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A Brief History of Remote Sensing
Applications, with Emphasis on L`andsat
Staniey A. Moraine
By 1997, at least six civilian land remote sensing satellite systems were
being operated by the United States, France, India, Japan, Canada, Russia, and
the European Space Agency. On command, all of them make measurements of
the land surface, transmitting spectral data to a global network of strategically
located ground receiving stations. Data from these earth-observing satellites are
used to map, monitor, and manage the earth's natural and cultural resources.
Perhaps the first person who believed that not only machines but humans,
too, could venture into space was Jules Verne, a French provincial lawyer with no
scientific or technical training (Mark, 1984~. Verne made the extraordinary
prediction that a rocket would be launched from Florida by means of chemical
propulsion, and that the crew would include three people (and a dog). First they
would only circle the moon and return to earth, as did Apollo 8. This would be
followed by a trip to the moon' s surface, the return to earth ending with a "splash
down" in the Pacific Ocean and recovery by a warship. Perhaps Verne's most
remarkable prediction was that Americans would make this first journey. What
he did not predict was that astronauts would be awed by the blue marble, or that
their photographs would so sensitize the world that subsequent human scientific
interest would shift toward space as a means for studying the earth. The United
States was not only the first to land on the moon, but beyond Verne's vision, it
also developed the first remote sensing satellites, whose profound importance to
today's concept of a global village cannot be overstated.
Most histories of remote sensing identify Gaspard Felix Tournachon as the
first person to photograph "remotely," using balloons above Paris in 1859. Bal-
loons were also used for aerial reconnaissance during the American Civil War.
28
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STANLEY A. MORAIN
29
By 1909, aerial photographs were being taken from airplanes for a wide range of
uses, including warfare, land-use inventory, and publicity. Aerial photography
remains an important application of remote sensing, with a sophisticated range of
cameras being used to collect information on geology, land use, agricultural
conditions, forestry, water pollution, natural disasters, urban planning, wildlife
management, and environmental impact assessments (Lillesand and Kiefer,
1987~. Evelyn Pruitt of the Office of Naval Research originally coined the term
"remote sensing."
GROWTH OF THE REMOTE SENSING COMMUNITY
The Environmental Research Institute of Michigan (ERIM) is credited with
organizing the first technical conference on remote sensing in the United States,
perhaps in the world. Its First Symposium on Remote Sensing of Environment,
sponsored by the Navy's Office of Naval Research (ONR), had 15 presenters and
71 participants (Environmental Research Institute of Michigan, 1962~. In the
audience was Dr. William Fischer of the U.S. Geological Survey (USGS), an
early advocate of an earth-observing system. The field was so new that Dana
Parker's inaugural address focused on fundamentals of the electromagnetic spec-
trum. In October 1962, the second symposium was held, drawing 162 partici-
pants to hear 35 technical papers (Environmental Research Institute of Michigan,
1963~. It was sponsored by the Geography Branch of ONR, the Air Force
Cambridge Research Laboratory, and the Army Research Office.
At the third symposium in October 1964,280 participants heard 54 technical
papers (Environmental Research Institute of Michigan, 1965~. By this time, all of
the principal government, academic, and private-sector motivators for an orbiting
resource satellite system were represented. Among the papers in the proceedings
was one by Dr. Robert Alexander from ONR. He gave the first announcement for
what evolved into Landsat-l. His abstract read:
The National Aeronautics and Space Administration is sponsoring a study of
the geographic potential of observations and experiments which might be car-
ried out from the remote vantage of earth-orbiting spacecraft. The investigation
will involve both the value of the science of geography and the expected practi-
cal applications of an earth-viewing-orbiting laboratory and other possible geo-
graphic satellite systems. Early emphasis will be on problems of systematizing
and managing the flow of geographic information which would result from
such a program. (p. 453)
The eighth symposium (Environmental Research Institute of Michigan,
1972), held 8 years after Alexander's announcement and only a few weeks after
the first Landsat-1 images had been released, included 14 presentations describ-
ing the utility and quality of the Landsat data. By that time, the broader field of
remote sensing had attracted over 700 participants who selected from a program
of 116 papers on topics including theoretical and applied engineering, natural and
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30
A BRIEF HISTORY OF REMOTE SENSING APPLICATIONS
cultural resource monitoring, state and local government applications, and even
environmental and public health issues.
