Science Writers’ Guide to Landsat 7

Science Writers’ Guide to Landsat 7

From monitoring croplands

in Arizona to mapping

ice streams in the Antarctic,

Landsat 7 will advance

earth science research.

March 1999
Science Writers’ Guide to Landsat 7

NASA’s Earth Observing System

The Earth Observing System (EOS), the centerpiece of NASA’s Earth science

program, is a suite of spacecraft and interdisciplinary science investigations

dedicated to advancing our understanding of global change.

The flagship EOS satellite, Terra (formerly EOS AM-1), scheduled for launch in

July 1999, will provide key measurements of the physical and radiative properties

of clouds; air-land and air-sea exchanges of energy, carbon, and water; trace gases;

and volcanoes. Flying in formation with Terra, Landsat 7 will make global high

spatial resolution measurements of land surface and surrounding coastal regions.

Other upcoming EOS missions and instruments include QuikSCAT, to collect

sea surface wind data; the Stratospheric Gas and Aerosol Experiment (SAGE III),

to create global profiles of key atmospheric gases; and the Active Cavity Radiometer Irradiance Monitors (ACRIM) to measure the energy output of the Sun. The

second of the major, multi-instrument EOS platforms, PM-1, is scheduled for

launch in 2000.

Interdisciplinary research projects sponsored by EOS use specific Earth science

data sets for a broader investigation into the function of Earth systems. Current

EOS research spans a wide range of sciences, including atmospheric chemistry,

hydrology, land use, and marine ecosystems.

The EOS program has been managed since 1990 by the Goddard Space Flight

Center in Greenbelt, Md., for NASA’s Office of Earth Science in Washington, D. C.

Additional information on the program can be found on the EOS Project Science

Office Web site (http://eospso.gsfc.nasa.gov).
Science Writers’ Guide to Landsat 7

1

Evolution of the Landsat Program

Landsat is the United States’ oldest

land-surface observation satellite

system. Although the program has

scored numerous successes in scientific

and resource-management applications,

Landsat has had a tumultuous history

of management and funding changes

over its 26-year history. Landsat 7 marks

a new direction in the program to

reduce the costs of data and increase

global coverage for use in global change

research.

The diversity of Landsat applications makes it unique among Earth

observation satellites. Images acquired

by Landsat satellites were used to

produce the first composite multispectral mosaic of the 48 contiguous

United States. They have been used to

monitor timber losses in the U.S. Pacific

Northwest, map the extent of winter

snow pack, and measure forest cover at

the state level. In addition, Landsat has

been used in to locate mineral deposits,

monitor strip mining, and assess natural

changes due to fires and insect infestations.

NASA launched the first satellite in

the Landsat series (originally called the

Earth Resources Technology Satellites)

on July 23, 1972. The program was given

the name Landsat in 1975. Efforts to

move the Landsat program into the

commercial sector began under the

Carter Administration in 1979 and

resulted in legislation passed in 1984

that charged the National Oceanic and

Atmospheric Administration (NOAA)

to transfer the program to the private

sector. The Earth Observing Satellite

Company (EOSAT) took over operation

in 1985 and was given rights to market

Landsat data.

Landsat 5 was launched in March

1984 and is still returning images.

Landsat 6, which was commercially built

and managed, was destroyed after

launch in October 1993 when the

rocket’s upper stage failed to fire.

With the passage of the Land

Remote Sensing Policy Act in 1992,

oversight of the Landsat program began

to shift from the commercial sector to the

federal government. Management was

transferred from NOAA to NASA and

the Department of Defense. President

George Bush authorized Landsat 7 in the

same year. The Department of Defense

withdrew from the program in 1994, and

NASA was named the lead agency

working with NOAA and the U. S.

Geological Survey (USGS).

NASA integrated Landsat 7 into its

EOS program in 1994. The agency is

responsible for the development and

launch of the satellite, and the development of the ground system. As the

operational era begins, Landsat 7 is

transitioning to a dual-agency program

between NASA and USGS. Future

management will be governed by a joint

agreement between the two agencies.

As part of NASA’s EOS series of

satellites, Landsat 7 will provide a

unique suite of high-resolution observations of the terrestrial environment.

While other sensors onboard the Terra

satellite, to be launched in July 1999, will

characterize daily changes at coarse

resolution, Landsat will provide data at
Science Writers’ Guide to Landsat 7

2

a finer resolution to allow for investigations of the causes of land-surface

change.

Landsat 7 will gather remotely

sensed images of land surface and

coastal regions for global change research, regional environmental change

studies, national security uses, and other

civil and commercial purposes. The

Landsat 7 project is part of NASA’s long

term, coordinated research effort to

study the Earth as a global environmental system.

The Landsat Science Team, composed of 14 scientific investigators, was

selected in 1996. These researchers are

conducting a range of studies designed

to exploit the characteristics of Landsat 7

for global change research. The satellite

will fly in near-formation with Terra,

observing the same ground track just a

few minutes apart. Landsat 7 will

capture and store in a U. S. archive

global landmass data once per season.

