characterization? For instance, can Spitzer

be used, even if its cryogenic coolant is depleted? And what about WISE (WideField Infrared Survey Explorer), due to be launched in 2009?

A2. The majority of existing astronomical telescopes are designed with limited fields

of view so they can focus on a specific object of interest. The fewer number of telescopes designed for survey work has relatively large fields of view (FOV) so that

they can cover more sky more quickly. For instance, the Spitzer telescope’s largest

FOV is only five arc minutes by five arc minutes, or less than 10 percent of the

area size that would be useful for a survey effort, usually considered to be at least

one by one degree FOV. In ‘‘back of the envelope’’ terms, this means it would take

Spitzer more than ten times longer to conduct the survey effort than a telescope designed for it, even if it were dedicated to the effort full-time. This of course

is not possible.

Of greater potential is the Wide-field Infrared Survey Explorer (WISE) since, as

its name implies, it has a wide FOV instrument. Currently being developed for a

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late 2009 launch for a six month astrophysics mission to map the infrared sky, the

WISE instrument is also capable of detecting many asteroids, of which a portion will

be NEOs. NASA is evaluating what it will take to make its operations useful to the

NEO survey effort. However, the limitations of WISE relative to what it takes to

do the NEO survey will limit the results NASA can get from it. Those limitations

are its static pointing capability, because it only points along the plane of its orbit

so a NEO must pass through that plane at some time to be detected by WISE, and

its limited lifetime of only six months—although NASA is exploring what it would

take to double that lifetime. If a spacecraft with the capability of WISE could operate for 10 years, it could go a long way towards completing the survey effort, but

in only six months it may detect only about 400 previously unknown NEOs.

The NASA study looked at all known spacecraft, including those operated and

planned by the Air Force, and although several of these projects provided potential

technology that could be used in a NEO survey spacecraft, no others had the right

combination of capability and operational application that would be useful to the effort.

Q3. The NEO Survey Analysis indicates that a space-based observatory has certain

advantages over ground-based telescopes. How seriously is NASA giving consideration to building and launching a space-based observatory?

A3. The space-based alternatives have both benefits and risks when compared with

ground-based assets. However, both types of systems can meet the Congressional

goal of surveying 90 percent of 140 meters objects outlined in the NASA Authorization Act of 2005 (P.L. 109–155). If a system is built, the benefits and risks would

be weighed against cost differences to make a selection. NASA does not have plans

for building either a ground or space-based asset for NEO detection within its budgeted program. However, there are a few programmed space flight opportunities for

competitive selection to which a capability might be proposed by the external community.

Q4. One deflection solution, suggested by NASA, is to detonate a nuclear device in

the vicinity of a PHO. What are the advantages and disadvantages of using this

approach? What circumstances would argue against using a nuclear device in

lieu of alternative approaches?

A4. The report on NEOs NASA submitted to the Congress in March 2007 did not

recommend any one specific deflection solution—different scenarios might require

completely different combinations of systems and solutions. However, the alternatives analysis for this report found:

• Deflection systems using nuclear explosives carry the highest deflection capability per kg of payload launched of the alternatives studied, therefore significantly reducing launch costs and increasing launch opportunities.

• Deflection systems using nuclear explosives were evaluated to be applicable

to the widest range of threats (size, composition, shape, spin rate, etc.), although other alternatives may have advantages in certain scenarios.

• Nuclear explosives were evaluated to be among the most reliable and repeatable of the deflection techniques evaluated, with the highest level of technology readiness relative to alternatives.

• Impulsive methods, including nuclear explosives and kinetic impactors, provide their deflection instantaneously. This improves performance in ‘‘quick response’’ scenarios and permits multiple successive attempts that are likely to

be necessary to achieve desired levels of deflection campaign reliability.

• Deflection systems using nuclear explosives are likely to be among the lowest

cost due to significantly lower launch costs, lower payload development costs,

and lower operations costs than slow push methods.

• Deflection systems using nuclear explosives carry unique operations and

launch safety risks, all of which must be evaluated in the event a credible

threat to the Earth is actually detected.

• Possible deflection scenarios cover a wide range of threat characteristics including size, mass, composition, spin rate, shape, cohesion, and number of

gravitationally bound objects. As the NASA study indicated, the alternatives

studied provide a ‘‘tool kit’’ of options to a decision-maker when an actual

threat becomes apparent.

Nuclear deflection is possibly the most effective option when cost, schedule, technology readiness, operational issues, and the need for characterization are considered, but it does have unique political, policy, and safety considerations. A series

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of one or more standoff nuclear devices may be the only option as the mass of the

threat grows, but there are some instances (e.g., when the risk of fragmentation is

high) where they may not be the primary selection.

To achieve the level of reliability likely to be required to mitigate a potential

threat, it is likely that multiple deflection techniques would need to be pursued as

part of a deflection campaign such that no technology or system is a single point

of failure. The use of nuclear explosives is evaluated to be very effective for many

threat scenarios, and it is one of many options in the tool kit of defection alternatives.

Questions submitted by Representative Dana Rohrabacher

Q1. The need for a comprehensive potentially hazardous Near-Earth Objects (NEO)

program seems to require expertise of several agencies. How do you suggest coordination be handled?

A1. At present, no department or agency of the United States is assigned the responsibility for a NEO contingency notification plan or the responsibility to mitigate

threats posed by potentially hazardous near Earth asteroids and comets. As with

other major natural disasters, a coordinated approach involving multiple federal

agencies would clearly be required. NASA has not developed a position on how responsibilities should be assigned among U.S. departments and agencies.

Q2. Describe some of the proposed mitigation techniques and their trade offs.

A2. The report on NEOs NASA submitted to the Congress in March 2007 examined

a number of techniques for deflecting a PHO that have been categorized as either

‘‘impulsive’’ or ‘‘slow push.’’ The tables below provide an overview of the impulsive

methods and the slow push techniques, where the velocity change results from the

continuous application of a small force, considered in the report. Each of these concepts is developed further in the report.

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In the impulsive category, the use of a nuclear device was found to be the most

effective means to deflect a PHO. Because of the large amount of energy delivered,

nuclear devices would require the least amount of detailed information about the

threatening object, reducing the need for detailed characterization. While detonation

of a nuclear device on or below the surface of a threatening object was found to be

10–100 times more efficient than detonating a nuclear device above the surface, the

standoff detonation would be less likely to fragment the target. A nuclear standoff

mission could be designed knowing only the orbit and approximate mass of the

threat, and missions could be carried out incrementally to reach the required

amount of deflection. Additional information about the object’s mass and physical

properties would perhaps increase the effectiveness, but likely would not be required

to accomplish the goal.

Non-nuclear kinetic impact alternatives are the most effective non-nuclear option,

transferring 10–100 times less momentum than nuclear options for a fixed launch

mass. Impact velocities, varying from 10–50 km/s, produced a factor-of-three variation in deflection performance. In addition, kinetic impacts are also sensitive to the

porosity, elasticity, and composition of the target and may require large performance margins if these characteristics are not well determined.

Slow push techniques analyzed in this study included a gravity tractor, which

could alter the course of an object using the gravitational attraction of a massive

spacecraft flying in close proximity, and a space tug, which could attach itself to a

PHO and move it using high-efficiency propulsion systems. An attached space tug

has generally 10–100 times more performance than the gravity tractor, but it requires more detailed characterization data and more robust guidance and control

and surface attachment technologies. This technique could be effective in instances

where small increments of velocity (less than one mm/s) could be applied to relatively small objects (less than 200 meters in diameter) over many decades. In general, the slow push systems were found to be at a very low technology readiness

level (with the exception of the gravity tractor, which was medium) and would require significant development efforts.

Q3. What is your assessment of the need for a nuclear deflection capability?

A3. There is no need for any deflection capability at this time. No impact threat

has yet been identified. If a timely detection capability is fielded, there will most

likely be significant warning time in which to develop other parts of the system such

as sufficiently capable characterization and deflection spacecraft.

Q4. What are the weakest links in the ‘‘system’’ considering the overall goal to protect

Earth from asteroid impacts?

A4. Finding any potential threats so that their orbits can be determined is the

weakest link by far. Unless we find threats, we will be unable to react. If we do

find threats in a timely manner, there will very likely be significant warning time

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in which to develop other parts of the system such as sufficient characterization and

deflection spacecraft

Q5. Dr. Donald Yeomans stated that the highest priority regarding NEOs is to ‘‘find

them early, find them early, find them early.’’ Yet NASA refused to recommend

a program to find them (140 meters and larger) early as directed by law. Why?

How does NASA justify this refusal?

A5. NASA recommended an approach commensurate with the resources the Agency

has been appropriated to accomplish its tasks.

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ANSWERS TO POST-HEARING QUESTIONS

Responses by Donald K. Yeomans, Manager, Near-Earth Object Program Office, Jet

Propulsion Laboratory

Questions submitted by Chairman Mark Udall

Q1. Planetary radar facilities have been cited as critical for providing more precise

orbital determinations of potentially hazardous NEOs. However, the two radar

facilities currently being used to obtain data on NEOs [Arecibo and Goldstone]

may not be available in the future. What are the implications should existing

planetary radar facilities become unavailable?

A1. While the two mentioned planetary radars cannot participate in the near-Earth

object (NEO) discovery process, they do provide very accurate range and velocity information that is not available with the traditional optical positional data used to

discover these objects. Together with optical observations, the use of radar data

within the NEO orbit determination process immediately refines the object’s orbit

and allows the NEO’s future motion to be accurately determined so that future close

Earth approach distances can be ascertained far earlier than would be the case

without the radar data. After several years of optical data taken at multiple returns

of the NEO to the Earth’s neighborhood, a NEO orbit computed based solely upon

the optical data can also accurately predict the object’s future motion. However, it

often takes many years before the necessary optical data are in hand and for the

more numerous smaller NEOs, the first discovery opportunity is often the best opportunity to gather the necessary data prior to a potentially threatening pass near

the Earth. In short, radar data are most critical for quickly identifying the most

threatening objects and should one be found on an Earth threatening trajectory, the

use of radar data could make the difference between having the time to mitigate

the threat or not.

Q2. Could you please explain how the Arecibo and Goldstone planetary radar facilities work together? How, if at all, would the loss of one of the facilities affect

the orbital determination of a potentially hazardous object? Would there be a potential effect on the accuracy, the time required for determining a trajectory, the

number of objects to be tracked, or some combination of these factors?

A2. As noted in the response to Question 1, the use of radar data allows for a rapid

identification of a potentially hazardous object (PHO) and a potentially Earth

threatening future encounter. Although the two planetary radars cannot ‘‘see’’ every

PHO at every return to the Earth’s neighborhood, the loss of one of the planetary

radars would substantially decrease the number of PHOs having the radar data necessary to quickly secure their orbits. Hence, without these radar observations, it

would take several years more of the optical data to secure their orbits to a point

where an Earth threatening encounter could be ruled out (or in). With the use of

radar data in the PHO orbit determination process, there would be far more time

to deal with the PHO if it turned out to be on an Earth threatening trajectory. The

Arecibo and Goldstone radar facilities are very complementary in that the 70 meter

sized Goldstone antenna is movable and can track objects within its range from horizon to horizon (8–10 hours). The 305 meter Arecibo antenna has nearly three

times the reach, or range, of the Goldstone antenna but can only track objects for

about two hours within 20 degrees of its overhead (zenith) position. Often a PHO

is first tracked by Arecibo and then by Goldstone (or vice versa) so the use of both

instruments is particularly valuable in terms of providing the extended observations

necessary to characterize the PHO’s size, shape, density, spin state and whether or

not it has a moon. Knowledge of these latter characteristics will be invaluable for

science and for selecting an appropriate mitigation technology—should that become

necessary.

Q3. The asteroid Apophis has been identified as an object that has a small chance

of impacting Earth in 2036. What role will Arecibo and/or Goldstone play in

improving our understanding of Apophis and refining predictions of a potential

impact?

A3. Potentially hazardous asteroid Apophis will make a very close approach to

Earth on April 13, 2029 coming as near as 4.6 Earth radii from the Earth’s surface

(i.e., lower than communication satellites in geosynchronous orbits about Earth).

With the aid of radar data taken in 2005 and 2006, the orbit of Apophis has been

accurately determined and an Earth collision in 2029 ruled out. However, in the unlikely event that Apophis passes within a 600 meter sized ‘‘keyhole’’ in space during

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the 2029 close Earth passage, Apophis will return seven years later and strike the

Earth (April 13, 2036). To further refine the existing orbit for Apophis and rule out

a passage through this tiny keyhole, we will need to understand and model some

very subtle perturbative effects due to the pressure of sunlight and the radiation

of heat from the surface of Apophis. In order to do this, it will be important to determine the size, shape and spin state of Apophis. Arecibo radar observations made

in early 2013 would allow these physical observations to be made. Together with

optical data, radar observations in 2013 would reduce the 2029 orbit uncertainties

by more than 90 percent. Thus, it is very likely that the passage of Apophis through

the 2029 keyhole (and impact in 2036) can be ruled out.

Q4. How do the capabilities of Pan-STARRS compare to that of LSST? Are they

complementary facilities for an expanded NEO Survey, or could one facility meet

the goal of detecting NEOs as small as 140 meters in size in a timely fashion?