The National Aeronautics and Space Administration (NASA) became an
official sponsor of ERIM symposia in 1971. In 1973, NASA's administrator
inaugurated the agency's decade-long program of University Research Grants to
stimulate cooperative research at the local level. In some cases it supported
construction of laboratory facilities and supplied the equipment needed to train
the 1970s generation of Ph.D. remote sensing specialists. By the mid- to late
1970s, many of these young professionals were employed on collaborative fed-
eral government research projects for proof-of-concept applications embracing
the whole range of natural and cultural resources. The Large Area Crop Inven-
tory Experiment (LACIE) and its spin-off AgriSTARS are examples of these
projects. The Application System Verification Tests (ASVTs) are another.
While these were not the only application development programs under way,
they were symptomatic of a massive spontaneous adaptation to fundamentally
new ways of studying the earth. Within little more than a decade of ERIM's first
symposium, the core remote sensing community had increased its numbers by
several orders of magnitude. This community brought about major changes in
organizational structures, became the basis for a new international research
agenda, and germinated the first seeds of thought on global habitability.
STIMULI FOR AN ORBITING RESOURCES SATELLITE
In 1946, the United States Army Air Corps requested that the RAND Corpo-
ration consider how objects might be inserted into orbit (Mark, 1988~. The study
resulted in a report titled Preliminary Design of an Experimental World-Circling
Spaceship (Burrows, 1986~. The proposed midget moon, or "satellite," would
provide "an observation aircraft [sic] which cannot be brought down by an enemy
who has not mastered similar techniques." After many aborted liftoffs and sys-
tem failures, the military successfully launched its first earth-observing satellite
in August 1960. It was called Discoverer and was expected to be an unclassified
system to support biomedical research and earth observations (Tsipis, 1987;
Whelan, 1985~. A few months after launch, however, a presidential directive
classified the Discoverer program and plunged it into deep secrecy. Only re-
cently have images collected by its successor, the Corona program, been declas-
sified for public use (McDonald, 1995~.
In parallel with the early military/intelligence programs in space, the scien-
tific and industrial communities in the United States were awakening to the
potential of space for providing a new world perspective. In 1951,6 years before
Sputnik 1, Arthur C. Clarke, a science fiction writer and prophet of technology,
proposed that a satellite could be inserted into orbit over the north and south poles
while the earth revolved beneath it, allowing humans to view the planet in its
entirety (Fink, 1980~. In April 1960, NASA and the Department of Defense
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STANLEY A. MORAIN
31
(DOD) launched the Television and Infrared Observational Satellite (TIROS-1)
into such an orbit, inaugurating the first experimental weather satellite (U.S.
Department of Commerce and National Aeronautics and Space Administration,
1987~. This system generated the first television-like pictures of the entire globe
in a systematic and repetitive manner. The ongoing series of TIROS satellites
became operational in 1966 as the TIROS Operational Satellites (TOS), renamed
the National Oceanic and Atmospheric Administration (NOAA) Polar Orbiting
Environmental Satellites (POES) in 1970 (Morain and Budge, 1996~.
Although the early weather satellites could not provide details on land processes
or use, they were invaluable in understanding the weather and thus providing warn-
ings of weather-related natural disasters, as well as information on rainfall of rel-
evance to agriculture and water management (Lillesand and Kiefer, 1987~.
The series of NOAA weather satellites carrying the Advanced Very High
Resolution Radiometer (AVHRR) from 1978 on was important not only to me-
teorological research and prediction, but also to studies of vegetation and land
use. Over the last two decades, AVHRR data have been used to construct vegeta-
tion indices for monitoring crop failures, urban climate, locust outbreaks, range
conditions, deforestation, and desertification (Ehrlich et al., 1994; Gallo et al.,
1993; Townshend and Tucker, 1984; Tucker et al., 1991~. The NOAA satellites
have been important in the development of famine warning systems, such as
those described by Hutchinson in this volume. These satellites are of much
coarser resolution than the Landsat series discussed below (one AVHRR image
can cover as many as 100 Landsat images), but the lack of detail is somewhat
compensated by the broad coverage, lower costs, and more frequent (twice daily)
flyovers. Roller and Colwell (1986) argue that the AVHRR images can be used
very efficiently to stratify land use and topography for more detailed studies with
Landsat and other higher-resolution satellites. At an even coarser scale, the
Geostationary Earth-Orbiting Satellite (GOES) provides the continuous hemi-
spheric coverage of cloud cover and other aspects of the atmospheric circulation
shown on evening weather forecasts as a visual confirmation of approaching
weather, particularly extreme events such as hurricanes. Other satellites, launched
predominantly for ocean research applications, such as Nimbus, SeaSat, and
SeaWifs, have provided information of relevance in coastal zone studies and
fisheries management (Consortium for International Earth Science Information
Network, 1997~.