Following an initial 60-70 day

checkout period, Landsat 7 will begin

normal operations. Daily commands

will be sent to the spacecraft defining

which images to record and when to

downlink data either to U.S. or international ground stations. NASA will

continue to manage day-to-day operations until October 2000, when they will

be turned over to USGS.

The Landsat 7 system will collect

and archive an unprecedented quantity

of high-quality multispectral data each

day. This dataset will, for the first time,

provide a high-resolution view of both

seasonal and interannual changes in the

terrestrial environment. The USGS Earth

Resources Observation Systems Data

Center (Sioux Falls, SD) will process,

archive, and distribute all U.S. Landsat

data. U.S. data will be acquired primarily at the EROS Data Center; supporting

ground stations in Alaska and Norway

will also be used.

The Landsat Project, located at

Goddard Space Flight Center (Greenbelt,

Md.), manages Landsat development for

NASA’s Office of Earth Science in

Washington, D.C. USGS operations will

be performed at a Mission Operations

Center at the Goddard Space Flight

Center and at the EROS Data Center.
Science Writers’ Guide to Landsat 7

3

A New Era of Landsat Technology

The instrument on board Landsat 7

is the Enhanced Thematic Mapper Plus

(ETM+). ETM+ is a passive sensor that

measures solar radiation reflected or

emitted by the Earth’s surface. The

instrument has eight bands sensitive to

different wavelengths of visible and

infrared radiation and has better resolution in the thermal infrared band than

the Thematic Mapper (TM) instrument

carried by Landsats 4 and 5. The

instrument’s calibration is good to

within 5 percent, making the ETM+ far

more accurate than its predecessors.

Landsat 7 data will be used to build

and periodically refresh a global archive

of Sun-lit, essentially cloud-free images

of the Earth’s landmass. With an upgraded data system on the ground,

Landsat 7 will collect 250 scenes per day,

each scene containing enough digital

data to fill a powerful home computer’s

hard drive. The Landsat 7 receiving

station will handle 4-5 times more data

than the existing program’s receiving

station.

During the Landsat program’s

management as a commercial operation,

it became increasingly expensive to

gather data. As a cost saving measure,

Landsat imagery was only collected

when a user requested it instead of as an

ongoing process, which is essential to

scientific studies. Landsat 7’s commitment to collecting and archiving all

scenes in the United States including

Alaska and Hawaii is a significant

change in the program.

Processing, distributing, and

archiving Landsat data will also be

significantly improved. Previous

Landsat data was often too expensive for

widespread scientific use. All Landsat 7

data received at the USGS EROS Data

Center receiving station will be archived

and available electronically within 24

hours and will be sold at cost. In addition to the main U.S. receiving station,

several international ground stations

will collect Landsat 7 data around the

globe, archive it, and make it available

through on-line Internet browsers. Steps

are being taken to link the browsers and

give users a single point of entry to the

network and easy access to Landsat

catalog information.
Science Writers’ Guide to Landsat 7

Launch of Landsat 7 is scheduled

for April 1999 from the Western Test

Range at Vandenberg Air Force Base,

Calif., on a Delta-II expendable launch

vehicle. The Landsat 7 satellite consists

of a spacecraft bus being provided by

Lockheed Martin Missiles and Space

(Valley Forge, PA) and the Enhanced

Thematic Mapper Plus instrument built

by Raytheon (formerly Hughes) Santa

Barbara Remote Sensing (Santa Barbara,

Calif.).

Continuity of data with previous

Landsat missions is a fundamental goal

of the Landsat program. To accomplish

this, images will be taken that are

consistent in terms of data acquisition

format, geometry, spatial resolution,

calibration, coverage characteristics, and

spectral characteristics with previous

Landsat data. Landsat 7 will image large

areas of the sunlit Earth daily, revisiting

the same areas every 16 days to refresh a

global archive. Digital copies of all

images in the archive will be available to

users for the cost of fulfilling the request.

At launch, the satellite, including

the instrument and fuel, will weigh

approximately 4,800 pounds (2,200

kilograms). It is about 14 feet long (4.3

meters) and 9 feet (2.8 meters) in diameter.

After being launched into a sunsynchronous polar orbit, the satellite will

use on-board propulsion to adjust its

orbit to a circular altitude of 438 miles

(705 kilometers) crossing the equator at

approximately 10 a.m. on its southward

track. This orbit will place Landsat 7

along the same ground track as previous

Landsat satellites. The orbit will be

maintained with periodic adjustments

for the life of the mission. A three-axis

attitude control subsystem will stabilize

the satellite and keep the instrument

pointed toward the Earth to within 0.05

degrees.

Daily commands will be sent to the

spacecraft defining which images to

record and when to downlink data either

to U. S. or international ground stations.

Launch and Mission Profile

4
Science Writers’ Guide to Landsat 7

5

Research Profiles

Volcanic hazards and lava lakes

Luke Flynn, University of Hawaii

Active lava

flows can be

distinguished

from older flows

that have

already begun

to cool.

