NASA/TM–2009–214182

The Astrophysics Science Division Annual Report 2008

William Oegerle and Francis Reddy, Editors

Pat Tyler, Graphical Editor

March 2009
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NASA/TM-2009-214182

The Astrophysics Science Division Annual Report 2008

William Oegerle

NASA Goddard Space Flight Center, Greenbelt, Maryland

Francis Reddy

SP Systems, Inc., Greenbelt, Maryland

Pat Tyler, Graphical Editor

SP Systems, Inc., Greenbelt, Maryland

March 2009

National Aeronautics and 

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iii

Astrophysics Science Division: Research and Missions

Contents

Introduction....................................................................................................................................1

I. 2008: Year in Review...............................................................................................................3

II. Awards.....................................................................................................................................5

III. Research .................................................................................................................................7

Gravitational Radiation from Merging Black Holes ............................................................7

Pulsar High Energy Emission ...........................................................................................8

Lab Astrophysics: High Energy Laboratory Astrophysics Using an X-Ray 

Microcalorimeter with an Electron Beam Ion Trap.............................................................9

Lab Astrophysics: Optical Properties of Astronomical Silicates 

with Infrared Techniques (OPASI-T) ................................................................................11

Atomic Data for X-ray Astrophysics .................................................................................12

The Swift BAT AGN Survey .............................................................................................13

Studies of Galaxies, Including Groups and Clusters .......................................................14

Determination of the Cosmic Near-Infrared Background 

Through Studies of the Zodiacal Cloud ...........................................................................16

The Infrared and X-ray Evolution of SNR 1987A: 

Analysis of the Supernova Blast Wave Interaction with the Surrounding Medium ..........17

WMAP Five-Year Results ................................................................................................18

Results from ARCADE.....................................................................................................20

Jets in Young Stars..........................................................................................................21

Numerical Modeling of Planet-Disk Interactions..............................................................22

Keck Interferometer Nuller Observations of Circumstellar Material.................................23

Resolved Observations of Debris Disks ..........................................................................24

IV. Research and Development ..................................................................................................27

Suborbital Projects ................................................................................................................27

Balloon-borne Experiment with a Superconducting Spectrometer (BESS).....................27

Super Trans-Iron Galactic Element Recorder (Super-TIGER).........................................28

Cosmic Ray Energetics and Mass (CREAM) ..................................................................29

InFOCuS (International Focusing Optics Collaboration for μCrab Sensitivity) ................30

X-ray Quantum Calorimeter (XQC) and Micro-X .............................................................31

Proto-EXIST.....................................................................................................................32

Gamma-Ray Burst Polarimeter........................................................................................33

X-ray Advanced Concepts Testbed (XACT).....................................................................34

Absolute Radiometer for Cosmology, Astrophysics, and Diffuse Emission (ARCADE)...35

Primordial Inflation Polarization Explorer ........................................................................36

Absolute Color Calibration Experiment for Standard Stars (ACCESS) ...........................36

Technology Development ......................................................................................................37

X-ray Calorimeter Development ......................................................................................37

X-ray Mirror Development: IXO and NuSTAR .................................................................39

GSFC 600-meter X-ray Beamline....................................................................................41

Laboratory Development of X-ray Polarimetry.................................................................41

Coded-Mask and CdZnTe Detector Development ..........................................................42

Detectors for Gamma Ray and Neutron Imaging ............................................................42

Phase Fresnel Lens Development for X-ray & Gamma-ray Astronomy ..........................43

Far-Infrared Detectors .....................................................................................................44

Large-format Bolometer Arrays for Astronomy and Cosmology ......................................45

Variable-delay Polarization Modulators for Exploring Inflation.........................................47
Astrophysics Science Division: Research and Missions

iv

MKID Detectors for Submillimeter Astronomy .................................................................48

Photon Counter Detector Development...........................................................................49

Fizeau Interferometry & Synthetic Imaging Formation Flying Testbeds (FIT/SIFFT).......49

Wide-field Imaging Interferometry Testbed......................................................................50

LISA Testbed: Stabilized Platform Interferometer for LISA Testing..................................51

V. Projects..................................................................................................................................53

Projects in Operation .............................................................................................................53

The Fermi Gamma-ray Space Telescope........................................................................53

WMAP Operations and Status.........................................................................................54

The Rossi X-ray Timing Explorer.....................................................................................55

XMM-Newton Guest Observer Facility ............................................................................56

Swift.................................................................................................................................57

Suzaku (Astro-E2) ..........................................................................................................57

INTEGRAL ......................................................................................................................58

Hubble Space Telescope: SM4 and Wide Field Camera 3..............................................59

The Galaxy Evolution Explorer .......................................................................................61

James Webb Space Telescope .......................................................................................63

Joint Dark Energy Mission (JDEM)..................................................................................65

Astro-H.............................................................................................................................66

SOFIA/SAFIRE................................................................................................................67

Gravity and Extreme Magnetism SMEX (GEMS) ...........................................................68

Mission Concepts ..................................................................................................................69

Absolute Spectrum Polarimeter (ASP) ............................................................................69

International X-ray Observatory (IXO) .............................................................................70

Laser Interferometer Space Antenna (LISA)....................................................................70

Extrasolar Planetary Imaging Coronagraph (EPIC).........................................................71

The Fourier-Kelvin Stellar Interferometer (FKSI) ............................................................73

Terrestrial Planet Finder/Galaxy Evolution Surveyor .......................................................74

Advanced Technology Large Aperture Space Telescope (ATLAST)................................75

Energetic X-ray Imaging Survey Telescope (EXIST).......................................................76

The Space Infrared Interferometric Telescope (SPIRIT)..................................................77

SAFIR Observatory..........................................................................................................78

High Energy Astrophysics Science Archival Research Center (HEASARC) ...................79

Gamma-ray burst Coordinates Network ...............................................................................80

VI. Education and Public Outreach in NASA’s Astrophysics Science Division............................81
1

Astrophysics Science Division: Research and Missions

Introduction

The Astrophysics Science Division (ASD) at Goddard Space Flight Center (GSFC) is one of the largest and 

most diverse astrophysical organizations in the world, with activities spanning a broad range of topics in theory, 

observation, and mission and technology development. Scientific research is carried out over the entire electromagnetic spectrum—from gamma rays to radio wavelengths—as well as particle physics and gravitational radiation. Members of ASD also provide the scientific operations for three orbiting astrophysics missions—WMAP, 

RXTE, and Swift, as well as the Science Support Center for the Fermi Gamma-ray Space Telescope. A number 

of key technologies for future missions are also under development in the Division, including X-ray mirrors, and 

new detectors operating at gamma-ray, X-ray, ultraviolet, infrared, and radio wavelengths.

ASD has a strong suborbital research program, with four balloon programs and three sounding rocket programs at present. The Division also supports research in the astronomical community through the High Energy Astrophysics Science Archive Research Center (HEASARC), which now also contains Cosmic Microwave 

Background data, as well as support services for observers using the Fermi, Suzaku, Integral, XMM-Newton, 

GALEX, RXTE, WMAP, and Swift missions. Finally, ASD has a strong Education and Public Outreach program, to convey the exciting discoveries from NASA missions to school teachers, students, and the public.

ASD staff includes 365 people, most of whom are scientists and engineers, along with a support staff of software 

programmers, resource analysts, and administrative personnel. There are about 80 civil servant scientists, and a 

much larger number of contractor and university-based scientists. Several dozen postdoctoral fellows and graduate students are also in residence. 

Organizationally, ASD comprises five laboratories: the Astroparticle Physics Lab (code 661; Neil Gehrels, chief); 

the X-ray Astrophysics Lab (662; Rob Petre, chief); the Gravitational Astrophysics Lab (663; Joan Centrella, 

chief); the Observational Cosmology Lab (665; Jonathan Gardner, chief); and the Exoplanets and Stellar Astrophysics Lab (667; Jennifer Wiseman, chief). Alan Smale heads the High Energy Astrophysics Science Archive 

& Research Center (HEASARC) Office, Phil Newman heads the Office of Scientific Computing, and Felicia 

Jones-Selden leads the Instrument Development Group. Division management includes William Oegerle (Director), Felicia Jones-Selden (Deputy), Curtis Odell (Assistant), Kim Weaver (Associate for Science) and Harley 

Thronson (Associate for Advanced Concepts). 

The overriding goals of ASD are to carry out cutting-edge scientific research, provide Project Scientist support 

for spaceflight missions, implement the goals of the NASA Strategic Plan, serve and support the astronomical 

community, and enable future missions by conceiving new concepts and inventing new technologies. 

William Oegerle

Director, Astrophysics Science Division

NASA Goddard Space Flight Center
Astrophysics Science Division: Research and Missions

2
3

Astrophysics Science Division: Research and Missions

I. 2008: Year in Review

The past year has been an eventful one for the ASD. 

Summarizing all of the noteworthy events during the 

year is a daunting task, much like describing the tip 

of an iceberg. There is much, much more below the 

surface, and the remainder of this document provides 

a broader and deeper view into ASD’s activities. However, even this whole document only describes a portion of the Division’s work. With that caveat in mind, 

here is 2008 in review.

The year began with a bang as the BESS-Polar II Antarctic balloon flight completed a successful 24.5-day 

flight, collecting an enormous amount of data on the 

spectra of cosmic-ray anti-protons. The data is still being analyzed and we look forward to the results soon. 

At the same time, the CREAM balloon payload (coinvestigators Barbier, Mitchell) was also in flight above 

the Antarctic. Its goal is to measure the high-energy 

cosmic-ray spectrum. 

While BESS was circumnavigating the South Pole, 

Neil Gehrels was delivering his Rossi Prize lecture 

“Gamma-ray Burst Discoveries with the Swift Mission” at the 211th AAS meeting in Austin, Texas, on 

behalf of the Swift team and himself (joint winners). It 

was a banner year for Neil, as he was inducted into the 

American Academy of Arts & Sciences in the Spring of 

2008, and then was awarded the Henry Draper medal 

by the National Academy of Sciences in early 2009. 

Other significant awards during the year include the 

Lindsay Award to John Baker and Joan Centrella for 

their work on the modeling of black hole mergers and 

the subsequent gravitational wave signatures, and the 

AAS Weber Prize to Pete Serlemitsos for his achievements in inventing new instrumentation for X-ray astronomy. 

Also in January 2008, the ASD team of Barry, Danchi 

and Kuchner announced the first results from the 

Keck Observatory Nulling instrument. As one of the 

first teams selected for Shared Risk science, they were 

observing at the Keck Observatory when the recurrent 

nova RS Oph erupted. The nuller observations provided interesting information on the evolution of the 

nova (described further in the Research section).

In Spring 2008, the X-ray Quantum Calorimeter 

(XQC) payload had a successful sounding rocket flight 

from White Sands, as described by Porter elsewhere 

here. This payload employs X-ray microcalorimeters 

developed at GSFC to study the diffuse soft-X-ray sky. 

This is a joint program with the University of Wisconsin (McCammon, PI; Porter, GSFC lead co-I).

The NASA Senior Review of Operating Missions was 

released in April 2008, with a few pleasant and also 

unpleasant surprises. ASD is involved in 7 out of the 

10 missions reviewed. On the pleasant side, Swift was 

rated the #1 mission in terms of science per dollar 

(the metric used), ahead of flagship mission Chandra, 

and was recommended for a funding augmentation. 

Also, the Suzaku mission was rated #4 (behind Swift, 

Chandra and GALEX). ASD provided mirrors for the 

Suzaku telescope, a soft-X-ray spectrometer (not currently operating), and runs the U.S. Guest Investigator program and distributes Suzaku data to the U.S. 

through the HEASARC archive. With budgets tight, 

it was recommended that US Guest Observer programs be eliminated for XMM and Integral by FY10, 

News about ASD missions and scientists frequently reach the public. On average, the division 

issues about between two and three releases and/or 

Web portal features each month. 

In 2008, three stories merited NASA media teleconferences: the Hubble Space Telescope’s first-ever 

visible-light observation of a planet around the nearby star Fomalhaut; the first all-sky image from the 

newly launched Fermi Gamma-ray Space Telescope: 

and the study of a gamma-ray burst so bright it could 

have been seen with the unaided eye — even though 

it occurred more than 7 billion light-years away. 

Other stories receiving significant media coverage 

include:

•	 Fermi’s discovery of gamma-ray-only 

pulsars;

•	 From Swift, the discovery of an X-ray 

pulse that signaled the first moments of a 

supernova explosion, as well as the detection 

of the farthest-known gamma-ray burst 

(12.8 billion light-years away);

•	 And a mysterious extragalactic radio 

background uncovered by a balloon-borne 

experiment named ARCADE. 
Astrophysics Science Division: Research and Missions

4

and that RXTE operations cease in February 2009. 

XMM and Integral are ESA missions and will continue to operate, and they will be reconsidered at the 

next Senior Review, where U.S. funding could potentially be restored. RXTE will continue to operate on a 

shoestring until it can also be reviewed again in FY10. 

In June, the results of the Senior Review of NASA Archives were announced, and HEASARC ranked second place, in a tie with MAST and NED and behind 

the very cost-effective ADS. Full in-guide funding was 

recommended for HEASARC.

On June 11, 2008, the Gamma Ray Large Area 

Space Telescope (GLAST) was successfully launched 

from the Cape, and renamed the Fermi Gamma-ray 

Space Telescope. A number of ASD scientists were 

deeply involved in the development of the Large Area 

Telescope (LAT) and its Anti-Coincidence Detector 

(ACD). The ACD was built at GSFC. After launch, 

GSFC also provides the Science Support Center for 

Fermi. Hats off to Steve Ritz (Fermi Project Scientist), 

Julie McEnery (Deputy), Neil Gehrels (Deputy), 

Alex Moiseev and Dave Thompson (ACD), Jerry 

Bonnell, David Band, Robin Corbet, Dave Davis, 

Masa Hirayama, and Bob Hartman (now Emeritus). 

The observatory is operating extremely well, and there 

were a number of early science results presented at the 

January 2009 AAS meeting, including the discovery a 

new class of pulsars that are only observable in gammarays. The Fermi collaboration released its LAT Bright 

Source List the first week of February 2009. This is 

the first public release of new sources detected by the 

observatory.

In Spring 2008, we received the good news that one 

of our Small Explorer (SMEX) proposals, the “Gravity and Extreme Magnetism SMEX” (GEMS), was 

selected for a Phase A study. GEMS is a mission dedicated to the study of black holes and other energetic 

phenomena through X-ray polarization, and is described in further detail later in this document. The 

Phase A report was submitted in December 2008, and 

a site visit is scheduled for April 2009, with selection 

a month or two later. If selected, this mission would 

open up a new research area in X-ray astrophysics. The 

Soft X-ray Spectrometer (SXS; Rich Kelley, PI) was 

also selected as a Mission of Opportunity instrument 

to fly on JAXA’s Astro-H mission in 2013. This spectrometer uses a microcalorimeter with a resolution of 

about 1000 (4 eV), and was developed at GSFC. 

The James Webb Space Telescope (JWST) was confirmed in July 2008 to enter into Phase C (the construction phase). This milestone was achieved after 

more than a decade of work by many folks at Goddard, 

including our JWST Project Scientists: John Mather, 

Jon Gardner, Mark Clampin, Matt Greenhouse, Bernie Rauscher, Chuck Bowers and George Sonneborn. 

Harvey Moseley is the PI for the microshutters, which 

will be delivered to ESA in Spring 2009, to provide a 

multi-object spectrograph capability for the NIRSpec 

instrument.

In Fall 2008, NASA HQ announced that the Joint 

Dark Energy Mission (JDEM) would not be competed. Instead, a JDEM Project Office was established at 

GSFC with the role of leading the mission development, in concert with DOE. JDEM science teams will 

be solicited through an Announcement of Opportunity in Spring 2009. A Science Coordination Group 

(chaired by Neil Gehrels) was formed, largely from the 

original JDEM concept study teams, and was tasked 

with working with the GSFC Project office to agree 

on a Reference Mission design. Several ASD scientists 

(Moseley, Hinshaw, Benford) are deeply involved in 

these activities. 

The phrase “All good things come to those who wait” 

was surely penned for the team waiting to carry out Servicing Mission 4 (SM4) on Hubble Space Telescope. 

SM4 was cancelled after the Columbia orbiter failure 

in 2003, and was resurrected by NASA Administrator 

Griffin in 2006. After a delay to Fall 2008, SM4 was 

once again delayed by an onboard failure of the Science Data Formatter only weeks before the mission. 

With SM4 launch now slated for May 12, 2009, we 

look forward to finally installing Wide Field Camera 3 

(Randy Kimble, lead NASA instrument scientist), the 

Cosmic Origins Spectrograph and the repair of STIS 

(Woodgate, PI) and ACS instruments. 

In 2009, we look forward to supporting the National 

Academy’s Astro2010 Decadal Survey of Astronomy 

& Astrophysics, successful completion of HST/SM4, 

selection of the next Small Explorer, continuing development for of instruments and hardware for NuStar, 

Asto-H and SOFIA, support of JDEM, and the initial 

flight of the Proto-EXIST (balloon).
5

Astrophysics Science Division: Research and Missions

II. Awards

In the last few years, a number of scientists in the Astrophysics Science Division (ASD) were singled out for 

extraordinary contributions to their respective fields. 

The most prestigious honor bestowed on an ASD scientist is 

the 2006 Nobel Prize for Physics, which was awarded jointly 

to Goddard’s John Mather and 

George Smoot of the University of California “for their discovery of the blackbody form 

and anisotropy of the cosmic 

microwave background radiation” using NASA’s Cosmic 

Background Explorer (COBE) 

satellite, which launched in 

1989. Mather joined Goddard as Project Scientist for 

the COBE mission, and his Nobel medal is now on 

display in the Building 8 lobby. He currently serves 

as Senior Project Scientist for the James Webb Space 

Telescope and is a Senior Astrophysicist in ASD’s Observational Cosmology Laboratory. 

In January 2009, two ASD 

scientists were recognized. 

Peter Serlemitsos of the X-ray 

Astrophysics Laboratory was 

awarded the American Astronomical Society’s Joseph Weber Award for Astronomical 

Instrumentation. The award 

recognizes the design, invention or significant improvement of instrumentation leading to advances in astronomy. The contributions of 

Serlemitsos led to major advances in both X-ray optics 

and multiwire proportional counters. These advances 

enabled many ground-breaking missions, including 

OSO-8, HEAO-1, RXTE, BBXRT, ASCA, Suzaku, as 

well as the upcoming Astro-H 

mission. 

In the same month, Neil Gehrels, who heads the Astroparticle Physics Laboratory, was 

awarded the 2009 Henry 

Draper medal by the National 

Academy of Sciences. The citation reads: “For his pioneering 

contributions to gamma-ray 

astronomy. His leadership of the Compton Gamma 

Ray Observatory and the Swift Mission has led to new 

insights into the extreme physics of active galactic nuclei and gamma ray bursts.” The National Academy 

of Science only presents this award every four years. 

In 2005, the Academy recognized Charles Bennett, 

another Goddard scientist, for his leadership of the 

WMAP mission. So, Goddard scientists have been 

awarded the last two Draper medals.

In March 2008, the 228th Class of Fellows of the 

American Academy of Arts and Science included 

Gehrels. The American Academy, founded in 1780 by 

John Adams, honors distinguished scientists and leaders in public affairs, business, administration, and the 

arts. Gehrels was inducted into the same class as filmmakers Joel and Ethan Coen, artist Richard Tuttle, 

soprano Dawn Upshaw and 

blues legend B. B. King. 

Last May, Joan Centrella, 

chief of the Gravitational Astrophysics Laboratory, and 

John Baker, an astrophysicist 

with the Numerical Relativistic Astrophysics Group, shared 

the John C. Lindsay Memorial Award for Space Science. 

Their groundbreaking computer simulations show what 

happens when two supermassive black holes collide and 

merge. This award recognizes 

the Goddard employee who 

best exhibits broad scientific 

accomplishments in the area 

of space science. 

Since 2006, ASD scientists have been 

recognized with numerous honors, 

including a Nobel Prize in Physics.

John Mather

Peter Serlemitsos

Neil Gehrels

Joan Centrella

John Baker
Astrophysics Science Division: Research and Missions

6

In 2007, Gehrels and the team for NASA’s Swift satellite were awarded the Bruno Rossi Prize from the 

American Astronomical Society (AAS). This annual 

award given by the AAS High Energy Astrophysics 

Division recognizes significant contributions in highenergy astrophysics. 

Later that year, the AAS awarded Harvey Moseley the Joseph 

Weber Award for instrumentation in recognition of his 

extraordinary contributions—

spanning two decades—to the 

development of astronomical 

detectors covering wavelengths 

from X-rays to the submillimeter. These detectors have 

been used in some of NASA’s 

most successful space missions, from the Cosmic 

Background Explorer (COBE) to the infrared space 

observatory Spitzer, that have profoundly changed our 

understanding of the universe. Moseley continues to 

focus his creative energies on the development of the 

microshutter array, a micromechanical device which 

will allow the James Webb Space Telescope to make its 

most critical observations 100 times faster.

Also in 2007, Ann Hornschemeier won the AAS Annie 

Jump Cannon Award. 

The Cannon Prize is for outstanding research and promise 

for future research by a postdoctoral woman researcher in 

North America.

In 2006, ASD’s Tod Strohmayer shared with AAS Rossi 

Prize with MIT’s Deepto 

Chakrabarty and Rudy Wijnands of the University of 

Amsterdam. Their work, done 

both independently and sometimes as collaborators, has been 

described as breakthrough 

in interpreting the complex 

signals emitted as X-ray light 

from millisecond pulsars. 

Harvey Moseley

Ann Hornschemeier

Tod Strohmayer

On the Web

ASD press archive

astrophysics.gsfc.nasa.gov/press/
7

Astrophysics Science Division: Research and Missions

III. Research

A few representative research programs in ASD are 

described below

Gravitational Radiation from Merging Black 

Holes

The numerical relativistic astrophysics group of the 

ASD Gravitational Astrophysics Laboratory continues 

numerical simulation studies of merging binary black 

hole systems. They are predicted to be among the 

most energetic astronomical events, releasing energy 

as much as 1055 erg/s in the form of gravitational radiation. Consequently these are among the key target 

sources for gravitational wave observation. Mergers of 

stellar-scale systems occur in the sensitivity band of 

ground-based observatories such as the Laser Interferometer Gravitational Wave Observatory (LIGO). 

The Laser Interferometer Space Antenna (LISA) will 

be sensitive to mergers of massive black hole systems 

ranging from roughly 10 thousand to 10 million solar 

masses at cosmological distances (to z ~ 10 and beyond). These observations form the basis for many of 

LISA’s science goals.

Einstein’s theory of General Relativity (GR) allows 

clear predictions for the physics of these mergers, but 

a full theoretical understanding of these energetic 

events and the gravitational-wave signals they produce 

requires detailed supercomputer simulations integrating the equations of GR. Following major advances in 

the basic techniques for these simulations in 2005–6, 

recent work at Goddard has included numerical studies of a variety of configurations of comparable-mass 

binary systems. 

Several of these studies have focused on providing a 

detailed characterization of the gravitational waveform 

signals generated in binary black hole mergers. These 

studies first focused on developing a thorough understanding of the gravitational-wave radiation generated by mergers of non-spinning black hole systems. 

In collaboration with researchers and the University 

of Maryland, the Goddard team (Baker, Centrella, 

Kelly, McWilliams, Thorpe, van Meter) developed an 

analytic representation of the waveforms that is consistent with the post-Newtonian approximation that 

applies before GR-effects become too strong, but also 

provides a close approximation to the numerical results describing the strong radiation generated in the 

final moments of merger. Currently, the team is working toward a thorough description of a simple class of 

spinning black hole systems, as well as an extension of 

the analytic waveform model to describe this broader 

class of systems.

The description of the merger radiation provided by 

these numerical simulations, while still incomplete, 

will provide a basis for drawing stronger inferences 

from gravitational wave observations. Researchers at 

Goddard are currently investigating how the merger 

signal predictions will enhance the precision with 

Gravitational energy produced in when binary 

black holes collide can impart a kick to the 

merged remnant when the radiation is emitted 

asymmetrically. Simulations suggest that these large 

kicks could have a dramatic impact on the relation 

between a merged massive black hole and its host 

galaxy. Credit: NASA

The description of the merger radiation 

provided by these numerical simulations 

will provide a basis for drawing stronger 

inferences from gravitational wave 

observations.
Astrophysics Science Division: Research and Missions

8

the accelerating field at low altitude along most field 

lines. But the decrease in the parallel electric field near 

the open-field boundary (which is assumed to be fully 

conducting) prevents pair production in a narrow slot 

gap, thereby screening the electric field there. Particles 

therefore can accelerate and radiate at high altitudes. 

The combination of relativistic aberration and traveltime delays causes all their radiation along the trailing 

side of the gap to arrive in phase as seen by a nonrotating observer, which forms caustics in the emission pattern. If the observer light-of-sight crosses the 

caustics from both poles, two sharp peaks are seen in 

the light curve. The model produces light curves very 

much like the ones seen from gamma-ray pulsars. 

As pulsars age, the slot gap becomes progressively 

wider, eventually filling the entire open-field region 

and accelerating particles over a large fraction of the 

magnetosphere. As slot gaps disappear in older pulsars—many being “recycled” millisecond pulsars, 

their gamma-ray efficiency increases to 10 percent or 

more of their spin-down power. Using this model, our 

population synthesis studies have predicted that Fermi 

will detect around 150 normal pulsars, with about half 

of these being radio-loud, and detect about 50 millisecond pulsars, about 12 being radio-loud.

In the six months since its launch (four in nominal sky 

survey), Fermi has so far discovered gamma-ray pulsations from 18 radio-loud pulsars (including 7 millisecond pulsars) and 14 radio-quiet pulsars. Including 

Fermi detections of previously known EGRET pulsars 

brings the total to more than three dozen. 

The large number of photons detected from the bright 

Vela pulsar has enabled Fermi to rule out a superexponential, high-energy cutoff of its spectrum that 

we predicted would be a consequence of near-surface 

pair cascades, thus placing the emission site in the 

which astronomers will be able to estimate the parameters of merging systems, including sky position and 

distance, with careful analysis of LISA data.

The large amount of gravitational energy produced in 

these mergers can lead to a significant back-reaction 

force on the remnant black hole when the radiation is 

emitted asymmetrically. Numerical relativity simulations indicated that this “kick” imparted to the merged 

black hole can be larger than 2,000 km/s in particular 

cases. Such large kicks would have a dramatic impact 

on the relation between a merged massive black hole 

and its host galaxy or proto-galaxy, impacting astronomical expectation beyond gravitational waves. The 

Goddard team continues to study these kicks with attention to the dependence of the kick on the binary 

parameters, particularly the ratio of the two black 

holes’ masses. These results will impact the likelihood 

of large kicks in generic merging systems.

It is not yet clear what potentially observable effects 

the strong dynamical gravity of these merging systems 

could have on any surrounding gas or other matter. 

The Goddard team has begun investigations tracing 

the trajectories of particles in the vicinity of the merging black holes, with plans for including more realistic 

models of possible surrounding gas, as warranted by 

ongoing preliminary investigations. 

Pulsar High Energy Emission 

Modeling and understanding the high-energy pulsed 

emission from rotation-powered pulsars—and, more 

recently, magnetars—has been a major endeavor for 

the last 25 years. In the last several years, Alice Harding and her collaborators have focused on predictions 

of gamma-ray light curves and phase-resolved spectra, 

as well as population statistics, for different emission 

models in preparation for the new pulsar discoveries 

by the Fermi Gamma-ray Space Telescope. In particular, we have been exploring a model for high-energy 

emission known as the “slot gap,” where particles are 

accelerated and radiate from the neutron star surface 

to near the pulsar’s light cylinder along the edge of the 

open magnetic field region. 

The slot gap model is a consequence of the electronpositron pair cascades that take place near the pulsar 

polar caps, which we have been studying since the early 1980s. In young pulsars, such pair cascades screen 

Our studies have predicted that Fermi 

will detect around 150 normal pulsars, 

with about half of these being radio-loud, 

and detect about 50 millisecond pulsars, 

about 12 being radio-loud.
9

Astrophysics Science Division: Research and Missions

radio pulse, for the whole population using the slot 

gap and alternative outer-gap models to compare with 

those of Fermi pulsars. We believe that, with the large 

number of Fermi pulsars detected over many decades 

in age and spin-down power, we will be able to finally 

map the geometry of particle acceleration in pulsar 

magnetospheres.

Lab Astrophysics: High Energy 

Laboratory Astrophysics Using an X-Ray 

Microcalorimeter with an Electron Beam 

Ion Trap

Our laboratory astrophysics program is designed to 

simulate astrophysical plasmas in the laboratory in order to benchmark and provide guidance to the atomic codes that form the basis of the spectral synthesis 

models used in X-ray astrophysics. These models are 

used to relate spectra observed from an astrophysical 

object to conditions in the source, including temperature, ionization-equilibrium, composition, density, 

turbulence and bulk motion. This work is fundamentally important as X-ray astrophysics begins to use 

high-resolution spectroscopy as the dominant tool in 

exploring the physics of X-ray emitting objects. 

This has already started with the observation of bright 

point sources with the high-resolution dispersive spectrometers on Chandra and XMM/Newton. It will become critically important with the upcoming Astro-H 

and International X-ray Observatories, where every 

observation will produce a detailed, high-spectralresolution image. Our program is designed to demonstrate and correct the accuracy of the spectral synthesis 

models in controlled ground-based experiments that 

will give us confidence that we have correctly ascribed 

observed spectral features to known conditions in the 

astrophysical source.

outer magnetosphere. We are currently modeling the 

expected light curves of both individual sources and 

the distributions of light curve characteristics, such 

as gamma-ray peak separation and phase lag with the 

These graphs illustrate the success of the slot gap 

model in explaining gamma-ray emission from the 

Crab pulsar. Top left: Model light curve for photon 

energies greater than 100 MeV and an observer 

angle of 100 degrees. Bottom left: Sky intensity 

map (observer angle vs. rotational phase). Top 

right: Model phase-averaged spectrum showing pair 

synchrotron (dashed), primary electron synchrotron 

(dot-dashed) and primary electron curvature (solid) 

radiation components.