A4. Both Pan-STARRS and LSST have the capability to be far more efficient in

finding NEOs than any of the currently operating surveys. The efficiency with which

a search telescope can detect NEOs is proportional to the size of the telescope’s aperture area multiplied by the telescope’s field of view. The four telescope array of

the planned Pan-STARRS has four 1.8 meter telescopes each with a field of view

of seven square degrees. LSST has a single 8.4 meter telescope (effective aperture

= 6.7 meters) with a 9.6 square degree field so LSST would be about five times more

efficient in terms of NEO discoveries. However, Pan-STARRS will be located on Hawaii in the northern hemisphere while LSST will be located in the southern hemisphere so these telescopes will be viewing different regions of the sky and will have

different weather patterns. Thus they will be very complementary search systems

and their observing schedules, search regions and data reduction techniques could

be coordinated to ensure a more efficient and robust search strategy. With a start

in 2014, the LSST, optimized for NEO searches (as described in Dr. Tyson’s testimony), could reach the goal of discovering 90 percent of the potentially hazardous

asteroids 140 meters and larger by 2026. In addition, with the Pan-STARRS four

telescope array also operational by 2010, the goal could be reached almost two years

earlier. Furthermore, the placement of Pan-STARRS in the north and LSST in the

south would provide for an increase in warning efficiency for those smaller and more

numerous objects that are discovered on their final approach to Earth.

Q5. The Discovery Channel Telescope is under construction and expected to become

operational in 2010. The telescope design is expected to enable versatility in its

use, which could include the detection of near-Earth asteroids. One estimate puts

the total cost of building the telescope at $40–50 million. What contribution, if

any, would this type of low-cost telescope provide to the expanded NEO Survey?

Should this system be considered as part of the next-generation search or as part

of a gap-filler until a Survey using LSST and/or Pan-STARRS gets underway?

A5. The Discovery Channel Telescope has an aperture size of 4.2 meters and when

used in the (as yet unfunded) prime focus mode, will have a field of view of 2.3

square degrees. For NEO discovery, it will then be about two times less efficient

than Pan-STARRS and 11 times less efficient that LSST. However, the Discovery

Channel Telescope will be far superior to any currently used NEO search telescopes

and could by itself discover more than 50 percent of the PHAs larger than 140 meters within ten years time. It will be located in Arizona so that it will be in a different region of the world (with different weather patterns) from both Pan-STARRS

and LSST. The Discovery Channel Telescope should indeed be considered part of the

next generation search.

Q6. What are the data management requirements to support the expanded Survey

and what should the priorities be in addressing those requirements? How big

a job is it likely to be?

Q6a. Dr. Green’s testimony indicates that NASA has started to evaluate the needs

of the Minor Planet Center to accommodate the increase in detection that will

result in an expanded survey. Should NASA consider other entities for handling data management under the expanded search? Should the data management task be competed?

A6a. Currently the Minor Planet Center (MPC) is receiving, processing and

archiving up to 75,000 observations each day and as the next generation of search

gets underway, that amount could increase 100-fold. Steps are already underway to

establish the interfaces necessary for the MPC to interact with the next generation

surveys and manage the enormous increase in data they will provide. In a change

from the current survey data processing procedures, the next generation surveys

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(e.g., Pan-STARRS, LSST) will do much of their own data processing, including the

identification of their nightly observations with existing asteroids, the computation

of preliminary orbits for newly discovered objects and the archiving of these data.

This moving object pipeline system (MOPS) is well along in its development and

both Pan-STARRS and LSST will take advantage of it. Hence, while the increased

work load on the MPC will be significant, much of the work will be carried out by

the surveys themselves. Steps are being taken to ensure that the transition to the

next generation search is smooth and that the data processing is nearly completely

autonomous so only a modest increase in staffing at the MPC will be required. In

the NASA call for Near-Earth Object Observations peer-reviewed proposals in early

2008, there will be an opportunity for other institutions to compete for the role that

the MPC in Cambridge Massachusetts is currently fulfilling.

Q7. How much time would be required to prepare a mitigation approach if a hazardous object were discovered to be on a collision course with Earth? How much

time would likely be available?

A7. Once the current NEO survey goal has been reached, some 90 percent of the

one kilometer and larger sized NEOs will have been discovered. Once the next generation search is complete, all of the one kilometer-sized NEOs will have been discovered along with 90 percent of those potentially hazardous objects larger than 140

meters. At that point, 99 percent of the statistical or actuarial risk from NEOs will

have been retired since it will then be possible to track their motions decades into

the future and determine if any among them represent a threat to Earth. This is

the key issue for getting on with the next generation search—we must find them

early enough to allow the time to mitigate if a true Earth threatening object is discovered. After the next generation of search is complete, 90 percent of the 140 meter

sized objects will have well understood future motions and should one of them have

a significant non-zero Earth impact probability, there would be typically decades to

further refine the orbit using optical and radar data and in the vast majority of

cases, these additional data will collapse the orbital uncertainties to such an extent

that troublesome future Earth encounters can be ruled out. If, in the unlikely event

that an Earth impact cannot be ruled out, there should be the necessary number

of years to place a spacecraft in orbit about the asteroid, track it and hence accurately monitor the asteroid’s motion to determine if the threat remains real. In addition, this rendezvous spacecraft would then be available to monitor the asteroid’s

motion subsequent to a deflection attempt (e.g., by an impacting spacecraft) to verify

that the attempt had been successful in avoiding the potential Earth impact at the

predicted time. This monitor spacecraft could also verify that the deflection attempt

did not push the asteroid into a tiny nearby keyhole in space that would bring it

back to a subsequent Earth impact. This latter possibility, while very unlikely, could

then be mitigated using the small gravitational ‘‘pull’’ of the close neighboring

spacecraft being used as a gravity tractor.

The development and flight of a rendezvous spacecraft along with the mitigation

approach would likely take 10–20 years depending upon the impactor’s orbit, the

available launch vehicle, the launch opportunities and the mitigation technique

itself. The next generation of search is designed to provide many decades of advance

warning time for the vast majority of Earth threatening asteroids.

Q8. Dr. Green’s testimony described NASA’s NEO contingency notification plan,

which lays out the procedures for notification up through the NASA Administrator if a NEO is detected with a significant probability of impacting Earth.

Does a notification or warning system exist beyond NASA for informing the public and federal and State disaster and emergency response agencies? If not, what

should be done?

A8. To my knowledge, there currently exists no notification or warning system beyond NASA for informing the public and federal/State disaster and emergency response agencies. However, the next generation of search for potentially hazardous

objects (PHOs) will dramatically increase both the number of known PHOs in the

population and the number of warnings where the risk of a PHO Earth impact cannot be immediately ruled out. During the next generation of PHO search, these

warnings could increase by up to a factor of 40 over what we currently experience.

I would recommend that the lines of communication be opened between NASA’s

NEO program and the U.S. disaster response agencies to begin the long-term planning for these warnings and for the rare circumstance where one of these PHO

warnings turns into a real threat.

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Questions for the Record Submitted by Representative Tom Feeney

Q1. NASA’s NEO report, delivered this March, provides several options for meeting

the goal of achieving 90 percent detection, tracking and characterization of Potentially Hazardous Objects, and the report establishes a clear relationship between resources invested and the time needed to achieve 90 percent coverage. In

essence, the report shows that for an additional investment of approximately

$536 million, we could buy-down a decade of time to complete the survey. In

your view, is that additional investment necessary? Does the threat posed by

PHOs compel faster completion of the survey?

A1. While the mean time between impacts for 140 meter sized potentially hazardous objects (PHOs) is approximately 5,000 years, the next impact is equally likely to occur tomorrow morning or in 5,000 years. The mean time between impacts

of the far more numerous 50 meter sized PHOs is about 700 years and hence the

impact probability for one of these impacts in this century is about 13 percent.

NASA currently invests approximately $4 million dollars per year in its NEO Observations program and if the current NEO surveys continue at the current level of

activity, it would take more than a century to reach the goal of finding 90 percent

of the PHOs larger than 140 meters. To reach this goal by the end of the 2020, as

requested in the NASA Authorization Act of 2005, the survey could be done with

the aid of a dedicated LSST class 8.4 meter telescope (2015 start time) or done using

a space-based infrared telescope of 0.5 or 1.0 meters (2012–2014 start). If the 2020

goal line is relaxed a few years, the 90 percent completion goal could be achieved

in 2026 with the LSST used in a shared mode with only 15 percent of the time being

devoted exclusively to PHO searches. As outlined in the testimony of Dr. Tyson, this

option would require about $125 million dollars for the entire effort through 2026.

The threat posed by PHOs is real and the impact of a 140 meter sized PHO would

strike the Earth’s surface with the energy equivalent of about 100 mega tons of TNT

explosives—roughly 7,700 times more energetic than the Hiroshima nuclear device.

Nevertheless, it is my personal opinion that, given the infrequency of impacts by

relatively large PHOs upon the Earth, there is no compelling reason to insist upon

a survey completion by 2020; a relaxation of the completion date by 5–10 years

would be acceptable.

Q2. What are the most difficult types of NEOs to detect? Is there, for instance, a portion of the sky that won’t be covered by ground-based facilities? Are there certain

types of orbits that make it difficult to detect and track asteroids and comets?

A2. With the exception of a single search telescope located in Siding Spring Australia, all current NASA supported NEO search telescopes are located in the northern hemisphere. However, the orbits of NEOs will, over time, bring them into view

from the northern hemisphere so that for discovery purposes, the paucity of search

telescopes in the south is not a particular problem. However, for warning of objects

that are on a final Earth threatening trajectory, northern and southern hemisphere

observation capabilities are required. The most difficult NEOs to detect include

those objects that 1.) spend most of their time interior to the Earth’s orbit (i.e., they

are rarely visible in a dark sky) or 2.) they do not often return to the Earth’s neighborhood. This latter scenario can arise because they have relatively long orbital periods about the sun or their orbital periods are similar to that of the Earth so they

can spend long periods of time before approaching the Earth or becoming visible in

the night sky.

Q3. Once the LSST and Pan-STARRS telescopes are operating, and surveys for

PHOs that are 140 meters or larger has commenced, what is the business and

public safety case for expanding the search to detect and track smaller PHOs—

for instance, down to a size of 50 meters? What are the cost and schedule implications?

A3. Fifty meters is roughly the lower size limit where a rocky Earth impacting object could be expected to cause ground damage from an air blast. That is, an object

of this size would not generally punch through the Earth’s atmosphere and strike

the Earth but it would be expected to cause an explosion a few kilometers above

the Earth’s surface and hence cause ground damage. For example, nearly 100 years

ago in June 1908, a 50 meter sized object is thought to have created a 5–10 megaton

(of TNT) explosive event in the Tunguska region of Siberia causing ground damage

over a region of 2,000 square kilometers.

As one moves down to smaller and smaller PHOs, they become more and more

numerous so while there may be more than 10,000 PHOs larger than 140 meters,

there is likely to be seven times that number of PHOs larger than 50 meters. The

current ongoing survey goal to discover and track 90 percent of the one kilometer

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and larger sized objects has discovered about five percent of the smaller objects

down to 140 meters in size. Similarly, simulations suggest that the next generation

search for PHOs down to 140 meters that includes only Pan-STARRS (2010 start)

and LSST (2014 start) will discover roughly 42 percent of the potentially hazardous

objects (PHOs) larger than 50 meters by the end of 2020 and 59 percent by the end

of 2029. If one were to include in the next generation search a one meter infrared

telescope in a Venus-like orbit (2014 start) in addition to the ground-based PanSTARRS and LSST surveys, the discovered population of 50 meter and larger sized

objects would be complete to the level of 78 percent at the end of 2020 and 92 percent complete by the end of 2029. However, this latter result would depend upon

a rather long 15 year lifetime for the infrared space telescope and would entail significant data down-link issues.

I am not aware of a study to determine survey costs for discovering and tracking

90 percent of the 50 meter sized PHOs but it would likely require far more resources than have been considered to date. It is true that the likelihood of Earth

being struck with a 50 meter sized PHO is about seven times that for a PHO of

140 meters. However, at some point there is a crossing between the diminishing

hazard from smaller and smaller objects and the increasing costs required to find

them. It should be noted that the completion of the goal to discover and track 90

percent of the PHOs larger than 140 meters would retire 99 percent of the actuarial

risk from PHOs of all sizes so this is the appropriate goal for the next generation

of search. A future study of this issue would have to determine whether or not a

comprehensive survey to discover 90 percent of the smaller PHOs down to 50 meters

in the near future would be cost effective.

Q4. During the hearing several witnesses mentioned the Air Force’s funding of the

Pan-STARRS telescope facility in Hawaii as a possible new ground observatory

that would be very adept at detecting NEOs. What is the status of Pan-STARRS

and the likelihood that all four telescopes will be built? Would the Air Force be

willing to make available a portion of the telescope’s time to NEO surveys if less

than four telescopes are built?

A4. The Pan-STARRS project is a University of Hawaii Institute for Astronomy effort that has been sponsored through United States Air Force grants beginning in

FY 2002. The project has been proceeding well in developing the world’s largest digital cameras, high precision wide field optics, and software systems to process and

archive an unprecedented stream of world class astronomical research data. The

ownership and operations of the Pan-STARRS systems is under the authority of the

University of Hawaii.

The ultimate goal is to construct four co-located 1.8 meter aperture telescopes

(PS4) that will function as a single unit each clear night to search the entire accessible sky twice each lunar month (about 28 days). It seems likely that the PS4 four

telescope system will be built within a few years, but the precise schedule will depend upon the availability and timing of the necessary funding as well as completing the construction permitting process that includes a federal environmental

impact statement (EIS). As noted in the EIS Preparation Notice published in the

Federal Register in January 2007, the preferred site is at the Mauna Kea summit

on the Big Island of Hawaii, and the alternate site is the Haleakala summit on the

island of Maui.