The photographs taken from manned space expeditions such as Gemini and
Apollo were used in several land inventory applications. In 1973, Skylab took
more than 35,000 images that have become classics in many resource manage-
ment and earth science texts. In recent years the Space Shuttle has taken numer-
ous images of sites of human interest, many at the request of researchers con-
cerned with deforestation, urbanization, pollution, and water resource
management.
The United States pioneered land remote sensing from space and has been
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32
A BRIEF HISTORY OF REMOTE SENSING APPLICATIONS
the unquestioned leader in the development and application of this unique tech-
nology. Americans take pride in having developed the Landsat program, as well
as other, more recent civilian programs. The evolution of Landsat, however, has
been neither linear nor predictable. The remainder of this chapter provides an
overview of its conception, genesis, and growth; its accomplishments and current
status; and its uncertain future. At this point, Landsat still dominates remote
sensing applications in the United States.
FORCES MOTIVATING THE DEVELOPMENT
OF REMOTE SENSING
At first, civilian space remote sensing consisted of experimental missions to
develop proofs of concept for any applications that had a sound scientific basis-
and some, perhaps, that did not. All of the missions conducted in the 1960s and
1970s, including those that acquired hand-held Gemini, Apollo, Skylab, and
Apollo-Soyuz photography and the early Landsats, were approved and funded as
experiments to advance space science. The forces that stimulated and motivated
today's Landsat program were numerous and complex. Five of the most compel-
ling were (1) the need for better information about the earth's features, (2) na-
tional security, (3) commercial opportunities, (4) international cooperation, and
(5) international law.
Need for Better Information
Society requires better information about the geographic distribution of the
earth's resources, and satellites help in obtaining this information. Earth now
supports more than 5 billion people, and human populations are growing at 1.5
percent per year, or 3 people per second. By 2000, the world's population will
exceed 6 billion. Nobody knows how many people the earth can sustain; some
guess 8 billion, while others say nearly double that number (McRae, 1990;
Ashford and Noble, 1996~. Regardless of how many people can be squeezed onto
the planet, however, there are limits to the renewable and nonrenewable re-
sources needed to support them. Efficient management of renewable resources
and judicious use of nonrenewable resources, as well as improved conservation
and protection of fragile and endangered environments, depend on timely infor-
mation about, and accurate analysis of, those resources. In the late 1960s, there
was a convergence of thought that the best means for acquiring the needed data
was earth-orbiting satellites that could provide continuous and nearly synoptic
coverage of terrestrial resources. This would be the case in particular for under-
standing and measuring earth system processes at regional, continental, or global
scales. Human numbers and human impacts on resources thus became an early
and globally compelling argument for studying the earth from space.
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STANLEY A. MORAIN
33
National Security
The U.S. government maintains national security, a mission that includes
using data from civilian satellites to protect and defend the nation against aggres-
sors. It is no secret that defense/intelligence satellites are assets for maintaining
national security. It is not as widely known, however, that the defense/intelli-
gence community has always used data from civilian satellite systems in carrying
out its security mission (National Space Council, 1989~. While there were, and
still are, many security limitations imposed on the first generation of earth-
observing systems, there was nevertheless a defensible argument that such a
system should be developed. It was recognized that timely information about the
global distribution of critical natural resources and the factors that affect global
environmental conditions is integral to national security and would be gleaned in
part from civilian systems. Indeed, the decision to build and launch Landsat-7
was driven partly by requirements of the defense/intelligence community (Office
of the President, 1992~.
Commercial Opportunities
The U.S. government encourages private-sector investment in the nation's
space program, including civilian earth-observing satellites. Remote sensing
technology was developed by aerospace industries under contract to federal gov-
ernment agencies to satisfy both government and public needs. Commercializa-
tion of this know-how is fundamental to American ideals and has been a stimulus
for continued industry investment. By the early 1970s, several industries, in-
cluding communications satellites and booster launch services, had already proven
the commercial value of the space environment. The prospects for similar finan-
cial gain from data on the earth's resources seemed self-evident, but a successful
experimental system would be a necessary first step. The assumption that data on
the earth's resources would have commercial value beyond their benefit for the
public good was thus a powerful argument for developing the Landsat program.