This system has produced well over two 

dozen peer-reviewed articles, and it has 

made critical measurements of absolute 

cross sections in L-shell Fe and Ni, as well 

as charge-exchange measurements in S, C, 

O, and Fe.
Astrophysics Science Division: Research and Missions

10

continuously for the past 8.5 years. It has produced 

well over two dozen peer-reviewed articles, and it has 

made critical measurements of absolute cross sections 

in L-shell Fe and Ni, as well as charge-exchange measurements in S, C, O, and Fe. Many investigations are 

on going.

GSFC first installed an X-ray calorimeter instrument 

at the LLNL EBIT facility in the summer of 2000, 

based on the engineering-model detector system for 

the Astro-E observatory. The system was significantly 

upgraded using technology developed for Astro-E2 in 

2003. A dedicated facility-class instrument designed 

from the ground up for laboratory astrophysics was 

installed in 2007. The current instrument, dubbed 

the EBIT Calorimeter Spectrometer (ECS), utilizes a 

32-channel X-ray calorimeter array from the Astro-E2 

program installed in a long-lifetime, automated laboratory cryostat that enables continuous experiments 

for up to 70 hours with a two-hour recharge. The detector array is populated with 16 mid-band (0.05-12 

keV) X-ray absorbers with 4.5 eV FWHM resolution 

at 6 keV, and 16 high-band (0.1-100 keV) X-ray absorbers with 30 eV FWHM at 60 keV. 

We are currently designing and constructing the 

fourth-generation instrument that will be based on 

detector technology from the IXO development program. It will be installed in a completely automated 

cryogen-free cryostat. The fourth-generation instrument is dubbed the Transition-Edge Microcalorimeter Spectrometer (TEMS) and will be composed of 

The basis of our program is a high-resolution, nondispersive, X-ray calorimeter spectrometer, a suite of 

very-high-resolution dispersive spectrometers, and the 

Electron Beam Ion Trap (EBIT) plasma generator at 

the Lawrence Livermore National Laboratory (LLNL). 

Other collaborating institutions include Stanford University and the National Institute of Standards and 

Technology. The LLNL EBIT can produce nearly any 

plasma conditions from low charge states in light elements to bare uranium with electron beam energies of 

up to 200 keV. Nearly any charge state of any astrophysically interesting element can be produced, either 

as a pure charge state or in a Maxwellian distribution 

at known temperature. 

Non-equilibrium ionization conditions can also be 

produced with almost any astrophysically interesting 

ionization parameter. Typical measurements in our 

program include spectral-line identification, absolute 

cross sections, recombination, charge-exchange recombination, and cross sections in thermal and nonthermal distributions. Measurements are related back 

to theory, the results of atomic calculations, and to the 

standard X-ray spectral synthesis models used in X-ray 

astrophysics. 

A key instrument in these measurements is a broadband, high-resolution X-ray calorimeter instrument 

provided by GSFC beginning in 2000 and now on its 

third revision. This system has been operated almost 

The ECS x-ray calorimeter instrument installed 

at the Electron Beam Ion Trap Facility at LLNL. 

Credit: NASA/LLNL

A spectrum of He and H-like Xe taken with the 

ECS instrument at EBIT using the high-band 

calorimeters. Credit: NASA/LLNL
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Astrophysics Science Division: Research and Missions

a checkerboard hybrid of 128 low-band (0.05-1 keV) 

pixels with 0.8 eV resolution at 1 keV, and 128 midband (0.05-10 keV) pixels with 2.0 eV resolution at 6 

keV. In addition, there will be a 64 channel high-band 

array (0.1-200 keV) with 30 eV resolution at 60 keV. 

The TEMS instrument will become the workhorse 

instrument in our laboratory astrophysics program to 

make sure that our measurements and understanding 

of atomic processes are ready to interpret the spectra 

we will obtain with the Astro-H and IXO observatories. TEMS will be installed at the EBIT facility in 

2010.

Lab Astrophysics: Optical Properties 

of Astronomical Silicates with Infrared 

Techniques (OPASI-T)

Astronomical dust is ubiquitous. It has been found in 

our own solar system, around nearby stars with debris 

disks, in star-formation regions and even in far-distant 

galaxies. This dust shields sources from our view at optical wavelengths, reprocesses short-wavelength light 

to longer wavelengths, and provides an environment 

where planets can form and grow. 

The OPASI-T program is designed to directly address 

two major questions. What are the optical properties 

of dust grains in the far-infrared, and how do these 

properties vary as a function of wavelength, temperature and crystallinity.

Stephen Rinehart and collaborators will conduct a 

series of laboratory experiments designed to answer 

these questions. Extinction due to silicate grains in the 

far-infrared (FIR) will be measured in a Fourier Transform Spectrometer (FTS), with supporting data at 

millimeter wavelengths provided by measurements in 

a waveguide. We will also measure the emission from 

these materials in the mid- to far-infrared using three 

complimentary experimental setups; a radiometric 

system, a thermal emission system, and a calorimetric 

emittance test. The optical properties of silicates will 

be measured over a wide range of temperatures, and 

magnesium-rich silicates will be tested in aggregate 

and crystalline form. We will employ these data to determine complex dielectric constants for the materials 

and predict spectral signatures that are present in astronomical objects.

The data obtained through the 

OPASI-T program is critical for 

interpretation of astronomical spectra 

obtained at long wavelengths.

In astronomical environments, silicate dust typically forms from the gas phase (d) into a highly chaotic 

condensate (c). Through annealing, the condensate can turn into a more ordered melt (or glass) containing 

some individual crystalline structures (b). Such annealing can occur, for instance, in the hot environment 

surrounding young stars. On Earth, silicates are often found in pure crystalline form (a), usually in metamorphic 

rock. Much laboratory work done to date has focused on analysis of such minerals, despite the fact that the 

high pressures needed to produce these highly ordered states does not exist in astronomical environments. 

Credit: NASA/OPASI-T.
Astrophysics Science Division: Research and Missions

12

Why do we see only outflow from objects which must 

be driven by inflow (accretion)? Does the outflow 

feed back its energy and gas to the host galaxy, thereby somehow coupling the accretion flow close to the 

black hole with the surroundings on a larger scale?

For the past six years, Kallman and colleagues have 

carried out a campaign to study warm absorbers and 

related X-ray spectra. These efforts can be divided into 

three components: 

•	 Ab initio calculations of atomic data unavailable 

from other sources. This consists primarily of inner shell photoionization cross-sections and related quantities (fluorescence line widths and energies). It makes use of the R-Matrix suite of atomic 

codes developed by M. Seaton and collaborators 

in the UK. 

•	 Hydrodynamic models for one possible scenario to 

explain AGN warm absorbers. This is an evaporative flow from the molecular torus responsible for 

obscuring the central black hole in type 2 AGN. 

The data obtained through the OPASI-T program 

is critical for interpretation of astronomical spectra 

obtained at long wavelengths. With the impending 

launch of Herschel and the capabilities provided by 

SOFIA, this will help address a wide range of astronomical questions. Primary funding for OPASI-T is 

through the ROSES APRA program, with a period of 

performance through FY10. Additional funding has 

been provided through the ESA’s Herschel program. 

Atomic Data for X-ray Astrophysics

The grating instruments on the Chandra and XMMNewton satellites have revealed the existence of absorption by partially ionized gas in many X-ray sources. These most notably include active galactic nuclei 

(AGN), as well as black holes and some neutron-star 

sources in our galaxy. The X-ray “warm absorber” spectra typically contain hundreds of identifiable absorption lines and are most often blueshifted by 100–1000 

km/s, superimposed on the compact object’s continuum radiation. The blueshift implies the existence of 

outflowing material, and simple estimates suggest that 

this can have important astrophysical implications. 

Why do we see only outflow from 

objects which must be driven by inflow?

10−10

10−5

100

θ=27°

E F

E 10−10

10−5

100 θ=30°

0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2

10−10

10−5

100 θ=35°

Energy (keV)

On the Web

XSTAR home page

heasarc.nasa.gov/lheasoft/xstar/xstar.html

Gas pressure contours and velocity vectors (left) and synthetic spectra for a simulation of a warm absorber 

flow from torus evaporation. This is one scenario that may explain AGN warm absorbers. Credit: NASA/

GSFC
13

Astrophysics Science Division: Research and Missions

•	 Support for a publicly available modeling code 

and related projects which is in widespread use 

in the X-ray astronomy community for modeling 

these spectra. 

The Swift BAT AGN Survey

During the last four years, the Swift Burst Alert Telescope (BAT) has been surveying the sky in the hard 

(15–200 keV) X-ray band while awaiting gammaray bursts. Because of its very wide field of view, the 

BAT obtains more or less uniform sky coverage and 

very deep exposures (on average more than 4 million 

seconds) compared to the smaller fields of view and 

shorter exposures of Integral. Thus, the BAT has obtained the most uniform and deepest exposures of the 

hard X-ray sky. 

The BAT sample is the first unbiased survey of active 

galactic nuclei (AGN) in the local universe. Because of 

the hard X-ray bandpass, there are no selection effects 

due to obscuration, galaxy properties or optical or radio properties because the hard X-rays pass through 

the obscuring material. We now know from Chandra 

and XMM observations and models of the X-ray background that most AGN are obscured in the optical 

and UV by dust and gas in the line of sight. The BAT 

data allow a direct comparison of selection effects for 

AGN across the electromagnetic spectrum. 

Because of the relatively low (compared to Chandra) 

BAT sensitivity, the majority of the objects are close 

(<z> ~ 0.03) and bright (MJ ~ 11) allowing detailed 

analysis of the host galaxies, through optical, UV, and 

IR spectra of the AGN and host galaxy. In addition 

to a catalog of objects, the BAT survey provides x-ray 

spectra and long term light curves for all the sources. 

This data set has already produced 13 refereed papers 

on AGN properties and several more are in progress. 

At the January 2009 AAS meeting, several of the newest results from the BAT survey were presented by 

Richard Mushotzky (X-ray Astrophysics Lab). These 

include:

•	 The discovery that the BAT-selected AGN live in 

galaxies in the “green valley,” i.e., between the blue 

and red peaks. Thus, the AGN is either cutting off 

star formation or is stimulated by star formation. 

The colors and magnitudes of the host galaxies 

at low z are different from that of the Chandraselected objects at z ~ 1. The z ~ 1 hosts are preferentially luminous red ellipticals, while the z ~ 0 

hosts are slightly more luminous (~ 0.5 mag than 

L* spirals indicating a strong evolution in the 

AGN hosts). 

•	 BAT-selected AGN galaxies are found much more 

often in close pairs/mergers (30–50%) than field 

galaxies (1–3%), which supports theoretical ideas 

about how AGN activity is triggered in the local 

universe and contradicts recent results from the 

SDSS AGN surveys. 

•	 Either the Eddington ratios of type II AGN are 

systematically less than type I AGN or their boSwift’s BAT Hard X-ray Survey offers the first 

unbiased census of active galactic nuclei in decades. 

Dense clouds of dust and gas, illustrated here, can 

obscure less energetic radiation from an active 

galaxy’s central black hole. High-energy X-rays, 

however, easily pass through. Credit: ESA/NASA/

AVO/Paolo Padovani

BAT-selected AGN galaxies are found 

much more often in close pairs/mergers 

(30–50%) than field galaxies (1–3%), 

which supports theoretical ideas about 

how AGN activity is triggered in the local 

universe.
Astrophysics Science Division: Research and Missions

14

lometric corrections are different, indicating that 

there are fundamental difficulties with simple geometrical unification models. 

•	 There exist objects at low z that show no evidence 

of an AGN in the UV-IR bands, either through 

spectroscopy or imaging (e.g., HST NICMOS 

images). This shows that AGN surveys, even in 

the very nearby universe, are incomplete. 

This work was part of the PhD thesis of Lisa Winter 

and of Mike Koss, both students at the University of 

Maryland, and Ranjan Vasudevan a student at Cambridge University.

Studies of Galaxies, Including Groups and 

Clusters

Many people are working on galaxy evolution across 

several of the laboratories in the Astrophysics Science 

Division at NASA GSFC. A few recent projects being 

carried out by Bruce Woodgate et al. and Ann Hornschemeier, Jenkins, Hammer et al. are highlighted 

here. 

The focus of Hornschemeier’s work has been on the 

X-ray properties of galaxies, including the nature of 

the X-ray/star-formation-rate correlation. The X-ray/

SFR correlation arises due to the regularity of the production of high-mass X-ray binaries in galaxies; there 

is also an analogous X-ray/stellar mass relation for lowmass X-ray binaries. Curiously, these correlations are 

found to hold across a broad range of galaxy properties. Recent work with Chandra and XMM has shown 

suppression in the X-ray emission (with respect to 

stellar mass and/or optical light) of galaxies in cluster 

and group environments versus the field (e.g., Hornschemeier et al. 2006). This may indicate a difference 

in the amount of X-ray emission per stellar mass, but 

current data are insufficient to tell. Hornschemeier 

(PI) is now conducting a large (0.5 deg2 area) survey in 

an off-center region of the cluster with XMM-Newton 

(220 ksec). Preliminary analysis shows the suppression 

is indeed extreme and efforts are underway to obtain 

ground-based optical spectroscopic data (MMT Hectospec) and other multiwavelength data to make detailed measurements of the stellar population ages and 

star-formation histories of these galaxies. 

The Coma Hectospec data have demonstrated conclusively that cluster galaxies falling into Coma have 

younger ages and that significant quenching of star 

formation is occurring as galaxies fall in to the cluster. The Spitzer IRAC data (PI, Hornschemeier) were 

published (with Jenkins) and show the possibility of 

a large population of dwarf galaxies that may be efficiently studied at infrared wavelengths. VLA work by 

Hornschemeier’s team has demonstrated that there are 

few star-forming galaxies at faint radio luminosities, 

in contrast with local field RLFs. Their Coma GALEX 

survey provides measurement of the GALEX NUV 

and FUV luminosity functions (LFs), which are the 

deepest UV LFs measured for a cluster thus far (including dwarf early-type galaxies). 

Galaxy X-ray emission appears to be 

suppressed with respect to stellar mass 

and/or optical light for galaxies in group 

environments. Efforts are underway to 

make detailed measurements of the starformation histories of these galaxies.

Spitzer IRAC data suggest the presence of a large 

population of dwarf galaxies in the Coma cluster that 

may be efficiently studied at infrared wavelengths. 

Credit: NASA/JPL-Caltech
15

Astrophysics Science Division: Research and Missions

Hornschemeier is also a coinvestigator on several 

Spitzer and HST projects to study twelve of the nearest Hickson Compact Groups to determine details 

of their star-formation histories. Data from these 

projects have shown that there is an “infrared color 

gap” between the early-stage compact groups (those 

just beginning to undergo interactions) and late-stage 

compact groups (dominated by ellipticals). It has also 

been shown that the IR spectral index can be used to 

identify active nuclei. There are also Chandra data on 

four of these galaxy groups, and Hornschemeier is collaborating with the Penn State Chandra ACIS team to 

study two more through Chandra guaranteed time.

Hornschemeier is working with John Mulchaey of 

Carnegie Observatories on a project to obtain widefield optical imaging of all twelve of the HCGs as a 

precursor to a spectroscopic campaign to measure the 

LF. Currently, Panayiotis Tzanavaris has been leading 

the observing and data reduction for the spectroscopic 

campaign (for which we have obtained ~ 4 nights of 

12 thus far). Tzanavaris is also reducing Swift UVOT 

data that permits a detailed study of the star formation 

properties of these Hickson Compact Groups using 

higher resolution imaging (2′′) than is available with 

GALEX (5–7′′). 

In addition to this group and cluster work, GSFC is 

heavily involved in study of individual galaxies and 

surveys of field galaxies. For instance, Leigh Jenkins 

et al. have been conducting a study to investigate how 

a strong bar affects the evolution of spiral galaxies, 

and in particular whether a bar can fuel active galactic nucleus (AGN) activity by funneling gas and dust 

in the galaxy disk toward the central region. Using 

new high-spatial-resolution X-ray imaging from the 

Chandra X-ray Observatory, together with supporting observations from the Hubble Space Telescope 

(optical) and Spitzer Space Telescope (infrared), Jenkins et al have been able to demonstrate for the first 

time that the nearby barred spiral galaxy NGC 1672 

possesses a faint, central X-ray nucleus surrounded by 

an X-ray-bright circumnuclear ring of star-formation. 

If the nuclear emission is due to low-level accretion 

onto an active supermassive black hole, this could be 

an example of a larger trend in which AGN activity is 

correlated with the presence of a strong bar, but obscured at optical wavelengths by star-formation activity in the same region. An initial investigation of more 

than 100 spiral galaxies observed with Chandra also 

shows some evidence that barred spiral galaxies may 

possess brighter X-ray nuclei, on average, that nonbarred galaxies.

Large multi-color imaging surveys are becoming available with sufficient depth to enable investigations of 

the high-redshift universe. David Bonfield (former 

NPP Fellow), Bruce Woodgate, Carol Grady, Don 

Lindler, and collaborators are involved in this work. 

Lyman-alpha emission provides a unique locator of 

high-redshift active galaxies with sufficient redshift accuracy to identify cluster membership, to find knots in 

the cosmic web, and to study the interaction of active 

galaxies with the IGM. Woodgate et al. have begun 

a single-band excess search for high-equivalent-width 

emission-line galaxies using the SDSS2 supernova 

survey and the CFHT legacy survey for 2.5 < z < 3 

galaxies with ~3,000 times the search volume of all 

previous narrow band searches. In January they demonstrated its feasibility by finding a Lyman alpha emitting galaxy at z = 2.75 by this method.

New high-resolution X-ray images from the 

Chandra X-ray Observatory, together with 

supporting observations from the Hubble Space 

Telescope (optical, shown here) and Spitzer Space 

Telescope (infrared), demonstrate that the nearby 

barred spiral galaxy NGC 1672 possesses a faint, 

central X-ray nucleus surrounded by an X-raybright circumnuclear ring of star-formation. Credit: 

NASA/STScI
Astrophysics Science Division: Research and Missions

16

removal of Galactic light. Models used for the subtraction of the zodiacal light are estimated to be accurate 

to a few percent of the zodiacal light intensity, but still 

are the main source of the large (20–50%) uncertainty 

of the near-IR EBL. We have therefore undertaken 

two projects that will provide a direct absolute measurement of the zodiacal light. 

Determining the Near-Infrared Extragalactic Background Light through Absolute Measurements of 

the Zodiacal Light (Eli Dwek, PI). The first method 

determines the absolute intensity of the sunlight scattered by the zodiacal (interplanetary) dust cloud in the 

J (1.25 mm) band by measuring Fraunhofer lines in 

the spectrum of the zodiacal light with a large étendue, 

high-resolution, ground-based spectrometer. These 

observations, combined with knowledge of the solar 

spectrum, will provide a measurement of the absolute 

brightness of the scattered light from the zodiacal light 

in the DIRBE J band. 

By carrying these measurements out in this spectral 

band of the Diffuse Infrared Background Experiment (DIRBE) aboard the COBE satellite, we will 

significantly improve the quality of the foreground subtraction of the DIRBE measurement and largely eliminate the major systematic uncertainty in the DIRBE 

determination of the NIR extragalactic background. 

Dwek’s team (Arendt, Kutyrev, Moseley, Silverberg) 

has designed and started to build a large étendue, highresolution spectrometer to observe near-infrared solar 

absorption lines in the zodiacal light. They have recently acquired two silicon Fabry-Perot etalons, which 

are critical parts of the spectrometer, and verified their 

spectral performance using spectral line source in the 

lab. It is expected that the telescope will be assembled 

in Spring 2009; the first zodiacal light measurements 

will be obtained later that year.

New Measurement of the Near-IR Extragalactic 

Background via Analysis of COBE/DIRBE Zodical Light Polarization (Richard G. Arendt, PI). The 

second method will derive new measurements of the 

Determination of the Cosmic Near-Infrared 

Background Through Studies of the Zodiacal 

Cloud

The Diffuse Infrared Background Experiment 

(DIRBE) instrument on the Cosmic Background Explorer (COBE) satellite was designed to measure the 

absolute brightness of the infrared sky in order to detect the extragalactic background light (EBL). At nearinfrared (NIR) wavelengths, EBL contains the spectral 

signature of energy releases from primordial stars, the 

first objects to illuminate the universe after the cosmological dark ages. Furthermore, EBL is the repository 

of all energy released from subsequent generations of 

stars formed during the course of galactic cosmic evolution, as well as the gravitationally powered energy released by accreting black holes in active galactic nuclei 

(AGN). Knowledge of the EBL at these wavelengths is 

therefore of prime cosmological interest, but its detection is impeded by the presence of strong foreground 

emission components.

Detection the Cosmic Infrared Background (CIB) first 

requires the removal of the zodiacal light, followed by 

Knowledge of the EBL at near-infrared 

wavelengths is of prime cosmological 

interest.

In order to reveal the EBL intensity in data from 

COBE’s DIRBE instrument, light sources within 

the solar system and the Galaxy must be subtracted. 

The blue S-shaped band in the all-sky view at top 

is thermal emission from the solar system’s zodiacal 

dust cloud. Credit: NASA/COBE
17

Astrophysics Science Division: Research and Missions

near-IR zodiacal light brightness through analysis of 

the previously unutilized polarization data obtained 

by DIRBE. The correlation of polarized and unpolarized intensities as a function of time provides a direct 

measure of the zodiacal light brightness relative to that 

of the Galactic and extragalactic backgrounds. 

This analysis will provide a new model-independent 

means of removing the zodiacal light from DIRBE 

data. The integrated intensity of cataloged stars from 

the 2MASS survey will be used to subtract the bulk 

of the Galactic emission, with the remaining fraction 

subtracted using a model. The residual intensity will be 

that of the EBL. Previous estimates of the near-IR EBL 

intensity are unexpectedly larger than the integrated 

light of galaxies that can be individually resolved. 

Our measurements will show whether the EBL really 

does contain a relatively bright and unresolved component or that the excess emission is only due to underestimated zodiacal light intensities. The EBL intensity 

is one of the most critical constraints in determining 

what future NASA missions like JWST will observe in 

deep imaging of the early universe.

The Infrared and X-ray Evolution of SNR 

1987A: Analysis of the Supernova Blast Wave 

Interaction with the Surrounding Medium

SN1987A is the most dramatically evolving supernova 

remnant (SNR) in the universe. Since its explosion 

on February 23, 1987, in the Large Magellanic Cloud, 

SN1987A has evolved from a supernova dominated 

by the emission from the radioactive decay of 56Co, 

57Co, and 44Ti in the ejecta to a supernova remnant 

whose emission is dominated by the interaction of the 

supernova blast wave with its immediate surrounding 

medium. This interaction is presently dominated by 

the inner equatorial ring (ER). 

Observations of the remnant with the Hubble Space 

Telescope since 1994 have revealed spectacular images 

of “hot spots” strung along the ER like beads on a 

necklace, with new spots continuing to appear as the 

blast wave propagates into the ring. These hot spots 

appear to be finger-like protrusions, representing the 

first ER material to be hit by the blast wave. Images of 

the ER obtained at 0.3–8 keV with the Chandra X-ray 

Observatory, at 12 mm with the Australian Telescope 

Compact Array (ATCA) at the Australian Telescope 

Facility, and at 11.7 and 18.3 μm with the T-ReCS 

mid-infrared imager at the Gemini-S 8m telescope 

show an overall similar morphology, characterized by 

The IR spectrum of the ring is dominated by 

emission from silicate dust, and evolving with time. 

Credit: NASA/Dwek et al.

Top left: This view combines the mid-infrared 11.7 

mm image of the SN 1987A’s equatorial ring (red) 

with the HST F625W image obtained on day 6502 

(yellow). Top right: The same view as at left, but with 

the HST image convolved to match the resolution 

of the T-ReCS 11.7 mm image. Bottom left: This 

view merges the Qa image from T-ReCS with the 

HST F625W image. Bottom right: The same view 

as at left, but with the HST image convolved to 

match the T-ReCS Qa angular resolution. Credit: 

NASA/Dwek et al.
Astrophysics Science Division: Research and Missions

18

Observations of the ER show that the IR light curve is 

continuing to evolve, suggesting significant changes in 

blast wave-ER interaction. The rapid changes observed 

in the IR spectrum of the ER are also seen in its optical 

and X-ray morphologies and are manifestations of the 

multifaceted interaction of the supernova blast wave 

with the complex structure of the ring. 

WMAP Five-Year Results

WMAP helped establish a simple and comprehensive 

cosmological model that connects the physics of the 

very early universe to the properties of the universe 

today. In this standard model, the universe is flat, homogeneous and isotropic on large scales. The universe 

is composed of radiation and atoms, but it is currently 

dominated by dark matter and dark energy. 

The first results from WMAP, based on one year of 

data, were released in 2003 and were followed up by 

three-year results in 2006. In 2008, the WMAP team 

released seven papers with results based on five years 

of data. The WMAP team at GSFC includes ASD scientists Hinshaw, Wollack, Kogut, and Bennett (now 

at JHU).

For Gaussian random-phase fluctuations, the angular 

power spectrum encodes the full statistical information in the map. Classic papers ( Peebles and Yu, 1970; 

Sunyaev and Zeldovich, 1970) relate the properties 

of the universe to the structure in the angular power 

spectrum. 

similar mean radii and surface brightness distribution. 

The X-ray emission is thermal emission from the very 

hot plasma, shock-heated to temperatures in excess 

of 3 × 106

 K by advancing, reflected, and transmitted 

shocks generated by the supernova blast wave. The optical emission arises from denser gas that is shocked by 

transmitted shocks in the ER, and the radio emission 

is synchrotron radiation from shock-accelerated electrons. The mid-infrared emission observed by Spitzer 

is comprised of line and continuum emission. The 

lines most likely originate from the optically bright 

dense knots, whereas the continuum that dominates 

the spectrum is thermal emission from collisionally 

heated dust residing in the X-ray emitting plasma. 

The morphological similarity between X-ray and midinfrared images of the ring demonstrates the dust resides within the hot X-ray emitting plasma. Consequently, combined Spitzer infrared spectra and X-ray 

observations of the ER provide important complementary information on the evolution of the interaction of 

the supernova blast wave with its dusty surroundings.

Eli Dwek and colleagues have carried out repeated 

infrared (IR) observations with the Spitzer satellite in 

order to follow the evolution of the infrared emission 

from SNR 1987A, in coordination with teams monitoring the remnant with HST, Chandra, and groundbased telescopes. The analysis by Dwek et al. has 

shown that the IR emission arises from silicate dust 

collisionally heated by the X-ray emitting plasma to 

temperatures of about 180 K. Comparison with the Xray emission has shown that the ratio between the IR 

and X-ray flux emitted by the shocked plasma decreases with time, providing the first observational evidence 

for grain destruction on a dynamical timescale.

The ratio between the IR and X-ray 

flux emitted by the shocked plasma 

decreases with time. This provides the 

first observational evidence for grain 

destruction on a dynamical timescale.

The full-sky map of the CMB temperature anisotropy 

from the five-year WMAP data. The foreground 

signals are greatly reduced using WMAP’s multifrequency data. Credit: NASA/WMAP
19

Astrophysics Science Division: Research and Missions

of the third peak, WMAP more accurately determines 

the cold dark matter density. This parameter is of great 

interest to both cosmologists and particle physicists. 

For cosmologists, it better constrains σ8

, the amplitude of matter fluctuations, and is an important input 

to dark energy constraints and cosmological simulations. For particle physicists, it constrains the dark 

matter self-annihilation cross-section. 

By combining WMAP data with other data sets that 

measure the kinematics of the local universe, we further improve some of the cosmological parameters 

(see table). The Hubble constant from WMAP data 

combined with SNe and galaxy BAO data yields H0

 = 

70.1 ± 1.3 km/sec/Mpc. This < 2% measurement of 

the Hubble constant is remarkable because it agrees 

closely with the results of more traditional means of 

measurement, which inspires strong confidence in 

the consistency of the cosmological model. It’s worth 

noting that measurement of the Hubble constant to a 

factor of 2 dominated much of the last 75 years of astronomy. Likewise, the age of the universe as measured 

by WMAP—13.73 ± 0.12 Gyr—is a < 1% measurement.

The polarization data have improved significantly with 

five years of WMAP data. The polarization (EE) power 

spectrum is now detected at 5σ in the multipole range 

of 2 ≤ l ≤ 7. This has important implications for the 

The standard ΛCDM model, defined by the six parameters given in the table, is a good fit to the five-year 

WMAP data, with χn

2 = 1.06. The model also fit the 

combination of WMAP data, baryon acoustic oscillations (BAO) data in the galaxy distribution, and supernovae (SNe) distance data.

With five years of data, WMAP has improved its measurements of sub-degree scale fluctuations, especially 

the third acoustic peak. By improving the precision 

The WMAP five-year data have 

improved its measurements of sub-degree 

scale fluctuations, especially the third 

acoustic peak, and provide new evidence 

for the existence of a cosmic neutrino 

background.

Top: The temperature (TT) spectrum of the 5-year 

WMAP data. The red curve is the best-fit ΛCDM 

model and the grey band is its cosmic variance 

uncertainty. With five years of data, the third 

acoustic peak is now coming into WMAP’s view. 

Bottom: WMAP’s temperature-polarization (TE) 

cross-power spectrum. This mostly arises from 

CMB scattering at z = 1090; the rise at the lowest 

multipoles is due to reionization at z ~ 11. Credit: 

NASA/WMAP

Best-fit ΛCDM parameters with five-year WMAP data

ΛCDM Parameter WMAP data only WMAP+BAO+SNe

Matter density, Ωmh2 0.123 ± 0.006 0.1369 ± 0.0037

Baryon density, Ωb

h2 0.02277 ± 0.0006 0.02265 ± 0.00059

Cosmological constant, Λ 0.742 ± 0.030 0.721 ± 0.015

Scalar index, ns 0.963 ± 0.014 0.960 ± 0.014

Optical depth, τ 0.087 ± 0.017 0.084 ± 0.016

Amplitude at 8 h-1 Mpc, σ8 0.796 ± 0.036 0.817 ± 0.026
Astrophysics Science Division: Research and Missions

20

signals. These activities, which are intricate, challenging, and time-consuming, are the focus of the WMAP 

Team’s effort.