Prior to construction of the four telescope array, a prototype single 1.8 meter telescope (PS1) has been built and sited at the Haleakala summit. The state-of-the-art

1400 megapixel (1.4 billion pixel) CCD camera has been built, tested and mated to

the telescope, and the telescope itself achieved ‘‘first light’’ on Aug. 22, 2006. Development is nearly complete of the image processing pipeline (IPP) and the Moving

Object Processing System (MOPS) that is designed to identify moving objects within

our Solar System (mostly asteroids), and preliminary testing is well underway. An

international consortium has committed $10M to fund a 3.5 year PS1 science mission that should begin in mid-2008. Once operational, the primary objective of PS1

is to discover near-Earth objects and it should be more than 20 times more efficient

at finding them than any currently operational NEO search effort. This will be true

even though the telescope will be conducting a suite of other scientific observations

including studies of outer solar system objects, planets around other stars,

supernova, galaxy clusters, and gravitational lensing. The supernova and gravitational lensing studies will significantly clarify our current understanding of the dark

energy and dark matter issues at the forefront of modern cosmology.

At this time, the best estimate for beginning PS4 construction is late 2009 or

early 2010. This is primarily due to the timescale for completing the EIS and obtaining the necessary construction approvals. If sufficient funding continues to be available, the likelihood is high to successfully complete the full system. Commissioning

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of the first one or two PS4 telescopes should begin in 2011 with the completed four

telescope suite becoming fully operational in 2013.

Q5. One deflection solution, suggested by NASA, is to detonate a nuclear device in

the vicinity of a PHO. What are the advantages and disadvantages of using this

approach? What circumstances would argue against using a nuclear device in

lieu of alternative approaches?

A5. There are two categories of mitigation responses for Earth threatening PHOs:

a relatively quick flight time impulsive push (perhaps by an impacting spacecraft

or a nuclear device) or a longer flight time rendezvous mission followed by either

an impulsive or slow push technique (e.g., gravity tractor). If there is sufficient time,

the longer flight time rendezvous is preferred because a resident spacecraft can provide both a verification that the asteroid is actually on an Earth threatening trajectory or not and it can verify that a deflection maneuver was successful. A nuclear

device could be used in a stand-off mode where the explosion is above the asteroid’s

surface so that the resultant neutron radiation then ablates the asteroid’s front side

and introduces a thrust in the direction opposite to the vaporizing material. A far

more efficient, but less controlled, technique could be achieved by placing the nuclear device upon, or below, the asteroid’s surface. A nuclear response may be required for a large (larger than a few hundred meters) PHO that is found to be on

an Earth-threatening trajectory and for which there is not sufficient time to use an

alternate technique. This is a very unlikely scenario since the larger objects that

might require a nuclear response are also the easiest to discover so a large Earth

threatening object will likely be discovered many decades in advance of the potential

impact event thus allowing the use of an alternate technology that lacks the problems of the nuclear option—problems that include launch safety, public concern and

the possible necessity to modify existing treaties. The advantages of using a nuclear

device are that one or more devices could deliver to an Earth threatening asteroid

far more energy per kilogram of delivered (launch) mass than any alternative mitigation technique and the technology is mature. The disadvantages include the surface interaction of such a powerful impulsive device with a PHO of unknown structure, which would introduce an uncertainty in the deflection response and possibly

a partial breakup of the asteroid itself. The latter scenario might introduce a shotgun-like effect upon the Earth unless the breakup and subsequent dispersal could

be initiated soon enough prior to a potential collision that the vast majority of the

small fragments would miss the Earth altogether. In short, a nuclear device option

should be maintained as a viable mitigation technology but utilized only in the relatively rare situations when a more controlled deflection technique is not adequate

or possible.

Questions submitted by Representative Dana Rohrabacher

Q1. The need for a comprehensive potentially hazardous NEO program seems to require expertise of several agencies. How do you suggest coordination be handled?

A1. NASA has been properly given the responsibility to discover, track and catalog

near-Earth objects (NEOs) and to determine if any of these objects pose a future

threat to Earth. For these efforts, a number of governmental and academic agencies

have provided advice and expertise along with survey search and computing facilities. My suggestion would be to maintain NASA’s lead role in these activities. In

the event a potentially hazardous object (PHO) is found to be on an Earth threatening trajectory, a mitigation technology effort may be required. Such an effort

would require that a spacecraft be built, launched, tracked and navigated to rendezvous with the PHO to monitor its motion and conduct a mitigation procedure if

that were warranted. Within the U.S., only NASA has that type of experience so

it would seem to me that NASA should be given the U.S. lead in mitigation technology planning as well. NASA should, of course, solicit suggestions and advice from

other relevant agencies. In particular, should a nuclear deflection mitigation attempt become necessary, other U.S. agencies (e.g., DOD, DOE) would need to be intimately involved in the mitigation attempt.

The threat of a PHO impact is an international problem and should have an internationally agreed upon solution. Such a threat could generate far more problems

than just the technologies required for mitigation—including effective communication with the public and disaster preparedness. To my knowledge, there has been

very little discussion within the international community to address the totality of

the PHO threat issues. There is an ongoing activity within the Association of Space

Explorers to address some of these issues and they plan to introduce a draft NEO

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mittee on the Peaceful Uses of Outer Space (COPUOS) during their 2009 session.

One possible way forward would be the assignment of responsibility to a particular

U.S. government agency to begin interagency discussions to define the NEO mitigation responsibilities of specific government agencies and to establish a recommended

strategy for selecting a mitigation technology option. These U.S. discussions and recommendations would then need to be coordinated and integrated with those arising

from the activities of the UN/COPUOS Scientific and Technical Subcommittee in

2009.

Q2. Describe some of the proposed mitigation techniques and their trade offs.

Q3. What is your assessment of the need for a nuclear deflection capability?

A2,3. Some of the following discussion has been mentioned in response to Representative Feeney’s question 5. For completeness, some points are repeated below.

Viable mitigation techniques for deflecting Earth threatening asteroids can be

grouped into two categories. The first category of mitigation techniques includes

‘‘slow push’’ technologies that are designed to change the asteroid’s orbital velocity

over relatively long periods of time. The second category includes impulsive events

that are designed to change the asteroid’s orbital velocity using the energy of an

explosive device or the energy imparted to the asteroid as a result of a high velocity

impacting spacecraft. Either category of mitigation technology would benefit from a

rendezvous spacecraft that would be placed in orbit around, or hover near, the hazardous asteroid. Radiometric tracking of this ‘‘monitor spacecraft’’ could be used to

dramatically improve the orbit of the asteroid and hence determine whether or not

it was actually a threat to Earth. Should a deflection maneuver prove necessary,

this monitor spacecraft could continue to track the asteroid during and after the deflection attempt to verify that the deflection was successfully carried out and the

asteroid would indeed miss the Earth at the predicted impact epoch. Finally, in the

very unlikely scenario that the deflection maneuver prevented an Earth impact at

a certain future epoch number 1 but pushed it toward a tiny keyhole in space that

would allow it to strike Earth at a subsequent impact epoch number 2, the monitor

spacecraft could be used as a gravity tug to move the asteroid the few hundred meters necessary to prevent the asteroid from entering the impact plane keyhole. In

short, if there is sufficient time, a monitor spacecraft should be maintained in the

immediate neighborhood of the Earth threatening asteroid.

Within the first category of slow push techniques, there are only a few viable

methods that could be used including the ‘‘tugboat’’ approach where the spacecraft

attaches to the asteroid and uses its thrusters to slowly tow it and the so-called

gravity tractor where a massive spacecraft uses its thrusters and the gravitational

attraction between the spacecraft and asteroid to gently pull the asteroid and alter

its orbital velocity and position in space. The tugboat approach presents significant

engineering challenges in that it must first secure the asteroid in its grip, and then

tow it using its thrusters, being careful to thrust only when the asteroid’s rotation

brings it back to the same position in space. The gravity tractor approach, with its

tiny pull capability, needs to be very close to a rotating irregular asteroid so it has

challenges in safely maintaining the necessary close proximity to the asteroid. Some

attention has been given to other slow push techniques including solar concentrators

or pulsed lasers that could focus intense radiation on the asteroid, ablate or vaporize

the near side material and thus introduce a small thrust in the opposite direction

from the material that is streaming off the asteroid’s side nearest the solar concentrator or laser device. Both of these techniques would provide significant engineering challenges and each system would have vaporizing material driven back toward

the devices themselves—thus attenuating the intensity of the focused radiation and

perhaps contaminating the system’s optics.

Within the second category of impulsive deflection techniques, the high velocity

spacecraft impact and the explosive device impulse techniques (including nuclear devices) are mature technologies. A high velocity impact of a spacecraft with comet

Tempel 1 was successfully carried out by NASA in July 2005 so the autonomous

navigation technologies for such a deflection technique have already been demonstrated. However, a high velocity impact of a spacecraft with a target asteroid will

produce only a modest change in the asteroid’s velocity and is only a useful technology if the asteroid is smaller than a few hundred meters in diameter or there

are many years available between the deflection attempt and the predicted Earth

impact.

One or more nuclear devices could be used in a stand-off mode where the explosion is above the asteroid’s surface so that the resultant neutron radiation then ablates the asteroid’s front side and introduces a thrust in the opposite direction to

the vaporizing material. A far more efficient, but less controlled, technique could be

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achieved by placing the nuclear device upon, or below, the asteroid’s surface. This

nuclear response may be required for a large (larger than a few hundred meters)

PHO that is found to be on an Earth threatening trajectory and for which there is

not sufficient time to use an alternative technique. The advantages of using a nuclear device are that one or more devices could deliver to an Earth threatening asteroid far more energy per kilogram of delivered (launch) mass than any alternative

mitigation technique and the technology is mature. The disadvantages include the

interaction of such a powerful impulsive device with the surface of a PHO of unknown structure, which would introduce an uncertainty in the deflection response

and possibly a partial breakup of the asteroid itself. The latter scenario might introduce a shotgun-like effect upon the Earth unless the breakup and subsequent dispersal could be initiated soon enough prior to a potential collision that the vast majority of the small fragments would miss the Earth altogether. In short, a nuclear

device option should be maintained as a viable mitigation technology but utilized

only in the relatively rare situations when a more controlled deflection technique

is not adequate or possible.

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ANSWERS TO POST-HEARING QUESTIONS

Responses by Donald B. Campbell, Professor of Astronomy, Cornell University;

Former Director, Arecibo Observatory

Questions submitted by Chairman Mark Udall

Q1. The asteroid Apophis has been identified as an object that has a small chance

of impacting Earth in 2036. What role will Arecibo play in improving our understanding of Apophis and refining predictions of a potential impact?

A1. During the close approach of Apophis to the Earth in 2013 at a distance of

about nine million miles, it is my understanding that radar observations with Arecibo and Goldstone combined with optical measurements will significantly reduce

the probability of a potential impact during its passage by the Earth in 2036. Arecibo observations in 2013 will provide some information about Apophis’s size but its

large distance will preclude the high resolution characterization measurements that

would provide detailed information about its shape and size.

Q2. Your testimony notes that ‘‘No study has been done of the precise role that the

Arecibo radar and how many hours of NEO observations will be needed when

the new, high sensitivity searches commence. . .. This needs to be done.’’ What,

specifically, would such a study entail, what entity or entities would be capable

of conducting it, and how much time do you believe such a study would require?

A2. Such a study would entail determining the number and distribution of the

hours of use of the radar system on the Arecibo telescope that would be needed for

follow-up astrometric and characterization observations of newly discovered NEOs

once the Pan-STARRS and LSST NEO searches are underway. Such a study would

be best carried out by the National Astronomy and Ionosphere Center, which operates the Arecibo Observatory for the NSF, with input from the scientists involved

with NEO radar observations and orbit determination at Arecibo and the Jet Propulsion Laboratories. The first Pan-STARRS system is expected to come online in

the next year leading to a significant increase in the NEO detection rate. Direct experience with this system will provide the best guide as to the needed increase in

the hours of operation of the Arecibo radar. Based on this, the study should be completed by early 2009.

Q3. What is the estimated cost of decommissioning the entire Arecibo observatory

and what is the estimated time that would be required to disassemble the facility?

A3. There is no current reliable estimate for the cost of decommissioning the entire

Arecibo Observatory. The National Science Foundation has contracted for a study

of the decommissioning costs. My understanding is that the contractor will deliver

their report to the NSF in February, 2008.

Questions from Representative Tom Feeney

Q1. NASA’s NEO report, delivered this March, provides several options for meeting

the goal of achieving 90 percent detection, tracking and characterization of Potentially Hazardous Objects, and the report establishes a clear relationship between the resources invested and the time needed to achieve 90 percent coverage.

In essence, the report shows that for an additional investment of $536 million,

we could buy down a decade of time to complete the survey. In your view, is that

additional investment necessary? Does the threat posed by PHOs compel faster

completion of the survey?

A1. Given the relatively low probability in any given year of an impact by a NEO,

in my view significant expenditures to complete the survey in a shorter time period

are not justified. If significant cost savings can be achieved by extending the deadline a small number of years beyond 2020 then this should be seriously considered.

Dr. Tyson’s testimony indicated that by devoting 15 percent of the observing time

on the LSST to NEO searches the 90 percent requirement could be achieved in

about 12 years. Assuming that the LSST begins operations in 2014, this would

mean a completion of the survey by 2026. This date does not include contributions

from other searches such as Pan-STARRS. Providing partial support for the construction and operating costs of the LSST for a NEO survey would appear to be a

cost effective method for completing the survey.