Full commercialization of both the space and ground segments may yet prove to
be intractable, but there is clearly a viable and profitable role for industry in
building space platforms, sensor systems, and ground processing facilities, as well as
providing value-added data processing services. The commercial value of space-
based remote sensing products and services is a hypothesis that will finally be tested
with several privately owned satellites scheduled for launch in 1998.
International Cooperation
The U.S. government seeks international cooperation on civilian earth-
observing satellites in order to better understand, manage, share, and protect the
earth's resources. The United States is committed to using space for peaceful and
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34
A BRIEF HISTORY OF REMOTE SENSING APPLICATIONS
defense purposes only. To this end, Americans want to share benefits from space
technology with other nations, but they also want to protect their commercial
interests. Earth observations from space have never been the sole domain of the
United States, and several nations now participate in this activity with competing
spacecraft and sensor systems. The argument for promoting cooperation among
nations was originally driven by opportunities for America to promote its foreign
policy objectives, but have evolved to include elimination of unnecessary redun-
dancies among different national programs and the savings that might be realized
from joint programs through cost sharing (Office of the President, 1996~. While
these objectives were not publicly articulated in the early 1970s, they were a
driving political force in the Landsat planning process.
International Law
Societies are governed by laws, rules, and regulations to maintain organiza-
tion and order not only on earth, but also in space. Societies establish laws by
which they govern against chaos and anarchy. Space law is relatively new to
jurisprudence, but it is a central force because it sets the rules by which all
nations, not just the space-faring ones, have a voice in how to participate in space
technology. Legal aspects of civilian space-based remote sensing are compli-
cated and sometimes controversial, especially regarding the issues of national
sovereignty, rights of privacy, and, most recently, commercial gain. The United
States has always argued strongly for an open-skies and nondiscriminatory data
distribution policy for civilian space data, believing the greatest good for the
greatest number will come from free and open exchanges of data and information
(Stowe, 1976; Office of the President, 1988~. When the United States implemented
the Landsat program, it made an extraordinary effort to ensure that every nation had
access to these data, even to the extent that foreign ground receiving stations were
installed.
THE EVOLUTION OF LANDSAT
The Landsat Concept
The concept of a dedicated, unmanned land-observing satellite emerged in
the mid-1960s from the complex milieu of synergisms and conflicting interests
described above. It arose primarily in ONR and USGS under the latter's late
director Dr. William T. Pecora (Waldrop,1982~. In fact, scientists within USGS,
working in cooperation with Dr. Archibald Park and others in the U.S. Depart-
ment of Agriculture (USDA), originally proposed to the (then) Bureau of Budget
(now Office of Management and Budget) that an Earth Resources Observation
Satellite (EROS) be built, launched, and operated. The Under Secretary of the
Interior announced the objectives of EROS in a memorandum dated July 12,
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STANLEY A. MORAIN
35
1967, and addressed to the Department of the Interior's assistant secretaries and
bureau heads (Luce, 1967~. These objectives were to (1) construct and fly an
earth-observing system by the end of 1969, and follow this with improved and
modified systems as required by the operational needs of resources programs;
(2) provide unclassified remotely sensed data to facilitate the assessment of land
and water resources of the United States and other nations; and (3) design specific
systems on the basis of users' data requirements, distribute such data to users, and
make operational use of the data in resource studies and planning. The overall
goal of the proposed EROS program was to acquire satellite remotely sensed data
in the simplest possible way, deliver these data to users in an uncomplicated
form, and ensure the data's easy use (Pecora, 1972~.
Since development of space technology was the responsibility of NASA, the
Department of the Interior's proposal was rejected. NASA Administrator James
Webb met with President Johnson to discuss Interior's announcement, and Webb
succeeded in retaining control of what was to become an "experimental" program
(Covert, 1989~. In cooperation with the Department of the Interior, USDA, and
other agencies, NASA designed an earth-observing satellite, obtained funding for
the project, and successfully launched the first Earth Resource Technology Satel-
lite (EATS-1) in July 1972.
Although unsuccessful with its own satellite system, the Department of the
Interior continued with an EROS program under the direction of USGS. The
EROS mission was to archive and distribute remotely sensed data, and to support
remote sensing research and applications development within Interior.2 To carry
out the EROS responsibilities, USGS built the EROS Data Center (EDC) in 1972.
After the launch of Landsat-l, Goddard Space Flight Center (GSFC) hosted
three symposia in quick succession (National Aeronautics and Space Administra-
tion, 1973a, b). These symposia were designed especially for their Landsat-
sponsored investigators to report "user identified significant results." The appli-
cation categories were agriculture/forestry, environment, geology, land use/land
cover, water, and marine. Each of the proceedings approached 2000 pages of text
and graphics, mainly detailing early application concepts and models. The
Landsat program had such a powerful impact in so many arenas that it was
declared operational in late 1979 after a prolonged debate among participating
government agencies (U.S. Department of Commerce, 1980~.