Results from ARCADE

The ARCADE project (Absolute Radiometer for Cosmology, Astrophysics, and Diffuse Emission; Kogut, 

PI) released results from the 2006 flight. The principal result from this flight was the detection of an extragalactic radio background approximately six times 

brighter than the integrated emission from known 

populations of radio point sources. The ARCADE 

data are consistent with a superposition of a blackbody 

CMB plus a power-law radio background 

with parameters

T0

 = 2.729 ± 0.004 K

TBG = 1.06 ± 0.11 K

b = –2.56 ± 0.04

at reference frequency n0

 = 1 GHz. 

epoch of reionization, and WMAP data has improved 

the determination of its redshift.

With the three-year data, WMAP detected the signature of reionization in the EE power spectrum. Quasar absorption-line data show that reionization was 

occurring at z ~ 6. With the five-year data, WMAP 

has shown that the bulk of reionization was significantly earlier than z ~ 6, and that the absorption-line 

data probes the tail end of the process. The WMAP 

five-year data are now powerful enough to show that 

reionization was an extended process.

The WMAP five-year data provide new evidence for 

the existence of a cosmic neutrino background: relativistic neutrinos are required by WMAP data alone at 

> 99.5% confidence, consistent with constraints from 

big bang nucleosynthesis, which probes an earlier 

epoch in cosmic history. Upper limits on the tensorto-scalar ratio, r, a measure of the gravitational wave 

background produced during inflation, improved by 

50% to r < 0.2 (95% CL), and the upper limit on the 

bispectrum amplitude, fNL, a measure of non-Gaussianity, has decreased by 30%.

For all of these cosmological results to be meaningful, 

the systematic measurement errors must be extremely 

well understood. Enormous effort has been expended 

to characterize the WMAP experiment: its calibration, 

systematic errors, noise properties, and foreground 

The five-year WMAP data has brought about a 

significant improvement in the amplitude of the 

fluctuations, σ8, and the cold dark matter density, 

Ωc

h2. Credit: NASA/WMAP

The likelihood for the redshift of sudden reionization. 

Although the maximum likelihood value is virtually 

unchanged from the three-year value, the data now 

significantly excludes sudden reionization at z ~ 6. 

Credit: NASA/WMAP

T T υ TBG

υ

υ

β

( ) = +0 ( )0
21

Astrophysics Science Division: Research and Missions

The detected background cannot easily be explained 

as the integrated emission of faint radio sources. Extrapolating measured source counts to fainter fluxes 

would require an implausible source density ~8 × 105

per square arcmin at limiting flux 0.3 nJy. 

Four papers describing the ARCADE instrument, the 

measurement of the sky temperature, the model of 

Galactic microwave emission, and the interpretation 

of the detected radio background have been submitted 

to The Astrophysical Journal. A press release described 

the ARCADE instrument and the radio background, 

and a press briefing was held at the January 2009 AAS 

meeting in Long Beach, Calif. ARCADE team members in ASD include Kogut, Wollack, Mirel, and Fixsen.

Jets in Young Stars

Bipolar jets associated with pre-main sequence (PMS) 

stars are some of the most visually striking manifestations of star formation, providing a “fossil record” 

of the mass-loss history of the protostar. Such jets are 

most conspicuous when the star is obscured either by 

its natal molecular cloud material or, for older systems, 

when the star is viewed at high inclination (e.g., edgeon) to its circumstellar disk. The ease of detection of 

such jets led to the expectation that mass loss via jets 

was limited to the first 105

 years of a protostar’s lifetime, 

was most common for low-mass protostars, and at 1–2 

Myr was seen in only 30% of stars (Cabrit 2002). New 

jets continue to be discovered, even in well-studied 

star-forming regions, and associated with higher-mass 

stars (Devine et al., 2000; Grady et al., 2004), indicating that jets are present over a wider range in stellar 

mass and age than previously suspected. 

Biases toward higher mass-loss-rate jets in the broadband or forbidden-emission-line surveys (e.g., Kenyon 

et al., 1998) can obscure correlations that are diagnostic of structural changes in circumstellar disks. The 

low jet frequency noted by Cabrit (2002) appears to 

be a consequence of disk survival. For Taurus at 1–2 

Myr, only 50% of stars have disks, with only 50% of 

PMS stars retaining disks at 1–2 Myr (Cieza et al., 

2007), and that a further 10% of stars by that age have 

thermal emission deficits consistent with cleared lanes 

or central cavities in the disk. Some of these “transitional” disks are associated with binary stars (Ireland 

and Kraus, 2008), while others have the combination 

of large cavities and detectable on-going accretion that 

suggests dynamical clearing by Jovian-mass planets 

(Rice et al., 2006; Lubow and D’Angelo, 2006; Pontoppidan et al., 2008). 

Our pilot survey for jets in HST coronagraphically imaged PMS stars demonstrates that jets are found from 

stars with disks extending into the dust sublimation 

radius. Non-detections are preferentially found for the 

transitional disks. If supported for a larger sample of 

stars, these data would suggest that the disappearance 

of jet activity in PMS stars with disks may be one of 

the first remotely-detectable signatures of planet formation. 

Bruce Wooodgate and Carol Grady are carrying out 

such a larger survey with the Goddard Fabry-Perot 

(GFP) at the Apache Point Observatory 3.5m telescope. Their target list includes: approved Herschel targets (on the open-time key project, GASPS); planned 

H-band coronagraphic polarimetric differential imaging targets (as part of the Subaru Strategic Exploration 

of Exoplanets and Disks [SEEDS] study); and a few 

objects that have been proposed in the HST cycle 16 

supplemental call. Previous spectral surveys for forbidARCADE detected an extragalactic 

radio background approximately six 

times brighter than the integrated 

emission from known populations of 

radio point sources.

The sky temperature measured by ARCADE after 

subtraction of Galactic emission. NASA/ARCADE
Astrophysics Science Division: Research and Missions

22

den emission (Kenyon et al., 1998) and broadband 

direct-imaging surveys (Stapelfeldt et al., 2008) can 

detect suitably oriented jets down to mass-loss rates 

of 10-8 M yr-1. 

The GFP offers higher emission-line-to-star contrast 

(x 200–600, compared to HST broadband imaging) 

with its suite of medium-band filters and choice of 

Fabry-Perot etalons. In the event of bright nebulosity 

or a bright star, further contrast gains can be achieved 

using a coronagraphic wedge. The GFP has allowed 

detection of jets at lower mass-loss rates (5x10-10 M

yr-1, MWC 480; Stecklum et al., 2009) well into the 

accretion-rate range of stars with transitional disks. 

In addition to jet detections, GFP data have proven 

invaluable in the interpretation of particular systems 

(e.g., PDS 144) and in planning high-contrast imaging. As of Nov. 2008, we have data for 50% of the 

SEEDS Taurus targets, the majority of the HST coronagraphically imaged Taurus T Tauri stars, and the 

majority of the HST coronagraphically imaged Herbig Ae stars.

Numerical Modeling of Planet-Disk 

Interactions

The recent discovery of a planet associated with the 

Fomalhaut debris disk has generated renewed interest in the physics of how planets shape circumstellar 

disks. Recognizing how planets can sculpt exozodiaOur pilot survey suggests that the 

disappearance of jet activity in PMS 

stars with disks may be one of the first 

remotely detectable signatures of planet 

formation. 

Left: Goddard Fabry-Perot Ha image of the Herbig Ae star MWC 480. The corongraphic wedge is needed 

to enable jet detection against the bright light of the star. Right: GFP color composite detail of the PDS 144 

system. The two bright stars in the field are 5.4” apart. Jet emission is detected in Ha, with red indicating 

receding (counterjet) material, and blue approaching material. Decelerating HH knots are in green. The 

southern Herbig Ae star is slightly extended in our GFP imagery, which prompted reanalysis of archival HST 

imagery. We identified PDS 144 as an i ~ 70o disk plus envelope, rather than a face-on disk. Credit: NASA
23

Astrophysics Science Division: Research and Missions

cal clouds, debris disks, and disks around young stellar objects can allow us to indirectly detect extrasolar 

planets that otherwise would go unseen and measure 

their masses and orbital parameters. This method may 

be the only way to detect extrasolar planets in long 

orbital periods (e.g., ~ 100 years) that are not selfluminous. Kuchner, his graduate student Christopher 

Stark, and postdoctoral fellow Hannah Jang-Condell 

work on this problem, modeling images of disks using 

NASA’s supercomputers. 

Except for the sun, the zodiacal cloud is the brightest 

component of the solar system in the optical and infrared. Proposed missions—like TPF, THEIA, NWO, 

ATLAST, ECLIPSE, EPIC, TOPS, etc.—that aim to 

directly image extrasolar analogs of the solar system 

must contend with light from zodiacal dust as potentially their primary astrophysical noise source. In 

particular, structure in exozodiacal clouds represents 

a challenge for these missions, since it can mimic the 

appearance of a planet.

Kuchner and Stark have developed a catalog of patterns 

that exo-Earths can create in exozodiacal clouds. This 

study (Stark and Kuchner, 2008) utilized a custom hybrid symplectic integrator to integrate the orbits of orders-of-magnitude more particles than previous simulations. It was the first to overcome the major source 

of noise that plagued prior simulations—uncertainty 

in the populations of mean-motion resonances—and 

make quantitative predictions for the contrast of the 

dust rings associated with terrestrial exoplanets.

More massive debris disks like that around Fomalhaut 

have different physics than the solar zodiacal cloud; 

in these disks, the collision time is comparable to the 

Poynting-Robertson time for the dominant grain size. 

These disks will be key targets for JWST, ALMA, and 

many other future observatories. Kuchner and Stark 

have developed an algorithm for incorporating collisions into their disk modeling code. This algorithm 

self-consistently solves for the first time both the dynamical equations and the mass-flux equations for a 

debris disk containing a planet.

Hannah Jang-Condell has developed a ray-tracing 

non-plane-parallel radiative-transfer code for modeling images of T Tauri and Herbig Ae disks. By iteratively solving the equation of hydrostatic equilibrium 

and the radiative transfer, this code predicts the appearances of disks shaped by hidden Jovian planets. 

Jang-Condell and Kuchner are working on applying 

this model to recent coronagraphic images of the disk 

around AB Aurigae, which show structures consistent 

with the predictions of the models.

Keck Interferometer Nuller Observations of 

Circumstellar Material

The Keck Interferometer Nuller (KIN) combines the 

mid-infrared light from the two Keck Telescopes to 

cancel out on-axis starlight and sense faint circumstellar material, like debris disks and exozodiacal clouds. 

Kuchner served as Science PI on the Keck Interferometer Nuller Shared Risk Science Team. Danchi and 

Barry also led aspects of this effort. 

The first science result from the KIN and the Shared 

Risk Science Team was an observation of the nova 

RS Ophiuchi 3.8 days after its outburst (Barry et al., 

2008). The data revealed the diameter of the dusty 

Proposed missions that aim to directly 

image extrasolar analogs of the solar 

system must contend with light from 

zodiacal dust as potentially their primary 

astrophysical noise source.

A ray-tracing non-plane-parallel radiative-transfer 

code predicts the appearances of disks shaped by 

hidden Jovian planets. This image shows the code 

applied to coronagraphic images of AB Aurigae. 

Credit NASA/GSFC
Astrophysics Science Division: Research and Missions

24

nebula associated with this system and showed how 

the nebula near the white dwarf was chemically different from more distant parts. The observations support a model in which the dust appears to be present 

between outbursts—possibly in the form of a spiral 

shock wave caused by the motion of the star through 

the wind of the red giant—and is not created during 

the outburst event.

The second result from the KIN team is the measurement of resolved flux from the young debris disk 51 

Ophiuchi (Stark et al., in prep.). Simultaneous modeling of data from the KIN, the MIDI interferometer, 

and Spitzer on this source point to a two-component 

disk: a radially confined edge-on ring of larger grains 

and an extended component of small grains, probably 

ejected from the inner “birth ring” of larger debris. In 

other words, 51 Ophiuchi appears to resemble other 

debris disks, like Vega, Beta Pictoris, and AU Microscopii, although the birth ring is much smaller—

only ~ 10 AU in size.

As part of the Shared Risk effort, Kuchner and his students have developed a software package called ZODIPIC that simulates images of our zodiacal cloud 

around nearby stars for use interpreting KIN data 

sets. ZODIPIC incorporates a simple active-mesh algorithm, an iterative dust-temperature calculator, and 

a library of optical constants that make it a generalpurpose debris-disk modeling tool as well. ZODIPIC 

has become a popular tool for planning missions like 

TPF, NWO, JWST, etc.

Kuchner now serves as PI on a Keck Interferometer 

Nuller key project that will follow up some of the 

sources observed during the Shared Risk time to make 

the deepest integrations ever made with the KIN. This 

data has just recently been acquired. Kuchner, Danchi, 

and Roberge all serve as coinvestigators on other KIN 

key projects 

Kuchner is also the PI of a new study of circumstellar 

material using a different interferometer: a SIM Science Study aimed at measuring the sizes and shapes 

of Kuiper Belt Objects, centaurs and asteroids in our 

own solar system. SIM should be able to improve current size measurements for these objects by a factor of 

several, and directly sense their axis ratios and rotation 

axes. This study will examine limb-darkening corrections, tomographic shape reconstruction, and observing strategies, with the help of Jianyang Li, postdoctoral fellow at the University of Maryland.

Resolved Observations of Debris Disks

The Hubble Advanced Camera for Surveys (ACS) coronagraph has been the prime instrument for discovering new resolved debris disks. Clampin is a member of 

the ACS Science Team and led the team’s debris-disks 

theme. This sought to survey debris-disk candidates 

primarily selected from Spitzer IR excesses. He also 

collaborates with Paul Kalas’ team at Berkeley in following up ground-based coronagraphic observations 

of debris disks. 

The primary motivation for attempting to obtain resolved imaging of debris disks is to understand how 

planetary systems evolve and to search for evidence of 

unseen planets in these debris-disk systems. Recent 

successes with the ACS disk program include new obOn the Web

Exozodi Simulation Catalog

asd.gsfc.nasa.gov/Christopher.Stark/

catalog.php.

Keck Interferometer

Nuller

The first science result from the Keck 

Interferometer Nuller was an observation 

of the nova RS Ophiuchi 3.8 days after its 

outburst that revealed the diameter of the 

dusty nebula associated with this system.
25

Astrophysics Science Division: Research and Missions

servations of HD 141569A (Clampin et al., 2003), 

which revealed detailed structures in the disk, and new 

disk discoveries such as HD 107146, the first G star 

with a resolved debris disk (Ardila et al., 2004), HD 

92945 (Clampin et. al., 2005), and HD 181327 (Schneider et al., 2006). Other solar type stars with debris 

disks discovered with ACS include HD 169344 and 

HD 51543 (Kalas et al., 2006). 

One of the most intriguing results from ACS is the 

Fomalhaut system. In the course of observations designed to discover co-moving objects, a dust belt was 

discovered (Kalas et al., 2005). The dust belt was especially interesting as it exhibited two characteristics 

suggestive of the presence of an exoplanet: The belt is 

offset from the central star and its inner edge is sharp. 

This discovery prompted further observations of the 

Fomalhaut disk. 

In the course of data analysis, a point source was found 

inside the belt in the approximate region where an 

exoplanet was predicted. The exoplanet candidate Fomalhaut b (Kalas et al., 2008) lies in the plane of the 

belt. It lies approximately 119 AU from the star and 

18 AU from the dust belt. Observations separated by 

1.73 years show evidence of counter-clockwise orbital 

motion. Dynamical models of the interaction between 

the planet and the belt indicate that the planet’s mass 

is at most three times that of Jupiter for the belt to 

avoid gravitational disruption. The flux detected at 0.8 

mm is also consistent with that of a planet with mass 

no greater than a few times that of Jupiter. 

The brightness at 0.6 mm and the lack of detection 

at longer wavelengths suggest that the detected flux 

may include starlight reflected off of a circumplanetary disk with dimension comparable to the orbits 

of the Galilean satellites. We also observed variability 

of unknown origin at 0.6 mm. Future observations of 

Fomalhaut are planned following the HST Servicing 

Mission in May 2009 to obtain an improved orbit for 

the exoplanet and a near-IR infrared spectrum. 

On the Web

The ZODIPIC IDL package

asd.gsfc.nasa.gov/Marc.Kuchner/home.html

The exoplanet candidate Fomalhaut b 

lies in the plane of the Fomalhaut’s dust 

belt. It lies approximately 119 AU from 

the star and 18 AU from the dust belt.

Astronomers using the Hubble Space Telescope 

took the first visible-light snapshot of a planet 

orbiting another star. Fomalhaut b orbits inside the 

sharp inner edge of Fomalhaut’s debris disk. Credit: 

NASA, ESA, and Z. Levay (STScI)
Astrophysics Science Division: Research and Missions

26
27

Astrophysics Science Division: Research and Missions

excess of purely secondary expectations. This may suggest a contribution from an exotic primary source, 

such as the evaporation of small primordial black holes 

(PBH) with initial mass around 5 × 1014 g, or the annihilation of candidate dark matter particles. 

To continue this investigation with much greater sensitivity, the BESS-Polar instrument was developed for 

long-duration balloon flights over Antarctica. The 

BESS-Polar magnetic-rigidity spectrometer uses a 

unique superconducting magnet with thin coils and 

cryostat and a precision trajectory-tracking system. The 

charge and velocity of incident particles are measured 

by a plastic scintillator time-of-flight system with two 

layers at the top and bottom of the instrument and 

one layer below the tracker inside the magnet bore. 

A silica aerogel Cherenkov detector rejects light background particles. With geometric acceptances of ~ 0.3 

m2 sr, BESS and BESS-Polar are the largest balloonborne magnet instruments. In a single long-duration 

flight, the BESS-Polar exposure greatly exceeds that of 

the PAMELA satellite instrument.

GSFC is responsible for the outer scintillators, the 

instrument electronics, and the Cherenkov detector 

PMTs. BESS-Polar integration and testing take place 

at GSFC and GSFC co-leads launch and flight operations. 

BESS-Polar I flew for 8.5 days in 2004—at a transient 

period prior to solar minimum—and reported 1,512 

antiprotons. BESS-Polar II recorded data with the 

magnet energized for 24.5 days in 2007–2008, flying 

at solar minimum, when the sensitivity of the antiproton measurements to a low-energy primary component is greatest, and is expected to have detected ~

10,000 antiprotons. Depending on the antiproton energy, this is 10–20 times the combined BESS 1995/97 

statistics. The instrument performed very well, and 

analysis of the 13.5 terabytes of data obtained on 4.7 

billion cosmic-ray events is well underway. 

IV. Research and Development

Suborbital Projects

Balloon-borne Experiment with a 

Superconducting Spectrometer (BESS)

BESS is a highly successful U.S.-Japan program that 

uses elementary particle measurements to study the 

early universe. It provides fundamental data on the 

spectra of light cosmic-ray elements and isotopes. 

BESS is led jointly by GSFC (PI, John Mitchell) and 

KEK, the Japanese High Energy Accelerator Research 

Organization (PI, Akira Yamamoto). Hams and Sasaki 

are GSFC colleagues also working on the project. Collaborating institutions in the U.S. are the University of 

Denver and the University of Maryland, and in Japan 

the University of Tokyo, Kobe University, and ISAS/

JAXA. 

BESS measures the energy spectra of cosmic-ray antiprotons to investigate signatures of possible exotic 

sources, and it searches for heavier antinuclei that 

might reach Earth from antimatter domains formed 

during symmetry-breaking processes in the early universe. The BESS collaboration carried out nine conventional northern-latitude flights between 1993 and 

2002, recording 2,237 cosmic-ray antiprotons and 

confirming that the majority are secondary products 

of the interactions of primary cosmic-ray nuclei with 

interstellar gas. 

Flights near solar minimum in 1995 and 1997, however, observed low-energy antiproton flux slightly in 

BESS-Polar I data provide the most 

stringent reported test of the presence of 

heavier antinuclei in the current universe. 

The BESS-Polar II instrument nears the start of its 

2007 flight in Antarctica. Credit: NASA/BESS
Astrophysics Science Division: Research and Missions

28

for atomic processes by which nuclei are selected for 

acceleration. Exploratory measurements with lower 

statistics will extend to Z = 56. Super-TIGER will also 

measure, with excellent statistical precision, the energy 

spectra of the more abundant elements 14 ≤ Z ≤ 28 at 

energies 0.8 ≤ E ≤ 10 GeV/nucleon. These measurements will permit a sensitive test of the hypothesis that 

microquasars or other phenomena could superpose 

features on the otherwise smooth energy spectra. 

Super-TIGER builds on the smaller TIGER instrument that was flown from Antarctica in 2001 and 

2003 for a total of 50 days. It produced the first 

measurements of individual element abundances for 

31Ga, 32Ge, and 34Se. Super-TIGER measures the 

charge and energy of incident nuclei using three layers of plastic scintillator, together with Cherenkov 

detectors employing both acrylic and silica aerogel 

radiators. Scintillating optical fiber hodoscopes give 

the trajectories of individual particles to enable corrections for pathlength through the detectors, detector response maps, and interactions in the atmosphere 

and in the instrument. 

GSFC is responsible for both the acrylic and aerogel 

Cherenkov detectors, the scintillators, the mechanical 

structure of the instrument and payload, and the highSuper-TIGER’s measurements will 

permit a sensitive test of the hypothesis 

that microquasars or other phenomena 

could superpose features on the otherwise 

smooth energy spectra.

No antinuclei heavier than antiprotons have been detected in BESS flights through BESS-Polar I. These 

data have provided the most stringent reported test of 

the presence of heavier antinuclei in the current universe, with a 95% confidence upper limit of 2.7 × 10-7

for antihelium/helium. If no antihelium is detected in 

BESS-Polar II data, this will be lowered by about a 

factor of ~ 3.

BESS has also carried out the only search to date for 

antideuterons, which may be produced in local processes—including the evaporation of PBH and supersymmetric particle annihilation—and has reported an 

upper flux limit of 3 × 10-4 (m2

 s sr GeV/nucleon)-1. For 

logistics reasons, the BESS-Polar II instrument could 

not be recovered in 2008 after its flight, or during the 

2008/09 Austral Summer. Recovery is planned for the 

austral summer of 2009/10, when the instrument will 

be returned to GSFC for refurbishment.

Super Trans-Iron Galactic Element Recorder 

(Super-TIGER)

Super-TIGER is a new, large-area balloon-borne instrument under development by Washington University in St. Louis (PI, W. Robert Binns), Caltech, 

GSFC, and JPL. John Mitchell leads the Super-TIGER effort at GSFC and with co-investigators Christian, De Nolfo, Hams, Link, Sasaki, and Barbier (now 

at NASA HQ). 

Super-TIGER will measure the individual abundances 

of elements over the range 30 ≤ Z ≤ 42 with high statistical accuracy to test and clarify the emerging model 

of cosmic-ray origin in OB associations and models 

BESS-Polar II nears liftoff in 2007. Credit: NASA/BESS
29

Astrophysics Science Division: Research and Missions

(France) CESR Toulouse (France), and UNAM (Mexico). At GSFC, Mitchell is the Institutional PI and 

Link is a coinvestigator. Barbier led the CREAM effort at GSFC until his move to NASA Headquarters 

in 2007; he is now a collaborator. 

In a series of long-duration balloon flights, CREAM 

will accumulate the large exposure needed to measure 

the energy spectra of the most common elements up 

to about 1015 eV. At these energies, measurements 

have depended on the detection by ground-based instruments of the showers of particles produced by interactions of primary cosmic rays in the atmosphere. 

These indirect measurements can only infer the identity of the incident particle. Direct measurements by 

CREAM will provide invaluable information on cosmic-ray composition, as well as the calibration data 

required to interpret airshower results. 

The combined CREAM and airshower data will test 

models of Fermi shock acceleration of cosmic rays 

in supernova remnants. Standard models for this 

mechanism predict that a rigidity-dependent acceleration limit should be reached, resulting in a progressive composition change with increasing energy from 

dominance by light elements to dominance by heavier 

elements. CREAM measures the charge of incident 

voltage system. In addition, instrument and payload 

integration will be carried out at GSFC. 

Super-TIGER has a total area of 5.6 m2

 and is only 60 

cm thick to maximize its geometric acceptance. The 

detector layout and minimal column density give an 

effective geometry factor of 2.5 m2 sr at Z = 34—seven 

times larger than TIGER. Super-TIGER can accomplish its goals in two typical long-duration Antarctic 

flights, with the first planned for 2012. 

Super-TIGER is a forerunner of the ENTICE (Energetic Trans-Iron Composition Experiment) instrument on the OASIS (Orbiting Astrophysical Spectrometer in Space) mission. OASIS is under study 

with NASA funding as an Astrophysics Strategic Mission Concept and will be presented for consideration 

by the Astro2010 Decadal Survey. In a three-year 

mission, ENTICE would provide the first statistically 

significant elemental-abundance measurements in the 

actinide range.

Cosmic Ray Energetics and Mass (CREAM)

The balloon-borne CREAM instrument was developed for direct measurements of cosmic-ray spectra 

1 ≤ Z ≤ 26 at total energies greater than 1011 eV to 

test models of cosmic-ray acceleration and to measure 

the energy-dependent abundance ratios of secondary cosmic-ray species to their primary progenitors to 

test models of cosmic-ray transport and storage in the 

Galaxy. The CREAM collaboration includes the University of Maryland (PI Eun-Suk Seo), GSFC, Pennsylvania State University, Ohio State University, Ewha 

Woman’s University (Korea) KyungPook National 

University (Korea), KAIST (Korea) LPSC Grenoble 

Detector configuration of the Super-TIGER 

instrument. Credit: NASA/Super-TIGER

The 2007 CREAM-III launch from Antarctica 

Credit: NASA/CREAM
Astrophysics Science Division: Research and Missions

30

nants, imaging of radio lobes of AGN to determine intergalactic magnetic field, and direct imaging of faint 

AGN to study the hard X-ray background. 

The design of sensitive hard X-ray instruments has 

traditionally been very challenging. However, developments in mirror and detector technologies, coupled 

with long-duration ballooning, have made possible 

sensitive observations in the hard X-ray band. CdZnTe 

is used for the detector material due to its excellent energy resolution. The mirror is a multi-layer-foil grazing-incidence mirror with focal length of 8 meters, 

but otherwise similar to the mirror produced at GSFC 

for Suzaku. The very long focal length required can be 

readily accommodated by a balloon instrument. The 

InFOCuS gondola has been built to provide accurate 

pointing accuracy and stability to take advantage of 

the spatial resolution afforded by the system. Besides 

providing interesting science, InFOCuS is also used 

as a technology pathfinder for future hard X-ray technologies.

InFOCuS has flown four times since 2000, and the 

next flight—from Alice Springs, Australia—is scheduled for 2010, with improved pointing control and 

detectors. The InFOCuS team is a collaboration of 

Goddard, Nagoya University, University of Arizona, 

and University of Maryland.

The InFOCμS flight gondola for the 2004 

Campaign. Credit: NASA/GSFC

nuclei using a plastic scintillator timing detector and 

a silicon pixel detector. Depending on the energy and 

species of the incident particle, its energy is measured 

by a silica-aerogel Cherenkov camera (CREAM-III, 

-IV), a transition radiation detector (CREAM-I), or a 

tungsten-scintillating optical-fiber calorimeter (all versions). The geometric acceptance of the TRD is ~ 1.3 

m2sr and the effective geometric acceptance (including 

interactions) for the calorimeter is about ~ 0.3 m2

sr 

for protons and greater for higher Z nuclei. 

GSFC responsibilities are to provide an acrylic Cherenkov detector for rapid particle identification—to preferentially trigger the instrument on nuclei heavier 

than He—and a scintillating optical-fiber penetration 

detector that aids triggering on high-energy events 

and gives a reference time for the timing scintillators. 

GSFC also supports integration and test of CREAM 

as well as launch and flight operations. 

Originally designed for the anticipated ultra-long-duration balloon capability, CREAM has flown four times 

over Antarctica in conventional long-duration flights, 

accumulating 118.5 days of exposure: 2004–2005, 42 

days; 2005–2006, 28 days; 2007–2008, 29 days; and 

2008–2009, 19.5 days. The fifth flight of CREAM is 

planned for the austral summer of 2009–2010. For 

this flight, a new TRD is being prepared by CERN 

(Switzerland) and JINR (Russia) to facilitate improved 

measurements of secondary-to-primary ratios.

InFOCuS (International Focusing Optics 

Collaboration for μCrab Sensitivity)

InFOCuS is a balloon-borne hard X-ray instrument 

(Jack Tueller, PI). The instrument uses focusing optics 

to achieve high sensitivity in the 20–80 keV range, 

excellent spatial resolution (< 1 arcmin) and permits 

hard X-ray spectroscopy. Science goals include, for 

example, imaging sites of cosmic ray acceleration and 

imaging 44Ti nuclear lines in young supernova remDirect measurements by CREAM 

will provide invaluable information on 

cosmic-ray composition, as well as the 

calibration data required to interpret 

airshower results. 
31

Astrophysics Science Division: Research and Missions

were made with the DXS shuttle-attached payload 

that used a scanning dispersive spectrometer. 

The XQC, however, is the first broadband non-dispersive, high-resolution spectrometer to probe the entire 

X-ray-emitting range, from M-shell Fe emission at 70 

eV up to 2 keV where the diffuse emission becomes 

dominated by unresolved extragalactic sources. In addition, the XQC payload is the first—and currently, 

the only—spaceflight implementation of an X-ray 

calorimeter array.