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Q2. What are the most difficult NEOs to detect? Is there, for instance, a portion of

the sky that won’t be covered by ground-based facilities? Are there certain types

of orbits that make it difficult to detect and track asteroids and comets?

A2. NEOs whose orbits are primarily interior (i.e., closer to the Sun) to Earth’s

orbit are more difficult to detect from Earth than those NEOs that spend most of

their time outside the Earth’s orbit because they need to be observed shortly after

sunset or shortly before sunrise.

Q3. Once the LSST and Pan-STARRS telescopes are operating, and surveys for

PHOs that are 140 meters or larger has commenced, what is the business and

public safety case for expanding the search to detect and track smaller PHOs—

for instance, down to size 50 meters? What are the costs and schedule implications?

A3. As discussed during the Hearing, the difficulties of finding NEOs increases as

their size gets smaller. The 140 meter size limit for 90 percent completion seems

a sensible and achievable goal for now in terms of the potentially available resources and costs. As pointed out by Mr. Schweickart, this search, if it is carried

out, should also find close to 50 percent of objects down to 50m in size. As the

search progresses, the issues related to a ‘‘complete’’ survey of smaller NEOs can

be realistically addressed and decisions made.

Q4. You state that Cornell was required by NSF to seek other funding commitments

to fill the void left by NSF’s reduction. What has been Cornell’s experience finding new funding? Are you optimistic that other sources will be found?

A4. Cornell representatives are in ongoing discussions with governmental and educational bodies in Puerto Rico and they are moderately optimistic that funding for

programs that enhance the role of the Arecibo Observatory in education and public

outreach can be obtained through, or in collaboration with, Island institutions. However, these programs would not, and should not, be a substitute for the observatory’s

basic research mission. It appears very unlikely that year-on-year funding can be

obtained from sources within Puerto Rico or elsewhere to partially support the operation of the observatory as a federally owned and funded scientific research institution except possibly, in the case of the observatory’s planetary radar program, from

NASA.

Q5. One deflection solution, suggested by NASA, is to detonate a nuclear device in

the vicinity of a PHO. What are the advantages and disadvantages of this approach? What circumstances would argue against using a nuclear device in lieu

of alternative approaches?

A5. I have not spent adequate time studying this issue to make an informed response to the question.

Questions submitted by Representative Dana Rohrabacher

Q1. With regard to NASA’s Spaceguard program, what changes, if any, do you recommend to make the program more effective? In your view, is further legislation

required from Congress to implement needed changes?

A1. I am not directly involved with NASA’s current Spaceguard program aimed at

discovering 90 percent of NEOs with sizes larger than one km. This program was

a search program and appears to be largely achieving its objectives. It is now important to move to the next stage currently under discussion, the discovery of 90 percent of NEOs larger than 140m, determination of which ones are truly potentially

hazardous via orbit determination and the investigation of possible mitigation

schemes based on characterization studies.

Q2. How important do you consider characterization in the overall NEO issue priorities?

A2. Characterization has two objectives: 1) The understanding of the range of properties exhibited by NEOs to inform the design of mitigation strategies; 2) The characterization of specific objects that pose a definite threat to Earth so that the appropriate mitigation strategy can be implemented. The first of these is ongoing and the

coming more sensitive searches will potentially provide a larger range of asteroid

characteristics to be included in mitigation studies. These studies need to be pursued. For the second case, clearly the identification of PHOs via searches coupled

with precise orbit determination to identify any objects that truly do threaten Earth

comes first with characterization an input to mitigation planning.

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Q3. What capabilities are required for a comprehensive deflection campaign?

A3. As discussed by Mr. Schweickart and others, the technology needed for a comprehensive deflection campaign largely already exists. What is missing is a program

with clear responsibility for its implementation vested in one organization.

Q4. What is your estimate of the number of undiscovered asteroids in the 140 meter

and above range? Describe the potential damage that an asteroid in the 140

meter range can cause striking an ocean within, say, 500 miles of a U.S. coast?

A4. The March 2007 NEO Report to Congress gives the estimated number of NEOs

greater than 140m in size as approximately 100,000. The impact energy for a 140m

NEO would be about 100 megatons of TNT equivalent. Published studies have

shown that the release of this much energy as a result of an impact into the ocean

would certainly have the potential for a very serious consequences to the local and,

perhaps, distant seaboards.

Q5. Asteroids are more easily detected in the infrared spectrum. An asset such as

the WISE satellite has an effective capability for searching for NEO’s infrared

output. Is WISE being tasked for this role? What other infrared detection devices

can or will be used to detect NEOs?

A5. I am not involved with the WISE satellite program. This question would be better answered by NASA.

Q6. Could you describe some of the losses that might occur to U.S. research in radio

and radar astronomy, and atmospheric sciences if the facility were to close as

threatened by one of the supporting NSF directorates? How is the telescope

unique? What unique research opportunities does Arecibo offer the U.S. and

global scientific community? What new research is scheduled and proposed for

Arecibo?

A6. Arecibo is the world’s largest single dish radio telescope with sensitivity in its

frequency band that is four to five times higher than any other single dish radio

telescope. It is also unique in that it is equipped with two very high powered transmitters used for radar studies of solar system bodies including NEOs and for studies

of the Earth’s ionosphere. Its great sensitivity has allowed Arecibo to play a critical

role in the study of pulsars with one notable example being the discovery of the binary pulsar PSR 1913+16 for which timing measurements, also using Arecibo, gave

the first strong evidence for the existence of gravitational waves. Russell Hulse and

Joseph Taylor received the Noble prize in 1993 for this work. Arecibo’s sensitivity

will continue to make it a major contributor via pulsar observations to study of

gravitational waves, tests of General Relativity, the properties of nuclear matter in

neutron stars, the electron density distribution and magnetic fields in our galaxy

and, potentially, black holes via the hoped for discovery of a black hole—neutron

star (i.e., pulsar) binary system.

Because of it sensitivity, Arecibo is the only radio telescope than can study gas

(i.e., neutral hydrogen in distant galaxies) over a cosmologically significant volume

allowing it to study how gas and dark matter are distributed and evolve through

cosmic time. This is one of the major current research programs at the Arecibo Observatory with participants from a significant number of universities and research

institutions in the U.S. and abroad.

Arecibo’s ionospheric research program is supported by the NSF Division of Atmospheric Sciences. Arecibo is the most sensitive component of a chain of incoherent

scatter ionospheric radars supported by the NSF stretching from the polar regions

to the magnetic equator. The results from coordinated observations by all the participants in the chain provides input into ionospheric modeling programs the results

of which impact the study of Space Weather and are potentially important for climate change studies. Arecibo’s location allowing it to study the ionosphere at midmagnetic latitudes makes it a unique contributor to this effort.

Arecibo is one of only two high powered radar systems with the capabilities for

studying solar system bodies and it is the most sensitive by a factor of about 20.

It makes major contributions to the orbit determination and characterization for

NEOs including comets, to studies of the surfaces and internal structure of the

Moon and terrestrial planets, and to the study of planetary satellites.

The closing of the world’s largest radio telescope means that its great sensitivity

will not be available for the ongoing research work described above or for other continuing research efforts. Perhaps just as importantly, it also means that Arecibo will

not be available to pursue new research opportunities that may arise in the future

that can be best exploited by utilizing a telescope with Arecibo’s sensitivity. The disVerDate 11-MAY-2000 18:21 Feb 21, 2008 Jkt 038057 PO 00000 Frm 00148 Fmt 6601 Sfmt 6621 C:\WORKD\SA07\110807\38057 SCIENCE1 PsN: SCIENCE1
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covery of pulsars is a classic example, it was almost as if the designers of the Arecibo telescope had pulsar research in mind before pulsars were discovered.

Q7. Please describe some of the resources that Arecibo provides for discovery and research programs and examples of results.

A7. As described above, Arecibo’s huge collecting area makes it the most sensitive

single dish telescope in the world. Its two high powered transmitters give it unique

capabilities for radar studies of solar system bodies and the Earth’s ionosphere. The

Observatory is also equipped with an array of optical instruments that are used for

studies of the lower part of the ionosphere.

Among Arecibo’s many accomplishments are: 1) the discovery of a significant

number of known pulsars including the binary pulsar that led to our best indication

that gravitational radiation exists and the first milli-second period pulsar, a class

of very fast rotating pulsars that are the most precise pulsar ‘‘clocks’’ needed, for

example, in the proposed pulsar gravitational wave ‘‘observatory’’; 2) The discovery

of the first planets around another star, in this case a neutron star; 3) The mapping

of the structure of the local universe from redshift (recessional velocity) measurements based on observations of neutral hydrogen in galaxies; 4) The discovery that

Mercury rotates 1.5 times for each orbital ‘‘year’’ about the Sun and, in conjunction

with the Goldstone radar and the NSF Green Bank Telescope, that Mercury has at

least a partially molten core; 5) The first mapping of the surface of Venus at high

enough resolution to study its surface features; 6) Confirmation of the existence of

binary NEOs; 6) The confirmation of the Yarkovsky leading to a revolution in our

ideas on how small asteroids move from the main asteroid belt between Mars and

Jupiter into the inner solar system to become NEOs; 7) Detailed studies of the electron density distribution, temperature, winds and composition of the Earth’s

ionosphere.

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ANSWERS TO POST-HEARING QUESTIONS

Responses by J. Anthony Tyson, Professor of Physics, University of California, Davis;

Director, Large Synoptic Survey Telescope Project

Questions submitted by Chairman Mark Udall

Q1. Your testimony notes that by making adjustments to the LSST observations, the

expanded NEO survey could be completed within 12 years and that ‘‘the current

cost estimate for LSST in 2006 dollars is $389M for construction and $37M per

year for operations. For a 12-year long survey, the 15 percent of the total cost

is $125M.’’ What is the breakdown of the $125M estimate for the NEO-related

activities, and is it inclusive of the 12-year operations? How confident are you

of that cost estimate, and why?

A1. The LSST construction and operations budget are based on proven estimating

practices of dividing the entire project into over 1,000 individual work tasks and obtaining documented cost estimates on each task either from commercial vendor estimates or engineering estimates. The total cost estimate also contains a 30 percent

contingency to absorb unexpected technical problems and/or higher costs than estimated today. The costing process and the estimates have been peer reviewed and

endorsed by an NSF panel of external experts. The $125M figure was calculated

from the extra effort in an LSST survey of the sky required to reach the Congressional goal of 90 percent completeness for Potentially Hazardous Asteroids (PHA)

of 140 meter diameter and larger. This extra effort was quantified through multiple

simulations of LSST operations. We are confident that this is an accurate estimate

of the level of effort required. This extra effort devoted to the PHA discovery program amounts to $120M during operations, plus $5M for development of advanced

orbit linking and operations pipeline software. The $120M is inclusive of the added

PHA portion of operations during the full 12-year survey.

Q1a. Your testimony also mentions that ‘‘To keep LSST on schedule, about $5M

should be spent on optimized NEO orbit software pipeline development in the

last phase of R&D and the construction phase. . ..’’ Is this funding included

in the $125M overall cost required to modify LSST for the NEO survey?

A1a. Yes.

Q1b. When would the required software development for the NEO survey need to

begin in order to start the Survey in 2014, assuming LSST commences operations at that time?

A1b. 2009.

Q1c. What approvals and funding are required before LSST can be developed and

how confident are you that LSST will be ready for operations in 2014–2015,

as noted in your testimony?

A1c. The LSST project has been funded for R&D by the NSF. The construction proposal to the NSF was reviewed in September 2007 and the project had been recommended to move on to the next milestone review in the fall of 2008. At this time

we are on track for NSF construction start in FY 2011. Long lead sub-component

fabrication has begun (such as the $21M primary mirror), with private funding.

Q2. You testified that ‘‘with LSST, one sees each one of these asteroids 100 to 200

times, even more. So, it is possible to derive a pretty good orbit for those, and

distinguish them from the background.’’ What is the level of accuracy in NEO

orbits that you estimate would be possible with LSST? What implications, if

any, would this have for further orbital determination from planetary radar facilities.

A2. In very general terms, the orbits from a single apparition set of observations

will be good enough for the NEO to be predicted and located again any time it

comes within range for the next several decades, and the path can be predicted well

enough to rule out any future impact with the Earth for many decades to come, for

the vast majority (over 99 percent) of detected objects. However, there will be, as

there are now (e.g., the asteroid Apophis) cases where the optical position data will

be unable to rule out a future impact, and radar facilities will be key assets for providing the observations needed to rule out (or in, if we should be unlucky) future

impacts for a small number of cases. It can be expected that radar will continue

to be needed for a similar number of key observations in the future as it has been

in the past. Radar however cannot be used to survey the sky and discover PHAs.

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Questions submitted by Representative Tom Feeney

Q1. NASA’s NEO report, delivered this March, provides several options for meeting

the goal of achieving 90 percent detection, tracking and characterization of Potentially Hazardous Objects, and the report establishes a clear relationship between resources invested and the time needed to achieve 90 percent coverage. In

essence, the report shows that for an additional investment of approximately

$536 million, we could buy-down a decade of time to complete the survey. In

your view, is that additional investment necessary? Does the threat posed by

PHOs compel faster completion of the survey?

A1. One can hasten the survey to some degree with greater expenditure on other

complementary systems. However, there is a natural limit to the minimum time

that a survey can be completed to, say 90 percent, which results from the fact that

the asteroids move in orbits with orbital periods of several years and often spend

years at a time simply out of the range of visibility from the Earth, or in some cases,

even from space. Thus, it is not possible with any detection system, no matter how

capable, to see all PHAs instantly, or even in a very short time. The fundamental

‘‘time constant’’ for surveying is the timescale of the orbit periods, that is, a few

years. This amounts to the ‘‘exponential time constant’’ of a survey, and to reach

90 percent takes a factor of two or three times the time constant, or about a decade.