In the decades to follow, however, Landsat-1 replacement satellites were the
subject of severe political uncertainty. The program witnessed a change of guard
among its staunchest supporters, and the satellites were casually labeled a "tech-
nology in search of an application." Kuhn's (1962) prescription for scientific
revolutions foreshadowed these developments by predicting a period of scientific
uncertainty, if not outright denial, by whole sectors of the science and technology
community. In the waning years of the twentieth century, complexity science
views such developments as inherent to self-adaptation in complex systems
(Waldrop, 1992~. Once a critical mass of support had been attained, the indi
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A BRIEF HISTORY OF REMOTE SENSING APPLICATIONS
vidual actions of sensor developers, data suppliers, data analysts, and end-users
ensured the continuity of the technology, even if its development seemed chaotic,
and even if the direction of that development was unclear. After a quarter-
century of successful data gathering, the fate of the Landsat program remains
uncertain, but the technology derived from the program continues to permeate
user communities and become more complex as the applications it has spawned
mature.
Even as the first Landsat was being prepared for launch, conflicts in agency
roles had begun to appear. NASA's charter was to engage in space research and
technology development. That charter did not include earth resource data han-
dling, processing, archiving, or distribution to a large and diverse scientific com-
munity, or to an even larger group of public and private users. Consequently,
NASA reached agreement with several resource management agencies to transfer
responsibility for the program' s ground segment, while NASA retained responsi-
bility for the space segment.
The Landsat System
ERTS-1 was launched from Vandenberg Air Force Base in California. A
Nimbus-type platform was modified to carry the sensor package and the data
relay equipment. ERTS-2 was launched on January 22, 1975. It was renamed
Landsat-2 by NASA, which also renamed ERTS-1 as Landsat-l. Three addi-
tional Landsats were launched in 1978, 1982, and 1984 (Landsat-3, -4, and -5,
respectively). As documented by USGS (1979) and by USGS and NOAA (1984),
each successive satellite system had improved sensor and communications capa-
bilities (see Table 2-1~.
TABLE 2-1 Background Information and Status of Landsat Satellites
Satellite Launched Decommissioned Sensors
Landsat-1 July 23, 1972 January 6, 1978 MSS and RBV
Landsat-2 January 22, 1975 February 25, 1982 MSS and RBV
Landsat-3 March 5, 1978 March 31, 1983 MSS and RBV
Landsat-4 July 16, 1982 a TM and MSS
Landsat-5 March 1, 1984 b TM and MSS
Landsat-6 October 5, 1993 c ETM
Landsat-7 May 1998 d ETM+
aIn standby mode
bOperational
CNever achieved orbit
dAnticipated launch
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STANLEY A. MORAIN
Landsats-1, -2, and -3
37
The first three Landsats operated in near-polar orbits from altitudes of 920
km. They circled the earth every 103 minutes, completing 14 orbits a day and
producing a continuous swath of imagery 185 km wide. To provide nearly
complete coverage of the earth's surface, 18 days and 251 overlapping orbits
were required. The amount of swath sidelap varied from 14 percent at the equator
to nearly 85 percent at latitude 81° north or south. These satellites carried two
sensors: a Return Beam Vidicon (RBV) and a MultiSpectral Scanner (MSS).
The REV sensor was a television camera designed for cartographic applications,
while the MSS was designed for spectral analysis of terrestrial features. The
MSS sensor scanned the earth's surface from west to east as the satellite moved in
its descending (north-to-south) orbit over the sunlit side of the earth. Six detec-
tors for each spectral band provided six scan lines on each active scan. The
combination of scanning geometry, satellite orbit, and earth rotation produced the
global coverage originally suggested by Arthur C. Clarke for viewing the earth' s
entire land surface. The spatial resolution of the MSS was approximately 80 m
with spectral coverage in four bands from visible green to near-infrared (JR)
wavelengths (see Table 2-2~. Only the MSS sensor on Landsat-3 had a fifth band,
in the thermal-IA. ERTS-1 delivered high-quality data for almost 4 years beyond
its designed life expectancy of 1 year and was finally shut down on January 6,
1978. Landsats-2 and -3 were decommissioned in February 1982 and March
1983, respectively.