To understand the complex “plumbing” beneath active volcanic lave lakes

and determine the amount of lava

flowing from them, Luke Flynn of the

University of Hawaii has been using

time series of Landsat images. Much of

his work has focused on the persistence

of volcanic eruptions at Hawaii’s

Kilauea volcano, which has been continually erupting since 1983. Another

objective of Flynn’s research – and one

critical to many residents of Hawaii – is

to map active lava flows and provide

advance warning to public safety

officials about these natural hazards.

Flynn and other volcanologists have

been using remote-sensing data from the

geostationary GOES satellite to monitor

volcanic eruptions in remote areas in

real time. The higher resolution of

Landsat data (30 meters as compared to

4 kilometers for GOES) can produce

maps of lava flows with pinpoint

accuracy, according to Flynn. With these

maps researchers can study the evolution of individual eruptions while they

are taking place.

With Landsat observations of the

heat emitted during eruptions, Flynn

can distinguish active lava flows from

older flows that have already begun to

cool. With this data, Flynn’s colleague

Andrew Harris is generating estimates

of the amount of lava erupting onto the

surface. Using similar Landsat data,

Flynn produces maps of the leading

edges of wildfires.

Flynn and Harris have also been

working with Landsat data of active

volcanic lava lakes around the world. In

addition to their work in Hawaii, they

are studying long-term observations of

eruptions in Mexico (Popocatepetl) and

Guatemala (Santa Maria and Pacaya).

Once they have compiled extensive

observations of an individual volcano,

they create a database of areas on the

volcano that are most prone to lava flow

hazards. Flynn plans to produce even

higher resolution maps of active lava

flows (15 m) with Landsat 7.

Flynn plans to collect Landsat 7 data

at a ground station in Hawaii as the

satellite passes over the state. He plans

to produce new Landsat 7 volcano (and

wildfire) hazard maps for the State of

Hawaii every 8 days.

Contact information: Luke Flynn, Hawaii

Institute of Geophysics and Planetology/

School of Ocean and Earth Science Technology, University of Hawaii, tel. 808-956-

3154; flynn@pgd.hawaii.edu.

University of Hawaii Public Information

Office, Florence Donne, tel. 808-956-7522;

donne@hawaii.edu.
Science Writers’ Guide to Landsat 7

6

Growth patterns of urban sprawl

Jeffrey G. Masek, University of Maryland

How do zoning

policies and

environmental

pressures

influence the

expansion of

urban

populations?

Traffic jams and air pollution in

large metropolitan areas are sure signs

of expanding populations. Across the

globe, 50 percent of the world’s population now lives in urban areas, a gain of

over one billion individuals in the last

30 years. In the United States, urban

growth can be counted in a census, but

how do these expanding populations

affect the landscape? Are urban areas

making good use of limited space or are

they succumbing to urban sprawl? How

do factors like zoning policies and

environmental pressures influence the

expansion of populations over the land?

Jeffrey Masek and Frank Lindsy,

geographers from the University of

Maryland, are using Landsat data to

study land use efficiency, which is the

amount of land area used by increasing

populations. Using Landsat data acquired between 1973 and 1996, Masek

and Lindsy mapped the growth of the

Washington D.C. metropolitan area.

They found that the Washington

area has expanded at a rate of 8.5 square

miles (22 square kilometers) per year

with notably higher growth during the

late 1980s, a trend that followed the

regional and national economy. They

also found distinct variations in the

efficiency of land use among neighboring counties in Maryland and Virginia,

in part reflecting the land use policies of

these jurisdictions.

Observing urban areas over time

with satellite imagery can also be used

to make predictions about future

growth. Landsat imagery can show

where the growth is taking place and

help geographers evaluate how different

urban planning programs effect population growth and land use, according to

Masek. Cities such as Portland, Ore.,

have strict planning and environmentally sensitive zoning laws, while many

Southwestern cities have grown with

few planning guidelines.

With Landsat 7 observations, Masek

and colleagues intend to evaluate

growth patterns of other cities around

the world. With a greater number of

images available, Masek can compare

cities once every two years to capture

detailed records of land use changes.

Contact information: Jeffrey G. Masek,

Department of Geography, University of

Maryland; tel. 301-405-8233;

jmasek@geog.umd.edu.

University of Maryland Office of University

Relations, Lee Tune, tel. 301-405-4679;

ltune@accmail.umd.edu.
Science Writers’ Guide to Landsat 7

7

“Dune reactivation” in the U. S. High Plains

Alexander F. H. Goetz, University of Colorado at Boulder

Some climate

models predict

these sandy

landscapes

could begin

blowing as they

did in the “dust

bowl” years.

More than 10 percent of the United

States’ High Plains region is made up of

sand dunes and sand sheets that are

currently stabilized by the natural

grasses growing on them and by irrigated farming. If future climate change

leads to increased temperatures and less

rainfall in this arid region, as some

climate models predict, these sandy

landscapes could be “reactivated” and

begin blowing as they did in the “dust

bowl” years of the 1930s.