Speeding things up from a decade requires near-Herculean effort, for example putting a rather large telescope in a ‘‘Venus-like’’ orbit, and even that reduces the time

by only a few years. On the other hand, time is our friend if we consider going a

little more slowly. Thus, backing off to a capable ground-based survey can reach the

goal set by Congress in only a few years longer than the 15 years (from 2005) originally mandated by the Congress. It is more important not to back off in the completeness level than in the time to achieve it. I share the opinion of many in the

NEA community that it is key to get started now on a capable survey, but that it

is not worth the investment in a space facility to shorten the survey by a few years.

Q2. What are the most difficult types of NEOs to detect? Is there, for instance, a portion of the sky that won’t be covered by ground-based facilities? Are there certain

types of orbits that make it difficult to detect and track asteroids and comets?

A2. Some NEOs are more difficult to detect than others, although ‘‘blind spots’’ in

the sky not covered by the surveys is not the cause of that difference. Any asteroid

in an orbit that can hit the Earth will spend some time in the visible part of the

sky, so it is only a matter of time before it passes into a visible region. The goal

of the survey is to find PHAs decades before an impact, not on final approach only

days before an impact. In the latter case, yes, an impactor can arrive from the direction of the sun and not be seen until it hits. But in the former case, during a close

(but not impacting) pass by the Earth, if it comes from the direction of the sun it

will become visible after closest approach as it moves away, and vice versa if it

comes from outside moving in. Thus, in either case, it will be seen by the survey

and duly cataloged for any future approaches or impact paths. The difficulty of finding PHAs is therefore mostly a matter of how often an asteroid passes within range

of the survey. One class that is difficult are objects in very long orbits, similar to

comets, that only come in close to the Earth every decade or so. We simply have

to wait until they come around. Another group are resonant objects that have orbit

periods that are close to multiples (including 1.0) of the Earth’s orbit period. Imagine an asteroid with a period very near 5.0 years, which comes close to the Earth’s

orbit when the Earth is on the other side of the sun. Every five years it is behind

the sun, so we can’t see it. At other times it is far from the sun (and also the Earth),

so even when it is in the view range of the survey it is very faint. Yet another group

are asteroids with very nearly 1.0 year orbit period. A number of these have been

discovered which appear to ‘‘loop’’ the Earth in eccentric or inclined orbits. These

objects drift away from the Earth’s vicinity after several annual loops, not to return

again for decades or longer, after they lose or gain one full circuit of the sun relative

to the Earth. There are undoubtedly other such objects currently parked on the opposite side of the Earth’s orbit that will slowly drift into near-Earth space, and could

be an impact hazard, but we cannot find them from the Earth until after they move

out from behind the sun. Nevertheless, an Earth-based survey would find them

years before any possible impact. One can find them sooner with a space-based survey in a different heliocentric orbit (say near Venus), but is it worth it? It is improbable that there is even one object as large as one km in diameter, and maybe only

a few larger than 140m, in such orbits, so the value of taking the extra effort to

find them is questionable.

Finally, comets are intrinsically difficult to track, due to the non-gravitational

forces of the gasses being emitted. Thus, it would be impossible to predict an impact

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with certainty very long in advance even if we found a rare comet on a potentially

collision course. And of course the long-period comets come around less than once

in a lifetime, so new ones never seen before keep coming. Finding and cataloging

comets far in advance of an impact is thus not possible with today’s technology or

any foreseeable technology.

Q3. Once the LSST and Pan-STARRS telescopes are operating, and surveys for

PHOs that are 140 meters or larger has commenced, what is the business and

public safety case for expanding the search to detect and track smaller PHOs—

for instance, down to a size of 50 meters? What are the cost and schedule implications?

A3. In my response to question 1 above, one can see that there is a clear diminishing return in value for cost of ever larger surveys of ever smaller PHAs. See also

the NASA report on the feasibility of extending the search for near-Earth objects

to smaller limiting diameters: http://neo.jpl.nasa.gov/neo/report.html The first generation ‘‘Spaceguard’’ survey has reduced the impact risk from about 1,000 casualties per year to about 100 per year, at a cost of a few tens of millions of dollars.

This is certainly quite good value returned. The next generation survey, to 140

meter diameter, should reduce risk by another 90 casualties per year, at a cost of

some hundreds of millions of dollars. The cost/benefit ratio of such a survey appears

to be in a justifiable range that is worthy of policy consideration. A further step,

say to 50 meter diameter, would seem on the face of it to be beyond the range of

what could be justified on a cost/benefit basis. In terms of cost and schedule, we

do not possess the technology at present to catalog 50 meter objects at large enough

distances to find a large fraction of them in, say, ten years at reasonable cost. However, the same systems that find 90 percent of objects larger than 140 meters in

ten years will find 90 percent of objects to 50 meters diameter over a longer time,

of order of a human lifetime. So by about 2100, we will eventually find nearly every

PHA that can make it through the atmosphere. That is sooner than the odds of the

next one hitting the Earth, so the level of patrolling of the skies contemplated by

LSST will very likely find the next impacting object before it finds us.

Q4. One deflection solution, suggested by NASA, is to detonate a nuclear device in

the vicinity of a PHO. What are the advantages and disadvantages of using this

approach? What circumstances would argue against using a nuclear device in

lieu of alternative approaches?

A4. Many of the implications of this question are matters of policy rather than

science. However, there are technical aspects. My comments are based on the 2006

NASA NEO workshop in Vail. A major disadvantage of nuclear approaches is that

we do not know how efficient a nuclear standoff explosion might be, or if it would

disrupt the body into fragments still largely traveling on the same path, or if it

would push it aside, as proposed. Thus, one cannot know in advance whether a

standoff explosion would be effective, or even if shown to be effective in a test case,

whether it would be equally effective on another asteroid—the one actually coming

our way. The same uncertainty accompanies the ‘‘kinetic impactor’’ method of deflection, but it is vastly more politically acceptable to conduct impact experiments, such

as the ‘‘Deep Impact’’ comet mission, than it would be to conduct nuclear tests in

space. Furthermore, the most likely scenario we may be faced with is the case of

an object that may, but with less than 100 percent certainty, be on a collision

course, but we will not know for sure until after the optimum time to take action.

In such a case, it would be politically difficult, as well as strategically dangerous,

to take action with nuclear explosions when such action might not be needed at all,

and even if so could produce unpredictable results. Much more prudent would be

an approach that is more controllable and can be monitored for effect, such as the

proposed combination of a rendezvous vehicle that can monitor the effect of a kinetic

impactor and serve as a ‘‘gravity tractor’’ as needed for fine-tuning the deflection.

In any case, one should weigh the benefit of developing deflection plans in advance

of a discovered need.

Questions submitted by Representative Dana Rohrabacher

Q1. With regard to NASA’s Spaceguard program, what changes, if any, do you recommend to make the program more effective? In your view, is further legislation

required from Congress to implement needed changes?

A1. The Pan-STARRS and LSST surveys are planned to use somewhat different

search patterns, and object identification algorithms, than those used by the current

surveys. Whether it would be cost-effective to implement changes of this nature in

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the current surveys is questionable when they will become obsolete in terms of

depth of survey very soon anyway. It would certainly be short-sighted to shut down

the current surveys in anticipation of the next generation before those surveys come

on line at some decent level, but NASA, and the Congress, should be prepared to

make the transition to the next generation as soon as it is possible to do so. To retire the risk from Potentially Hazardous Asteroids, Congress could do two things:

(1) assure that a ground-based survey capable of achieving 90 percent completeness

for PHAs of larger than 140 meters gets started as soon as possible and, (2) assure

availability of the Arecibo radar (since that will continue to be an occasionally essential asset into the next generation of surveys.)

Q2. How important do you consider characterization in the overall NEO issue priorities?

A2. Physical observations, to measure sizes, shapes, spins, densities, mineralogy,

and so forth of discovered asteroids is of very high scientific interest, but is of secondary importance as far as the impact hazard issue is concerned. The statistical

characterization method has serious limitations when a robust characterization of

that particular asteroid with our name on it is required. Characterizing a statistically meaningful subset of discovered objects is necessary in order to understand

the population (for example, to even know what fraction of objects larger than a

given size have been discovered), but this can be done from observations of a small

fraction of the discovered population that happens to be most easily observable, thus

it is not necessary to have a large commitment of telescopes as large or even larger

than the survey instruments, as has sometimes been claimed. This is not to say that

no commitment is needed, but it can be satisfied with existing facilities currently

engaged in asteroid observations.

Q3. What capabilities are required for a comprehensive deflection campaign?

A3. This is outside the purview of the LSST project. While R&D is needed, my personal opinion is that deployment of deflection hardware should wait until a demonstrated need is discovered.

Q4. What is your estimate on the number of undiscovered asteroids in the 140 meter

and above range? Describe the potential damage that an asteroid in the 140

meter range could cause striking an ocean within, say, 500 miles from a U.S.

coast.

A4. It is estimated that there are about 20,000 NEAs larger than 140 meter in diameter, and presently, there are somewhat over 3,500 known, leaving about 17,000

undiscovered. In terms of Potentially Hazardous Asteroids, there are approximately

4,000 total estimated, and about 600 known. A 140 meter diameter asteroid striking

the ocean 500 miles (800 km) from shore might produce a tsunami wave a meter

or two in height as it approaches the shore. The ‘‘run up’’ amplification depends a

great deal on the off-shore depth profile, but might be a factor of two or three, to

a height of five meters or so. Such a wave might run inland a km or so, depending

on the flatness of the land on shore. The effects of such an impact tsunami could

be comparable to a major hurricane, and the chance that the impact would be at

a particularly vulnerable location rather than somewhere else is comparable to that

for a hurricane.

Q5. Asteroids are more easily detected in the infrared spectrum. An asset such as

the WISE satellite has an effective capability for searching for NEO’s infrared

output. Is WISE being tasked for this role? What other infrared detection devices

can or will be used to detect NEOs?

A5. Infrared technology is not yet mature enough to be competitive with optical (reflected sunlight) surveying. From the ground, the highly emissive and absorbing atmosphere reduces thermal IR sensitivity to less than that of optical, regardless of

detector technology. From space, IR has a modest theoretical advantage, less than

one might suppose because the resolution of a given aperture telescope in the thermal IR is about twenty times less than at visible wavelengths, and the background

level of sky brightness and confusing sources, after allowing for the reduced resolution, is substantial. There are some technological problems: detector arrays are not

yet as large as those for optical wavelengths, to operate efficiently they need to be

cooled to the limit (or beyond) of passive cooling systems, and with many images

each with billions of pixels there would be on-board computation challenges.

While WISE will survey the entire sky and, indeed, detect many asteroids, there

are a number of reasons that it will not be capable of making a substantial contribution to the PHA survey. First, the WISE survey strategy does not have a cadence

that is tuned to discovering and cataloging moving objects. Moreover, with only a

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six-month mission, many PHAs will be out of range and completely unobservable

during the brief period of mission operations. Finally, its modest instrument (0.4

meter aperture, 0.8 degree field of view) is not well-suited for this purpose. However, WISE will make great strides in the realm of asteroid characterization. The

four separate IR band passes will allow the characterization of a large number of

asteroids, some of which may not be actually discovered until later. This information, combined with optical catalogs, such as the Sloan Digital Sky Survey, will enable subsequent PHA surveys such as LSST to make good statistical inferences

about the makeup and size of new discoveries. WISE will detect a lot of asteroids,

but is not capable of replacing even present optical survey systems, let alone systems like Pan-STARRS or LSST, even if re-tasked solely to the NEA survey. The

advance of IR technology should be monitored for its potential to contribute to NEA

surveys, but at present it does not appear to be mature enough to contemplate

changing from ground-based optical surveys to space-based IR surveys.

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ANSWERS TO POST-HEARING QUESTIONS

Responses by Russell ‘‘Rusty’’ L. Schweickart, Chairman and Founder, B612 Foundation

Questions submitted by Chairman Mark Udall

Q1. How well understood are the potential approaches to deflecting asteroids? What

is the confidence level in the technologies that would be required? What information is needed to assess the various approaches, and how will decisions be made

on which mitigation strategy to take?

A1. The basic elements of an asteroid deflection are quite well understood. One

must alter the orbit of the asteroid to 1) miss a direct Earth impact, and 2) avoid

passing through any of the hundreds of return keyholes as the asteroid passes by

the Earth. The technologies which have the required capability for the first of these

objectives are kinetic impact (KI) and nuclear stand-off explosion. KI is essentially

running into the asteroid in a specific direction with a specific velocity, similar to

what was done in 2005 by the Deep Impact spacecraft running into comet Tempel

1. A stand-off nuclear explosion in space has never been done but on a theoretical

basis should work. Both techniques can be characterized as strong but imprecise.

Therefore essentially all asteroids which might threaten impact can be deflected

from a primary impact (98–99 percent can be deflected using KI). However such a

deflection has no possibility of insuring that the asteroid will not pass through any

of hundreds of return keyholes resulting in a certain impact within several years.

Therefore a precision deflection capability using the gravitational tractor (GT) concept (or other if any become available) is needed to immediately follow-up the imprecise primary deflection to insure that no keyhole passage is permitted.

There need to be detailed analytic assessments and simulations performed on all

three techniques. The KI and GT techniques should ultimately be flight tested on

a real (but non-threatening) asteroid to fully validate a deflection campaign. I do

not recommend demonstrating the nuclear explosion concept, although simulations

could, and should be run.