The XQC spectrometer is based on a 36 pixel X-ray 

calorimeter array that was designed and produced at 

GSFC. Each pixel in the calorimeter array is relatively 

large at 2mm x 2mm, and has an energy resolution 

at O VII Ka of better than 8 eV FWHM. The detector array is operated at 50 mK using a small adiabatic 

demagnetization refrigerator built at the University of 

Wisconsin. The payload does not use an X-ray optic 

since this would significantly reduce the grasp of the 

X-ray Quantum Calorimeter (XQC) and 

Micro-X

The X-ray Quantum Calorimeter (XQC) is a broadband, non-dispersive X-ray spectrometer built to study 

the soft X-ray background in the band from 0.05 to 2 

keV. The ASD research team members include Porter, Kelley, Kilbourne, Bandler, Adams, Eckart, Smith, 

Serlemitsos, and Soong. Collaborating institutions include the University of Wisconsin (Madison), MIT, 

University of Miami, University of Florida and the 

National Institute of Standards and Technology.

The spectrometer was built to differentiate the spectral 

components that are thought to make up the ubiquitous soft X-ray background, including emission from 

the Local Bubble, the Galactic halo, and solar-wind 

charge exchange in the exo-atmosphere and the heliosphere. The superposition of these temporally and 

spatially variable sources can create a complicated 

spectral picture that requires high-resolution spectroscopy to unwind. Detailed spatial maps first were 

made with sounding rockets, then with ROSAT, and 

the first high-resolution spectra in the 0.25 keV band 

XQC payload is the first—and 

currently, the only—spaceflight 

implementation of an X-ray calorimeter 

array. Micro-X will provide some of the 

first detailed high-resolution spectra of a 

supernova remnant.

The XQC payload uses a 6x6 pixel X-ray calorimeter 

array develop and produced at GSFC. Each pixel in 

the array is 2 mm x 2 mm, and utilizes a 0.8-umthick HgTe X-ray absorber. The detector array has 

an energy resolution better than 8 eV FWHM at 

600 eV and has a nominal operating band from 

0.05 to 2 keV. Credit: NASA/XQC

Preliminary spectrum of the soft X-ray background 

centered at galactic coordinates 30°, +60° as 

observed with the XQC during its fourth flight in 

March 2008. The spectrum shows line emission 

from several highly charged ions and is likely a 

superposition of several emission mechanisms. 

Credit: NASA/XQC
Astrophysics Science Division: Research and Missions

32

and produced by GSFC and will be read out using a 

cryogenic SQUID multiplexer and room-temperature 

electronics jointly developed by GSFC and NIST. 

GSFC will also provide the refurbished SXS X-ray optic with 200 cm2

 collecting area at 1 keV and a 2.5 

arcmin PSF. 

Micro-X will provide some of the first detailed highresolution spectra of a supernova remnant, with about 

40,000 counts expected during the flight. The payload 

will be the first opportunity to utilize high-spectralresolution, broadband, spatial-spectral imaging, and 

will provide a glimpse of what we can expect from 

Astro-H and then IXO in the future.

Proto-EXIST

EXIST is a concept for an all-sky hard-X-ray imaging 

mission (see the mission concept section of this document for more information). ASD team members include Gehrels, Barthelmy, Tueller, Band, and Skinner. 

Proto-EXIST is a balloon-based instrument to develop the technology for the EXIST mission. It will fly in 

spring 2009 from Ft. Sumner, New Mexico. It is lead 

by Josh Grindlay (CfA), with significant contributions 

from Goddard. Goddard is developing the Command 

and Data Handling (C&DH) electronics in the frontend detector array electronics (i.e., everything after the 

detector ASIC). 

experiment, but is instead collimated to a one-steradian field of view. 

The XQC has flown four times since 1995, with the 

most recent flight in March 2008. The fourth flight 

used a detector array with four times the collecting 

area of previous flights and is based on technology 

developed for the Astro-E2 program. The data from 

the fourth flight is currently being processed, but preliminary results show significant contributions from 

C IV, O VII, OVIII, Fe XVII, and Fe XVIII. Previous 

flight have placed constraints on certain types of dark 

matter, and have detected and placed limits on Local Bubble emission from M-shell transitions in Fe IX, 

X, and XI. Flight five of the XQC is planned for late 

2009 and will use a new, refined version of the largearea detector design for flight 4.

The Micro-X payload is designed to be the first X-ray 

calorimeter payload using focusing X-ray optics. It 

uses significant design heritage from the XQC program, including a very similar adiabatic demagnetization refrigerator. However, the detector and readout 

technology are derived from the Constellation-X (now 

IXO) program. The Micro-X payload will use a 121 

pixel (11 × 11) X-ray calorimeter array with superconducting transition edge (TES thermistors) operating 

at 50 mK. It is designed to have an energy resolution 

of 2 eV (FWHM) across the energy band from 0.05 to 

2 keV. The Micro-X payload will use a focusing optic 

designed and produced at GSFC for the SXS sounding rocket that flew in 1989 and is the predecessor 

of the optics used for BBXRT, ASCA, Astro-E2, and 

Astro-H.

The Micro-X payload is scheduled to fly during 2011 

to observe the bright eastern knot of the Puppis-A supernova remnant. The detector array will be designed 

Each of the eight Detector Crystal Units (DCUs, 

left) is a 20 × 20 × 5mm CZT plus hybridizer board, 

plus ASIC. They plug into a Detector Crystal Array. 

Credit: NASA/GSFC

This photograph shows a single DCA plugged into 

an FPGA Controller Board (FCB), which holds 

eight of them. Four FCBs constitute the detector 

array for one of Proto-EXIST’s two telescopes. 

Credit: NASA/GSFC
33

Astrophysics Science Division: Research and Missions

Gamma-Ray Burst Polarimeter

The Gamma-Ray Burst Polarimeter (GRBP) is an 

instrument designed for a small satellite called MidSTAR-2 planned for launch by the U.S Naval Academy (Joe Hill, PI, and K. Jahoda, co-I). The GRBP 

utilizes Time-Projection Chamber (TPC) technology 

in a new way to make polarization measurements of 

X-rays in the 2–10 keV energy band. The TPC polarimeter enables the design of much higher sensitivity and wider field-of-view instruments. GRBP is designed to satisfy three requirements: 

•	 To demonstrate a new technology in a space environment for the first time.

The Proto-EXIST balloon gondola, built by 

NASA’s Marshall Space Flight Center, will hold 

two coded-aperture telescopes (orange) and a star 

camera (green) for absolute attitude information. 

The coded-aperture masks at the front end of the 

telescopes are not shown in this sketch. Credit: 

NASA/MSFC

•	 To measure the polarization of the Crab Nebula, 

the only source for which the polarization has 

been conclusively measured in the X-ray band.

•	 To measure the polarization of 5 to 10 gamma-ray 

bursts (GRBs) in a two-year mission.

Polarization measurements of even a handful of GRBs 

will allow us to discriminate between different theories 

about the mechanisms behind these hugely powerful 

and enigmatic events. A demonstration of the GRBP 

instrument will increase the technology readiness level 

for future missions. This year, the GRBP team has designed and built one of the four GRBP modules. The 

module has been assembled and is currently undergoing test. Four of the six electronics boards have been 

prototyped and are being tested in the lab. The preamp board is in fabrication, with expected delivery at 

the end of January 2009. The design of the Command 

and Data Handling (C&DH) board is still in progress 

due to several changes in flight opportunity.

The design of the flight detector enclosure and detectors is almost complete but will not be completely finalized until we successfully complete the end-to-end 

This image shows the assembly of the first detector 

module for the Gamma-Ray Burst Polarimeter. 

Two detectors (3 × 6 cm2

 area and 5 cm deep) 

share a single drift electrode (center) and the copper 

field-shaping electrodes on either side. Gold wire 

will complete the field shaping over the top of the 

detectors. Credit: NASA GSFC/USRA-CRESST/

Southern Illinois Univ. at Carbondale
Astrophysics Science Division: Research and Missions

34

test at the beginning of March 2009. The flight designs of three of the six electronics board are complete 

and are in layout with delivery is expected at the end 

of April 2009.

The MidSTAR-2 spacecraft has not yet been manifested, so the team has been investigating alternative 

launch opportunities. The most likely scenario that is 

compatible with the instrument delivery schedule is 

that GRBP will be tested on a sounding rocket. This 

will accomplish the first two goals and prove the design such that a satellite version could be built to measure the polarization of GRBs.

X-ray Advanced Concepts Testbed (XACT)

XACT is a new suborbital X-ray payload being developed at GSFC to test and advance Technology Readiness Levels (TRL) of several technologies that could 

enable future missions (Gendrau, PI). The scientific 

objective of XACT is to measure the X-ray polarization properties of the Crab Nebula, the Crab pulsar, 

and of the accreting binary Her X-1. Polarimetry is a 

powerful tool for astrophysical investigation that has 

yet to be exploited in the X-ray band, where it could 

provide unique insights into neutron stars, black holes, 

and other extreme-physics environments. 

With powerful new enabling technologies, XACT 

will demonstrate X-ray polarimetry as a practical and 

flight-ready astronomical technique. The technologies 

XACT will bring to flight readiness will also provide 

important new capabilities for NASA missions in 

space-based X-ray spectroscopy, timing and photometry. XACT combines new ultra-lightweight optics, 

advanced photoelectric X-ray polarimeters, and novel 

calibration sources in a standard sounding rocket payload.

The XACT optics—lightweight concentrators optimized for unresolved sources—will provide the largest focused X-ray-collecting area ever achieved on 

a sounding rocket. Currently under development at 

GSFC, they will have the largest focused collectingarea-to-mass ratio ever flown, enabling future spacebased missions that require truly enormous throughput and low background.

The XACT polarimeters are the latest innovation in 

photoelectron tracking devices that combine a large 

polarization response with high quantum efficiency 

to achieve unprecedented sensitivity. ASD scientists 

recently originated this polarimetry technique, based 

on the negative-ion Time Projection Chamber (TPC), 

and are currently developing it for astrophysical and 

heliospheric missions in the 1–100 keV band. The 

TPC polarimeter was the basis for two recent Small 

Explorer proposals and is under development with 

GSFC internal R&D funds and in four ongoing ROSES-funded projects. XACT will leverage these efforts 

to deliver the polarimeters at a low incremental cost.

Polarization measurements of even 

a handful of GRBs will allow us to 

discriminate between different theories 

about the mechanisms behind these 

hugely powerful and enigmatic events.

XACT will demonstrate X-ray 

polarimetry as a practical and flight-ready 

astronomical technique.

This graph shows parameters relevant to XACT 

sensitivity as a function of energy: effective area 

of XACT optics, a pair of 25-cm diameter X-ray 

concentrators (blue), quantum efficiency (red) and 

modulation (green) of the TPC. Credit: NASA/

GSFC
35

Astrophysics Science Division: Research and Missions

 XACT will demonstrate in-flight calibration using a 

modulated electronic X-ray source that can be pulsed 

for arbitrary and commandable intervals. Such a source 

can be used to provide calibration information on 

demand. This minimizes the associated background 

and results both in higher sensitivity and observatoryscheduling freedom for future missions.

The XACT goals are accomplished with a simple flight 

plan that is well within the launch and recovery envelopes of a standard Black Brant IX at the White Sands 

Missile Range. The first launch will be in December 

2011 to observe the Crab. This will be followed by a 

second launch in June 2012 to look at Her X1.

Absolute Radiometer for Cosmology, 

Astrophysics, and Diffuse Emission 

(ARCADE)

The Absolute Radiometer for Cosmology, Astrophysics, and Diffuse Emission (ARCADE; Kogut PI) is 

a balloon-borne instrument to measure the absolute 

spectrum of the cosmic microwave background and 

diffuse radio continuum at the poorly measured centimeter wavelength band between the COBE/FIRAS 

measurements at millimeter wavelengths and radio 

surveys at long wavelength. ARCADE features a double-nulled instrument in a novel open-aperture cryogenic payload, with no windows between the cold (2.7 

K) optics and the ambient atmosphere. 

ARCADE measured the blackbody spectrum of the 

cosmic microwave background, finding a temperature 

T0 = 2.729 ± 0.004 K with precision approaching that 

of the COBE/FIRAS instrument, despite the balloon 

environment. A major find was the detection of an 

extragalactic radio background some six times brighter 

ARCADE measured the blackbody 

spectrum of the cosmic microwave 

background with precision approaching 

that of the COBE/FIRAS instrument, 

despite the balloon environment. 

ARCADE takes flight July 2006. Credit: NASA/

ARCADE

The ARCADE payload is prepared for launch at 

Columbia Scientific Balloon Facility in Palastine, 

Texas. Credit: NASA/ARCADE
Astrophysics Science Division: Research and Missions

36

GHz). It will detect the signature of inflationary gravity waves to a factor of three fainter than the lowest 

value predicted by inflationary models. The unbiased 

survey of sub-millimeter polarization will also provide an important probe of the interstellar dust cirrus 

and the large-scale structure of the Galactic magnetic 

field.

Absolute Color Calibration Experiment for 

Standard Stars (ACCESS)

ASD scientists Rauscher and Woodgate are collaborating with Johns Hopkins University in a series of rocket-borne suborbital missions to provide observations 

than can be accounted for from the integrated emission of known populations of faint radio sources. 

ARCADE also produced a number of technological 

innovations, including the development of a black absorbing paint, a calibration target with reflection less 

than -40 dB within a height 0.7l, and the demonstration of fully cryogenic open-aperture optics for a new 

generation of far-IR instrumentation.

Primordial Inflation Polarization Explorer 

The Primordial Inflation Polarization Explorer (PIPER) is a new mission to measure the polarization of 

the cosmic microwave background to search for the 

signature of primordial gravity waves excited by an 

inflationary epoch in the early universe. Alan Kogut 

is the PI, and ASD team members include Benford, 

Chuss, Fixsen, Hinderks, Hinshaw, Moseley, Staguhn, 

and Wollack. 

PIPER achieves unprecedented sensitivity by combining several technologies pioneered by Goddard researchers.

•	 Large-format bolometric detectors. PIPER will fly 

5,120 transition-edge superconducting bolometers in a Backshort-Under-Grid (BUG) architecture.

•	 A Variable-Delay Polarization Modulator (VPM) 

injects a time-dependent phase delay between orthogonal linear polarizations to cleanly separate 

polarized from unpolarized radiation. 

•	 Open-aperture cold optics. PIPER’s twin telescopes fit within the old ARCADE dewar and will 

operate at 1.5 K to provide background-limited 

sensitivity.

PIPER will map the northern sky in both linear and 

circular polarization, at wavelengths 1500, 1100, 850, 

and 500 mm (frequencies 200, 270, 350, and 600 

PIPER will detect the signature of 

inflationary gravity waves to a factor 

of three fainter than the lowest value 

predicted by inflationary models.

PIPER sensitivity (red) compared to the gravitational 

wave signal predicted by WMAP (blue band). 

PIPER is an order of magnitude more sensitive 

than the European Space Agency’s planned Planck 

mission. Credit: NASA/PIPER

Researchers at GSFC and Johns Hopkins are 

collaborating on development of the ACCESS 

detector system. Credit: NASA/ACCESS
37

Astrophysics Science Division: Research and Missions

of standard stars for the Joint Dark Energy Mission 

(JDEM). The Absolute Color Calibration Experiment 

for Standard Stars (ACCESS; Kaiser, PI) will transfer 

the National Institute of Standards and Technology 

(NIST) absolute calibration standards to the bright 

stars Vega and Sirius with an accuracy and precision 

of < 1%. 

Establishing spectrophotometric standard stars to this 

precision is a critical requirement of type Ia-supernovae-based dark energy investigations, and it improves 

both the absolute and relative calibration that is the 

underpinning of the standard-star network and the 

basis of astrophysical calibrations. ACCESS also extends our understanding of stellar physics through observations of A-stars and cool stars.

GSFC is providing the ACCESS detector system (DS). 

The ACCESS DS leverages NASA’s substantial investment in JWST and HST detectors. The focal plane 

array will be a 1K × 1K HgCdTe device, with the 

composition tailored to produce a long-wavelength 

cutoff at ~ 1.7 mm, and the CdZnTe growth substrate 

removed to provide high near-IR quantum efficiency 

and response through the visible to the near UV. Such 

devices have been pioneered for the HST/Wide Field 

Camera 3 (WFC3) program by Teledyne Imaging 

Sensors (TIS). The band gap corresponding to the 1.7 

mm cutoff yields low dark current at operating temperatures near 150K.

Ongoing work focuses on requirements development. 

In particular, the team is writing the functional and 

performance specification for the SIDECAR application specific integrated circuit (ASIC). Although 

the SIDECAR itself will be selected from non-flight 

JWST inventory and the thermal/mechanical interfaces are therefore defined, ACCESS requires some 

modifications to existing software. Because the ACCESS detectors will be selected from existing WFC3 

inventory, modifying the SIDECAR software drives 

the critical path.

Technology Development

X-ray Calorimeter Development

An X-ray calorimeter determines the energy of an 

incident X-ray photon by measuring a small change 

in temperature. Three types of X-ray calorimeters 

presently dominate the field, each characterized by 

the thermometer technology. The first two types use 

temperature-sensitive resistors: semiconductors in the 

metal-insulator transition and superconductors operated in the superconducting-normal transition. The 

third type uses a magnetic thermometer. These can be 

considered the three generations of X-ray calorimeters, 

although further development of each is proceeding.

The Soft X-ray Spectrometer (SXS) on Astro-H, expected to launch in 2013, will use an array of silicon 

thermistors with HgTe X-ray absorbers that will operate at 50 mK. Both the semiconductor and superconductor calorimeters have been implemented in 

small arrays. Kilopixel arrays of the superconducting 

calorimeters are just now being produced, and it is 

anticipated that much larger arrays will require the 

non-dissipative advantage of magnetic thermometers. 

Goddard Space Flight Center is the only institution 

playing a leading role in the development of each of 

the three dominant X-ray calorimeter technologies. 

The ASD microcalorimeter team includes Simon BanEstablishing standard stars to this 

precision is a critical requirement of 

type Ia-supernovae-based dark energy 

investigations.

This HAWAII-1R SCA from Teledyne Imaging 

Sensors is used in Hubble’s Wide Field Camera 3. 

It’s similar to the one that will be flown by ACCESS. 

Credit: NASA.
Astrophysics Science Division: Research and Missions

38

dler, Rich Kelly, Caroline Kilbourne, Scott Porter, 

postdocs Megan Eckart and Steve Smith, and coop 

student Jack Sadleir. 

The main development in the silicon-thermistor calorimeters since XRS/Suzaku has been in their HgTe 

absorbers. GSFC has been working closely with EPIR, 

a company that was awarded an SBIR contract to 

develop HgCdTe material with substantially lower 

heat capacity than the material used for XRS that yet 

thermalizes the energy of X-ray photons reproducibly 

and uniformly. Although process refinement is still in 

progress, the GSFC calorimeter team plans to use this 

material in the SXS array. Better than 4 eV resolution 

at 6 keV has been achieved using samples of EPIR 

HgCdTe in the size needed for SXS (0.83 mm wide). 

The SXS thermistor array itself is based heavily on the 

XRS design, but will include better heatsinking to reduce the impact of cosmic-ray heating. 

Over the past few years, Goddard has developed a 

microcalorimeter design that incorporates a micronsthick Au or Au/Bi absorber, designed to thermalize 

the absorbed energy quickly, with a superconducting transition-edge sensor (TES) made from a Mo/

Au proximity-effect bilayer. In this novel design, the 

absorber makes direct contact with the TES only in 

normal-metal regions that are used to reduce noise in 

these sensors, which allows the use of a high-quality 

electroplated gold layer as the foundation for the absorber. A further constraint, that the high-conductance 

absorber not electrically short out the sensor, results in 

an unusual T-shaped geometry for the contact. 

These devices consistently achieve energy resolutions 

of 2–3 eV FWHM at 6 keV. The pixels are sufficiently uniform that a 2x8 SQUID multiplexer read-out 

demonstration, done in collaboration with colleagues 

at the National Institute of Standards and Technology, 

achieved better than 3 eV resolution in all 16 pixels using the common biasing inherent to the design of the 

electronics. Fabrication of the first 32 × 32 arrays has 

just been completed, and such arrays with the highdensity microstrip wiring needed to read each pixel in 

the array will be produced in spring 2009. 

Goddard has also developed position-sensitive TES 

calorimeters. These devices join multiple absorbers to 

a single TES via different thermal links, and the pulse 

shape is used to determine which absorber received 

the X-ray photon. Four-absorber versions have demonstrated an energy resolution of 6 eV at 6 keV, and 

variations with larger absorbers and with more absorbers are being studied.

Goddard is part of an international collaboration 

(including Brown University, Heidelberg University, 

NIST/Boulder and PTB/Berlin) to develop magnetic 

calorimeters. The Goddard emphasis has been on deGoddard Space Flight Center is the 

only institution playing a leading role 

in the development of each of the three 

dominant X-ray calorimeter technologies.

Mn Ka spectrum measured with a silicon-based 

calorimeter using improved HgCdTe X-ray absorber 

material. Resolution better than 4 eV has been 

achieved in many pixels compatible with the design 

of the SXS of Astro-H.

This is electron micrograph of a uniform TES 

array with Au/Bi absorbers. The close-up view on 

the right shows an individual pixel. The absorber 

is cantilevered over the underlying substrate 

everywhere except in the T-shaped contact area.
39

Astrophysics Science Division: Research and Missions

signs that can be implemented in closely packed arrays. 

Goddard has been fabricating arrays of superconducting niobium meander inductors onto which a layer of 

magnetic material (Au:Er) is deposited. When a current is passed through the meander, a magnetic field 

is produced in the magnetic material. When an X-ray 

is absorbed, the heating changes the magnetic permeability, and therefore the inductance of the meander. 

The change in inductance of the meander changes the 

current both through the meander and through the input coil of the SQUID. The first magnetic calorimeter 

arrays with absorbers have achieved 5.4 eV resolution 

at 6 keV, and there remains potential to substantially 

improve on this in the near future, perhaps even to 

under 1 eV. Position-sensitive magnetic calorimeters 

analogous to the TES-based version are also under development.

X-ray Mirror Development: IXO and NuSTAR

Mirror technology development for the International 

X-ray Observatory (IXO), formerly known as Constellation-X, continues at GSFC and is led by Will 

Zhang. Zhang and his team have all but demonstrated 

that the thermal glass slumping technology will not 

Results of a two-column by eight-row multiplexing 

demonstration using a Goddard array and NIST 

SQUID multiplexing electronics at NIST. The black 

points show histograms of Mn Ka X-rays from an 

55Fe source for each pixel acquired simultaneously, 

with vertical offsets for clarity and fits overlaid in 

blue/red.

Schematic of a position-sensitive calorimeter, in 

which four pixels are formed from four absorbers 

and a single TES. The graph shows 6 keV pulses 

measured experimentally by such a device. The 

absorbers are each connected to the TES with a 

different thermal link (G), so X-ray events in the 

four absorbers produce different pulse shapes. 

This view shows the read-out circuit for meanderbased magnetic calorimeters. An X-ray absorber can 

be affixed to each meander, making possible very 

large, close-packed arrays. 
Astrophysics Science Division: Research and Missions

40

only meet the original 15′′ requirement, but also most 

likely will be able to achieve the 5” goal.

In November 2007, a pair of mirror segments were 

aligned and bonded for the first time and tested in an 

X-ray beam at ASD’s X-ray beamline in Area 200 at 

GSFC, when an image quality of 14.7′′ was achieved. 

This result agrees well with theoretical predictions 

based on optical metrology of the mirror surfaces and 

validates the approach adopted for IXO. 

Another significant development is the fabrication of 

“forming mandrels” in a collaborative effort between 

ASD and the Goddard Engineering Directorate. Up 

until very recently, forming mandrels only meeting the 

original 15′′ requirements were available. In the last 

six months, this collaborative effort has been able to 

fabricate for the first time a mandrel that meets the 

5′′ IXO requirement. This mandrel is being used to 

develop techniques to fabricate mirror segments that 

will meet the 5′′ requirement, including the slumping 

and coating processes.

The Nuclear Spectroscopic Telescope Array (NuSTAR) 

is a Small Explorer under development (Harrison/

Caltech, PI). ASD/GSFC is a member of the team, 

with the responsibility of providing glass mirror substrates using a glass-forming technology that has been 

developed in the last few years at GSFC by Zhang. 

These substrates will be shipped to the Danish Space 

Research Institute to be coated with multi-layers to 

enhance their reflectivity of high-energy (10–80 keV) 

X-rays. They will then be shipped to Columbia University for alignment and assembly into two mirror 

modules. 

Work began in February 2008 with facility modification and procurement of ovens and other necessary 

equipment. The work completed on schedule and 

within budget. The entire mirror substrate production 

facility, located in Building 22 at Goddard, became 

fully operational on September 1, 2008. Production 

preparation work and personnel training took place in 

the subsequent three and a half months. 

The thermal glass slumping technology 

will not only meet the original 15′′

requirement, but also most likely will be 

able to achieve the 5′′ goal.

Left: The X-ray test chamber in Area 200, where 

a pair of mirror segments was tested in November 

2007. Right: The resulting X-ray image and a graph 

of the encircled energy fraction vs. diameter for it. 

Credit: NASA/GSFC

Left: The IXO mandrel is being figured on a 

polisher in Building 5 at GSFC. Right: A surface 

contour map of the finished mandrel, which meets 

IXO requirements for making 5′′ mirrors. Credit: 

NASA/GSFC

Left: The NuSTAR mirror substrates production 

facility in Building 22, Room 198. The facility 

includes clean tents, ovens, and load carts. This chart 

shows the axial figure quality distribution (arcsec) 

of the first batch of mirror substrates produced on 

December 15, 2008. The red dashed line represents 

the NuSTAR requirement. Credit: NASA/GSFC
41

Astrophysics Science Division: Research and Missions

fractive X-ray optics as well as IXO/Constellation-X 

X-ray optics.

Laboratory Development of X-ray Polarimetry

The charge signal associated with the photoelectric absorption of X-rays has been exploited over many years 

for imaging, timing, and spectroscopy. It has long been 

recognized that a polarization signature is also present, 

as the photoelectron direction is correlated with the 

photon electric-field vector.

Measuring the direction of the photoelectron track in 

a practical detector is complicated by the fact that the 

photoelectron track length is small (< 10-2) compared 

to the photon absorption depth. However, Costa et al. 

(2001) demonstrated that a gas proportional counter 

with a finely pixelated readout can make polarization 

measurements in the X-ray band. Careful choices of 

gas composition and pressure allow tuning of the photoelectric path length; current practical technologies 

require that the photoelectron track be between 100 

and 1000 microns in the band of interest.

Over the last few years, members of the X-ray Astrophysics laboratory (Jahoda, Black, Hill, Deines-Jones, 

Swank) have concentrated on exploiting photoelectric 

polarimetry in geometries suitable for Explorer class 

missions. Initial efforts led to the use of thin-film transistor arrays to create readout planes which could, in 

principle, be arbitrarily large (Black, 2003; Black et 

al., 2004) and led to a 2003 SMEX proposal: the Advanced X-ray Polarimeter. 

Recent efforts have focused on increasing the efficiency by exploiting a Time Projection Chamber readout 

(Black et al., 2007). In this geometry, the track is drifted perpendicular to the photon direction of incidence 

to a readout plane. This innovation decouples detector 

The first batch of flight mirror substrates was produced 

on December 15, 2008, as scheduled. The production 

will continue until December 2009, when 4,815 mirror substrates (plus 15% spares) will have been delivered. 

GSFC 600-meter X-ray Beamline

The GSFC 600-meter X-ray beamline is located at 

the Goddard Geophysics and Astronomy Observatory (GGAO) about five miles from Goddard’s main 

campus. It was originally built for technology development associated with the Black Hole Imager (BHI) 

vision mission, but now also supports optics testing 

for IXO and Astro-H. Keith Gendreau of the X-ray 

Astrophysics lab is the beamline’s lead scientist.

The beamline consists of a 10-inch diameter steel vacuum pipe 600 meters long with three stations. An X-ray 

source building at one end supports a number of X-ray 

sources, including Oxford tubes, Manson sources with 

standard vacuum fittings. 

An optics building located 150 meters down the pipe 

from the X-ray source building has a 1m-class vacuum 

changer, where X-ray optics or other experiments can 

be placed in the beam. Another 450 meters down the 

pipe is a third building containing a 1m × 4m chamber, followed by an X-ray CCD detector. 

This longer chamber supports testing of X-ray optics 

with focal lengths up to 10 meters. The longer chamber is used primarily to support IXO and Astro-H 

development, but it can also handle sounding rocket 

payloads. 

Each station of the beamline is powered and has phone 

and Internet access. The facility can support remote 

testing control through the Internet links. Gendreau 

and collaborators have obtained X-ray fringes using a 

grazing-incidence X-ray interferometer in this facility. 

They have also demonstrated diffraction-limited reEach station of the beamline is 

powered and has phone and Internet 

access. The facility can support remote 

testing control through the Internet links.
Astrophysics Science Division: Research and Missions

42

depth (i.e., efficiency) from the ability to image the 

track (polarization sensitivity).

The TPC geometry can be adapted to the focal plane 

of an X-ray optic to study the polarization of faint 

persistent sources (as is proposed in the Gravitational 

and Extreme Magnetism SMEX) as well as for the 

large-area, large-field-of-view detectors that would be 

required to study polarization from bright transients 

(Hill et al., 2007).

Coded-Mask and CdZnTe Detector 

Development 

It is not possible to focus gamma-rays with current 

technology, so the wide-field Burst Alert Telescope 

(BAT) on Swift uses a technique called coded-aperture 

imaging to image and localize incoming gamma-rays. 

Gamma rays are detected at the focal plane by 32,768 

pieces of CZT. 

ASD (Barthelmy, Tueller, Okajima) has three development efforts to improve CZT detectors for new mission applications:

•	 the electronics and packaging for the Proto-EXIST and EXIST missions;

•	 a strip detector for the InFOCuS balloon instrument;

•	 and a pixelated detector for homeland security 

uses. 