Information about the dunes in this

800,000 square-kilometer region –

encompassing parts of Colorado, South

Dakota, Nebraska, Kansas, Oklahoma,

Texas, and New Mexico – has been

available for decades. However, a

systematic study of the relationship

between humans and the land and landuse change on a large geographic scale

is only now possible utilizing satellite

observations.

Alexander Goetz, professor of

geological sciences at the University of

Colorado is leading a research team to

create an effective way to assess how the

High Plains will be affected by future

climate change. Using Landsat 5 data

from 1984 to the present, Goetz’ team

has completed a detailed study of land

cover change in northeastern Colorado

and is creating a 15-year database of

land cover and human-induced land

cover changes in the region.

One of the more striking observations is the dramatic shift from dry-land

farming and flood irrigation to centerpivot irrigation since 1985. Some of the

pivots are located in the dune areas and

these spots would become dune reactivation sites if the irrigation were discontinued, according to Goetz.

Combining land-cover data with

meteorological and future climate data

in a regional climate model, Goetz plans

to produce a model-based method for

estimating future dune reactivation and

identifying the areas with the highest

potential for reactivation. The team will

also investigate the potential effect of

abandoning farmed and irrigated lands

on dune reactivation.

Landsat 7 data will provide the

researchers with many more images

than are currently available, since the

team will acquire images from every

pass of the satellite over the region. With

multiple images during a growing

season, they can more precisely distinguish crop types and change. Goetz

expects that by extending the Landsat

dataset beyond 2000, he will be able to

catch a significant drought year, which

will help to validate models for the

effect of low rainfall in the High Plains.

Contact information: Alexander F. H. Goetz,

Director, Center for the Study of Earth from

Space, Cooperative Institute for Research in

Environmental Sciences, University of

Colorado, tel. 303-492-5086;

goetz@khroma.colorado.edu.

Office of Public Relations, Jim Scott, tel.

303-492-3114; jim.scott@colorado.edu.
Science Writers’ Guide to Landsat 7

8

Spring run-off contaminants in lakes

John Schott, Rochester Institute of Technology

In large lakes the

“thermal bar”

can become

potentially toxic

to plants and

animals.

As snow begins to melt at the close

of winter, large lakes receive warm

spring river run-off carrying pollutants

that are potentially harmful to phytoplankton and the fish that feed on

them. The warmer water initially stays

near the shoreline, not mixing with the

cold winter lake water. Salt, sediment,

fertilizer and chemical pollutants in the

run-off are concentrated in a small band

of warmer water close to the shore called

the thermal bar. By June, the lake’s

waters are well mixed, and pollutants

brought into the lake are very dilute.

Most lakes in regions that have cold

winters and warm summers have an

annual episode of thermal bar formation. But only in large lakes does the

thermal bar persist for two months and

become potentially toxic to lake plants

and animals.

John Schott, of the Rochester Institute of Technology’s Digital Imaging and

Remote Sensing Laboratory, is using

Landsat imagery to help predict the

extent, duration, and impacts of the

thermal bar formation in the Laurentian

Great Lakes. For the two months that the

bar persists, it controls most of the fluid

flow in the lakes and has a dramatic

impact on water quality. Landsat offers

the unique opportunity to study both the

thermal bar processes and the direct

impact on the water quality at both

whole lake scales and localized scales.

The combination of spectral coverage,

synoptic perspective, and high resolution is a unique asset that may be used

to further understand the water quality

issues affecting Great Lakes coastal

waters.

Schott’s work may eventually be

helpful in understanding how the

release of industrial pollutants into the

Genesee and Niagara rivers during the

thermal bar formation in Lake Ontario

effect the lake’s ecosystem. Thermal bar

formation occurs during the spring

when plants and animals in the lake are

in the early stages of development.

Schott and his research team are

using Landsat data to determine how

large-scale hydrodynamic processes in

the Great Lakes control water quality.

The thermal bar formation is modeled

using Landsat data and three-dimensional hydrodynamic models. Eventually, the models will track the annual

evolution of the thermal bar and attempt

to predict the bar’s formation several

months in advance.

Contact information: John Schott, Rochester

Institute of Technology, Digital Imaging and

Remote Sensing Laboratory, tel. 716-475-

5170; jrspci@ritvax.isc.rit.edu.

University News Service, Kathy Lindsley,

tel. 716-475-5061; kjlcom@rit.edu.
Science Writers’ Guide to Landsat 7

9

Land use in tropical rain forests

David Skole, Michigan State University

The cause of

deforestation is

being studied

with socioeconomic and

ecosystem

models.

Even though tropical deforestation

is a well-known problem, the rate of

deforestation in the tropics is currently

known to only a very general degree.

Recent research using Landsat images of

forest loss over a decade from the mid1970s to mid-1980s found that an

average of 6200 square miles of forest

were lost each year in the Brazilian

Amazon. The annual rate in the smaller

Southeast Asia region was estimated to

be 4800 square miles per year. A key

problem facing scientists today is

determining deforestation rates and

understanding their causes and effects.