An actual deflection decision is virtually independent of the technology. A deflection campaign would require two coordinated missions, first a transponder/gravity

tractor (t/GT) mission to precisely pin down the asteroid orbit and confirm a pending

impact. If confirmed the t/GT would observe the subsequent KI impact from a safe

distance, then pull in close to the asteroid to 1) confirm a successful primary deflection, and 2) determine whether or not the asteroid is headed for a return keyhole.

In the unlikely case that the asteroid is headed for a keyhole the t/GT would then

be employed to make a small but precise modification in the asteroid’s new orbit

to assure the asteroid misses the keyhole. This sequence is the only way, using existing technology, to guarantee a successful deflection. In the extremely improbable

event (probability of occurrence once per 100,000+ years) that the asteroid at issue

is too large for a KI deflection, a nuclear stand-off explosion would be needed as

a substitute. The precision component (t/GT) would still be essential to the success

of the deflection campaign.

The decision to deflect, per se, would of necessity be an international decision due

to the inherent shifting of risk from one geographic region to another during any

deflection. The Association of Space Explorers (ASE) is working on the deflection decision process in cooperation with the United Nations. While the action will of necessity be the responsibility of one or more space-faring nations, the decision process

will involve many nations since the uncertainty in the impact point and the shifting

of risk during any deflection will involve nations across the planet.

Q2. How mature are the non-nuclear versus the nuclear technologies for deflecting

an asteroid?

Q2a. What should the priorities be in further developing those technologies?

A2a. The non-nuclear (KI) technology is a flight proven technique having been used

(albeit for different purposes) during the Deep Impact mission of July 4, 2005. The

primary difference is that comet Tempel-1 (the target of the Deep Impact spacecraft)

was significantly larger than those asteroids likely to require deflection. Furthermore there is an unknown (likely small) possibility of fragmentation of the asteroid.

Finally the ‘‘momentum multiplier,’’ the degree to which the ejection of debris from

the kinetic impact multiplies the effectiveness of the impact, is highly variable and

uncertain. The last two factors can, and should, be validated by an actual demonstration mission.

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The nuclear stand-off explosion is entirely theoretical. While terrestrial weapons

effects analysis is a highly developed and sophisticated field of knowledge the use

of nuclear explosions in space is not well understood and cannot, without modification of existing treaties, be tested. Proponents of the use of nuclear explosions generally feel very confident in their computer models, but atmospheric and vacuum explosions are very different from one another. Additionally the concerns mentioned

above re KI also apply to the nuclear option, i.e., the possibility of fragmentation

and the uncertainty of the ‘‘multiplier’’ effect. The primary difference in eliminating

these uncertainties is that there is no impediment to testing KI in a demonstration

mission whereas demonstrating a nuclear stand-off in an actual mission would be

a major international political challenge, not to mention arguably a treaty violation.

The gravity tractor (GT) is not in a ‘‘versus’’ situation, being a necessary component of any deflection campaign, nuclear or non-nuclear. In terms of technology maturity the primary challenge for the GT is engineering the control and guidance software for the ‘‘towing’’ maneuver. Engineering simulations of the GT are about to

get underway and testing should be done in an actual flight demonstration. A slightly modified Don Quixote mission (a NEO deflection mission considered by the European Space Agency) could simultaneously demonstrate both the KI and t/GT concepts.

Priority should clearly be given to developing and testing the KI and t/GT concepts since they are the most likely to be called on for deflection. Only one to two

percent of potential deflection challenges would require a nuclear option and that

percentage will drop essentially to zero as the revised search program is executed

over the next 15–20 years.

Q3. What do you see as the most important next step in advancing our understanding of deflection approaches?

A3. Testing and demonstrating both the kinetic impact (KI) and gravity tractor (t/

GT) concepts. As mentioned above a slight modification of ESA’s Don Quixote mission could fully validate both components of a deflection campaign in a single program for a total cost of between $500M and $1B dollars. In a cooperative program

with ESA, NASA’s share of this would be comparable to the cost of an average lowcost scientific mission.

Q4. What do you think would be the most appropriate next steps in addressing the

governance issues discussed at the hearing?

A4. Step 1 would be to assign responsibility to NASA for 1) analyzing and developing NEO impact warning concepts, and 2) for developing and testing NEO deflection technology.

Search is important, without question. However someone now needs to be working

through the complex issues of what we do when we discover a NEO which ‘‘has our

address’’ on it. . . or, more likely appears to have our address on it. With the exception of flight testing the deflection concepts, these actions require very little money;

the task is primarily to conceptually work through the complex issues involved.

Step 2 would be to address the larger question of overall responsibility for handling this devastating but preventable natural hazard. This issue is particularly

challenging in that unprecedented levels of destruction are at issue and in the process of eliminating the risk of an impact for everyone certain nations will of necessity

have to accept a temporary increase in risk to their populations. Such a collective

international decision will require considerable diplomatic efforts involving not only

cost sharing, but also liability, indemnification, oversight and other sensitive considerations. While the technical aspects of warning and deflection will inform many of

these considerations the primary challenge embedded here is national and international policy.

In addressing this it would seem that no single Congressional committee has appropriate jurisdiction. Therefore at the outset the Congress and the Administration

would benefit from the issue being considered in depth by an appropriate highlyregarded professional organization, such as the National Academies.

Questions submitted by Representative Tom Feeney

Q1. NASA’s NEO Report, delivered this March, provides several options for meeting

the goal of achieving 90 percent detection, tracking and characterization of Potentially Hazardous Objects, and the report establishes a clear relationship between resources invested and the time needed to achieve 90 percent coverage. In

essence the report shows that for an additional investment of approximately

$536 million, we could buy-down a decade of time to complete the survey. In

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your view, is that additional investment necessary? Does the threat posed by

PHOs compel faster completion of the survey?

A1. This is an excellent public policy question, not a technical one. I believe that

the following are considerations which should be taken into account in addressing

the issue.

1. A growing segment of the general public is aware of the NEO threat. A

smaller, but also growing segment of the public is aware that we have the

technology today to not only warn us of a pending impact but also to prevent

a devastating impact. Over the next decade, under any circumstances, there

will be a number of what will be reported in the press as ‘‘close calls.’’ There

will also likely be several, perhaps even hundreds, of NEOs that will appear

to be threatening and will be reported (and misreported) by the public media.

The issue, and its ‘‘solution,’’ will become widely known to the public.

2. A widely stated fact is that ‘‘If we know about them, we can do something

about it. The ones we need to worry about are the ones we don’t know

about.’’ The public will come to know that the survey could be accelerated

by 10 years at the cost of foregoing a single scientific satellite, or less (see

comment below). Alternatively adding $500M to the NASA budget over 5–

7 years would suffice.

3. 2008 is the 100th anniversary of the ‘‘Tunguska Event.’’ There will be a great

deal of publicity about this and many legitimate and not so legitimate presentations and discussions.

4. Every hurricane, earthquake and tsunami which creates great damage in the

next decade will be another poster child for the possibility of a NEO impact,

especially if one occurs in temporal proximity to a NEO ‘‘near miss.’’

5. From an ‘‘objective’’ perspective the NASA/JPL staff could compute the probability of an impact of various sizes occurring in the absence of the faster

survey and compute the cost-effectiveness of the additional $536M of ‘‘insurance.’’ (In rough terms, using Apophis as an example, the cost of an impact

is approximately $400B. If the probability of an Apophis impact (and its

unfound cohorts) not being found is one in 1000 then the actuarial value of

finding it in time to prevent the impact is $400M. Such an actuarial analysis

could be performed).

Note: Dr. J. Anthony Tyson, Director of the LSST, testified at the hearing that

if NASA were to fund 15 percent of the LSST costs it would effectively have at its

disposal, for $125M, a dedicated LSST and be able to meet the Congressional 140

meter goal within 12 years from LSST by 2026.

Q2. What are the most difficult types of NEOs to detect? Is there, for instance, a portion of the sky that won’t be covered by ground-based facilities? Are there certain

types of orbits that make it difficult to detect and track asteroids and comets?

A2. There are two factors which are critical; size and type of orbit. Small NEOs can

only be seen when they are very close to the Earth compared with larger NEOs.

There are also many more small NEOs than large ones (e.g., 1,000 NEOs larger

than one km in diameter vs. 40,000 NEOs larger than 140 meters diameter, and

800,000 at 40 meters and larger.) and therefore the vast majority of unfound NEOs

are at the smallest end of the spectrum of those which can do damage on the

Earth’s surface.

The second factor is the orbit size. Those NEOs whose orbits are smaller than the

Earth’s, i.e., whose orbits lie primarily inside the Earth’s orbit, spend most of their

time with a ‘‘look angle’’ too close to the Sun and its glare to be seen by optical telescopes. They are typically seen for a month or two for several years in succession,

followed by many years when they cannot be seen at all. These NEOs are classified

as Atens. When an Aten is also small the two issues compound such that a 40–140

meter diameter object may be seen only once or twice in a decade. Obtaining an accurate orbit is therefore quite difficult for these objects.

As pointed out in the NASA report, a space-based telescope placed in a Venuslike orbit would be able to look outward (i.e., away from the Sun) and both discover

and track these Atens which are challenging to observe from the Earth’s surface.

Comets (long period comets) orbit the Sun in very large orbits which extend beyond the orbit of Jupiter. They are only detected when they approach the Sun within the orbit of Jupiter and begin to out-gas due to gradual heating. From detection

to the time they cross the Earth’s orbit is typically only several months. This is inadequate time to mount a deflection and they are generally not considered objects

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from which we can protect ourselves. Happily they are also one percent of the asteroid problem and are therefore (currently) disregarded.

Q3. Once the LSST and Pan-STARRS telescopes are operating, and surveys for

PHOs that are 140 meters or larger has commenced, what is the business and

public safety case for expanding the search to detect and track smaller PHOs—

for instance, down to a size of 50 meters? What are the cost and schedule implications?

A3. As regards ‘‘the business case’’ (the potential for ‘‘mining’’ asteroids) essentially

the only issue is the cost to get to the asteroid. This depends entirely on the specific

orbit, with those in Earth-like orbits being the least costly to target. Even a 40

meter diameter asteroid weighs in at 100,000 metric tons; a great deal of potentially

useful resource for development. Therefore since there are many more small asteroids than large the most promising targets for resource utilization will be found

among this population.

Public safety is at issue any time an asteroid impacting the Earth can cause significant damage at the surface. The Earth’s atmosphere protects us from NEOs

smaller than 30–40 meters. Those in the vicinity of 40–100 meters may not reach

the surface but will explode with such energy in the lower atmosphere that they

create devastation at the surface even without reaching it per se. At sizes larger

than 100–150 meters they reach the surface of the Earth substantially intact causing even greater damage and potentially tsunamis if they impact the ocean.

It is clearly a policy judgment but I (representing the Association of Space Explorers) consider a Tunguska-like impact to be approximately the threshold size at

which public demand would mandate a deflection effort (this assumes that the NEO

is known in advance and projected to impact). Had the Tunguska asteroid (approximately 45 meters in diameter, exploding with five megatons of energy or 333 Hiroshima bombs) exploded over a city instead of the middle of a Siberian forest it would

likely have killed everyone in the city. It therefore seems prudent, from a public

safety consideration, to ultimately extend the search down to this (or some equivalent) threshold limit.

What needs to be recognized is that in the process of reaching the goal of 90 percent of the population of NEOs 140 meters and larger we will also discover approximately 40–50 percent of the NEOs 50 meters and larger. Without any further investment in larger telescopes an additional two decades (i.e., 2040) of search (which

will be done in any case in order to monitor the larger NEOs) will ultimately extend

this figure to near 90 percent. If one chooses to reach the 90 percent discovery level

for 50 meter objects earlier (say by 2030) then either larger ground based telescopes

or a modest (∼1 meter) space telescope in Venus-like orbit would have to be employed. The life cycle cost of this would approximate $1B according to NASA’s estimation in their NEO Report to Congress.

Q4. One deflection solution, suggested by NASA, is to detonate a nuclear device in

the vicinity of a PHO. What are the advantages and disadvantages of using this

approach? What circumstances would argue against using a nuclear device in

lieu of alternative approaches?

A4. The only advantage of using a nuclear device over a kinetic impactor (KI) is

in those rare instances where the total impulse required to deflect the NEO at issue

is greater than can be provided by the KI. Assuming adequate warning (i.e., 15–

20 years) this threshold is reached at approximately a 400 meter diameter NEO.

An object of this size is statistically encountered only once every 100,000 years. At

the current time we have discovered about 40 percent of NEOs this size and the

probability that any of these will impact Earth in the next 100 years is zero. By

completion of the new survey (140 meters) we will have discovered about 95 percent

of the 400 meter NEOs. Assuming that none of them is about to strike the Earth

(very highly likely) it is only the remaining five percent still unknown which would

pose a threat necessitating the use of a nuclear device for deflection. The probability

of one of these residual five percent striking Earth is once per 2,000,000 years.

The other, also very unlikely circumstance in which a nuclear device would be required is if, in the next few decades we discover a NEO of almost any size which

is predicted to impact within 5–10 years from discovery. Since the probability of the

smallest objects of concern (therefore the most populous and most likely to impact)

is once in 1,000 years, the probability of encountering one of these in the next 10

years is one in 10,000. This small number is further reduced by the fact that at the

completion of the 140 meter survey we will have discovered only (say) 50 percent

of the 50 meter objects and therefore there would be only a 50 percent chance that

we would have discovered such an impactor before it hit.