The proto-EXIST and EXIST effort are described elsewhere. 

The CZT strip detector for InFOCuS is a 20-micron 

2-D pattern of strips on 2mm CZT. ASD is working with Goddard’s Engineering Directorate on this 

effort for the actual electrode fabrication on the CZT 

material. This InFOCuS detector is 26 × 26 × 2mm 

and uses the XA1 ASIC that we have previously used 

in the pixelated InFOCuS detector and for the SwiftBAT detector array. There is also a parallel effort to 

use the newer VATAGP7 ASIC from Gamma MedicaIDEAS, Inc.

The homeland security effort involves a 20 × 20 ×

5mm CZT crystal with an 11 × 11 pattern of pixelated electrodes. Takashi Okajima (code 662) is working 

with the Engineering Directorate on this effort.

Detectors for Gamma Ray and Neutron 

Imaging

Stanley Hunter is leading a group that is developing 

the Three-Dimensional Track Imager (3-DTI) for 

gamma-ray astronomy. The 3-DTI is a large-volume 

time-projection chamber (TPC) with two-dimensional micro-well detector (MWD) readout. Each well of 

the MWD is a gas proportional counter with gain. 

The 3-DTI development is motivated by the technology requirements for a future gamma-ray telescope 

that will provide optimum angular resolution over 

the energy range from 0.5 to 500 MeV. Gamma-ray 

imaging, i.e., determination of the photon incident 

direction, energy, and polarization, is accomplished 

by tracking the Compton recoil electron or electronpositron pair resulting from photon interactions in the 

xenon TPC gas. 

Beginning in 2007, this group has received funding 

from the Defense Threat Reduction Agency (DTRA) 

to extend the 3-DTI technology to imaging of neutrons from passive and active interrogation of special nuclear materials (SNM). The performance goal 

An example of a 3He(n,p)T interaction recorded by the 3-DTI/NIC. The left and right panels show the X-Z 

and Y-Z projections, respectively, from the 3-DTI. The incident neutron is indicated by the white arrow. The 

recoil proton (long track) and triton (short track) fragments are clearly seen emanating from the interaction 

vertex. The other track images are probably elastic scattering of neutrons on 3

He nuclei. 
43

Astrophysics Science Division: Research and Missions

of the Neutron Imaging Camera (NIC) is to detect 

small amounts (~1 kg) at moderate (30–50m) standoff distances in short (~5 minute) integration times. 

The NIC application replaces the Xe gas in the 3-DTI 

with 3

He and tracks the proton and triton fragments 

resulting from neutron capture on 3He, 3He(n,p)T. 

During the last year, the group has built and tested a 

10 × 10 × 15 cm3

 3-DTI prototype. This prototype 

has a 10 × 10 cm2

 MWD readout with 512 channels 

of charge amplifier and transient digitizer electronics. 

Recently, we have been testing this NIC prototype in 

a neutron beam at the Naval Surface Warfare Center 

Carderock Division (NSWC/CD). Analysis of many 

3

He(n,p)T interactions recorded by the 3-DTI/NIC 

gives a measure of the device’s angular resolution of 

about 11 degrees. The next phase of this work is to 

design, build, and test a 25 × 25 × 50 cm3

 prototype 

of the 3-DTI/NIC. 

Phase Fresnel Lens Development for X-ray & 

Gamma-ray Astronomy

As compared to other wavelengths, astronomical observations in the X-ray and gamma-ray energy regimes 

have been constrained by limited sensitivity and angular resolution. Diffractive optics, specifically Phase 

Fresnel Lenses (PFLs) have high throughput at hard 

x-ray and gamma-ray energies and in principle can 

achieve diffraction-limited angular resolution, translating into milli-arcsecond to micro-arcsecond imaging in the X-ray and gamma-ray bands. Furthermore, 

PFLs are capable of being scaled to large, meter-size 

dimensions, leading to dramatic improvements in sensitivity. 

The fabrication and characterization of the imaging 

performance of PFLs geared towards astronomical 

use have been hampered by the inherent long focal 

lengths and fabrication of macroscopic lenses with 

the needed micro-feature size. The availability of sufficiently long x-ray beam lines and advances in MicroElectrical-Mechanical System (MEMS) fabrication 

techniques have ameliorated these impediments in regards to ground-based performance characterization. 

Advances in formation-flying spacecraft systems make 

an eventual mission feasible, and a team of scientists 

from ASD/GSFC and the University of Maryland are 

collaborating with the GSFC Guidance, Navigation, 

and Control (GN&C) Systems Engineering Branch, 

under a GSFC IRAD award, to further develop the 

formation-flying aspects. The team includes Krizmanic, Streitmatter, Arzoumanian, Gendreau, and Gehrels 

at GSFC, and Badilita, Ghodsssi, Morgan and Skinner at Maryland.

The University of Maryland has employed gray-scaled 

lithography to fabricate silicon PFLs in a scalable format suitable for astronomical instrumentation, and 

the team has measured near diffraction-limited performance with high efficiency in focusing 8 keV X-rays 

at the GSFC 600-meter Interferometry Testbed. The 

results demonstrate performance approximately a factor of 2 away from the diffraction limit, corresponding to an angular resolution of 25 milli-arcseconds, 

and with a measured absolute efficiency of 38% at 8 

keV, which is 76% of the theoretical maximum that 

includes absorptive effects. Furthermore, a previously 

unseen interference effect induced by our specific implementation of these PFLs that is responsible for the 

reduction in measured efficiency has been observed 

and characterized. Second generation PFLs have been 

Advances have been made in 

overcoming one of the main limitations 

of purely diffractive optics, the narrow 

bandwidth within which the superb 

angular resolution is obtained. 

A prototype PFL fabricated at the University of 

Maryland using gray-scale lithography. Credit: 

Univ. of Maryland
Astrophysics Science Division: Research and Missions

44

fabricated and tested at their design energy of 17.4 

keV and complete characterization is in progress.

Advances have been made in overcoming one of the 

main limitations of purely diffractive optics, the narrow bandwidth within which the superb angular resolution is obtained. The solution to this chromaticity 

problem is obtained by introducing a refractive component along with the PFL to construct an achromat. 

The refractive component is fabricated at GSFC using 

diamond turning and initial experiments have used a 

refractive component to alter the focal length of our 

8 keV PFL, bringing the performance closer to the 

diffraction limit. Experimentation in the near future 

will incorporate a true achromat and demonstrate 

near diffraction-limited performance over a much 

larger energy range as compared to purely diffractive 

optics. These results will demonstrate the superior imaging potential in the x-ray/gamma-ray energy band 

for PFL-based optics in a format that is scalable for 

astronomical applications.

Far-Infrared Detectors

The past decade has seen dramatic advances in many 

areas of long wavelength astrophysics. WMAP, following the great successes of Cosmic Background Explorer (COBE), has confirmed our general understanding 

of the early universe and allowed us to quantify critical 

parameters — its age, composition, and early evolution. Spitzer has provided an extraordinary imaging 

and mid-infrared spectroscopic capability, which has 

resulted in an increasingly improving picture of the 

evolution of galaxies over the life of the universe. Herschel will be launched soon, and will provide our first 

large-scale look at the high-redshift universe in the 

submillimeter. JWST, to be launched in a few years, 

will provide a window into the epoch of galaxy formation to clarify the processes that produced the present 

universe. 

Future far-infrared and millimeter facilities will play 

an important role in clarifying and extending this 

work. More than half the power of high-luminosity 

galaxies is emitted in the rest-frame far infrared, so far 

infrared and submillimeter imaging and spectroscopy 

is required for a full understanding of the physics of 

these systems. The next steps in NASA’s profoundly 

The imaging performance of missions employing 

PFL-achromats compared to other telescopes. The 

MASSIM mission is designed to perform milliarcsecond imaging in the X-ray band. Credit: 

MASSIM Strategic Concepts Proposal, Gerry 

Skinner, PI

Left: The GISMO detector array. Right: MUSTANG detector array.
45

Astrophysics Science Division: Research and Missions

successful science program are currently being developed and the priorities for the space missions, supplemented by suborbital missions, being established. 

SOFIA, now nearing completion, will be a key facility for imaging and spectroscopic follow-up of Spitzer 

and Herschel discoveries. Measurements of the polarization of the CMB promise to allow us to distinguish 

among models of the first instants of our universe. Further in the future, great advances in sensitivity, angular 

resolution, and overall instrument capability will be 

realized by large cryogenic telescopes in space, such as 

SAFIR, SPIRIT, and SPECS. High-performance farinfrared detector arrays are required for all this high 

priority work. 

The far-IR instrument development group in ASD 

(Benford, Chuss, Moseley, Staguhn, Voellmer, Wollack) have ongoing research projects to develop, implement, and field these detector arrays. Our large-format 

filled arrays will enable major advances in space-borne, 

sub-orbital, and ground-based infrared, far-infrared 

and sub-millimeter instrumentation. 

One recent success has been the development of a long 

wavelength (2 mm) camera based on a 128-element 

close-packed planar bolometer array that uses novel 

superconducting thermistors read out by SQUID 

multiplexers. This instrument, named GISMO, has 

been used for observations on a ground-based telescope, where it has already provided a great advance in 

our knowledge of the technology and produced new 

astronomical measurements. Its detector array is designed to be able to scale to 1,280-pixel arrays. 

We have also fielded the detector subsystem for the 

MUSTANG 3 mm camera, a facility instrument at 

the Green Bank Telescope. Its detector array is smaller 

and less scalable than GISMO’s. However, its observing runs have also produced cutting-edge high-resolution observations at long wavelengths. 

Large-format Bolometer Arrays for Astronomy 

and Cosmology

The last decade has seen revolutionary increases in 

the utility of submillimeter and millimeter observations, both for cosmological studies and for large-scale 

surveys of our galaxy. This increase in scientific performance has resulted in rapid increases in observing 

speed that have been driven by exponential growth in 

the performance and size of detector arrays for the l > 

100 μm spectral range. 

The detector group in the Observational Cosmology 

Laboratory (Benford, Chuss, Moseley, and Wollack, 

with Christine Allen from Engineering) has been centrally involved in the production of high-performance 

The far-IR instrument development 

group’s large-format filled arrays 

will enable major advances in spaceborne, sub-orbital, and ground-based 

infrared, far-infrared and sub-millimeter 

instrumentation.

The Orion KL region as viewed by GISMO (left) 

and MUSTANG (right).

A combined observation using both detectors 

provided a new measurement of the thermal-tononthermal spectral-energy distribution of the Orion 

nebular region (Dicker et al., in preparation). 
Astrophysics Science Division: Research and Missions

46

bolometer arrays since the 1980s. In the early 1980s, 

they developed processes that allowed the fabrication 

of large arrays of bolometers with performance near 

theoretical limits. Detector arrays were developed for 

use on the Kuiper Airborne Observatory, and later 

they were provided for applications in submillimeter 

spectrometers and imagers for use on the Caltech Submillimeter Observatory (CSO) and the James Clerk 

Maxwell Telescope. These arrays were among the first 

large arrays to be applied at these wavelengths, and 

with their first results, showed the promise of large arrays, even with existing facilities. 

In the first years of this decade, the GSFC team developed a 12 x 32 detector array for the HAWC facility instrument on SOFIA. The prototype array in this 

development became the SHARC-II detector for the 

CSO, where it is a facility instrument, and remains the 

highest-performance 350 μm receiver in operation. 

In the past 4 years, GSFC has transitioned almost 

completely to transition-edge (superconducting) sensor (TES) detectors and has produced the detector 

systems for the Atacama Cosmology Telescope (ACT). 

This instrument, using three 32 x 32 arrays— the largest in use—is in its first year of operation, measuring 

the small-scale fluctuations in the CMB and SunyaevZeldovich (SZ) effect. The GSFC group has several 

arrays in the field, where they are demonstrating the 

detector technology and producing useful science; see 

the previous section on far-IR detectors for detailed 

description of these instruments and their scientific 

results. The success of this development is due to the 

strong fabrication and test capability of GSFC combined with a close collaboration with NIST (Boulder) 

for SQUID-based amplifiers and multiplexers.

With the increasing format of the detector arrays, the 

engineering of the array system is an increasingly large 

element of the development program. For the past 

three years, the GSFC team has been developing integrated submillimeter- and millimeter-wavelength arrays based on the NIST SCUBA II 32 x 40 multiplexer. 

While the SCUBA II instrument is in its early stages 

of demonstration, the detectors developed for it are 

not easily modified for low-background applications 

encountered from space, airborne, and balloon-based 

imagers and spectrometers. Therefore, the GSFC team 

is developing versatile arrays that can be optimized for 

a wide range of backgrounds and wavelengths of operation but that will interface to the SCUBA II multiplexer. 

This development relies on a range of capabilities developed at GSFC over the past years: Micromachining 

of large arrays of 1μm thick detectors; production of 

low noise TES thermometers; and the production of 

interconnections between the detector and its multiplexer using superconducting indium bump bonds.

Most steps required to allow the production of this 

array are complete. The device has been successfully 

micromachined and the backshort/absorber array to 

create the correct electromagnetic conditions for pixel 

absorption has been demonstrated. The two remaining steps, whose developments are now in progress, 

are the production of superconducting through-wafer 

vias and the production of 0.1 K TES thermometers 

of the correct resistance. The schedule is to have a detector bump bonded to an engineering-grade array by 

The success of recent developments 

is due to the strong fabrication and test 

capability of GSFC combined with a 

close collaboration with NIST (Boulder) 

for SQUID-based amplifiers and 

multiplexers.

Bump-bonding technology is essential for the 

integration of large arrays to SQUID multiplexers. 

This figure shows a 32 x 40 dummy array which 

is bump bonded to a dummy multiplexer. This 

work builds on a GSFC bump-bonding capability 

developed in the production of the microshutter 

arrays for the NIRSpec on JWST. Credit: NASA/

GSFC
47

Astrophysics Science Division: Research and Missions

September 2009, with the production of detectors for 

the PIPER experiment in FY 2010.

These arrays, which can be produced with quantum 

efficiency near unity, are expected to be primary research tools for GSFC and our collaborators for several years. We plan to deploy them in the PIPER CMB 

polarization experiment, SAFIRE on SOFIA, and in a 

range of ground-based and airborne applications (e.g., 

a potential upgrade to HAWC). The goal is to strike 

a balance between development and application that 

allows rapid progress to be made in CMB studies and 

far-infrared astronomy, and to be a resource for the 

wider community.

Variable-delay Polarization Modulators for 

Exploring Inflation

The study of the cosmic microwave background (CMB) 

with missions such as COBE and WMAP has proven 

to be one of the most valuable tools in decoding the 

physics of the early universe. To explain the observed 

flatness and the origin of structure, it has been hypothesized that the universe underwent an early epoch of 

exponential expansion known as inflation. If inflation 

occurred, it is expected to have left a small, polarized 

signature on the CMB. Measurement of such a signal would provide direct evidence for this inflationary 

epoch, along with a means by which to measure the 

physics of the first 10-32 second of the universe. 

Polarization modulation provides a means for extracting the small polarized signal from inflation from the 

large unpolarized CMB. To this end, variable-delay 

polarization modulators (VPMs) are being developed 

for a space-based instrument to measure the polarization of the CMB by Chuss, Wollack, Moseley, Benford, Hinshaw and Voellmer in the ASD Observational Cosmology Lab. These modulators consist of a 

polarizing grid placed parallel to and in front of a movable mirror. By varying the grid-mirror separation, the 

phase between two orthogonal linear polarizations is 

also varied. This leads to a modulation of a single linear Stokes parameter with little contamination from 

the instrument. 

VPMs are potentially well suited for a space mission 

because they avoid the use of dielectrics that require 

complex antireflection coatings. The modulation motion can be accomplished using small linear motions 

that can be done with reliable frictionless flexures. In 

addition, VPMs can be constructed large enough to 

cover the primary aperture of the telescope. This is 

advantageous in that it allows the modulation to be 

encoded on the signal before it can be contaminated 

by the instrument.

 Prototype VPMs have been constructed for use with 

the Hertz submillimeter polarimeter. These have been 

demonstrated at the Submillimeter Telescope Observatory in Arizona. The team is currently working on 

second generation VPMs for use in two pathfinder 

systems: PIPER, a funded balloon-borne CMB poPolarizing Grid

Input Port Output Port

Movable Mirror

Phase delay

VPMs consist of a polarizing grid placed parallel 

to and in front of a movable mirror. By varying 

the grid-mirror separation, the phase between two 

orthogonal linear polarizations is also varied.

A

a

B

50 cm

15 cm

Grid Flattener

Grid/Mirror

Piezoelectric

Motor

Mirror Sled

Flexure

Capacitive Sensor

Left: The submillimeter prototype VPM, constructed 

for use with the Hertz submillimeter polarimeter. 

Right: A larger grid for a CMB VPM. 

Measurement of CMB polarization 

would provide direct evidence for 

inflation and a means by which to 

measure the physics of the first 10-32 

seconds of the universe
Astrophysics Science Division: Research and Missions

48

larization experiment (PI, Kogut) and POINCARE, a 

proposed ground-based CMB polarimeter. 

MKID Detectors for Submillimeter 

Astronomy

Ed Wollack and collaborators are actively pursuing the 

extension of Microwave Kinetic Inductance Detectors 

(MKIDs) technology to the 38–400 μm spectral regions via a novel detector concept. Of the high-performance detector-array technologies currently being 

developed, the MKIDs may have the greatest promise 

for scaling to very large arrays (~105

 detectors). Such 

arrays can provide high quantum efficiency and can be 

designed to provide background-limited performance 

over a wide range of incident powers, making them 

candidates for a wide range of instruments, ranging 

from suborbital imagers to spaceborne spectrometers. 

Such large-format detector technologies are much 

needed in this important spectral region. Many of 

the primary diagnostics of a large range of galactic 

processes require observations in this spectral range. 

The far-infrared dust emission from normal and ultraluminous galaxies peaks in this spectral range, and its 

measurements are essential for understanding the energy production mechanisms and processes in the galaxies. Fine-structure lines of O III, NIII, O I, C I, and 

N II fall in this spectral range. These lines can provide 

high-quality measurements of elemental abundances 

and physical conditions in the emitting regions. Many 

excited states of molecules, such as CO, are seen in 

this spectral range, and provide the capability to probe 

physical conditions in hot molecular clouds. Low-lying transitions of hydrides in this spectral region can 

probe cores of cooling clouds, providing information 

on star-formation processes. The goal is to produce 

detectors which will permit the use of these powerful 

diagnostic tools in future missions.

Presently, MKID detectors employ a resonant tank 

circuit made from a superconducting transmission 

line. Its quality factor, Q, and central frequency are 

read out using a microwave reflectometer. Millimeterwave radiation is coupled into the device from an 

antenna, where it breaks Cooper pairs in the superconductor. This results in a change in the kinetic inductance of the microwave circuit, causing a change 

in the frequency and Q of the circuit. This technique 

works well at frequencies where the radiation can be 

coupled into the device using antennas and superconducting transmission lines. At frequencies above the 

superconducting gap of Nb, quality transmission lines 

are difficult to produce, so a different approach must 

be adopted. To achieve the desired sensor performance 

in the desired band, we modify this scheme by choosing the resonator metallization geometry and material 

properties consistent with its necessary roles in absorption of the incident wave and readout of the detector 

signal. The incoming light, with photon energy much 

greater than the superconducting gap, interacts with 

the spiral microwave transmission line. 

In the approach under development, the meander is 

chosen to have a surface-impedance and filling factor 

such that it presents the optimal matching impedance 

to the incoming wave, about 157 W per square. When 

Many of the primary diagnostics of a 

large range of galactic processes require 

observations in the submillimeter range. 

This a sketch shows the sensor topology under study. 

Photons with energy greater than the gap energy 

are absorbed in the meander. The quasiparticle 

excitations change the center frequency and Q of 

the 1 GHz stepped-impedance spiral resonator.
49

Astrophysics Science Division: Research and Missions

the optical power is absorbed, it excites quasiparticles 

in the superconducting spiral, modifying the kinetic 

inductance of the line. The transmission line is configured as a l/2 stepped impedance resonator, designed 

to have a resonant frequency of ~1 GHz. The Q of 

the un-illuminated resonator can be controlled by appropriate selection of the coupling Q to the transmission line. The device is optimized for a particular application by choosing the unloaded Q to be equal to 

the Q caused by quasiparticle dissipation at maximum 

power. The density of quasiparticles is a measure of 

our signal, and is sensed by the change in frequency 

and Q of the readout resonator.

Pending successful laboratory demonstration of 

the devices, a test of an array will be conducted in a 

350μm imager at the Caltech Submillimeter Observatory (CSO). This collaborative effort is led by Edward 

Wollack and includes S. Harvey Moseley (ASD), and 

Wen-Ting Hsieh, Thomas Stevenson and Kongpop 

U-yen of Goddard’s Engineering Directorate and Professor Jonas Zmudizian of Caltech. 

Photon Counter Detector Development

Work is on-going in the Exoplanets and Stellar Astrophysics Lab to develop photon-counting detectors 

for space in the UV, visible and near-IR by Woodgate, 

Kimble, Rauscher, Norton and Hilton.

For the UV, a new class of photocathodes are under development with higher QEs than were available in the 

Hubble, FUSE and GALEX era, based on new ternary 

materials becoming available such as p-doped AlGaN 

and MgZnO, in both planar and nano-wire forms. By 

cesiating GaN, QEs of 50-65% at 180 nm, a factor ~6 

higher than flown on HST/STIS, have been obtained. 

A GaN photocathode has been transferred into a diode tube with the QE stable for two years, and into an 

EBCCD imaging tube in collaboration with Rutgers 

University. 

Work continues via ROSES/APRA funding to extend 

the wavelength range and to obtain higher QEs and 

compatibility with microchannel plates (MCPs). SBIR 

programs funded by NASA are also developing silicon 

MCPs with AlGaN photocathodes. Woodgate, along 

with GSFC engineering, university, NIST and commercial partners, plans to build these photocathodes 

into EBCCD and EBCMOS and MCP detectors.

In the visible, photon-counting EMCCDs are being 

tested for use in future space spectrographs for faint 

objects such as exoplanet atmospheres, and will use 

fast controllers to reduce Clock Induced Charge to extend the useful dynamic range of the photon-counting 

regime.

In the Near-IR the use of InGaAs photocathodes in 

EBCCD detectors are being investigated, including 

the extension of useful external QE at cold temperatures for long exposures via an SBIR program.

Fizeau Interferometry & Synthetic Imaging 

Formation Flying Testbeds (FIT/SIFFT)

The primary goal of the FIT/SIFFT project is to mature the command and control algorithms required to 

enable formation-flying sparse-aperture/interferometric imaging missions. These systems must collectively 

operate over ~12 orders of magnitude, from the nanometer to the kilometer scale, and will therefore consist 

of “staged-control” algorithms operating in smaller, 

overlapping regimes but operating cooperatively over 

the full dynamic range. 

K. Carpenter (667) is the PI of the effort and key coinvestigators include: R. G. Lyon (GSFC), D. Mozurkewich (Seabrook Engineering), D. Miller (MIT), 

and P. Stahl (MSFC). The GSFC-located FIT is developing and demonstrating closed-loop control, utilizing feedback from the science data, of the tip, tilt, 

piston, and translation of mirrors in a sparse array and Quantum efficiency versus wavelength for cesiated 

GaN processed at GSFC.
Astrophysics Science Division: Research and Missions

50

of the overall system to keep beams in phase and to 

optimize imaging. 

The SIFFT uses the MIT Synchronized Position Hold 

Engage Reorient Experimental Satellites (SPHERES) 

on the Flat Floor facility at MSFC and on the International Space Station (ISS) in Earth orbit to address 

constellation-wide sensing and control of the formation-flying spacecraft. SIFFT is developing and demonstrating specific algorithms for autonomous precision formation flying and efficient synthetic imaging 

maneuvers of an array of spacecraft. 

The end goal of this research is to combine these two 

systems into one system that will provide staged-control over the full dynamic range needed to enable these 

missions. While the detailed design of these testbeds 

are based on the Stellar Imager (SI) mission, the technologies being advanced will help enable numerous 

additional missions being considered by NASA for 

flight, including the Space Infrared Interferometric 

Telescope (SPIRIT), Sub-Millimeter Probe of the 

Evolution of Cosmic Structure (SPECS), Life Finder 

(LF), Black Hole Imager (BHI/MAXIM), and Planet 

Imager (PI), as well as smaller precursor missions, such 

as the Fourier Kelvin Stellar Interferometer (FKSI), SI 

Pathfinder, selected Exo-Planet Probes, and ESA’s Pegase. 

Wide-field Imaging Interferometry Testbed

Leisawitz and Rinehart are developing a broadly-applicable technique for wide field-of-view “double Fourier” 

(spatial and spectral) interferometry and evaluating its 

practical limitations. The Space Infrared Interferometric Telescope (SPIRIT; see the Mission Concepts section) could employ this technique — an analogue to 

integral field spectroscopy — to image stars, planetary 

systems, and galaxies in the far-IR at 100x better angular resolution than the Spitzer Space Telescope while 

simultaneously providing information-rich spectra.

In 2008 the Wide-field Imaging Interferometry Testbed was moved from its development lab to a new, 

state-of-the-art Advanced Interferometry and Metrology (AIM) Lab, a major project milestone. In the AIM 

Lab, WIIT replicates the functionality and behavior of 

a space-based interferometer because the data are practically free of environmentally induced errors, such as 

wavefront distortion due to air turbulence, fluctuations in temperature and humidity, and vibrations. 

Funding support for this research comes from the 

ROSES APRA program. The period of performance 

runs through FY11, by which time wide-field imaging 

interferometry will have matured to TRL 6.

Left: FIT Phase 1 Testbed at GSFC, without baffles 

for clarity. Right: The FIT Phase 2 array plate in 

assembly, with 11 of 18 mirrors/actuators installed.

SIFFT: SPHERES on the MSFC flat floor (left) and 

aboard ISS right.

On the Web

Stellar Imager

hires.gsfc.nasa.gov/si
51

Astrophysics Science Division: Research and Missions

LISA Testbed: Stabilized Platform 

Interferometer for LISA Testing

A fundamental issue in the ground testing of LISA 

interferometry components is the presence of ground 

noise, both seismic and thermal. LISA interferometric 

sensitivity is at the picometer level, while ground noise 

over that timescale is of the order of microns. To provide an environment for testing that is stable over long 

timescales at the picometer level, Camp and colleagues 

constructed a stabilized platform testbed.

Hexapod actuators support platforms separated by 

one meter, located inside a vacuum system. An iodine 

stabilized laser system is used to measure the relative 

motion of the platforms by using optical components 

to form Michelson interferometers between the platforms. 

The Michelson interferometer output is then fed back 

to a hexapod actuator to stabilize the distance between 

the platforms. This results in a suppression of relative 

motion of the platforms, creating an environment 

which is sufficiently stable for LISA interferometry 

testing. The stability of the system is monitored with 

an independent stabilized laser. 

The stability of the testbed is within a factor of 5 of 

the LISA requirement of 30 picometer/sqrt(Hz) at 1 

mHz. The limiting noise source is cross-coupling of 

the unstabilized pitch degree of freedom to length, 

and is under investigation.

In achieving this level of performance, the following 

noise sources were investigated, all of importance to 

the LISA interferometry design.

•	 Optical component bonding stability

•	 Laser frequency stabilization

•	 Cross-coupling of multiple degrees of freedom

•	 Effect of thermal variation on alignment and optical pathlength

The stability of the testbed is within a 

factor of 5 of the LISA requirement.

The LISA Testbed uses hexapod actuators to support 

platforms separated by one meter, located inside a 

vacuum system. An iodine stabilized laser system 

measures the relative motion of the platforms 

by using optical components to form Michelson 

interferometers between the platforms. Credit: 

NASA/GSFC

Testbed optical components that comprise the 

Michelson interferometers measure the relative 

motion of the platforms. They are bonded to a ULE 

block mounted on each hexapod. Credit: NASA/

GSFC

This plot shows the closed loop stability of the 

testbed, within a factor of 5 of the LISA requirements 

at 1 mHz. Credit: NASA/GSFC
Astrophysics Science Division: Research and Missions

52

With the testbed stable at the LISA requirements, it 

can be actuated in a known, precise manner in both 

length and alignment. Thus it can be used, for example, to test the response of the phasemeter to known 

phase variations, or to test the response of the optical 

blocks to known length and alignment variations. It is 

also envisioned that the testbed will be used to characterize the pointing stability of the steering mirror 

mechanism, and other LISA system components.
53

Astrophysics Science Division: Research and Missions

V. Projects

Projects in Operation

The Fermi Gamma-ray Space Telescope

GSFC personnel are extremely active in all aspects 

of Fermi (formerly the Gamma-ray Large Area Space 

Telescope, GLAST), both at the mission level and 

within the instrument teams. Highlighted here is GSFC’s role in Fermi’s Large Area telescope (LAT), some 

of the current LAT activities, and some of the missionlevel work, including the Science Support Center.

The ACD. The Anticoincidence Detector (ACD) 

subsystem of the LAT was designed, integrated, and 

tested at Goddard. The segmentation (89 individual 

scintillating tiles), based on the original idea by Bill 

Atwood (UCSC), maintains the acceptance at the 

highest gamma-ray energies, a major advance relative 

to the EGRET design. The wavelength-shifting fibers 

were installed into the scintillator tiles at Fermilab, 

and the front-end electronics chips were designed at 

SLAC. The tiles are arranged to minimize gaps, and 

the overall detection efficiency for charged particles 

is better than 0.9997. Jonathan Ormes, the Goddard 

Director of Space Sciences at the time, managed the 

early design efforts. Alex Moiseev is the ACD scientist who had the principal responsibility for the design during all phases, and David Thompson was the 

subsystem scientist-manager. The successful ACD is 

due to the work of many people at Goddard and elsewhere, and it also provided a good training experience 

for students.