David Skole of Michigan State

University is involved in several initiatives to study the rates, causes, and

effects of tropical deforestation in the

Amazon Basin, Southeast Asia, and

Africa. Using Landsat imagery, his

research analyzes changes in forest

cover at a 30-m resolution and models

the effects of this on the carbon cycle. By

combining satellite imagery with

socioeconomic data, Skole is also

searching for the economic and social

causes of deforestation.

Using three different wavelength

bands of Landsat Thematic Mapper

imagery to quantify the vegetation

characteristics, Skole’s team categorizes

land cover into primary rain forest,

regrowing rain forest, agricultural

clearings, and other classes. These data

are manipulated using a geographic

information system to explore patterns

and rates of land cover change. The

geospatially referenced information is

then fed into socioeconomic and terrestrial ecosystem models to explore the

causes and effects of deforestation.

Skole’s team is currently analyzing

Landsat 5 imagery from the 1990s for the

Brazilian Amazon and Southeast Asia to

develop estimates of recent tropical

deforestation. In addition, they are

performing multi-year studies in the

Amazon basin to determine the year-toyear changes in deforestation rates.

These data will be important not only in

yielding the rate of deforestation but for

the analysis of carbon uptake by tropical

rain forests and for understanding the

social and economic causes.

With the launch of Landsat 7, the

amount of data available for this research will increase dramatically. Highly

detailed, near-real-time analysis will be

possible with the new imagery, allowing

for rapid assessment of land use and

land cover change.

Contact information: David Skole, Director,

Basic Science and Remote Sensing Initiative,

Department of Geography, Michigan State

University, tel. (517) 432-7774;

skole@pilot.msu.edu.

Media Communications Office, Sue Nichols,

tel. 517-355-2281, nichols@pilot.msu.edu.
Science Writers’ Guide to Landsat 7

10

Precision farming and land management

Susan Moran, U.S. Department of Agriculture

Crop yields can

be increased by

monitoring plant

health and plant

cover from

space.

For farmers and land managers,

increasing crop yields and cutting costs

while reducing environmental pollution

is a constant challenge. To accomplish

this goal, many farm managers are

looking for new technologies to help

them decide when and where to irrigate,

fertilize, seed crops, and use herbicides.

Currently the decisions are based on

very limited data collected in “spot

checks” from the ground.

Recent technological advances in

geographic information systems (GIS)

and computer modeling are playing a

part in farm management and precision

farming. Using data collected by satellites, important agricultural factors like

plant health, plant cover and soil moisture can be monitored from space,

providing a much bigger picture of the

land surface that can be combined with

other technologies to help cut costs and

increase crop yields.

Susan Moran, a US Department of

Agriculture Agricultural Research

Service soil scientist, based in Phoenix,

Ariz., developed a method to help

farmers with resource management by

combining Landsat images with radar

data from several polar orbiting satellites. Although Landsat sees the surface

very clearly, its usefulness is limited

because it can’t see through clouds, and

it only flies over a particular area once

every 16 days. Most farm management

decisions require information on a daily

or biweekly basis. Radar can see through

clouds and be collected daily, but the

resolution is not as good as Landsat. The

combination of radar and Landsat gives

a continuous record of the land surface

and vegetation health.

The thermal band on Landsat can

detect crop health by seeing plants

transpire, or lose moisture through their

leaves—a factor directly related to plant

health. When plant transpiration rates

decrease, growth rates decrease and the

plants appear unhealthy. Managers use

this information to target where to

fertilize and irrigate. Other Landsat

bands can see the extent of vegetation

cover while radar can pick up moisture

in the soil.

The methods developed by Moran

are already in use by land managers

through a Cooperative Research and

Development Agreement with a commercial image supplier. The 24-hour

turnaround of the new Landsat 7 data

will enable expanded applications of

remote sensing in agricultural and

natural resource monitoring.

Contact information: Susan Moran, U. S.

Department of Agriculture, Agricultural

Research Service, U. S. Water Conservation

Laboratory, tel. 520-670-6380, x171;

moran@tucson.ars.ag.gov.

USDA Agriculture Research Service

Current Information Branch, Marcia Wood,

510-559-6070, mwood@asrr.arsusda.gov.
Science Writers’ Guide to Landsat 7

11

Health of temperate conifer forests

Curtis E. Woodcock, Boston University

Forest

destruction

from natural

causes can be

distinguished

from human

activities.

Fire, drought, and humans all can

destroy forests and their ecosystems.

While much attention is paid to deforestation in tropical rainforests, very few

comprehensive studies have been done to

address changes in the Earth’s temperate

conifer forests. Temperate conifer forests

lie at latitudes above tropical forests and

below boreal forests and account for

much of the forested area in the United

States and Europe.

Understanding changes occurring in

temperate conifer forests is important for

understanding environmental issues

including wildlife habitat protection,

watershed management, timber harvest,

and understanding the role of human

activities on changes in regional climates.