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The bottom line is that non-nuclear means are able to handle 98–99 percent of

the current population of dangerous asteroids (those above the threshold mentioned

above) and this will grow to well over 99.9 percent within the next two decades as

we discover most of the remaining NEOs which would require nuclear means.

But why not (NASA asks) use nuclear if it will work? Because the entire issue

of NEO deflection is ultimately a collective (i.e., international) decision and the

world has clearly and unequivocally stated in treaties and elsewhere that it wants

to keep nuclear weapons out of space. Can the U.S. act unilaterally? Of course. Is

this wise? Absolutely not. Where non-nuclear means are adequate to do the job

there is no objective reason for considering nuclear explosives.

From the technical perspective the use of a nuclear device will also be highly unpredictable. The potential for fragmenting the NEO will be extremely difficult to

rule out given the very unlikely case that an actual flight demonstration on an asteroid will be available. Furthermore the total impulse imparted to the NEO will

be highly uncertain (as will be that of the kinetic impactor) and unlike the kinetic

impactor which is easily tested, this uncertainty will remain. In any circumstance

both the kinetic impactor and the nuclear stand-off explosion (or any other impulsive deflection technique) will not provide the precise orbit change needed to insure

that the NEO will not pass through a return keyhole after the primary deflection

maneuver. Therefore a deflection campaign must of necessity include the weak but

precise deflection capability of a gravity tractor (GT) or other precision deflection

technique to ‘‘trim’’ or slightly adjust the primary deflection in the event that it is

headed for a keyhole post-primary deflection.

In summary; those circumstances requiring the strength of a nuclear deflection

are extremely improbable (and will become much less probable over time) and, given

international treaties and world opinion against nuclear explosives in space the sufficiency of non-nuclear means will be the option of choice.

Questions submitted by Representative Dana Rohrabacher

Q1. With regard to NASA’s Spaceguard program, what changes, if any, do you recommend to make the program more effective? In your view, is further legislation

required from Congress to implement needed changes?

A1. Reading the question in the narrow sense, i.e., the Spaceguard Survey per se,

I would emphasize recommendation #1 in my written testimony that the Congress,

whether through Authorization or Appropriations, should require that NASA comply

with the law and both recommend and initiate a search program (and supporting

budget) to meet the 140 meter goal. Whether it takes 15 years or 17 years is far

less important than that a specific program be committed to and initiated.

Reading the question in its broader sense, i.e., the Spaceguard Survey as the overall initiative to protect the Earth from asteroid impacts, I would call on the Congress to expand NASA’s current limited activities to include 1) developing a recommended NEO impact warning concept, and 2) developing and testing NEO deflection technology. (These are contained as recommendations #3 & 4 in my written testimony.) Not only is it important that we move ahead regarding the issue of ‘‘what

do we do when we find one with our address on it?’’ but by systematically thinking

through the issues involved in warning and mitigation, the search program per se

will begin to focus on the most critical information needed rather than simply meeting a somewhat abstract numerical quota.

One further observation here; under any circumstance the discovery rate of NEOs

will dramatically increase in the immediate future due to the introduction of PanSTARRS and LSST into the search process. There is no doubt whatever that given

the considerable expansion in the number of NEOs discovered we will find many

that will appear to threaten impact with Earth. If, by way of illustration, the current discovery rate of NEOs that appears to threaten impact is one per year, then

even without any further commitment by NASA, that rate of discovery of apparently

threatening NEOs will rise to 30 or more per year over the next 5–7 years. This

will, without question, get the attention of the press and the public. Therefore it is

critical that specific action beyond the search program be underway to assure the

public that their safety is being responsibly attended to.

Q2. How important do you consider characterization in the overall NEO issue priorities?

A2. Let me emphasize immediately that I am in the minority in what I am about

to say, even among my fellow NEO community peers. I believe that my minority

position is justified, having arguably thought through the deflection issues more

thoroughly than most of my compatriots.

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I believe that characterization of NEOs, in the classic sense of learning the specific technical characteristics of asteroids per se (thermal, structural, mineralogical,

and other descriptive characteristics) is not a priority in regard to protecting Earth

from impacts. With respect to classical scientific values it is very important; but protection of the Earth from impacts is a public safety issue, not a scientific one.

The basis for this low priority is that the inherent performance of the kinetic impact deflection concept (and nuclear explosion as well) is highly uncertain and variable. The momentum imparted to a NEO by crashing into it is determined more by

the energy and the variable nature of the impact geometry than by any knowledge

that can be gained through classical characterization efforts. Each NEO is unique

and likely non-homogeneous. The effect of an impact will vary depending on the

slope of the surface on which it happens to impact as well as on the specific local

structural characteristics. The rotation of the NEO, whether it is hit a glancing

blow, and whether there happens to be buried ice or other volatiles at the specific

impact site are also both unknowable and likely highly variable.

Therefore the technical parameter beta (the ‘‘momentum multiplier’’) has a wide

range, usually approximated today as ranging from two to 10 or more. This large

uncertainty, even assuming heroic characterization efforts, will never be reduced to

a reliably predictable single value. Therefore a kinetic impact or nuclear explosion

will always produce a range of predicted deflection results, e.g., 3–20 Earth radii,

or 2–15 Earth radii. It is this intrinsically uncertain nature of the impulsive deflection techniques which risks deflecting the NEO such that it will miss the Earth

(good) but risk passing through a return keyhole (bad). For this reason it will always be necessary to have an observer spacecraft, with a transponder and precision

deflection capability (e.g., gravity tractor), standing by in real time to both confirm

the success of the primary deflection and execute a precise adjustment to the deflection to avoid a future keyhole passage and subsequent impact.

Given that the primary deflection will always have a degree of uncertainty sufficient to risk passage through any of hundreds of return keyholes, a precision orbit

adjustment capability will always be required. This statement will remain true regardless of any amount of money spent on NEO characterization, given the many

variables of a kinetic impact or nuclear explosion having nothing to do with NEO

characteristics. So why spend the money when the inherent uncertainties can (and

must) be handled by the precision trim capability?

Conversely, if one is (and we should be) interested in the potential for utilization

of asteroidal resources at some future time, then characterization of NEOs is very

important indeed. This is, however, classical science in its proper role and not public

safety.

Q3. What capabilities are required for a comprehensive campaign?

A3. A comprehensive deflection campaign (for a ‘‘direct’’ NEO impact threat) will

consist of the following 5 steps;

1) The launch and rendezvous of a transponder equipped spacecraft (t/GT) with

the NEO,

2) The determination (confirmation) of a pending impact based on the dramatically improved orbit determination,

3) The launch and impact of a kinetic impactor (KI),

4) The determination of the precise post-impact NEO orbit, and

5) A precise orbit adjustment (trim) maneuver if the NEO is determined to be

headed toward a return keyhole (t/GT).

Given that the primary deflection may place the NEO on a path toward a return

keyhole, a precision deflection capability will always be necessary. Therefore since

a gravity tractor (or other future precision deflection technology becomes available)

will also have a transponder aboard the spacecraft for steps 1, 4, and 5 would logically be a single transponder/gravity tractor (t/GT) combination.

If the threatening asteroid is being deflected not from a direct impact but rather

from a keyhole (with subsequent impact), then only steps 1, 2, and 5 need be employed. An example of this situation is the current Apophis case where, if in 2013

it is determined that the NEO is indeed headed for the 7/6 keyhole in its 2029 close

approach to Earth, a t/GT mission alone can be utilized to affect the deflection (i.e.,

steps 1, 2 and 5 above.)

Q4. The need for a comprehensive potentially hazardous NEO program seems to require expertise of several agencies. How do you suggest coordination be handled?

A4. The primary technical expertise required for a comprehensive NEO impact mitigation capability lies within NASA per se. The exception to this is the remote possiVerDate 11-MAY-2000 18:21 Feb 21, 2008 Jkt 038057 PO 00000 Frm 00160 Fmt 6601 Sfmt 6621 C:\WORKD\SA07\110807\38057 SCIENCE1 PsN: SCIENCE1
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bility of encountering a NEO threat which exceeds the capability of the kinetic impactor for primary deflection. If it is deemed prudent to prepare for this unlikely

eventuality then NASA will need to coordinate with DOE regarding nuclear standoff deflection capabilities and requirements. This coordination can be done in much

the same manner as currently done when NASA utilizes nuclear materials (e.g.,

RTGs) or as was done in the recently canceled Prometheus program which utilized

a nuclear reactor.

Q5. Describe some of the proposed mitigation techniques and their trade offs.

A5. There are three techniques available with no new technological developments

required prior to use. In all three cases there is significant engineering required.

(Many neutral observers would challenge these statements for the nuclear stand-off

option, however I will not challenge the advocates here.) These three divide into two

types; the impulsive (virtually instantaneous action) techniques of kinetic impact

(KI) and nuclear stand-off explosion, characterized by significant total impulse capability but with a highly unpredictable outcome, and the ‘‘slow push’’ technique

(using NASA’s term) of the gravity tractor, characterized by a modest total impulse

capability but high precision and full controllability. Either of the impulsive techniques would necessarily be used in concert with the latter to insure a fully successful deflection.

The nuclear option has the disadvantages of both political opposition, especially

international, and technological uncertainties which can never (in all likelihood) be

tested prior to potential use. The guidance and timing constraints to achieve a

planned result in addition to the possible fragmentation of the NEO are all significant challenges which will persist until actual use is attempted. A further leap of

faith is taking at their word the nuclear effects experts who claim that the behavior

of a NEO exposed to a pulse of neutrons will behave as the computer models predict. On the positive side the total impulse available for altering the orbit of a NEO

is potentially greater than any other option.

The kinetic impact (KI) and gravity tractor (GT) technologies use available and

proven technology, albeit in both cases engineering software needs to be developed

and tested. Both techniques can, and should, be fully tested and demonstrated. This

should be done in the near future to provide both official and public confidence prior

to the time that a threatening NEO is discovered. The KI concept could also cause

NEO fragmentation, but in this case it can be tested early and inform operational

design to provide confidence in actual use. The GT concept is completely benign

since it makes no contact with the NEO and can easily be tested and its performance validated in the immediate future.

There have been other deflection concepts proposed but all, in one way or another,

require advanced technology development, the resolution of key unknown factors, or

pose less cost effective solutions than those currently available. All such techniques

should be further investigated and analyzed to support decisions on future technology development and testing. None, however, should be considered to be currently ready for deployment as are the three recommended above.

Q6. What is your assessment of the need for a nuclear capability?

A6. There is a very limited, near-term value in having a nuclear capability conceptually available for NEO deflection. The need is very limited, however, and a determination of the high cost and complexity of further development of this technique

must be judiciously weighed against the very low probability of it being needed viz.

non-nuclear techniques.

Based on current analysis it appears that the KI technique can provide the total

impulse to deflect any NEO up to approximately 400 meters in diameter given 15–

20 years of warning. Given that the statistical frequency of a 400 meter NEO impacting Earth is about once per 100,000 years the probability of needing to use nuclear deflection is approximately .05 percent over the next 50 years. (I use 50 years

on the assumption that by that time more capable non-nuclear technologies will be

developed.) Further reducing this probability is the fact that we have already discovered about 40 percent of the 400 meter NEOs and none has any possibility of impacting Earth in the next 100 years. The likelihood therefore drops to .03 percent

based on the remaining 60 percent of yet to be discovered 400 meter NEOs. However based on similar reasoning, by the completion of the new 140 meter search program in ∼15 years the completion rate for 400 meter NEOs will approximate 95 percent of the population reducing further the probability of needing to use nuclear

technology to about .004 percent. Finally, for warning times exceeding 20 years or

so any significant development costs can await such warning and still be ready for

deployment if needed.

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The missing element in the above paragraph is the similarly very low probability

that within the next 15 years a 400 meter or larger NEO will be discovered with

an impact date within 20 years, i.e., an ‘‘immediate’’ impact. In this instance only

the extant nuclear technology would be available for use. The probability of this situation arising can be approximated based on the statistical impact rate of 400 meter

NEOs at once per 100,000 years. This is based on all of the 400 meter NEOs being

unknown. If we assume that it will take approximately 20 years to discover ‘‘all’’

of the 400 meter NEOs then the probability a 400 meter NEO impacting within the

next 20 years is one in 2,000 or .05 percent. However since we have already discovered 40 percent of the 400 meter NEOs and will reach about 95 percent within the

next 15 years, this probability is .03 percent now and will diminish to .004 percent

within 15–20 years.

The public policy question is then, what expense is justified in investing specifically in preparing nuclear technology for use in deflecting NEOs over the next 20

years with the probability of use being about one in 10,000? Beyond that timeframe

adequate warning time will permit this investment if and when needed.

My personal opinion is that this investment is not justified, other than perhaps

some minor analytic studies.

Q7. Why, in your written testimony, do you state that the most important question

you have been asked by the Committee is ‘‘What governance structures need to

be established to address potential NEO threats?’’

A7. From my work on this issue over the past six years it has become evident to

me that the most challenging aspect of protecting the Earth from NEO impacts will

be the decision-making process. Without elaboration, ‘‘we can know something is

coming at us, and we can have something to do about it, but unless we can make

the decision to take action, we will still end up like the dinosaurs.’’ Clearly this is

an overly dramatic statement since the likelihood of being struck by a small NEO

which might devastate a city-sized area is 1000s of times more likely than an extinction event. Nevertheless it clearly makes the point that warning and deflection

are simple compared with the world making a coordinated decision to mount a NEO

deflection campaign.