Current Fermi LAT Activities. The LAT Principal 

Investigator is P. F. Michelson (Stanford). Within 

the LAT team, throughout the development, GSFC 

members played key roles. Presently, the major roles 

include the following: N. Gehrels (Senior Scientist 

Advisory Committee [SSAC] chair and Publication 

Board [PB] member); A. Harding (Galactic Sources 

Group coordinator), E. Hays (Spectral Analysis Study 

group lead), J. McEnery (Analysis Coordinator, SSAC, 

PB, GRB commissioner); A. Moiseev (active in electron analysis); S. Ritz (Deputy PI, SSAC, PB); D. J. 

Thompson (Multiwavelength Coordinator, Catalog 

Group coordinator, SSAC). Band, Bonnell, Cillis, 

Corbet, Davis, Ferrara, Hirayama, Hunter, Sambruna, 

Shrader, and Stecker are affiliated-scientist members of 

the LAT team. 

The current PhD students are T. Johnson and W. Micaville (both at University of Maryland), and the postdocs are O. Celia, T. Cheung, and V. Vasileiou. ASD’s 

data analysis has been to work directly with the international team, rather than to define “Goddard” analyses. This has been very successful. Leading by example 

has helped to foster a strong and productive collaboration, and GSFC personnel have played central roles in 

most of the major LAT science results thus far.

Fermi Mission and SSC. The Fermi mission is managed at Goddard, and the Mission Operations Center 

(MOC) is located here. Ritz is the Project Scientist, 

and McEnery, Thompson, and Gehrels are Deputy 

Project Scientists. Alice Harding and Liz Hayes play 

key roles in data analysis and theoretical interpretation of Fermi observations. The Fermi Science Support Center (FSSC) is also located at Goddard and is 

led by C. Shrader. The FSSC functions can be divided 

into three main roles.

•	 The mission planning and operations branch compiles and optimizes the Fermi observation plan 

(including responding to and evaluating Target of 

Opportunity requests). This branch runs weekly 

planning meetings to coordinate observatory opThe fully assembled Fermi Anticoincidence Detector erations across all mission elements.

prior to thermal blanket installation. Credit: NASA/

GSFC
Astrophysics Science Division: Research and Missions

54

then data are transferred to the Science Team, which 

runs its own checks. 

There have been six unplanned interruptions to survey 

operations. The failure of a single battery cell caused 

one interruption early in the mission. High-energy 

charged particles caused three single-event upsets, 

and the spacecraft was returned to normal survey operations soon after each. Operations were recently interrupted because a transponder became intermittent; 

the alternate transponder is now used.

There is no significant degradation anywhere on the 

observatory. WMAP is passively cooled; there is no 

cryogen-related lifetime limitation. Of the ~ 50 kg 

of remaining fuel, a typical station-keeping maneuver 

requires only ~ 0.5 kg. Fuel is not a limitation to the 

lifetime of the mission.

Solar eclipse shadows were forecast for October 2007 

and January 2008. After careful planning and peerreview, we executed a maneuver to avoid these eclipses. 

This was the largest maneuver since the early mission 

and it went smoothly. 

As of January 2009, WMAP has been in orbit for 7.5 

years and is still taking data at L2. With additional 

data, WMAP will enable significant science advances 

in a number of areas. These include: 

•	 a more accurate determination of the density of 

dark matter; 

•	 a more accurate determination of the amplitude 

of primordial fluctuations; 

•	 improved constraints on neutrino properties; 

•	 a more detailed characterization of reionization; 

•	 improved sensitivity to gravitational waves, including the ability to rule out the popular m2

j2

theory of inflation; 

•	 The analysis software and databases branch developed the high-level analysis software in partnership with the LAT and Gamma-ray Burst Monitor (GBM) instrument teams. Extensive testing, 

both internally and in “beta” tests by members 

of the Fermi Users Group, was performed. The 

FSSC also serves data to the community, working 

with the HEASARC to ensure that the analysis 

tools and data formats conform to standards in 

high-energy astrophysics. All data servers are up 

and running; high-level LAT data and all GBM 

data are currently publicly available; the portal to 

the low-level LAT data is currently being used and 

tested by the LAT instrument team and will be 

made publicly available in fall 2009, per the mission timeline.

•	 The user-support branch of the FSSC is responsible for running the Fermi guest investigator program, developing proposal preparation tools, providing documentation, running workshops, and 

answering questions via an electronic helpdesk. 

Last year’s Cycle 1 was very successful, and the 

Cycle 2 proposal deadline is March 6, 2009.

Supporting all three branches of the FSSC is a group 

of talented programmers and software engineers who 

build and maintain the software infrastructure and web 

pages. The MOC is staffed by an outstanding Flight 

Operations Team and is supported by a small sustaining engineering group. All the mission elements are 

functioning together efficiently and seamlessly.

WMAP Operations and Status

WMAP launched from Cape Canaveral on June 30, 

2001, aboard a Delta II rocket. From launch to orbit 

about the second Lagrange point (L2), WMAP mission operations have been extremely smooth and reliable. WMAP continuously surveys the sky in a compound spin and precession that generates the desired 

scan pattern. There are no pointed observations. Planning is required for about four station-keeping maneuvers per year. Data are downlinked to the Deep Space 

Network and then relayed to the WMAP Science and 

Mission Operations Center (SMOC) at Goddard. 

The down-link contacts allow for real-time checks of 

health and safety. The SMOC runs Level-0 processing, 

The spring 2008 review approved two 

additional years of flight operations 

through the end of FY10, which would 

produce a total of nine years of data.
55

Astrophysics Science Division: Research and Missions

•	 the ability to determine whether claimed nonGaussianity is statistically significant; 

•	 improved models of Galactic foregrounds, which 

will be vital for Planck and other experiments that 

look for gravitational waves; and 

•	 improved measurements of microwave emission 

from planets and from Galactic and extragalactic 

sources.

The WMAP program is reviewed every two years by the 

Headquarters Senior Review of operating astrophysics 

missions. The last review, in spring 2008, approved 

two additional years of flight operations through the 

end of FY10, which would produce a total of nine 

years of data. The project will return to the next Senior Review, in spring 2010, to request additional data 

analysis funding to release the final data products. 

The Rossi X-ray Timing Explorer

The Rossi X-ray Timing Explorer (RXTE) celebrated 

its birthday on Dec. 30, 2008, and began its 13th cycle 

of observations. Jean Swank is the Project Scientist and 

Tod Strohmayer became the Deputy Project Scientist 

in 2006. In its long and productive history, RXTE is 

responsible for numerous discoveries resulting in three 

Rossi Prizes—to Strohmayer and Chakrabarty (2006), 

Kouveliotou (2003) and Bradt and Swank (1999)—

more than 80 PhD theses and over 1,600 refereed 

publications. 

The observation planning, instrument monitoring, and 

calibration updates are carried out with the part-time 

contributions of an experienced team (including Keith 

Jahoda, Craig Markwardt, and Nikolai Shaposhnikov 

at Goddard). Improvements in background determination and response matrices continue to be made.

The Science Operations Center (SOC), with Frank 

Marshall as director, assisted by Robin Corbet as Science Operations Facility manager, and the GSFC Mission Operations group have worked together to continue to automate operations and reduce manpower 

and expenditures, while preserving RXTE’s ability to 

accommodate new information about targets of opportunity (TOOs) (implemented by SOF personnel 

Evan Smith and Divya Pereira). RXTE’s most-used 

follow-up capability is currently for time-scales of 

1–2 days. It is possible to have follow-up observations 

within hours for a select subset of requests, but transients that harbor millisecond pulsars, active periods 

of magnetars, the lifecycles of galactic black hole transients, and, of course, the active periods of blazars require a response on the order of days that is sustained 

for days to weeks. RXTE remains the mission that is 

requested to carry out these observations. 

The RXTE project has submitted proposals to each of 

NASA’s Senior Reviews of the Astrophysics Operating Missions since 1994. The 2006 review confirmed 

RXTE’s operations through the 2008 review, by which 

time the project had developed a program to extend 

operations through February 2009. The 2008 review 

concluded that funds were not available for further 

funding of the longest operating of the competed astrophysics missions. However, continued reductions 

in operating costs have allowed cycle 13 to extend 

through September 2009 and possibly further. The 

possibility of extension of RXTE’s mission for an additional year is being explored. This will allow the torch 

of X-ray coverage of variable sources to be passed to 

other missions (MAXI, Astrosat).

RXTE’s repeated observations of targets have resulted 

in discoveries related to phenomena that are relatively 

rare. A program of monitoring pulsar spin history 

resulted in the discovery of magnetar-like behavior 

in the young pulsar PSR J1846–0258 in Kes 75 (by 

post-doctoral fellow Fotis Gavriil). Low-mass binaries 

monitored for changes in the quasi-periodic oscillations (QPO) were found to have intervals of coherent 

oscillations (Aqu X-1, SAX J1748.9–2012 in NGC 

6440, HETE J1900.1–2455). Coverage of the QPO 

and spectra of multiple Galactic black holes allows 

the correlations to be related to fundamental properties of mass and spin (as by postdoctoral researcher 

Nikolai Shaposhnikov). RXTE’s observing flexibility 

means that it can provide X-ray coverage of gammaContinued reductions in operating 

costs have allowed RXTE’s cycle 13 to 

extend through—and possibly beyond—

September 2009.
Astrophysics Science Division: Research and Missions

56

The GOF is involved in the cross-calibration between 

the XMM-Newton instruments and other X-ray observatories (e.g., Chandra, Suzaku, ASCA, and ROSAT), which enhances the utility of multi-observatory 

data analysis. This has been a major activity the last 

two years, with major XMM-Newton GOF participation in the International Astronomical Consortium 

for High Energy Calibration (IACHEC). It is now 

becoming clear, thanks to the efforts of the XMMNewton SOC at the European Space Astronomy Center (ESAC) and the GOF, that the XMM-Newton 

calibration has become very reliable and that direct 

comparison of Chandra and XMM-Newton results on 

clusters of galaxies has revealed a previously unknown 

error in the Chandra calibration that has major implications for cosmology (Snowden et al., 2008).

The GOF has prepared an Optical Monitor (OM) 

source catalog (Kuntz et al., 2008, in press) to compliment the X-ray source catalog produced by the 

XMM-Newton Survey Science Centre (SSC). The 

database contains entries for every source detected in 

OM observations. The GOF worked with the STScI 

to make the OM catalog and data available through 

the Multimission Archive at Space Telescope (MAST), 

considerably increasing the data availability to optical 

astronomers.

The XMM-Newton archive at the GSFC GOF mirrors all public data in the ESA XMM-Newton Science 

Archive (XSA) at the SOC, as well as proprietary data 

for U.S. PIs. This mirroring of the data reduces the 

high data load at the European Space Operations Center site, and provides a much faster data-transfer rate 

within North America, as well as allowing use of the 

unique capabilities of the BROWSE database.

The GOF consists of Project Scientist Mushotzky and 

about nine other support scientists and programmers. 

The scientific return to the community is exceptionally high for such a lean staff. 

ray transients that Fermi finds active (e.g., 3C 454.3, 

3C 66A).

XMM-Newton Guest Observer Facility

ASD operates the U.S. XMM-Newton Guest Observer Facility (GOF). ESA has allocated resources to support European XMM-Newton users, but has looked 

to the U.S. GOF to provide support to the large U.S. 

community. GOF activities include facilitating the 

submission of GO proposals to ESA and the supplying of expertise, analysis software, documentation, 

new data products, and access to the data, including 

both the distribution of proprietary data to PIs and to 

the full public science archive. The GOF organizes the 

GO budget submission and review process and manages the distribution of awarded funds. 

A U.S. XMM-Newton Users Group under the chairmanship of Mission Scientist Richard Griffiths (Carnegie Mellon University, CMU) provides community 

oversight of GOF activities. Richard Mushotzky is the 

NASA Project Scientist for XMM. The XMM-Newton 

GOF works in conjunction with the GSFC GOFs of 

other high-energy astrophysics missions (e.g., RXTE, 

Integral, Swift, and Suzaku) to lower costs and to ensure consistency in the areas of the budget proposal 

process, FITS tools, database structure, web pages and 

archival access. Cost savings are leveraged by sharing 

resources, techniques, expertise, and reusing software.

GOF activities cover a very wide range of endeavors 

in support of XMM-Newton, and include the following: science analysis software support, development of 

software tools (QuickSim, Xsim, PIMMS, and update 

of HEASARC multi-mission software (Browse, etc.)) 

to support XMM. The GOF created and maintains 

the extensively used “ABC Guide” for the analysis of 

XMM-Newton science data. 

Direct comparison of Chandra 

and XMM-Newton results on clusters 

of galaxies has revealed a previously 

unknown error in the Chandra 

calibration that has major implications 

for cosmology.

On the Web

The XMM-Newton Guest Observer Facility

xmm.gsfc.nasa.gov
57

Astrophysics Science Division: Research and Missions

Swift

Swift is a NASA Explorer mission, with international participation, that is designed to find gamma-ray 

bursts, and study them over a wide range of wavelengths from gamma-rays to optical light. It was 

launched in 2004 and is in its extended mission phase 

with re-entry in 2020. 

Gamma-ray bursts (GRBs) are the most powerful explosions the universe has seen since the Big Bang. They 

come from all directions in the sky and last from a few 

milliseconds to a few hundred seconds. GRBs are believed to occur in the collapse of some massive stars 

into supernovae or when two neutron stars merge. 

However, the details of how such intense pulses of radiation are produced are still not well understood.

To observe GRBs, Swift has three telescopes onboard. 

The Burst Alert Telescope is a coded-aperture gammaray detector that operates between 15 and 150 keV. It 

detects gamma-ray bursts and rapidly localizes them 

to approximately three arcminutes. Once this has happened the spacecraft slews (usually within one minute) 

to point its two narrow-field instruments at the burst. 

The X-Ray Telescope measures the 0.2–10 keV X-ray 

flux from the GRB’s afterglow and localizes the source 

to within five arcseconds. The Ultraviolet/Optical telescope collects data between 1600 and 6000 Angstroms 

and provides a sub-arcsecond position for the burst. 

Swift distributes these positions for each GRB to other 

observatories within seconds of obtaining them.

In the four years since launch, Swift has detected and 

localized approximately 400 GRBs. Some of the mission’s key scientific accomplishments have been:

•	 Finding afterglows for short, hard GRBs and determining that the short, hard GRB 050509B occurred in an elliptical galaxy. This provided support for the theory that short, hard bursts are due 

to the merging of binary neutron stars and not the 

collapse of massive stars.

•	 Detecting GRB 080913A, the most distant known 

GRB with a redshift of 6.7. This burst occurred 

when the universe was only one billion years old.

•	 Observing GRB 080319B, a GRB with an afterglow that was bright enough to see with the naked 

eye from a dark site.

•	 Compiling X-ray light curves of several hundred 

Swift GRBs, which led to a canonical X-ray light 

curve for afterglows, and has provided much new 

information on the nature of the central engine.

Swift is a powerful transient observatory that is increasingly being used for non-GRB science. Currently about half the papers on Swift findings are from 

non-GRB fields, and the fraction is growing. A few 

examples include: observing more than 300 targets 

of opportunity per year; making multiwavelength 

observations of comets, stellar flares, CVs and novae; 

obtaining 70 ultraviolet light curves of all classes of 

supernovae; observing galactic transients and AGNs; 

and undertaking the most sensitive all-sky hard X-ray 

survey yet performed.

Swift has been widely recognized as a ground-breaking mission. Swift was ranked first in the 2008 Senior 

Review. PI Neil Gehrels and the Swift Team won the 

2007 Rossi Prize, and GRB 080319B (the naked-eye 

gamma-ray burst) was named one of the top ten science news stories of 2008 by the American Institute 

of Physics.

The Swift mission has a Guest Investigator Program 

that is open to the world astrophysics community. In 

2008, Swift awarded 780 hours of observing time and 

1.8 million dollars in research funds to guest observers. 

The oversubscription rate has been growing and was 

more than 4 during Cycle 4. Swift also has an open 

target of opportunity program. These observations are 

often made within 24 hours of being requested and 

can be made within 30 minutes.

Suzaku (Astro-E2) 

Suzaku (Astro-E2) is the fifth in a series of Japanese Xray astronomy satellites, launched by the Japan Aerospace Exploration Agency (JAXA) on July 10, 2005. 

Currently about half the papers on 

Swift findings are from non-GRB fields, 

and the fraction is growing.
Astrophysics Science Division: Research and Missions

58

Like ASCA before it, Suzaku is a joint Japanese-U.S. 

mission, developed by the Institute of Space and Astronautical Science of JAXA (ISAS/JAXA) in collaboration with GSFC and many other institutions.

Suzaku’s scientific payload includes three co-aligned 

instruments, of which two are functional. The X-ray 

Imaging Spectrometer (XIS) consists of four imaging 

CCD cameras, three of which are front illuminated 

(FI: energy range 0.4–12 keV) and one back illuminated (BI: energy range 0.2–12 keV). Each XIS is located at the focal plane of a dedicated X-ray telescope 

(XRT). The second functional instrument is a nonimaging collimated Hard X-ray Detector (HXD) sensitive in the 10–600 keV band. The third instrument, 

the X-Ray Spectrometer (XRS), ceased operation 

shortly after launch due to a spacecraft design error. 

GSFC’s role includes supplying the XRTs and the XRS 

“insert” (detector, adiabatic demagnetization refrigerator and LHe cooler), development of data processing 

software, operation of the U.S. Guest Observer Facility, and administration of the U.S. Guest Observer 

Program. Rob Petre is the NASA Project Scientist and 

Lorella Angelini is the Deputy Project Scientist.

The XIS and HXD are healthy and stable, and have 

produced an abundance of data from a wide variety 

of cosmic X-ray sources. Key unique Suzaku observations include: measurement of cluster properties beyond their virial radius; broadband measurements of 

AGN revealing simultaneously complex absorption, a 

relativistically broadened Fe K line, and a reflection 

continuum to 20–40 keV; determination of the spin 

of Galactic black holes and the radius of accreting neutron stars using their relativistically broadened Fe line; 

and hard X-ray sensitivity sufficient to measure the 

spectrum of each of the hundreds of AGN detected 

by Swift.

U.S. observers have access to 50% of the observing 

time (including 12% through joint Japan/U.S. observations), as well as access to all archival data. In the 

third observing cycle (April 2008–March 2009) Long 

Proposals (observing time > 300 ks) were introduced 

to the program. In the current observing cycle, key 

projects (observing time > 1Ms) were introduced. 

Also, joint Suzaku-Chandra observations will become 

available through the Chandra GO program, and we 

are making arrangements for collaborative programs 

with other missions (Swift, Fermi).

Suzaku received a high ranking (fourth, of nine missions) from the 2008 NASA Senior Review of operating missions. Funding is secure through FY2011, and 

the opportunity exists to extend U.S. participation 

through a proposal to the 2010 Senior Review. The 

most substantial issue arising from the Senior Review 

is that Guest Observer funding has been reduced to 

a token level: roughly $500,000 per year, or $8,000–

$10,000 per successful proposal.

The Suzaku GOF is responsible for: processing and 

archiving of the full mission data set and distribution 

of data to U.S. GOs; development and maintenance 

of proposal and observation planning tools and documentation; maintaining the calibration database; supporting proposal reviews; assisting GOs analyze data; 

and ensuring grant funds are distributed in a timely 

way. The GOF staff consists of three full-time scientists 

(Koji Mukai, Kenji Hamaguchi, Katja Pottschmidt) 

and one programmer, plus part-time support from 

HEASARC staff.

INTEGRAL 

INTEGRAL, the INTErnational Gamma-Ray Astrophysics Laboratory, is an ESA mission for which 

NASA has been a partner since its selection in 1995. 

It was launched in October 2002 and has now completed more than six years of successful scientific operations. 

INTEGRAL carries two main instruments—the 

high-resolution gamma-ray spectrometer, SPI, and the 

high-angular-resolution gamma-ray imager, IBIS—as 

well as X-ray and optical monitors. Together, these 

instruments provide unprecedented spectral coverage 

from the optical to gamma-ray energies up to 10 MeV 

Joint Suzaku-Chandra observations 

will become available through the 

Chandra GO program, and we are 

making arrangements for collaborative 

programs with other missions (Swift, 

Fermi).
59

Astrophysics Science Division: Research and Missions

as well as excellent imaging capabilities at hard X-ray 

and gamma-ray energies.

The scientific goals of the INTEGRAL mission are varied and far-reaching. The SPI instrument is a codedmask germanium spectrometer with excellent energy 

resolution in the low-energy gamma-ray regime, from 

20 keV to 8 MeV. It was designed to study, in detail, 

gamma-ray lines produced through a variety of processes. These include the decay of radioactive isotopes 

produced in supernovae and novae as well as the annihilation of positrons near the center of our Galaxy. SPI 

can trace the production of these radioactive isotopes 

and positrons by mapping the locations and intensities 

of the resulting gamma-rays. These studies lead to a 

better understanding of the chemical evolution of the 

Galaxy, Galactic star formation rates, and the inner 

workings of supernovae and novae.

The IBIS imager is a coded-mask gamma-ray telescope 

that operates between 15 keV and 10 MeV. The sensitivity and angular resolution of this telescope makes 

it extremely useful for observing Galactic black hole 

and neutron star binary systems as well as active galactic nuclei (AGN). To this end, a significant portion of 

the INTEGRAL observing time has been spent scanning the Galactic disk and Galactic Center region in 

an effort to monitor the known Galactic X-ray binary 

population and discover new sources. Studies of these 

binary systems give us a better understanding of the 

end products of stellar evolution.

In the six years since launch, there have been numerous notable discoveries, including:

•	 Discovery that the Galactic 511 keV emission due 

to positron annihilation is not symmetric about 

the Galactic Center. This has significant implications for determining which source(s) are producing these positrons.

•	 Observations of the gamma-ray lines from the decay of both 26Al and 60Fe in the Galaxy suggest 

that much of the 26Al is produced in core-collapse 

supernovae.

•	 Discovery of a large number of X-ray binary 

systems containing a super-giant companion. 

Among this class of objects, two subclasses have 

been identified: systems with highly absorbed soft 

X-ray spectra and systems that exhibit very fast 

transient behavior. The hard X-ray sensitivity of 

IBIS and its monitoring observing program were 

instrumental for these discoveries.

Since launch, INTEGRAL has operated as an international observatory with observing time available 

to U.S. scientists. NASA has an INTEGRAL Guest 

Investigator Program that provides funding for U.S. 

scientists who were successful in obtaining observing 

time. In 2008, the INTEGRAL Guest Investigator 

Program has funded 24 observing programs for a total 

of $450,000. 

The US INTEGRAL Guest Observer Facility maintains a copy of the full INTEGRAL public data archive and supports U.S. scientists with their data analysis. Neil Gehrels is the NASA INTEGRAL Project 

Scientist.

Hubble Space Telescope: SM4 and Wide Field 

Camera 3

The Hubble Space Telescope Program (HSTP) resides 

at Goddard. This organization has overall responsibility within NASA for the technical, scientific, and 

programmatic management of the observatory. The 

responsibilities of HSTP include operation of the 

Hubble observatory, both through spacecraft engineering and the implementation of Hubble’s science 

GSFC personnel completed integration of Wide 

Field Camera 3 in early 2008. The instrument 

successfully underwent a comprehensive 

environmental test program and now awaits launch. 

Credit: NASA/GSFC
Astrophysics Science Division: Research and Missions

60

participate as full members of the SM4 mission team 

in responding to any contingencies that may arise. The 

insertion of each payload element or the completion 

of each instrument repair culminates in “aliveness” 

and “functional” tests to provide an initial assessment 

of its viability. The project scientists at both Goddard 

and JSC are heavily involved in these tests. In the case 

of the new and repaired instruments they are responsible for assessing whether or not the tests resulted in a 

conclusion of “pass” or “fail.”

With the insertion of WFC3 and COS—and the expected repair of two heavily used instruments already 

onboard Hubble—ACS and STIS—both of which 

failed due to power supply problems, Hubble will be 

more powerful than ever before. The replacement of 

key spacecraft components—gyros, batteries, instrument computer and fine guidance sensor—should extend Hubble’s operational life by an additional 5–10 

years. 

Randy Kimble also serves as the Lead Instrument 

Scientist for the Hubble’s new Wide Field Camera 3, 

which is a powerful general-purpose imager, covering 

wavelengths from the near ultraviolet to the near infrared. WFC3’s UV/VISible (UVIS) channel covers the 

200–1000 nm range with a 4K × 4K pixel mosaic of 

UV-enhanced, low-noise CCDs. Beautifully complementary to the I-band-optimized Wide Field Channel 

of ACS, WFC3’s UVIS channel is particularly powerful in the near-UV (200–400 nm) range, where it 

offers survey speeds 30 to 100 times those of previous imagers. This capability will be particularly well 

suited to study, for example, the recent star formation 

history of nearby galaxies. The IR channel (850–1700 

nm), which utilizes a novel HgCdTe focal-plane array custom-developed for WFC3, similarly provides a 

powerful upgrade from Hubble’s current infrared camera, NICMOS. WFC3’s superior sensitivity and larger 

field of view combine to yield a survey speed increase 

of more than 20 percent, which will be invaluable for 

program with the Space Telescope Science Institute 

(STScI). We develop all new hardware that astronauts 

will install on Hubble during servicing missions, including new scientific instruments, tools used by the 

astronauts, and hardware carriers designed to deliver 

equipment to orbit in the space shuttle’s payload bay. 

Finally, we work with NASA’s Johnson Space Center 

(JSC) to develop the detailed choreography of each 

Hubble servicing mission.

Five scientists in ASD provide essentially full-time 

support to the HSTP: Senior Project Scientist David 

Leckrone; Deputy Senior Project Scientist Mal Niedner; Project Scientist for HST Development Randy 

Kimble; Project Scientist for HST Operations Ken 

Carpenter; and Associate Senior Project Scientist Stephen Rinehart. At the highest level, the overarching 

function of the HST Project Science staff is to assure 

that Hubble continually meets its scientific performance requirements and remains at the forefront of 

research..

Servicing Mission 4 (SM4) will be the fifth—and, 

in all likelihood, the last—shuttle servicing mission 

to Hubble. SM4 is currently scheduled for May 12, 

2009. The HST Project Scientists are continuously 

and deeply engaged in the development, planning, 

and training for the servicing mission. One important 

function is the assignment of mission priorities and 

the development of response plans for a large suite of 

possible contingencies during the mission. The payload manifest for SM4 consists of the following (in order of priority): gyroscopes (RSUs); Wide Field Camera 3 (WFC3); replacement instrument computer 

(SIC&DH-R); Cosmic Origins Spectrograph (COS); 

batteries; repair of either the Advanced Camera for 

Surveys (ACS-R) or the Space Telescope Imaging 

Spectrograph (STIS-R); a replacement Fine Guidance 

Sensor (FGS2-R), other required instrument repairs; 

and selected enhancement of spacecraft insulation 

blankets (NOBLs). 

The project scientists have important, well defined 

roles during the mission itself. Leckrone and Kimble 

will be part of the HSTP mission team at JSC, while 

Niedner, Carpenter and Rinehart will work with the 

SM4 operations team at Goddard. During the 12-hour 

orbit (EVA) shifts, they will continuously monitor the 

progress being made by the astronauts in orbit. They 

Following a successful Pre-Ship Review 

that certified WFC3’s flight readiness, 

the instrument was shipped to KSC and 

inserted into its carrier in preparation for 

SM4.
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Astrophysics Science Division: Research and Missions

studies of high-redshift galaxies in the early universe 

and for continued investigation of dark energy.

The GSFC Detector Characterization Laboratory, 

which is jointly staffed and managed by ASD and 

GSFC’s Engineering Directorate, has provided invaluable support to the development and characterization 

of candidate focal plane arrays for the instrument, selection of the flight units, and investigation of subtle 

detector behaviors for optimizing the interpretation of 

detector data in flight. 

Following delivery of the final flight detector assemblies from Ball Aerospace in late 2007, GSFC personnel completed integration of the instrument in early 

2008. In flight configuration, the instrument successfully underwent a comprehensive environmental test 

program (acoustics, EMI/EMC, thermal-vacuum) in 

the first half of 2008. The thermal-vacuum test included a thorough science calibration to acquire the necessary performance data to support the on-orbit observing program. Following a successful Pre-Ship Review 

that certified the flight readiness of the instrument, 

WFC3 was shipped to KSC, where it was inserted 

into its launch carrier in preparation for SM4. WFC3 

remains in this configuration awaiting launch and the 

start of its eagerly anticipated scientific operations.

The Galaxy Evolution Explorer 

The Galaxy Evolution Explorer (GALEX), a Small 

Explorer (SMEX) ultraviolet survey mission, is in its 

sixth year of science operations. All flight and ground 

systems are currently healthy. 

Most of the GALEX science team and most of the 

science operations are at Caltech. Approximately onethird of GALEX observing time is dedicated to a robust Guest Investigator program, operated by GSFC 

(30 to 35 GI programs annually). Susan Neff (ASD) is 

the GALEX Mission Scientist. 

GALEX is in the process of delivering its fifth (annual) GALEX Data Release (GR5) to MAST (MultiMission Archive at Space Telescope), which serves 

both GRs and GI data to the scientific community. 

GALEX is primarily a survey instrument, designed to 

obtain large, homogeneous imaging samples in two 

bandpasses (Far-UV, 1350–1800Å, and Near-UV, 

1800–2800Å) that are sensitive tracers of recent star 

formation. The resulting samples are cross-matched 

with wide and deep surveys at other wavelengths; a 

particularly rich match is with the Sloan Digital Sky 

Survey. GALEX also can provide wide-field, low-resolution spectroscopy, useful, e.g., for identifying HST/

COS targets. 

The primary GALEX mission (completed in late 2006) 

had the goals: 

•	 Calibrate UV observables to star formation rate 

(SFR); 

•	 Measure star-formation history (0 < z < 1.5); 

•	 Explore the UV universe. 

This GALEX image of the variable star Mira extends across more than 3 degrees and shows—for the first 

time—a tail that trails at least 13 light-years behind the star Credit: NASA/GALEX. 