Previously, researchers have only

been able to monitor changes in specific

locations with Landsat data due to its

limited availability. Boston University

geographer Curtis E. Woodcock and

colleagues used Landsat to monitor how

drought in the late 1980s and early 1990s

affected forests in California’s Sierra

Nevada. During the drought, Woodcock

found that Landsat images could recognize areas where trees were dying due to

lack of water, a factor making the trees

more susceptible to disease and the forest

more susceptible to fire.

With the help of the frequent and

comprehensive coverage of Landsat 7,

Woodcock and colleagues plan to create a

global monitoring system for temperate

conifer forests. The monitoring system

will measure the rates of destruction of

conifer forests due to natural causes

such as drought and fire and anthropogenic clearing due to harvest or development of forest lands. The monitoring

system will also track the regrowth of

forests and successional change in

vegetation.

The new system will work in conjunction with NASA EOS land cover

change studies based on the EOS Moderate-resolution Imaging

Spectroradiometer (MODIS). The

MODIS instrument will fly aboard the

Terra satellite set for launch in July 1999,

and will be used to identify large areas

of significant changes in forest lands.

Following up with the finer spatial

resolution data from Landsat will allow

determination of the type of changes and

their geographic extent.

Contact information: Curtis E. Woodcock,

Department of Geography and Center for

Remote Sensing, Boston University, tel.

617-353-5746; curtis@bu.edu.

Office of Public Relations, Shauna LaFauci,

tel. 617-353-2399; slafauci@bu.edu.
Science Writers’ Guide to Landsat 7

12

Ice flows may

move more

quickly and

slide into the

sea if the forces

driving them

change.

The stability of the West Antarctic

Ice Sheet is an issue of active research

and societal concern because of the

potential economic impact resulting

from an increase in global sea level. The

West Antarctic Ice Sheet, riddled with

deep crevasses and flowing ice streams,

contains over 700,000 cubic miles (3

million cubic kilometers) of ice.

Researchers are studying how the

ice moves and what forces cause the ice

to flow. If the forces change, the ice

sheets may flow much more quickly and

slide off the continent into the sea.

Monitoring these changes from the

ground is difficult because treacherous

conditions allow researchers to collect

only a limited amount of measurements.

Robert Bindschadler, a glaciologist at

NASA’s Goddard Space Flight Center,

uses Landsat data in a variety of ways to

make more information available for

determining the ice sheet’s behavior.

Landsat’s high spatial resolution allows

individual crevasses to be tracked over

time. Using these natural markers not

only provides many more velocity data

to be collected, but concentrates the

measurements in the most rapidly

moving and most dangerous areas.

Other surface features such as

flowstripes formed by rapid ice flow are

also being used to uncover the history of

the ice sheet. Bindschadler and colleagues have analyzed surface features

on the Ross Ice Shelf, a vast area of ice

attached to the continent but floating on

the ocean, to determine the past 1000

years of ice flow over much of West

Antarctica.

Recently Landsat data have increasingly been used to create more useful

maps for scientific research.

Bindschadler is combining Landsat data

with past surveys of the latitude, longitude, and elevation of known locations

around the Antarctic continent to create

a library of image control points. The

library is available on the Internet for use

by researchers.

Landsat 7 data will enhance techniques developed at Goddard to study

ice motion and flow history by providing

finer spatial resolution, more continuous

spatial coverage, and an updated view of

the ever-changing Antarctic ice sheet.

Contact information: Robert Bindschadler,

NASA Goddard Space Flight Center,

bob@igloo.gsfc.nasa.gov.

Goddard Public Affairs Office, Lynn

Chandler, 301-614-5562;

lychand@pop100.gsfc.nasa.gov.

Gradual changes in the Antarctic ice sheet

Robert Bindschadler, NASA Goddard Space Flight Center
Science Writers’ Guide to Landsat 7

13

Landsat

imagery is being

used to identify

different types

of dry biomass

on the ground.

Mapping wildfire hazards in Yosemite

Jan van Wagtendonk, U. S. Geological Survey

In recent years, wildland fires have

become more intense resulting in

increased loss of human life and natural

resource damage. An important factor

in dealing with this problem is information on the amount and condition of dry

biomass on the ground, which acts as

fuel that feeds wildland fires. With

information about fuels, fire managers

can better predict potential fire behavior, make more informed tactical and

strategic decisions, and conduct treatments to reduce the amount of dry

biomass.

U. S. Geological Survey researcher

Jan van Wagtendonk from the Western

Ecological Research Center’s Yosemite

National Park station, and Ralph Root,

from the USGS Center for Biological

Informatics in Denver, have been

examining the use of time series of

Landsat Thematic Mapper imagery for

developing a technique to identify fuel

types based on seasonal changes in plant

condition. Six Landsat scenes at onemonth intervals during the 1992 growing season are being examined using

hyperspectral analysis, a type of analysis

that deals with large data sets with

several spectral bands.