The key to understanding this claim lies in the use of the word ‘‘world.’’ Without

going into too much technical detail the need for a coordinated international decision arises from a combination of the orbital mechanics of NEO impact and the need

for those nations at risk, and those nations placed at risk by the deflection itself,

being involved in the decision. Such up front questions as who pays?, will there be

indemnification for the deflecting entity?, will a deflection be mounted at all or

should we ‘‘take the hit’’ are all examples of the need for international coordination.

What has not yet been generally recognized, even within the ‘‘NEO community’’

is that in many (if not most) instances we will not be able to wait until after it is

certain that a NEO will impact before launching a deflection campaign. The slow

development of precise knowledge of the NEO’s orbit over time, combined with the

episodic nature of the collection of this knowledge assures that in many cases the

quality of our knowledge at the latest possible time a deflection can be launched

will require that we launch on probabilities of impact less than one. In certain instances where the threat is a NEO headed for a return keyhole prior to impact this

launch decision may have to be made with the probability of impact being as low

as one in 100 or even less.

These observations translate on the ground into challenging international sociopolitical issues. When the probability of Earth impact is less than one, all we know

is that there is a risk corridor extending completely across the Earth’s surface, anywhere within which the NEO could hit, if it is indeed headed for impact. This generally narrow corridor (usually only 10s of kilometers wide) will cross many national

boundaries thereby limiting which countries are at risk of an impact. However

which specific country is destined for impact if a deflection is not completed is unknown, and will generally remain so until a transponder is brought into position at

the NEO by the t/GT spacecraft, the first element of a deflection campaign. Therefore a decision to deflect will be of great interest to many but not all countries (the

risk corridor may cross as few as two to or as many as 10 or more countries). Will

only these few countries called on to decide on a deflection and bear the cost? Or

is the world community as a whole to debate the justification for sharing the cost?

Will all, or a few, or none provide indemnification for the designated deflection entity? And by whom is the deflection to be performed and how will that nation, or consortium be chosen? Etc., etc. This is only a small sampling of the many difficult decisions that must be made in order to initiate a NEO deflection. Can such a decision

be made unilaterally? Of course. However the implied liability and international

furor should such an act be executed will likely inhibit such action. Even if, e.g.,

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the U.S. is threatened by such an impact and a unilateral action would seem justified, the consequence of such action would be to place other nations temporarily at

risk in the process of deflecting the impact away from the planet.

Clearly from this brief discussion it can be seen that the deflection (or mitigation)

decision process will involve very difficult international political negotiations and

trade-offs. The U.S. will have to be represented and indeed may well play a dominant role in such determinations. However the nature of the issues, while informed

by technical realities, is primarily socio-political and it is doubtful that this responsibility would logically fall to NASA. Other logical candidates, in my personal order

of priority would be Department of State, Department of Homeland Security, and

Department of Defense.

How this assignment of responsibility is to be determined is the public policy challenge to which I referred in my written testimony. Notwithstanding the challenging

nature of the issues I believe the process of deciding this issue should start immediately given the protracted debate which will soon be initiated within the United

Nations. This issue is currently on the UN Committee on Peaceful Uses of Outer

Space (COPUOS) agenda for 2009 and the Association of Space Explorers is leading

an international effort to draft a proposed UN Program for Asteroid Threat Mitigation which will be presented in the 2009 COPUOS session. The U.S. needs to be

prepared to not only participate but lead in these discussions.

Q8. You’ve made a number of recommendations regarding actions that should be

taken by NASA and/or the Congress. Could you please estimate the cost of implementing these recommendations?

A8. B612 Foundation has no credible capability to make such cost estimates. Nevertheless, with this being said I will address the question as best I can based on many

years of working in the industry and on analogous program experience. I will refer,

without elaboration, to the recommendations in my written testimony in addressing

the question.

Recommendation 1. ‘‘. . .the Congress should again direct NASA in the clearest language possible to comply with the law and recommend a search program and supporting budget.’’

The cost of complying with this recommendation is specifically addressed in the

NASA report to Congress. In addition, however, I strongly advise consideration of

the oral and written testimony presented at the hearing by Dr. J. Anthony Tyson,

Director of the LSST Project. Dr. Tyson pointed out that NASA could, in fact, and

contrary to the NASA estimated cost in its report, obtain effectively a dedicated

LSST for 15 percent of the life cycle cost of the telescope by contributing a total of

$125M to the LSST Project.

Recommendation 2. ‘‘. . .NASA should produce a supplement to its Report to Congress based on new knowledge which has come to light since it began its analysis.’’

Given the baseline work already accomplished in the preparation and delivery of

the NASA NEO Report to Congress and the relatively few but critical issues missed

by NASA, it would seem that this supplement to the Report could be accomplished

at 15–25 percent of the cost of the initial report. This is, however, purely a guess.

Recommendation 3. ‘‘NASA should assign someone in its NEO Program to the specific task of thinking through, analyzing and understanding the NEO deflection challenge.’’

The cost of implementing this recommendation is simply the cost of one or possibly two additional FTEs at JPL.

Recommendation 4. ‘‘NASA should validate a basic NEO deflection capability

through the execution of a demonstration mission.’’

As described in my testimony a slight modification to ESA’s proposed Don Quixote

program could validate the fundamental elements of a full deflection campaign.

Were NASA to undertake this full program on its own the program would involve

the design, launch and execution of two relatively simple space missions in concert.

The cost should therefore approximate the cost of two typical scientific missions or

$600–800M.

If, as should certainly be seriously considered, NASA were to cost share a cooperative program based on ESA’s Don Quixote program with the Europeans, its cost

share should drop to below $400M.

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Recommendation 5. ‘‘. . .that the Congress expressly assign to NASA the technical

development elements of protecting the Earth from NEO impacts as a public safety

responsibility.’’

This recommendation’s costs are largely covered by the combination of recommendations 3 & 4 above. The primary issue here is not any specific action but

rather a clear and unequivocal assignment of responsibility. The development and/

or testing of any new technology, in addition to that in recommendation 4, would

be handled and cost justified on a case by case basis in future NASA budgets based

on justified need.

Recommendation 6. ‘‘. . .that the Congress study the issue of overall governmental

responsibility for protection of the Earth from NEO impacts, perhaps with the assistance of specialized policy entities, and ultimately hold public hearings to engage a

wide perspective on the issue.’’

The cost of this recommendation would be the cost of a directed policy study (e.g.,

contracted to the National Academies by NASA) for perhaps $1–2M plus the cost

of Congressional hearings on the issue.

Q9. Can you give an example or two of why NASA needs to think about deflection

and not just about search and discovery?

A9. I interpret this question to mean not ‘‘why NASA?’’ but rather ‘‘why does deflection and not just search and discovery need to be thought about now?’’

The answer is that within the next 15 years, assuming that the Congressional 140

meter goal is responsibly addressed, we will be adding hundreds of thousands of

NEOs to the existing database. Of this total approximately 150,000 of the NEOs discovered would, if they threaten an Earth impact, be equivalent to the Tunguska impact or larger and therefore be candidates for deflection. The remaining hundreds

of thousands would be small enough that the atmosphere would prevent serious

damage.

Working by similarity to the existing NEO database, of these 150,000 NEOs there

will likely be 4500 or more (∼3.2 percent of the total database) with a non-zero (i.e.,

some actual) probability of Earth impact within the next 100 years. Of these 4500,

if one or two percent are of comparable or greater concern than Apophis and 2004

VD17 in the current database (both mentioned in the NASA Report) then there will

be on the order of 45–90 NEOs of what might be called elevated concern by 2022.

Of these NEOs it is highly likely that several, if not many, will have potential impact dates which will challenge our readiness to respond, i.e., by 2022 we will have

dozens, and perhaps as many as 100 NEOs in our database which appear to be

threatening, and many of them will have uncomfortably short response times.

Knowing this to be the situation (and the numbers are clearly only approximate)

from both statistics and similarity to our actual experience to date, it would be irresponsible to wait until the completion of the survey program and only then begin

to develop a response plan. Were we to do that it would be immediately clear that

our response capability would be delayed by perhaps 10 years or more. The consequence of such a delay would be that for 10s of potential impact threats, which

we could have responded to if we had directed NASA to ‘‘think about deflection and

not just search and discovery’’ could not be prevented but only mitigated through

evacuation, etc.

Is it likely that any of these NEOs of elevated concern would actually impact? By

definition, elevated concern means that they would have an unusually high probability of impact. If this elevated impact probability averaged one in 1,000 than in

the example above the probability of any of them being an actual impact would be

∼4.5–9 percent. This, as in most things NEO, is a public policy/public safety call.

But given the relatively low cost of being prepared I believe that the public would

be justifiably outraged if they were asked to accept a five percent chance of an impact for 10 years which could have been prevented by thinking ahead and allocating

less than one half of one percent of the NASA budget to being prepared.

(161)

Appendix 2:

ADDITIONAL MATERIAL FOR THE RECORD

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NASA REBUTTAL TO REMARKS MADE BY MR. SCHWEICKART DURING THE NOVEMBER

8, 2007, HEARING REGARDING NEAR EARTH OBJECTS

The report on Near-Earth Objects NASA submitted to the Congress in March

2007 explicitly addressed a keyhole scenario on page 22, scenario A1. Figure 4 in

this report shows that in any case where a small momentum change is required to

deflect a threat, such as with a keyhole, the number of deflection options increases.

The NASA report does not agree with the characterization that ‘‘primary’’ and then

‘‘potentially secondary’’ deflections are required. Instead it finds that, more generally, a series of missions will most likely always be planned to ensure that a particular threat does not impact the Earth with acceptable certainty. The study team

also found that the options analyzed in the study would be a toolkit from which a

deflection campaign could be designed, depending on the specifics of the threat scenario. The NASA report does not characterize post-deflection keyholes as a ‘‘minefield.’’ The report found that the likelihood of diverting a threatening object by a

well-designed deflection mission into a keyhole to be very unlikely, and that even

in this unlikely occurrence, a follow-on mission would by design be ready to complete the deflection. The report also does not indicate that this secondary deflection,

if necessary, would necessarily be best performed by a slow push method.

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STATEMENT OF THE PLANETARY SOCIETY

IN SUPPORT OF PLANETARY RADAR

AT THE ARECIBO OBSERVATORY

PROTECTING THE EARTH

Less than a century ago, a near-Earth object (NEO) slammed into Siberia, devastating 1,000 square miles. If it had struck just a few hours earlier or later in a

populated area, it could have killed several hundred thousand people. NEOs pose

a real and dangerous threat to Earth.

In the past few years, we have been discovering, tracking, and characterizing the

comets and asteroids that travel through our neighborhood of space. We have

learned much—about near-misses, the probability of collisions, the diversity of asteroid and comet physical properties, and the effects of impacts in the past. We have

even learned that one asteroid, named Apophis, will pass closer to Earth in 22 years

than our geosynchronous communications satellites, and its trajectory has a small

probability of taking it on a collision course with Earth seven years after that.

Radar tracking is the only way to precisely know the probability of impact, and

the Arecibo telescope is the most powerful instrument for the job, 20 times more

sensitive for NEO radar tracking than any other instrument in the world. Unfortunately, Arecibo is slated to be closed by the National Science Foundation in a misguided attempt to free up funding for new projects that do not yet exist.

Arecibo is the largest radio-telescope in the world. It has been, and continues to

be, an enormously productive scientific facility, covering a broad range of science

studies. While its contributions to radio astronomy, ionospheric and atmospheric observations have proven valuable for the past several decades, it is its planetary

radar capabilities that remain unique. Because of Arecibo’s powerful one-million

watt transmitter, and the large 1,000-foot aperture, the telescope is uniquely able

to characterize potentially hazardous NEOs and determine the danger they pose.

Radar signals from this facility are the only ones that can be regularly used for

reaching and tracking NEOs that may be coming close to Earth.

The cost of operating Arecibo is just a few million dollars per year. Isn’t the safety

of Earth worth that?

In addition to tracking NEOs, Arecibo has returned other recent important results

from planetary radar, including the best physical characterization of any potentially

hazardous asteroid as large as a kilometer, ultra precise determinations of

Mercury’s spin state that reveal that planet to have a molten core, and the identification of several binary asteroids in the near-Earth population.

Arecibo is caught in a bureaucratic argument. The Arecibo Observatory is a National Science Foundation (NSF) operation, but they consider the subject of NEOs

and planetary radar to be in NASA’s bailiwick. NASA supports ground-based astronomy, and supported the Arecibo radar for many years, but the agency now objects to picking up the funding of what is currently an NSF program.

The House Science and Technology Committee has been the leading government

advocate for understanding the nature and possible threat from objects (NEOs) that

might impact the Earth. In the past, the Committee has had to direct NASA to provide increased support to this area. The Planetary Society has no position on whether this should be a NSF program or a NASA program; but, we strongly feel that

it should be an American program with congressional support. We urge you to provide such support to keep the Arecibo planetary radar operating.

The Planetary Society recently conducted a privately funded, international competition to design a mission to tag the asteroid Apophis, in case its Earth approach

is close enough to require higher accuracy tracking. The competition attracted thirty-seven proposals and has generated much public interest.

The cost of a tagging mission to Apophis would be at least $100 million—and the

only way to know if such a mission is necessary is to refine the current estimate

of Apophis’ orbit with the powerful radar tracking of a telescope like Arecibo. Avoiding one unnecessary tagging mission would more than pay back any investment of

funds to keep Arecibo open. And if some object out there really is on a collision

course with Earth and we don’t have the means to track it properly, the price we

would pay would be astronomical.

Thank you for your consideration.

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