On the Web:

GALEX publications 

www.galex.caltech.edu/researcher/data.html
Astrophysics Science Division: Research and Missions

62

The GALEX Extended Mission (EM), endorsed by the 

2006 and 2008 Senior Reviews, is carrying out several 

Legacy Surveys designed to: extend the UV/SFR calibration to low-mass, low-metallicity, and transitional 

galaxies; relate star-formation history to environment, 

mass, halo mass, assembly history, and star-formation 

regime; determine the primary drivers of SF history 

(by linking SF history to halo mass and assembly history, environment, AGN and their evolution, and the 

intergalactic medium). 

GALEX observations have been used to determine 

the cosmic star-formation (SF) history in the nearby 

universe. The standard model of hierarchical structure formation predicts that large structures grow late. 

However, GALEX results clearly show that while SF 

occurred in massive galaxies over the period 1 < z < 4, 

after that it moved to less and less massive hosts (Martin et al., 2007; Wyder et al., 2005; Arnouts et al., 

2005; Schiminovich et al., 2005).

The UV-optical color-magnitude diagram (UVOCMD) is a powerful tool for separating and relating 

galaxy types, properties, and evolutionary histories, 

The UV-optical color-magnitude diagram 

(UVOCMD) is a powerful tool for separating and 

relating galaxy types, properties, and evolutionary 

histories. GALEX UVOCMDs first identified the 

tendency of AGN to occur preferentially in the 

“green valley.”

HST images of GALEX-discovered compact 

UVLGs reveal that they represent a complex merger 

of multiple, lower-mass, gas-rich subunits that echo 

the morphology and physical properties of high-z 

LBGs. Top row: HST images. Bottom row: The 

same images artificially redshifted to z ~ 3, where 

morphology is uncertain. 

SFR density as a function of redshift, separated by 

galaxy stellar mass, over the range 0 < z < 1.2.
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Astrophysics Science Division: Research and Missions

largely because of the great leverage obtained with 

the UV (SFR)—optical/NIR (stellar mass) color. The 

UVOCMD can be measured accurately in very distant 

samples, and may be considered an HR diagram for 

galaxies in which stellar mass is the major predictor of 

galaxy properties. GALEX UVOCMDs first identified 

the tendency of AGN to occur preferentially in the 

“green valley.” (Wyder et al., 2007; Schiminovich et 

al., 2007; Martin et al., 2007) 

GALEX has discovered a rare population of UV-luminous galaxies (UVLG), low-redshift starbursts with 

properties similar to high-redshift Lyman Break Galaxies (LBGs) (Heckman et al., 2005). GALEX deep 

surveys show that these UV-luminous galaxies (UVLGs) are the fastest-evolving component of the UV 

galaxy population. (Schiminovich et al., 2005) and are 

less dust-attenuated than other local starbursts, such 

as ULIRGs. This is consistent with an early stage of 

chemical evolution (Basu-Zych, et al., 2007; Hoopes 

et al., 2007). HST images of GALEX-discovered 

compact UVLGs reveal that they represent a complex 

merger of multiple, lower-mass, gas-rich subunits that 

echo the morphology and physical properties of high-z 

LBGs. Missions and Instruments in Development

James Webb Space Telescope

The James Webb Space Telescope (JWST) is a large 

(6.5m), cold (50K) facility-class general-purpose observatory that will be launched into orbit around the 

Sun-Earth L2 point in 2013. It is the successor to the 

Hubble and Spitzer space telescopes. Its science goals 

range from detecting the first galaxies to form in the 

early universe to observing objects in our solar system. 

Time on the telescope will be allocated to the community through annual peer-reviewed proposals, in 

a manner similar to Hubble. The prime contractor is 

Northrop Grumman Space Technologies; the Science 

and Operations Center is located at the Space Telescope Science Institute. For the prime mission, NASA 

is partnering with the European and Canadian Space 

Agencies.

The ASD provides scientific direction for JWST 

through seven project scientists. The Senior Project 

Scientist is John Mather and his deputy is Jonathan 

Gardner. The other members of the team: Matthew 

Greenhouse (Instrumentation), Bernard Rauscher 

(deputy); Mark Clampin (Observatory), Charles Bowers (deputy); and George Sonneborn (Operations). 

The ASD is currently seeking to hire an Associate 

Project Scientist for Integration and Test who will join 

the team to watch over the assembly, integration, test 

and commissioning of the Integrated Science Instrument Module (ISIM), the Optical Telescope Element 

(OTE) and the observatory.

JWST is the successor to the Hubble 

and Spitzer space telescopes. Its science 

goals range from detecting the first 

galaxies to form in the early universe to 

observing objects in our solar system.

Artist’s view of the James Webb Space Telescope. 

Credit: NASA/JWST

A primary mirror segment is prepared for cryogenic 

optical testing in the XRCF at MSFC. Credit: 

NASA/MSFC
Astrophysics Science Division: Research and Missions

64

Mather chairs the JWST Science Working Group 

(SWG), and the Project Scientists are thoroughly integrated with the management and engineering teams, 

participating in reviews, project meetings, serving on 

change-configuration boards, and participating in decisions. The JWST SWG recently published a thorough description of the JWST science goals and technical implementation as a special issue of the refereed 

journal, Space Science Reviews (Gardner et al., 2006). 

They have also produced a series of white papers extending the science case in certain areas, including astrobiology, exoplanet coronagraphy, exoplanet transits, 

first-light galaxies, and resolved stellar populations. An 

additional white paper on solar system observations 

is in preparation, and the white paper on exoplanet 

transits is being extended and prepared for refereed 

publication.

In 2008, JWST was confirmed for implementation, a 

transition that began with the Preliminary Design Review in April 2008. The Project is now in phase C/D, 

and the project is working towards the Critical Design Review (CDR) in late 2009. All four instruments 

have passed their CDRs and are scheduled to be delivered to Goddard for integration into the ISIM starting in early 2010. The 18 primary mirror segments, 

three spares, and the secondary and tertiary mirrors 

have been constructed out of light-weight beryllium 

and are in various stages of grinding and polishing. 

An engineering-demonstration segment and the first 

flight segment went through cryogenic figure test at 

MSFC in January 2009. The mission has been managed within the same budget and scheduled launch 

date since 2005.

Simulated JWST spectra of a transiting habitable 

Earth-sized ocean planet. Credit: NASA/JWST

An engineering model of the Mid-Infrared 

Instrument went through thermal vacuum testing 

in 2008

A single JWST microshutter. The Microshutter 

Assembly consists of a mosaic of four subunits 

producing a final array of approximately 750 

(spectral) by 350 (spatial) individually addressable 

shutters with 200 × 450 milliarcsec openings and 

250 × 500 milliarcsec pitch. The minimum aperture 

size is 1 shutter (spectral) by 1 shutter (spatial) at 

all wavelengths. It represents the first time that a 

true multi-object spectrograph has flown in space. 

Credit: NASA/GSFC
65

Astrophysics Science Division: Research and Missions

At the conclusion of these community-led studies, 

NASA and DOE announced plans for developing 

JDEM as an agency strategic mission with a NASA 

Announcement of Opportunity (AO) solicitation for 

JDEM flight-mission science investigations. The agencies also published their memo of understanding for 

joint development of the mission, including space and 

ground segments and science instrumentation. NASA 

then established the JDEM Project Office at the Goddard Space Flight Center to implement the NASA 

portion of the agreement. 

In October 2008, NASA and DOE selected a Science Coordination Group (SCG) via an open “Dear 

Colleague” letter to distill a reference mission from 

the above concept studies consistent with programmatic constraints for mission implementation and a 

boundary condition enabling three prime experimental methods for the investigation of dark energy. The 

chair of the SCG is the NASA JDEM Project Scientist 

Dr. Neil Gehrels (ASD) and members of the SCG include ASD scientists Benford and Moseley.

The primary initial task of the GSFC JDEM Project 

has been to work, with the guidance of the SCG, to 

create a set of mission requirements, and a reference 

mission that will meet them, to support the release of 

the science investigation AO. The JDEM project has 

been examining the design space required to accommodate all of the principal measurement techniques 

funded for study; which include Baryonic Acoustic 

Oscillations, Type 1a supernovae, and weak lensing. 

The current design incorporates solutions required to 

robustly carry out all three types of measurements. 

The concept for this reference mission is the point of 

departure for the phase A mission study now in progress (Oct. 2008 through Sept. 2009). The JDEM Phase 

A study will focus exclusively on enabling the specific 

science investigations selected by the AO. We expect 

that the investigators selected by this AO will form a 

The ASD is directly responsible for two hardware 

items, both within the Near-Infrared Spectrograph 

(NIRSpec), an instrument that is part of the ESA contribution to the mission. The Microshutter Assembly 

(MSA) is led by PI Harvey Moseley with contributions from Robert Silverberg and a number of contractor scientists. The MSA will enable simultaneous 

spectra of more than 100 objects—the first time that a 

true multi-object spectrograph has flown in space. The 

MSA is scheduled for delivery to ESA in March 2009. 

The detectors in the NIRSpec are also being built at 

Goddard, under the leadership of Bernard Rauscher, 

and will also be delivered in 2009. Both Rauscher and 

Moseley are members of the NIRSpec Science Teams 

and will participate in their Guaranteed Time Observations.

Joint Dark Energy Mission (JDEM)

The 1998 discovery that the expansion of space is accelerating was described by the journal Science as the 

breakthrough of the year and one of the most important scientific problems of our time. The implication 

that three-quarters of the energy in the universe is due 

to an unknown entity now called “dark energy” may 

revolutionize our understanding of cosmology and 

physics when this phenomenon is one day fully characterized. Observations with ground-based and orbital 

assets, including HST, Chandra, and WMAP, confirm 

the acceleration. However, to advance understanding in this critical area of new physics, we need a new 

space-based experiment to extend ground-based measurements of dark energy to the early universe with 

high precision. 

Between 2003 and 2006, NASA solicited concepts for 

such a dark energy mission to inform joint planning 

between the agency and its partner, the U.S. Department of Energy (DOE). The latter set of missionconcept studies completed in September 2008. ASD 

scientists were heavily involved in all three funded 

mission concepts. Benford, Carpenter, and Sonneborn 

were on the DESTINY (supernovae and weak lensing) 

science team; Moseley, Hinshaw, Oegerle, and Bowers 

were on the ADEPT (baryon acoustic oscillations and 

supernovae) team; and Woodgate, Rauscher, Kimball, 

and Greenhouse were members of the SNAP (supernovae and weak lensing) team. 

To advance understanding of dark 

energy, we need a new space-based 

experiment to extend ground-based 

measurements to the early universe with 

high precision.
Astrophysics Science Division: Research and Missions

66

standing flight Science Working Group to advise the 

JDEM Project throughout all future phases of mission 

development and operations.

The GSFC JDEM Project utilizes the skills of a broad 

cross-section of GSFC personnel, including project 

managers, project scientists, resources/financial specialists, and engineers. It is a collaborative effort across 

multiple GSFC directorates, including Science, Engineering, and Flight Projects). The GSFC Project looks 

forward to working with its counterparts within the 

DOE, and if current negotiations are fruitful, within 

the European Space Agency (ESA) as well. 

Astro-H

The X-Ray Astrophysics Laboratory is collaborating 

with ISAS/JAXA to implement an X-ray calorimeter 

spectrometer for the Astro-H mission. In response 

to the 2007 NASA Announcement of Opportunity 

soliciting investigations for Small Explorer (SMEX) 

missions and Missions of Opportunity (MO), a group 

headed by Richard Kelley of the X-Ray Astrophysics 

Laboratory was selected to provide key components of 

a high-resolution X-ray calorimeter spectrometer that 

will constitute one of the observatory’s primary science 

instruments. 

The Soft X-Ray Spectrometer (SXS) will consist of a 

64-pixel X-ray calorimeter array with better than 7 eV 

resolution (and a goal of 4 eV) to provide high-resolution X-ray spectroscopy over the 0.3–12 keV band 

with moderate imaging capability. The Goddard team 

is to provide the detector system, adiabatic demagnetization refrigerator (50 mK operational temperature), 

electronics, blocking filters and X-ray mirror, while 

ISAS/JAXA is responsible for the dewar system and 

the rest of the science instruments, the spacecraft, 

launcher, and mission operations. The dewar will be 

a hybrid cryogen/mechanical cooler system for redundancy, and the X-ray mirror will build on the Goddard legacy of providing lightweight, high-throughput 

mirrors.

Astro-H is a facility-class mission to be launched on a 

JAXA H-IIA into low Earth orbit in mid-2013. The 

Astro-H mission objectives: trace the growth history 

of the largest structures in the universe; provide insights into the behavior of material in extreme gravitational fields; determine the spin of black holes and 

the equation of state of neutron stars; trace shock-acceleration structures in clusters of galaxies and SNRs; 

and investigate the detailed physics of jets. Achieving 

The X-Ray Astrophysics Laboratory 

at Goddard was selected to provide 

key components of a high-resolution 

X-ray calorimeter spectrometer that 

will constitute one of the observatory’s 

primary science instruments. 

The Astro-H spacecraft. Credit: JAXA

An overview of planned instrumentation for 

Astro-H. Credit: NASA/JAXA
67

Astrophysics Science Division: Research and Missions

these objectives requires the SXS and three additional 

scientific instruments to provide a very broad, simultaneous energy bandpass. 

The Hard X-ray Imager (HXI) will perform sensitive 

imaging spectroscopy in the 5–80 keV band; the nonimaging Soft Gamma-ray Detector (SGD) extends the 

Astro-H energy band to 300 keV, and the Soft X-ray 

Imager (SXI) expands the field of view with a newgeneration CCD camera.

The proposed SXS science investigation comprises 

building and delivering the SXS instrumentation and 

carrying out a six-month observing program in collaboration with ISAS/JAXA. The baseline mission includes two years of funding for the SXS science team 

and support for processing and archiving the SXS 

data for a total of three years. A Science Enhancement 

Option (SEO) was also proposed to provide the US 

community with access to Astro-H beyond the baseline program. Under the SEO, U.S. scientists will be 

able to propose for Astro-H observing time and obtain 

grant support. Working collaboratively with JAXA, a 

U.S. Guest Observer Facility will process, distribute, 

and archive data from all four Astro-H instruments, 

and provide observers with analysis tools and support. 

NASA will address the SEO portion of the proposal at 

a later date.

SOFIA/SAFIRE

The Submillimeter and Far-InfraRed Experiment (SAFIRE) on the SOFIA airborne observatory is a spectrometer operating at wavelengths between ~ 100 mm 

and ~ 450 mm (Harvey Moseley, PI; Dominic Benford, Deputy PI). SAFIRE’s key science goal is to investigate line emission in galaxies at wavelengths not 

visible from the ground and to map the variation in 

this line emission in nearby galaxies. SAFIRE’s top priority observations will be to measure emission lines in 

the Galactic center, to map emission lines in nearby 

galaxies, and to understand the physics of the cores 

of ultraluminous galaxies from the local region to 

the high-redshift universe through far-infrared finestructure line emission. SOFIA will fly at an altitude 

where the atmosphere is mostly transparent, permitting SAFIRE to achieve a high point-source sensitivity at most wavelengths. When SAFIRE achieves first 

light in 2013, it will add substantial capability to the 

first-light instrument complement of SOFIA. 

SAFIRE is a cryogenic instrument in a space-constrained environment, so developing and implementing a suitable optical design is challenging. During the 

past year, optical design trade studies have transformed 

the original proposed design—an imaging Fabry-Perot interferometer—into a dual long-slit tunable grating spectrometer. The new design has the advantage of 

higher efficiency, faster observations for most sources, 

and increased flexibility in wavelengths of operation. 

Each of the gratings (and corresponding bandpass filters and slits) would be interchangeable to permit a 

wide variety of wavelength ranges—perhaps to wavelengths as short as 28 mm (where JWST’s MIRI cuts 

off). The most common optical configuration would 

When SAFIRE achieves first light in 

2013, it will add substantial capability to 

the first-light instrument complement of 

the SOFIA airborne observatory.

The SOFIA observatory. A mechanical prototype detector array. 
Astrophysics Science Division: Research and Missions

68

feature one grating channel operating between 120 

mm and 180 mm with a velocity resolution of around 

100 km/s and a slit size of 8′′ × 320′′, and another 

channel at 205 mm to 300 mm at 170 km/s with a slit 

size of 12′′ × 320′′. This configuration permits studies 

of the ionized carbon line at 158 mm simultaneously 

with the ionized nitrogen line at 205 mm.

The enabling technology for SAFIRE is its large-format superconducting bolometer arrays, under development by scientists in ASD (Harvey Moseley and 

team). In order to span the wide wavelength range 

envisioned—over two octaves—SAFIRE has been 

designed with a pair of 32 × 40 (1,280 pixel) arrays. 

This provides for both a long slit width and a large 

instantaneous velocity resolution of ~ 3000 km/s that 

enables rapid mapping of nearby galaxies and searches 

for redshifts or more distant sources. 

Gravity and Extreme Magnetism SMEX 

(GEMS) 

The information contained in the polarization of Xray fluxes has long been viewed as the unexplored 

handle on the geometrical and magnetic structures 

of X-ray-emitting regions. Sensitivity to the effects of 

strong gravity around black holes and the virtual pair 

creation of strong magnetic fields in neutron stars give 

polarization a special place as a probe of fundamental 

physics. 

In December 2008, a Phase A Concept Study Report 

was submitted to the SMEX program for the Gravity 

and Extreme Magnetism SMEX (GEMS). Jean Swank 

is the Principal Investigator. The GEMS team is very 

excited that their design could carry the most efficient possible 2–10 keV polarization experiment for 

a SMEX envelope, and that it would be able to make 

ground-breaking measurements of many classes of Xray source. The team is preparing for the site visit of 

the Review committee, to be held in April 2009. 

GEMS carries three telescopes, with each of the mirrors being a copy of the 4.5m focal length Suzaku mirror. The detectors behind the mirrors are Time Projection Chambers in which micropattern gas detectors 

record the tracks of photoelectrons as they lose energy. 

The mirrors and the polarimeters for GEMS are optimized for 2–10 keV. The spacecraft will rotate at 0.1 

rpm to allow systematic affects to be detected and corrected. The rotation allows a student experiment from 

co-investigators at University of Iowa to measure the 

polarization at 0.5 keV by scattering these X-rays out 

of the beam from one of the mirrors into a small proportional counter. 

The 1972 rocket flight detection of polarization of 

the Crab Nebula X-ray flux was followed by spacecraft efforts to detect polarization in bright sources 

using Bragg scattering instruments. These had good 

sensitivity to the polarization of an X-ray but very low 

sensitivities as instruments. The sensitivity of the photoelectric effect to the polarization of the X-ray raised 

the possibility of more efficient instruments. To use 

this effect it is necessary to track the ejected electrons 

whose distribution is peaked around the direction of 

the electric vector. In several early laboratory efforts 

to do this, the tracks were too short. It was achieved 

in a potentially practical way by Bellazini at INIF, as 

reported in the paper by Costa et al. (2001). 

The GEMS team believes this design 

could carry the most efficient possible 

2–10 keV polarization experiment for a 

SMEX envelope, and that it would be able 

to make ground-breaking measurements 

of many classes of X-ray source.

The grating set available for SAFIRE. 
69

Astrophysics Science Division: Research and Missions

Work on micropattern gas detectors in ASD led to a 

2003 SMEX proposal for the Advanced X-Ray Polarimeter (AXP), in collaboration with Palo Alto Research Center and the Italian INFN and IASF-CNR. 

While AXP was not selected, funding for detector 

development permitted continued laboratory work. 

The GEMS polarimeters are several times more efficient than the AXP polarimeters. Detector work in the 

X-Ray Astrophysics Lab led to adopting the detectors 

used in particle-physics experiments to our application. 

The more efficent polarimeters will make possible 

measurement of polarization to an accuracy of about 

1% for representatives of stellar black holes, supermassive black holes, neutron star pulsars (including magnetars), and supernova remnants. The baseline science 

program can be carried out in nine months with 35 

targets. In the balance of a two-year mission, a General 

Observer (GO) program could measure the polarizations of as many more targets. The Science Operations 

would be set up to support GOs as well as the baseline 

mission. 

GEMS combines the X-Ray Astrophysics Laboratory’s 

interests in instruments and in the physics of astrophysical sources. Polarization data, as well as timing 

and spectroscopy data, will provide a robust guide to 

resolving alternative interpretations of X-ray emission 

in various cosmic sources. 

Mission Concepts

Absolute Spectrum Polarimeter (ASP)

The Absolute Spectrum Polarimeter (ASP) is an Explorer-class mission concept to measure the polarization pattern and frequency spectrum of the cosmic 

microwave background. ASP will measure the linear 

polarization produced by gravity waves excited during 

an inflationary epoch shortly after the Big Bang. Such 

a signal is expected to exist; its detection would have 

profound consequences for both cosmology and particle physics. Not only would it establish inflation as 

a physical reality, but it would provide a model-independent determination of the relevant energy scale (~

1015 GeV) some twelve orders of magnitude beyond 

those accessible to particle accelerators.

ASP uses a cryogenic Michelson interferometer to 

measure the differential spectrum between two independent inputs in two orthogonal linear polarizations. 

ASP will measure the frequency spectrum of the Stokes 

I, Q, and U parameters from 1 cm through 60 mm 

wavelength. Its high sensitivity and broad spectral coverage enable a range of science goals. The polarization 

on large angular scales encodes the ionization fraction 

as a function of redshift, providing critical inputs for 

models of reionization and structure formation. 

Measurements of the CMB blackbody spectrum provide an independent determination of reionization 

through the Sunyaev-Zeldovich spectral distortion 

and will search for evidence of dark matter decay 

or annihilation in the very early universe (107

 < z < 

103

). ASP will measure the spectra of the temperature 

and polarization anisotropy to confirm their cosmological origin, and will measure both the far-infrared 

background and its power spectrum to test models of 

structure formation. Its measurements of the diffuse 

interstellar medium include full-sky maps of the major C+, N+, OI, and CO lines as well as thermal dust, 

free-free, and synchrotron emission.

ASP will measure the spectra of the 

temperature and polarization anisotropy 

to confirm their cosmological origin 

and will measure both the far-infrared 

background and its power spectrum to 

test models of structure formation.

Schematic view of the Absolute Spectrum 

Polarimeter spacecraft. Credit: NASA/GSFC
Astrophysics Science Division: Research and Missions

70

International X-ray Observatory (IXO)

IXO is a new X-ray telescope with joint participation 

from NASA, the European Space Agency (ESA), and 

Japan's Aerospace Exploration Agency (JAXA). This 

project supersedes both NASA's Constellation-X and 

ESA's XEUS mission concepts. IXO is a facility-class 

mission for launch circa 2020 that will address the 

leading astrophysical questions in the "hot universe" 

through its breakthrough capabilities in X-ray spectroscopy, imaging, timing, and polarimetry.

IXO will measure the spin of black holes, a fundamental property that, for supermassive black holes, reveals 

whether black holes grow mainly by accretion or by 

mergers. IXO will reveal the physics of accretion near 

the last stable orbit, measuring general-relativistic effects in the strong field limit. For neutron stars, IXO 

will determine the mass-radius relationship, thereby 

constraining the equation of state and QCD models 

of matter at these densities. In galaxy clusters, IXO 

will measure the velocity structure, mass, and metallicity distribution of the dominant baryon component, 

the hot intracluster gas. Not only will this provide a 

deep understanding of evolution of large-scale structure, but samples of clusters at various redshifts provide important and independent constraints on the 

cosmological model and dark energy. 

Extending away from clusters and groups is the cosmic 

web, where half of the baryons in the local universe are 

expected to reside but have not been detected. IXO 

will detect these missing baryons and it can test predictions for the formation and topology of the cosmic 

web. Furthermore, IXO will yield insight into feedback 

mechanisms in the universe on many scales: through 

studies of supernova remnants, outflows in starburst 

galaxies, and AGNs across cosmic time. 

Much of this science requires a panchromatic approach. IXO covers the 0.1–40 keV energy range, 

complementing the capabilities of the next-generation 

observatories such as ALMA, LSST, JWST and 30m 

ground-based telescopes. IXO builds on three decades 

of successful X-ray telescope development, including the currently operating Chandra X-ray Observatory (NASA) and XMM-Newton mission (ESA). The 

spacecraft configuration for IXO features a single, 

large X-ray mirror assembly and an extendible optical 

bench, with a focal length of ~20m, and a suite of focal 

plane instruments. Areas of technology development 

include X-ray optics, detector and cooling systems. 

The NASA portion of this project is led by GSFC (the 

Project Scientist is Nicholas White, Deputy Project 

Scientist is Ann Hornschemeier, and the Observatory 

Project Scientist is Rob Petre).

Laser Interferometer Space Antenna (LISA)

The Laser Interferometer Space Antenna (LISA) is a 

joint ESA-NASA project to design, build and operate 

a space-based gravitational wave detector. Space-time 

strains induced by gravitational waves are detected by 

measuring changes in the separation of fiducial masses 

with laser interferometry. Three spacecraft form an 

equilateral triangle with 5- million-kilometer-long 

sides defined by six proof masses, located in pairs at 

the vertices. Changes in the separations are monitored 

interferometrically to achieve a usable sensitivity in 

the frequency band between 1 × 10-4 and 0.1 Hz

The science objectives of the missions are:

•	 Understand the formation and growth of massive 

black holes and their host galaxies;

IXO is a facility-class mission for 

launch circa 2020 that will address the 

leading astrophysical questions in the 

"hot universe"

Mechanical engineering model of the IXO spacecraft. 

The front of the spacecraft has a sunshade for the 

opening of the X-ray mirror. Shown here is the 

slumped-glass mirror concept. The orange aft end of 

the spacecraft features an extendible optical bench; 

the instrument focal plane is at the end. Credit: 

NASA/IXO
71

Astrophysics Science Division: Research and Missions

•	 Make precision tests of general relativity and dynamical strong-field gravity;

•	 Survey ultra-compact binaries and study the morphology the Galaxy;

•	 Explore stellar populations and dynamics in galactic nuclei;

•	 Probe new physics and cosmology.

Although the gravitational wave spectrum has not yet 

been explored, LISA is expected to make precision 

measurements of the following sources:

•	 Merging massive black holes resulting from galaxy 

and proto-galaxy mergers: 102

–107 solar masses, z 

< 20, tens to 100 per year;

•	 Stellar mass black hole inspirals: ~10/106 solar 

masses, z < 1, tens to 100 per year;

•	 Galactic and extra-galactic ultra-compact binaries: 

tens of thousands, confusion foreground;

•	 Cosmological backgrounds, bursts and unforeseen sources.

The LISA Project Office is at GSFC. The Gravitational 

Astrophysics Laboratory provides the Project Scientist 

(Tuck Stebbins), three Deputy Project Scientists (Steve 

Merkowitz, Jeff Livas, Jordan Camp), and about 10 

other scientists who support project formulation, mission system engineering, technology development, 

risk reduction activities, astrophysical source studies, 

numerical relativity calculations of source waveforms, 

LISA data analysis research, and LISA Pathfinder data 

analysis. 

Goddard scientists support all aspects of project formulation, notably requirements development and 

flowdown, system analysis, system modeling, design 

of all mission elements, trade studies and document 

preparation. Goddard technology development work 

focuses on lasers, laser frequency stabilization (including pre-stabilization and arm-locking), and I&T technologies. Goddard risk-reduction activities include 

telescope construction, prototyping a critical mechanism, and control system modeling. The numerical 

relativity group in the Gravitational Astrophysics Lab 

has led the way in producing merger phase waveforms 

for inspiraling black holes, a crucial ingredient in LISA 

data analysis.

Extrasolar Planetary Imaging Coronagraph 

(EPIC)

Direct imaging/characterization of exosolar planets is 

predicated on the ability to unambiguously detect planets in the presence of diffracted/scattered light from 

the parent star, its exozodiacal light and other objects 

in the field of view. Astrometric missions can detect 

Earth-mass planets and determine orbital parameters 

yet cannot determine the zodiacal light—crucial for a 

future exosolar terrestrial imaging mission. 

EPIC is an alternative approach which images and 

characterizes jovian planets and exozodi disks around 

single, binary and ternary stars. It would provide the 

first direct measurements of a range of fundamental 

physical characteristics of exosolar giant planets—a 

step toward the long-term goal of imaging exosolar 

The numerical relativity group in 

the Gravitational Astrophysics Lab has 

led the way in producing merger phase 

waveforms for inspiraling black holes, a 

crucial ingredient in LISA data analysis.

LISA will use three spacecraft to form an equilateral 

triangle with 5-million-kilometer-long sides defined 

by six proof masses, located in pairs at each vertex. 

Credit: NASA/ESA
Astrophysics Science Division: Research and Missions

72

terrestrial planets (Mark Clampin, PI; Gary Melnick/

CfA, Deputy PI; Rick Lyon, Project Scientist).

Science goals are achieved by a 1.65-meter telescope 

coupled to a visible nulling coronagraph (VNC) delivering broadband starlight suppression (109

 @ 125 

mas) and permitting direct observation and broadband (0.4 – 1.0 um) spectral characterization. EPIC 

is aligned with the strategic objectives of NASA per 

“The New Age of Exploration” and fulfills the goal of 

“Vision for Space Exploration,” which calls for planet 

searches. EPIC meets the recommendations of the 

Exoplanetary Task Force (ExoPTF) to characterize 

exosolar disks and is a funded Astrophysics Strategic 

Mission Concept study (ASMC). The results of the 

study will be presented to the Decadal review. 

EPIC has been proposed as a NASA/Discovery mission. The EPIC team, including industrial partners 

Lockheed-Martin (telescope & VNC), Ball Aerospace 

(S/C bus) and the GSFC Instrument Design Center, 

have conceived a mature design using heritage technology (Kepler, Deep Impact) for a Probe class mission (< 

This image shows a simulated EPIC planetary 

detection. Credit: NASA/EPIC

Artist's concept of the EPIC spacecraft. Credit: 

NASA/EPIC

A schematic view of the EPIC Visible Nulling 

Coronagraph. Credit: NASA/EPIC

EPIC would provide the first direct 

measurements of a range of fundamental 

physical characteristics of exosolar giant 

planets—a step toward the long-term goal 

of imaging exosolar terrestrial planets.
73

Astrophysics Science Division: Research and Missions

$800M). The design includes extensive mission- and 

systems-level engineering down to the sub-system/

component level, leading to a well-balanced error budget with a low-risk design and realizable mission.