Using the time series, changes in

annual grasslands, for instance, can be

traced as the plants green up in the

spring and dry during the summer. This

fuel type can be distinguished from

alpine meadows which dry at a different

rate. Similarly, biomass from deciduous

hardwood can be distinguished from

evergreen hardwood, which retains its

leaves.

 Van Wagtendonk has also used

single-scene Landsat images to classify

different types of fuels over the past five

years. Maps produced from this analysis

have been used to predict the behavior

of two large wildland fires in 1994 and

1995 that were being allowed to burn to

meet resource objectives.

The addition of a panchromatic band

on Landsat 7 will enhance the capability

to distinguish tree density classes, which

directly affects fuel moisture content and

wind speeds near the ground. Seasonal

changes can also be tracked more easily

with the more frequent observations

Landsat 7 will make.

Contact information: Jan van Wagtendonk,

U. S. Geological Survey, Biological

Resources Division, Western Ecological

Research Center, Yosemite Field Station,

El Portal, Calif.; tel. 209-379-1885,

jan_van_wagtendonk@usgs.gov.

Sonoran Desert Field Station, University of

Arizona, Gloria Meander, tel. 520-670-6896

x1, gloria_meander@usgs.gov.
Science Writers’ Guide to Landsat 7

14

Glossary

Band (channel). A band is a slice of

wavelengths from the electromagnetic

spectrum. Landsat ETM+ has eight

bands which collect radiation from

different parts of the electromagnetic

spectrum. Of the eight bands, three

bands are visible light, one band is

panchromatic, three bands are infrared,

and one band is thermal infrared.

Enhanced Thematic Mapper Plus

(ETM+). The sensor aboard Landsat 7

that picks up solar radiation reflected by,

or emitted from the Earth.

Electromagnetic radiation. Energy

transfer in the form of electromagnetic

waves or particles that propagate

through space at the speed of light.

Electromagnetic spectrum. The entire

range of electromagnetic radiation. The

spectrum usually is divided into seven

sections. From the longest wavelengths

to the shortest: radio, microwave,

infrared, visible, ultraviolet, x-ray, and

gamma-ray radiation.

Geostationary orbit. An orbit in which a

satellite is always in the same position

with respect to the rotating Earth. The

satellite travels around the Earth in the

same direction, at an altitude of approximately 22,000 miles (35,800 kilometers).

Infrared radiation. Electromagnetic

radiation with wavelengths between

about 0.7 to 1000 micrometers. Infrared

waves are not visible to the human eye.

Longer infrared waves are called thermal infrared waves.

Multispectral image. A remote sensing

image created using data collected from

more than one band.

Panchromatic. Sensitive to all or most of

the visible spectrum, between 0.4 and 0.7

micrometers. Landsat 7 has a panchromatic band.

Passive sensor. One type of remote

sensing instrument, a passive sensor

picks up radiation reflected or emitted

by the Earth. ETM+ is a passive remote

sensing system.

Polar orbit. An orbit with its plane

aligned parallel with the polar axis of

the Earth. Landsat’s polar orbit is 438

miles (705 kilometers) above the Earth.

Radar. Short for “radio detection and

ranging,” radar sends out short pulses of

microwave energy and records the

returned signal’s strength and time of

arrival.

Resolution. A measure of the amount of

detail that can be seen in an image.

Scenes. Each Landsat image collected is

called a scene. Each scene is 115 x 106

miles long. The globe is divided into

57,784 scenes.

Synoptic view. The ability to see large

areas at one time, such as an entire

metropolitan area.

Thermal infrared. Electromagnetic

radiation with wavelengths between 3

and 25 micrometers.

Visible radiation. The electromagnetic

radiation that humans can see as colors.

The visible spectrum is made up of

wavelengths between 0.4 to 0.7 micrometers. Red is the longest and violet

is the shortest. Landsat 7 has three

visible bands in red, green, and blue.
Science Writers’ Guide to Landsat 7

15

Contact Information

Landsat 7 Science Team

Darrel Williams

Landsat 7 Project Scientist

Code 923

NASA Goddard Space Flight Center

Greenbelt, MD 20771

301-286-8860

Darrel.L.Williams.1@gsfc.nasa.gov

James Irons

Deputy Landsat 7 Project Scientst

Code 923

NASA Goddard Space Flight Center

Greenbelt, MD 20771

301-286-8978

jim_irons@gsfc.nasa.gov

Samuel Goward

Landsat 7 Science Team Leader

University of Maryland

Department of Geography

College Park , MD 20742

301-405-4050

sg21@umail.umd.edu

Jeffrey Masek

Landsat 7 Deputy Team Leader

University of Maryland

Department of Geography

College Park, MD 20742

301-405-8233

jmasek@geog.umd.edu

Robert Bindschadler

Code 971

NASA Goddard Space Flight Center

Greenbelt, MD 20771

301-286-7611

bob@igloo.gsfc.nasa.gov

Robert Cahalan

Code 913

NASA Goddard Space Flight Center

Greenbelt, MD 20771

301-286-4276

cahalan@clouds.gsfc.nasa.gov

Luke Flynn

University of Hawaii

Hawaii Institute of Geophysics &

Paleontology

2525 Correa Rd.

Honolulu, HI 96822

808-956-3154

flynn@waterloo.pgd.hawaii.edu

Alexander Goetz

University of Colorado

Boulder CSES

Campus Box 216

Boulder , CO 80309

303-492-5086

goetz@cses.colorado.edu

Susan Moran

U.S. Department of Agriculture

Water Conservation Lab

2000 E. Allen Rd.

Tucson, AZ 85719

520-670-6380

moran@tucson.ars.ag.gov

Frank Muller-Karger

University of South Florida

Dept. of Marine Science

140 7th Avenue South

St. Petersburg, FL 33701

813-893-9186

carib@carbon.marine.usf.edu
Science Writers’ Guide to Landsat 7

16

Frank Palluconi

Jet Propulsion Laboratory

M/S 183-501

4800 Oak Grove Dr.

Pasadena CA 91109

818-354-8362

frank.d.palluconi@jpl.nasa.gov

John Price

765 10th Street

Boulder, CO 80302

303-939-9991

71147.1425@compuserve.com

John Schott

Rochester Institute of Technology

Center for Imaging Science

54 Lomb Memorial Dr.

Rochester NY 14623

716-475-5170

jrspci@ritvax.isc.rit.edu

David Skole

Michigan State University

315 Natural Science

East Lansing MI 48824

517-355-4649

skole@pilot.msu.edu

Kurtis Thome

University of Arizona

Meinel Building

P.O. Box 210094

Tucson AZ 85721

520-621-4535

kurt@titan.opt-sci.arizona.edu

James Vogelman

Hughes STX Corporation

U.S. Geological Survey EROS Data

Center

Sioux Falls, SD 57198

605-594-6062

vogel@edcserver1.cr.usgs.gov

Curtis Woodcock

Boston University

Dept. of Geography

675 Commonwealth Ave.

Boston MA 02215

617-353-5746

curtis@bu.edu

Program Management

Phillip A. Sabelhaus

Landsat 7 Project Manager

NASA Goddard Space Flight Center

Greenbelt, MD 20771

301-286-8536

Phillip.A.Sabelhaus.1@gsfc.nasa.gov

Ray Byrnes

USGS Land Satellite Program Liaison

508 National Center

Reston, VA 20192

703-648-4787

rbyrnes@usgs.gov

R. J. Thompson

USGS Landsat Program Manager

USGS EROS Data Center

Sioux Falls, SD 57198

605-594-6161

rjthompson@usgs.gov

Public Affairs

David Steitz

Public Affairs Office

Rm 5N22

NASA Headquarters

Washington, DC 20546

202-358-1730

david.steitz@hq.nasa.gov

Lynn Chandler

Public Affairs Office

Code 130

NASA Goddard Space Flight Center

Greenbelt, MD 20771

301- 614-5562

lychand@pop100.gsfc.nasa.gov
Science Writers’ Guide to Landsat 7

17

Allen Kenitzer

Public Affairs Office

Code 130

NASA Goddard Space Flight Center

Greenbelt, MD 20771

301-286-2806

akenitze@pop100.gsfc.nasa.gov

Wade Sisler

Executive TV Producer

NASA Goddard Space Flight Center

Greenbelt, MD 20771

301-286-6256

wade.e.sisler.1@gsfc.nasa.gov

Ron Beck

USGS EROS Data Center

Sioux Falls, SD 57198

605-594-6551

beck@usgs.gov

Cathy Watson

USGS Office of Outreach

119 National Center

Reston, VA 20192

703-648-4732

cwatson@usgs.gov

Web Sites

The Landsat 7 Program

http://geo.arc.nasa.gov/sge/landsat/

landsat.html

Information on Landsat satellite data,

program news, program history and

chronology, and instrument details.

Landsat 7 Gateway

http://landsat.gsfc.nasa.gov/

Program and technical information,

educational materials, an image gallery,

and NASA organizational information.

Landsat 7 Science Team

http://www.inform.umd.edu/geog/

landsat7/

The “Public information about Landsat 7

Science Activities” section contains

instrument details, how images are

acquired, and contact information for

science team members.

Landsat 7 Images

Individual stills of new Landsat 7

images can be obtained by contacting

Ron Beck, USGS EROS Data Center,

Sioux Falls, SD 57198; tel. 605-594-6551;

beck@usgs.gov.

A “pre-launch resource videotape” of

Landsat scenes and animations is

available for media use from the

Goddard Space Flight Center’s Public

Affairs Office. Contact Deanna Corridon

for more information; tel. 301-286-0041.
Earth Observing System Project Science Office

Code 900

NASA Goddard Space Flight Center

Greenbelt, MD 20771

NASA’s Earth Science Enterprise

Code Y

NASA Headquarters

Washington, DC 20546

U.S. Geological Survey

EROS Data Cemter

Sioux Falls, SD 57198

NP-1999-02-022-GSFC