GSFC IR&D funding is enabling demonstration of 

the critical VNC technology via the VNC testbed 

and Null Control Breadboard (NCB). This vacuum 

testbed will demonstrate the requisite TRL-6 requirement of 109

 contrast in 15% passband for greater than 

1,000 secs.

The Fourier-Kelvin Stellar Interferometer 

(FKSI) 

The long-term focus of planet-finding efforts at NASA 

has been directed toward the search for extrasolar terrestrial planets, like those in our own solar system, 

within the habitable zone around stars similar to our 

own Sun, e.g., F, G, and K main sequence stars. Our 

present theoretical understanding is that all planets 

form out of material in primordial disks from which 

the stars themselves accreted material. Thus, the formation of planets is intimately linked to the evolution 

of circumstellar disks, which for mature stars like our 

own Sun, have optically thin “debris disks” in their 

habitable zones.

Recent studies of the requirements for planet-findingand-characterization missions such as the Terrestrial 

Planet Finder (TPF) have shown that the amount of 

exozodiacal emission from warm and hot dust in the 

habitable zone is a crucial parameter. Observations 

of planets in stellar systems with more than about 10 

times the zodiacal light as our solar system will be extremely difficult, as exozodiacal dust emission (and/

or scattering) interferes with the observer’s ability to 

detect the faint emission from an earthlike planet. 

Thus it is crucial to observe all of the likely targets for 

TPF to determine the amount of exozodiacal emission around nearby stars with sufficient accuracy for 

the flagship missions. In particular we must answer 

the question: What is the star-to-star statistical distribution of exozodiacal material in the habitable zone 

around nearby stars? The need for this measurement is 

documented in the report from the ExoPlanetary Task 

Force (Lunine et al., 2008). This measurement can be 

made with a small infrared interferometer having apertures ~0.5–1m in diameter and which is passively 

cooled to about 60 K.

One such implementation is the Fourier-Kelvin Stellar 

Interferometer (FKSI) mission, which is an infrared 

space interferometer comprised of two 0.5m-aperture 

telescopes on a 12.5m baseline on a boom, operating 

in the spectral range 3 to 8 (or 10) microns, and passively cooled to about 60 K. Bill Danchi is the Principal Investigator for FKSI. The main goals for this mission are the measurement and characterization of the 

exozodiacal emission around nearby stars, debris disks, 

spectroscopic characterization of the atmospheres of 

known exoplanets, and the search for and characterization of super Earths around nearby stars. 

The FKSI mission has been reviewed in the context of 

the Exoplanet Community Forum 2008 and has been 

included in the notional timeline developed for the 

area of “Direct Infrared Imaging of Exoplanets” as a 

candidate for a mid-sized or Probe-class strategic misFKSI's main goals are the measurement 

and characterization of the exozodiacal 

emission around nearby stars, debris 

disks, spectroscopic characterization of 

the atmospheres of known exoplanets, 

and the search for and characterization of 

super Earths around nearby stars.

Artist’s conception of the FKSI mission concept. 

This prototype planet-finding mission has been 

extensively studied. Credit: NASA/GSFC
Astrophysics Science Division: Research and Missions

74

sion (see the Exoplanet Community Forum Report, 

Chapter 4). Most of the technical risks have been 

retired through technology investments for JWST, 

SIM, and TPF-I/Darwin, and most technologies are 

at a Technical Readiness Level (TRL) sufficient for advancement to Phase A. This mission could receive a 

Phase A start in the next 2–5 years with only modest 

technology investments.

Terrestrial Planet Finder/Galaxy Evolution 

Surveyor

A terrestrial-planet finding telescope with a large, 

external occulter (TPF-O) has been under development at Goddard since December 2005. It is the outgrowth of a Discovery proposal led by W. Cash (Univ. 

of Colorado) with Goddard as lead NASA center. 

The proposal was to provide JWST with an occulter, 

which would enable it to discover Earth-size planets 

that might be habitable. The experience gained in that 

proposal effort led Goddard scientists and engineers 

to consider an optimal TPF-O: a 4m UV-optical telescope equipped with cameras and integral-field spectrographs, paired with a 50m occulter flying 70,000 

km in front of the telescope along the line of sight to 

the target star.

Today, Goddard scientists are helping to refine that 

concept by participating in two of NASA’s astrophysics mission concept studies. Roberge is a coinvestigator on the New Worlds Observer (W. Cash, PI), and 

Heap, Kuchner, Lindler, and Lyon are co-investigators 

on the ExoPlanet Characterizer, now incorporated 

into THEIA (D. Spergel, PI). 

They are also carrying out independent research supported entirely by Goddard:

•	 Design a testbed for TPF-O to explore the starlight-suppression properties of the occulter and to 

demonstrate closed-loop control of the occulter 

(Lyon & Heap).

•	 Develop the science case for TPF-O with special 

emphasis on the 100-fold increased sensitivity to 

photosynthesizing organisms enabled by a UV 

ozone camera (Heap & Lindler). The science case 

is buttressed by design reference missions, which 

allow the scientific gains to be quantified.

•	 Develop “revolutionary” astrophysics instrumentation for TPF-O, as directed by the 2000 Astrophysics Decadal survey panel. Heap and Lyon are 

collaborating with Massimo Robberto (STScI) to 

develop a concept for a wide-field imager/multiobject spectrograph primarily for studies of galaxy 

evolution but applicable to studies of dark energy 

and dark matter as well. Like the instrument proposed for SPACE (now incorporated into EUCLID), the spectrograph would use commercial 

digital micromirror devices (DMDs) to mask off 

An early proposal to outfit JWST with 

an occulter to enable discovery of Earthsize planets has led Goddard scientists 

and engineers to consider an optimal 

planet-finding occulter misison.

Goddard scientists and engineers are considering an 

optimal planet-finding occulter: a 4m UV-optical 

telescope paired with a 50m occulter flying 70,000 

km in front of the telescope along the line of sight 

to the target. Credit: NASA/GSFC

On the Web

Exoplanet Community Forum Report

exep.jpl.nasa.gov/documents/

Forum2008_268_small.pdf
75

Astrophysics Science Division: Research and Missions

selected objects for spectroscopy. However, the 

TPF-O version will have miniaturized fore and 

aft optics to the DMDs so as to make room for 

an array of multiobject spectrographs sampling a 

wide field of view.

Advanced Technology Large Aperture Space 

Telescope (ATLAST)

ATLAST is a concept study consisting of three point 

designs for an 8- to 16-meter UV/optical/NIR observatory designed for operation in a halo orbit at the 

Sun-Earth second Lagrange point (SEL2). ATLAST 

would have an angular resolution 5–10 times better 

than the James Webb Space Telescope (JWST) and a 

sensitivity limit 40–300 times better than the Hubble 

Space Telescope (HST). This concept was selected for 

study by NASA as one of the Astrophysics Strategic 

Mission Concept studies in preparation for the National Academy’s Astro2010 Decadal Survey. Marc 

Postman (STScI) is the Principal Investigator and 

GSFC is the managing NASA Center. Team members include JPL, NGST, Ball Aerospace and scientists 

from the community. ASD scientists involved in the 

study include Mark Clampin, Ted Gull, Rick Lyon, 

Bill Oegerle, Jennifer Wiseman, and Bruce Woodgate, 

as well as a number of people from the GSFC Engineering Directorate. 

The ATLAS Telescope is envisioned as a flagship mission of the 2025–2035 period designed to address 

one of the most compelling questions of our time: Is 

there life elsewhere in our Galaxy? It will have the capabilities required to explore the nearest ~1,000 stars 

capable of harboring life for Earth-size planets and 

characterize their spectra. ATLAST will also be a next 

generation UV/Optical Great Observatory—in the 

model established by HST—that is capable of achieving breakthroughs in a broad range of astrophysics 

and adaptable to addressing scientific investigations 

yet to be conceived. Indeed, such a telescope would 

revolutionize the study of galaxy evolution, enabling, 

for the first time, measurements of the kinematics of 

both the gaseous and stellar components of the smallest dwarf galaxies. It would yield such precise constraints on hierarchical-structure formation models 

that a new era of “precision galaxy evolution” would 

ensue. The superb spatial resolution would also allow 

unprecedented studies of resolved stellar populations 

in nearby galaxies.

Two of the point designs (for an 8m monolithic mirror telescope and a 16m segmented, deployable-aperture telescope) are enabled by NASA’s plans for a large 

Cargo Launch Vehicle (the Ares V), which will have 

a fairing size of 9–10 meters in diameter and the lift 

capacity to take 100 metric tons to SEL2. The 8-meter 

monolith telescope would fit into the Ares V fairing 

with the secondary fully deployed in an upright position. This eliminates a lot of risk in deployment in 

orbit. The 16m segmented-aperture telescope builds 

on the JWST heritage in terms of its segmented design 

and folded packaging. 

A third point design, being studied primarily at GSFC, 

is for a 9.2m segmented telescope that would fit into 

the fairing of an Evolved Expendable Launch Vehicle 

(EELV), such as the Delta IV heavy. All three point 

designs are identifying the technology investments 

The ATLAS Telescope is envisioned as a 

flagship mission of the 2025–2035 period 

designed to address one of the most 

compelling questions of our time: Is there 

life elsewhere in our Galaxy?

One of three designs under study for ATLAST is 

a 16m segmented-aperture telescope. This builds 

on the JWST heritage for its segmented design and 

folded packaging. Credit: NASA/STScI/J.
Astrophysics Science Division: Research and Missions

76

needed to enable these telescopes, such as lightweight 

mirrors with accurate figures, active wavefront sensing 

and control, and large-format detector technologies, 

to name just a few. The ATLAST study report will be 

delivered to NASA in April 2009 and to the Decadal 

Survey committee for consideration.

Energetic X-ray Imaging Survey Telescope 

(EXIST)

EXIST is a concept for an all-sky hard-X-ray imaging and gamma-ray burst mission (Grindlay/CfA, PI). 

ASD team members include Barthelmy, Gehrels, Tueller, Band, and Skinner. 

EXIST is based on proven technology and would image and temporally resolve the entire sky in every two 

95-minute orbits. It would detect extremely faint highenergy X-ray sources in the 5–600 keV range, which 

is poorly explored but particularly important for the 

discovery and study of black holes. EXIST's primary 

science objectives are to:

•	 Study the earliest stars, reionization and development of structure in the universe with prompt 

hard X-ray and prompt followup NIR measurements of GRBs at z >7

•	 Constrain the accretion luminosity of the universe 

by measurements of high-luminosity obscured 

AGN at z ~0-2.5, low-luminosity AGN at z <0.5 

and dormant AGN (from tidal disruption events) 

at z <0.1

•	 Provide the most sensitive wide-field measures of 

the transient universe with X-ray/OIR studies of 

blazars, black hole transients and high-energy variables (including stellar flares) with full-sky coverage every 3 hours, in synergy with GLAST and 

PanSTARRS, as well as LSST, JWST and other 

planned facilities.

The EXIST mission has evolved into the following 

configuration of three instruments: the High Energy 

Telescope (HET), an Infrared Telescope (IRT), and a 

Soft-X-ray Imaging telescope (SXI). In preparation for 

reports to the Astro2010 Decadal Survey, EXIST has 

conducted studies in the Goddard Instrument Design 

Lab (IDL) and the Mission Design Lab (MDL). The 

HET is 4.5m2

 of 5mm-thick CZT under a coded-aperture mask; the detectors are shown in the suborbital 

section under Proto-EXIST. The FOV is 90 × 70 deg 

at the 10%-coded region. 

The mask is composed of two scales: a 3-mm-thick, 

15-mm-cell-size mask pattern and a 0.3-mm-thick, 

1.25-mm-cell-size pattern. This allows for quick localizations of gamma-ray bursts (GRB) within 10 sec using the course scale. The spacecraft then slews to point 

the IRT and SXI narrow-field telescopes within 120 

sec. The IRT makes rapid imaging and spectral measurements to determine the redshift of the burst with 

~600 sec. The SXI makes localizations, lightcurves, 

and spectra in the 0.2-8 keV band. In addition to 

rapid localization of GRBs, EXIST will also conduct 

a full-sky hard-x-ray survey (5–600 keV) localizing 

EXIST would detect extremely faint 

high-energy X-ray sources in the 5–600 

keV range, which is poorly explored but 

particularly important for the discovery 

and study of black holes.

The EXIST mission Instrument Module (spacecraft 

not shown). The three instruments are the High 

Energy telescope (HET), the Infrared Telescope 

(IRT) and the Soft X-ray Imager telescope (SXI). 

Credit: NASA/GSFC
77

Astrophysics Science Division: Research and Missions

~30,000 AGN and hard-x-ray transients (Galactic and 

extra-galactic).

The Space Infrared Interferometric Telescope 

(SPIRIT)

In 2004–5, with funding from NASA’s Origins Probe 

Mission Concept Study program, Leisawitz and collaborators from ASD led a nationwide team of scientists, a Goddard-based engineering team, and four 

industry partners to develop a concept for the Space 

Infrared Interferometric Telescope (SPIRIT). SPIRIT 

is a two-telescope Michelson interferometer operating 

over the wavelength range 25 to 400 mm and offering a powerful combination of spectroscopy (l/Dl ~

3000) and subarcsecond-angular-resolution imaging 

in a single instrument. 

With angular resolution two orders of magnitude better than that of the Spitzer Space Telescope and with 

comparable sensitivity, SPIRIT will provide the data 

needed by astrophysicists to (a) learn how planetary 

systems and habitable planets form; (b) find and characterize exoplanets; and (c) learn how galaxies form 

and change over time. SPIRIT will also take advantage of an untapped and promising realm of discovery 

space, enabling scientists to ask and answer questions 

not yet imagined.

The 2000 Decadal Survey recommended a “rational 

coordinated program for space optical and infrared 

astronomy [culminating in the assembly of] a spacebased, far-infrared interferometer.” SPIRIT was explicitly recommended in the 2003 Community Plan for 

Far-IR/Submillimeter Space Astronomy as a practical 

step on the path ultimately leading to a kilometerbaseline interferometer, which will require formation 

flight. In response to community interests expressed 

in a May 2008 workshop, Leisawitz et al. (2008) described possible enhancements and estimated costs 

associated with extending the Origins Probe SPIRIT 

mission concept to a concept for a facility-class observatory. A 2009 community-based white paper titled 

"Far-Infrared/Submillimeter Astronomy from Space: 

SPIRIT will enable studies of 

astrophysical processes associated 

with the formation and development 

of galaxies and revolutionize our 

understanding of planetary system 

formation.

SPIRIT, shown in this artist's concept, is a 

structurally connected far-IR interferometer for 

imaging and spectroscopy. Credit: NASA/GSFC

SPIRIT will map the distribution of gas and dust 

in young and developing planetary systems to test 

theoretical models and elucidate the planet formation 

process. SPIRIT will trace the distribution of water 

in its gaseous and solid states and teach us how our 

planet acquired its life-enabling oceans. Credit: 

NASA/GSFC
Astrophysics Science Division: Research and Missions

78

Tracking an Evolving Universe and the Emergence 

of Life" recommends SPIRIT for Phase A study by 

the end of the coming decade. SPIRIT is described 

in a white paper submitted to the Astro2010 Decadal 

Survey. The paper and additional information about 

SPIRIT are available at http://astrophysics.gsfc.nasa.

gov/cosmology/spirit/,

SAFIR Observatory

The Single Aperture Far-Infrared Observatory (SAFIR) is a concept for a large (10m class), cold (4–10 

K) space telescope for wavelengths between 20 μm 

and 1 mm. It will provide sensitivity that is a factor 

of 100 or greater than that of Spitzer and Herschel, leveraging their capabilities and building on their scientific legacies. Covering this scientifically critical wavelength regime, SAFIR will complement the expected 

wavelength performance of future flagship endeavors, 

JWST and ALMA. 

This Vision Mission will probe the origin of stars and 

galaxies in the early universe and explore the formation 

of solar systems around young, nearby stars. Endorsed 

as a priority by the National Academy of Sciences Astronomy Decadal Survey and successive NASA space 

science roadmaps, SAFIR addresses a huge science 

need that is matched by promising and innovative 

technologies that will allow us to satisfy it.

In exercising those technologies it will create the path 

for future infrared (IR) missions.

The key science objectives for SAFIR are: 

•	 Probe the earliest epochs of metal enrichment and 

see the galaxy-forming universe before metals; 

•	 Resolve the FIR cosmic background and trace the 

formation and evolution of star-forming and active galaxies since the dawn of the universe; 

•	 Explore the connection between embedded nuclear black holes (active nuclei) and galaxy formation; 

•	 Track the chemistry of life by measuring prebiotic 

molecules, ices, and minerals from clouds to nascent solar systems. 

•	 Identify young solar systems from debris-disk 

structure and map the birth of planetary systems 

deep within obscuring envelopes. 

Under the auspices of a NASA Vision Mission concept study, the SAFIR team (including ASD scientists 

Benford, GSFC lead, and Danchi, Leisawitz, Mather, 

Moseley) refined the scientific goals of the mission, exSAFIR addresses a huge science 

need that is matched by promising and 

innovative technologies that will allow us 

to satisfy it.

Artist's concept of the Vision Mission design for 

SAFIR—an 8–10m deployable telescope based on 

JWST technologies. Credit: NASA/GSFC

A sketch of CALISTO—a 6m monolithic, offaxis mirror design that provides a downscaled but 

possibly more cost-effective version of SAFIR. 

Credit: NASA/JPL
79

Astrophysics Science Division: Research and Missions

plored promising approaches for its architecture, and 

sharpened their understanding about remaining technological challenges in order to recommend optimal 

strategic investments. 

The results of this work have recently appeared in an 

AIAA volume by Marc Allen titled NASA Space Science Vision Missions. The baseline configuration is a 

JWST-based architecture with maximal heritage on 

the overall design. More recently, a downscaled but 

possibly more cost-effective version of SAFIR, named 

CALISTO, has been developed under JPL leadership. 

Its modest-aperture off-axis design minimizes obstructions, reduces deployments, and decreases mass, at the 

loss of some sensitivity and angular resolution. This 

may be affordable in the coming decade if endorsed by 

the Astro2010 Decadal Survey.

High Energy Astrophysics Science Archival 

Research Center (HEASARC)

Since its inception in 1990, the HEASARC has been an 

essential element of NASA’s astrophysics missions. The 

HEASARC’s archive services allow scientists to identify, display, cross-correlate, download and analyze data 

from a variety of past and current missions including 

ASCA, BeppoSAX, Chandra, CGRO, Einstein, Fermi, 

INTEGRAL, ROSAT, RXTE, Suzaku, Swift, WMAP, 

and XMM-Newton and provide access to a wide range 

of multiwavelength sky surveys, astronomical catalogs, 

and other resources. The HEASARC’s scientific and 

technical staff produces a variety of widely used software packages, provides expertise in the analysis of archived data, and helps to evolve the archive interfaces 

to better serve the science community. 

The data and software standards developed by the 

HEASARC provide the underlying infrastructure for 

the interpretation of data from a wide variety of missions. This multi-mission approach has substantially 

reduced the mission costs while increasing science return. Papers using the HEASARC datasets comprise 

10% of the total astronomical literature and include 

some of the most highly cited papers in the field.

Since 1998 the HEASARC has enjoyed formal links 

with the Smithsonian Astrophysical Observatory 

(SAO), host of the Chandra X-ray Center, with an SAO 

scientist serving as HEASARC associate director. This 

approach integrates Chandra data into the HEASARC 

while recognizing the special requirements of a Great 

Observatory-class mission. The strong collaboration 

between these centers and seamless access to Chandra 

data from the HEASARC attest to the success of this 

approach. The HEASARC’s SAO branch also produces and maintains important analysis capabilities, such 

as the immensely popular DS9 image processing and 

analysis package. 

In June 2008, the HEASARC merged with the Legacy 

Archive for Microwave Background Data Analysis 

(LAMBDA) to better support the broad science goals 

of NASA’s Physics of the Cosmos theme. Within the 

next four years, the newly combined organization 

(which retains the HEASARC name) will ingest observations from eight currently operating missions and 

up to nine upcoming missions, simultaneously serving 

data from these and more than 30 archival missions to 

the community from an archive that is projected to 

reach 40+ terabytes by 2012.

In 2008, NASA HQ conducted a Senior Review of 

NASA’s astrophysics archive centers. The HEASARC 

was ranked joint second out of the six facilities evaluated and received a small funding augmentation to assist 

with the incorporation of datasets from key upcoming 

international missions (AGILE, MAXI, and ASTROSAT) and expand its efforts to develop science-based 

topical archives. The HEASARC is also a core partner 

in a recently-approved joint NSF/NASA program to 

manage and operate the U.S. Virtual Astronomical 

Observatory.

In addition to the HEASARC/LAMBDA merger and 

a steady stream of new software enhancements and upPapers using the HEASARC datasets 

comprise 10% of the total astronomical 

literature and include some of the most 

highly cited papers in the field.

On the Web

Cosmic Times 

cosmictimes.gsfc.nasa.gov
Astrophysics Science Division: Research and Missions

80

a continuing effort to maintain and evolve software 

and data standards for new missions. 

In addition to the archive, the HEASARC Office 

(Code 660.1) also performs oversight and coordination for the Guest Observer Facilities and Science 

Support Centers for Fermi, INTEGRAL, RXTE, 

Suzaku, Swift, WMAP, and XMM-Newton. These facilities assist the astrophysics community in proposing 

and analyzing data from their missions and provide 

NASA HQ with critical organizational support for its 

Peer Review and program-selection activities. Some of 

these facilities also support mission operations, create 

analysis software, process data, and deliver data to the 

archive. Recent achievements and future expectations 

for these facilities are included in the sections for the 

respective missions.

Gamma-ray burst Coordinates Network 

Since 1992, ASD has operated the GRB Coordinates 

Network (GCN). The GCN distributes positions, 

light curves, images, and spectra on gamma-ray bursts 

and other gamma-ray transients in real time collected 

from five active missions to over 600 recipient sites 

(telescopes, missions, observers, etc.). These GCN 

Notices enable rapid follow-up observations. 

Notices are distributed using a combination of Internet socket and email-based methods. Through GCN 

Circulars and Reports, the network also collects and 

distributes worldwide the results of follow-up observations made by the recipients of GCN Notices.

grades for the fundamental HEAsoft, CalDB, XSPEC, 

Skyview and HERA packages, 2008 was also notable 

for: 

•	 the opening of the HEASARC Fermi archive; 

•	 release of the HEASARC Browse Notification service, which informs the user when new data are 

available in the archive for any specified source; 

•	 the appointment of a new HEASARC Director 

(Alan Smale); 

•	 the beginning of a major new initiative to revision 

and redesign HEASARC’s data access and data retrieval systems. This work will continue in 2009, 

along with further investigation of the sciencebased topical archive concept and development of 

plans to incorporate new datasets from upcoming 

missions.

Funding permitting, during 2009 the HEASARC EPO 

program will print and distribute the Cosmic Times 

posters and continue to conduct Cosmic Times workshops. Cosmic Times is a curriculum-support project 

that traces how our understanding of the nature of the 

universe has changed over the past century. The project includes hardcopy posters, on-line lessons and a 

teacher guide, and it is largely funded by a multiyear 

IDEAS grant. We will also produce the 13th edition of 

the "Imagine the Universe!" CD-ROM — for the first 

time in DVD format. As in previous editions, this will 

contain captures of the "Imagine the Universe!" and 

Starchild web sites, along with the Astronomy Picture 

of the Day materials. The DVD-ROMs will be distributed at teacher conferences and via the NASA CORE 

and other relevant websites.

Looking further ahead, priorities within the 2009–

2012 timeframe include the development and implementation of archives for NuSTAR, the two groundbased CMB experiments ACT and SPT, some current 

Explorer Program mission candidates, and the upcoming international missions; continuing support for the 

HEASARC’s exponentially growing data holdings and 

retrievals; a closer integration of archive access and 

analysis tools; development of science-based topical 

archives; and enhanced interoperability with other archive centers and the Virtual Observatory, along with 

On the Web

The Gamma-ray burst Coordinates Network

gcn.gsfc.nasa.gov
81

Astrophysics Science Division: Research and Missions

goal of this program is to educate teachers about cutting-edge research and have them design projects to 

incorporate the science into their high school physics 

classes. The 2007–2008 BETA focused on the topic 

of black holes and strong gravity and was highly successful.

Several programs and efforts target audiences in outof-schooltime settings. Afterschool Universe, an afterschool astronomy program, introduces middle-school 

children to the universe beyond the solar system. This 

program was launched nationally in 2008 and has 

been received with great enthusiasm by the afterschool 

community all across the country. More than 150 afterschool program leaders were trained to deliver this 

program in 2008 and the list of partnerships and implementers steadily grows.

The Family Science Night (FSN) program works with 

families and their middle-school children to engage 

them in science. FSN is offered monthly at the Goddard Visitors’ Center and is a joint effort between the 

Astrophysics and Heliophysics Divisions at Goddard. 

It is an extremely popular program with the local 

community and received a Goddard Honor Award in 

2008. This program will be expanded to be nationwide in 2009.

The Big Explosions and Strong Gravity (BESG) program targets Girl Scouts aged 11 to 13. This is a oneday event where girls meet real scientists and join them 

for a day of hands-on exploration into supernovae and 

black holes. Girls whose interest in science is piqued by 

this event can participate in a follow-on program, the 

A.C.E. of Space club (A.C.E. stands for Astronomical 

Cosmic Exploration). This is a girl-led club and the 

members explore different parts of the universe during 

their meetings over the course of a year. 

The ASD EPO group has also been active with developing museum displays and exhibits. The group 

developed a display for the Goddard Visitors’ Center 

VI.Education and Public Outreach 

in NASA’s Astrophysics 

Science Division

The Astrophysics Science Division (ASD) supports a 

strong and vibrant Education and Public Outreach 

(EPO) program. The EPO team includes members 

who support various NASA astrophysics missions 

and programs, including ACE, Beyond Einstein, 

HEASARC, Integral, JWST, Suzaku, and RXTE. The 

team also supports a broader EPO effort that is not 

mission specific and covers ASD science and technology. 

There are several notable EPO efforts in ASD serving a 

diverse range of audiences. We have developed a wide 

variety of curriculum support materials for teachers 

over the years. One such ongoing effort is the “Cosmic Times” project, which presents the history of our 

understanding of the nature of the universe through 

the 20th and early 21st century. The series traces this 

history from the confirmation in 1919 of Einstein’s 

theory of gravity, to Hubble’s discovery of the expanding universe, the development and evidence for the 

Big Bang, and finally the discovery of dark energy. Additional curriculum support materials developed over 

the years are available to educators through our “Imagine the Universe!” website.

In 2007–2008, the ASD also ran a year-long education program for high-school physics teachers called 

the Beyond Einstein Teachers’ Academy (BETA). The 

Every month, the Goddard Visitor Center hosts 

the NASA Family Science Night program. Credit: 

NASA/GSFC.

The EPO group’s continuing efforts 

bring the “Universe Down to Earth.” In 

2009, major new programs will support 

the International Year of Astronomy.
Astrophysics Science Division: Research and Missions

82

one of the featured groups at the Smithsonian Folklife 

Festival in 2008. The ASD EPO group played a major 

role in organizing the representation of Astrophysics at 

NASA. Similarly, we played a key role in LaunchFest, 

the Goddard Open House held in Sept. 2008.

The group continues its efforts to bring the “Universe 

Down to Earth” with its ongoing efforts as well as major new efforts planned in support of the International 

Year of Astronomy in 2009.

in 2007 highlighting the science and technology programs in the Division. We also developed a traveling 

exhibit for the James Webb Space Telescope in 2008, 

as an add-on to the highly popular Hubble Space Telescope traveling exhibit. This exhibit will travel to three 

locations in 2009. 

In addition, the ASD also has a dynamic online presence and a growing new media effort. We have several popular sites targeted at the public and educators. 

These include StarChild, Cosmicopia and Imagine the 

Universe! The ASD EPO group produced a set of podcasts in 2007 titled “Blueshift.” A new media effort 

that includes podcasts and blogs has been launched 

in 2009 in support of the International Year of Astronomy. 

For JWST, we launched a major online outreach effort 

in 2008. We developed an online Flash game to teach 

the visitor about modern telescopes such as Hubble 

and JWST and their commonalities and differences 

with traditional telescopes. We also ventured into SecondLife and established a presence on Facebook that 

has been extremely popular. Finally, we developed an 

online interactive version of the JWST traveling exhibit to reach the public that will not be able to travel 

to the exhibit locations. 

The ASD EPO group was a major participant in several high-profile outreach efforts in 2008. NASA was 

High school physics teachers learned about black 

holes and strong gravity in the Beyond Einstein 

Teachers’ Academy in July 2007. Four follow-up 

meetings were held during the 2007–2008 school 

year. Credit: NASA/GSFC.

On the Web

ASD EPO

astrophysics.gsfc.nasa.gov/outreach/

Afterschool Universe

universe.nasa.gov/afterschool/

Beyond Einstein Teachers’ Academy

beyondeinstein.nasa.gov/education/beta.html

Big Explosions and Strong Gravity

bigexplosions.gsfc.nasa.gov

Blueshift

universe.nasa.gov/blueshift/

Cosmic Times

cosmictimes.gsfc.nasa.gov

Cosmicopia

helios.gsfc.nasa.gov

Family Science Night

sdo.gsfc.nasa.gov/epo/families/fsn.php

Imagine the Universe!

imagine.gsfc.nasa.gov

James Webb Space Telescope

www.jwst.nasa.gov

StarChild

starchild.gsfc.nasa.gov