TABLE 2-2 Radiometric Range of Bands and Resolution for the MSS Sensor
Band
Wavelength Resolution
Landsats-1,-2,-3 Landsats-4,-5 (micrometers) (meters)
4 1 0.5-0.6 79182a
5 2 0.6-0.7 79/82
6 3 0.7-0.8 79/82
7 4 0.8-1.1 79/82
8b 10.4-12.6 237
aThe nominal altitude was changed from 920 km for Landsats-1 to -3 to 705 km for Landsats-4
and -5, which resulted in a resolution of approximately 79 and 82 m, respectively.
bLandsat-3 only.
SOURCE: U.S. Geological Survey and National Oceanic and Atmospheric Administration, 1984.
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Landsats-4 and -5
A BRIEF HISTORY OF REMOTE SENSING APPLICATIONS
Landsats-4 and -5 carried both the MSS and a more advanced sensor called
the Thematic Mapper (TM).3 Their orbits were somewhat lower than those of
their predecessors at 705 km and provided a 16-day, 233-orbit repeat cycle with
image sidelap that varied from 7 percent at the equator to nearly 84 percent at
latitude 81° north or south. The MSS sensors aboard Landsats-4 and -5 were
identical to earlier ones. Both sensors detected reflected radiation in the visible
and near -IR bands, but the TM sensor provided seven spectral channels of data
as compared with only four channels collected by MSS. The wavelength range
for the TM sensor spanned the blue through mid-IR bands (see Table 2-3~. The
16 detectors for the visible and mid-IR bands in the TM sensor provided 16 scan
lines on each active scan. The TM sensor had a spatial resolution of 30 m for the
visible, near-IA, and mid-IR bands and a spatial resolution of 120 meters for the
thermal-IA band. As with all earlier Landsats, sensors on these satellites imaged
a 185-km swath. Today, Landsat-4 has lost all capability to communicate TM
data and is in standby mode. Landsat-5 has lost its Tracking and Data Relay
Satellite System (TDRSS) capability, but continues to provide data via direct
downlink to the United States and the international ground stations.
TABLE 2-3 Radiometric Range of Bands and Resolution for the TM Sensor
Band,Wavelength Resolution
Landsats-4,-5(micrometers) (meters)
10.45-0.52 30
20.52-0.60 30
30.63-0.69 30
40.76-0.90 30
51.55- 1.75 30
610.40-12.50 120
72.08-2.35 30
SOURCE: U.S. Geological Survey and National Oceanic and Atmospheric Administration, 1984.
Landsat-6
Landsat-6 was launched on October 5,1993, but failed to achieve orbit. It was
similar to Landsats-4 and -5 in terms of spacecraft design and planned orbital con-
figuration. The MSS and TM sensors were replaced by an improved TM sensor
called the Enhanced Thematic Mapper (ETM), from which no data were received.
ASSESSING THE IMPACT
Beyond the personalities and visions that led to Landsat-l, the program's
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A BRIEF HISTORY OF REMOTE SENSING APPLICATIONS
etated/unvegetated areas, forested/unforested lands, urban/nonurban areas, and
agricultural/nonagricultural lands. Each of these categories served as the founda-
tion for formulating upward-spiraling interpretations of human economic uses of
the land, for assessing environmental health, and for addressing what would later
be called earth system science (U.S. National Aeronautics and Space Administra-
tion, 1988~.
It was, moreover, recognized that, by virtue of its 18-day orbital repeat cycle,
Landsat-1 would offer scientists their first unrestricted opportunity to observe
synoptic changes in surface covers that would be impossible to obtain using
aerial platforms. The temporal dimension of remote sensing had always been
appreciated, but seldom employed usefully outside DOD because high-quality
time-series data were essentially nonexistent. With Landsat-l, the time dimen-
sion not only was a key design parameter, but also was immediately recognized
by the scientific community as an essential ingredient in spectral analyses. By
holding solar azimuth relatively constant with an equatorial crossing of approxi-
mately 9:30 a.m., the orbital design offered an opportunity to calibrate spectral
readings radiometrically across latitudes and longitudes and throughout the an-
nual greening and yellowing cycles of vegetation. Attention shifted sharply away
from building spectral libraries to monitoring temporal changes and patterns.
Time was also the enabling parameter for promoting a deeper understanding
of physical models in several land analysis applications (Reeves, 1975; Colwell,
1983~. In surface hydrology, for example, measurements from data collection
platforms were merged experimentally with Landsat-1 data to monitor spatial
and temporal changes in the water levels of Lake Okeechobee in order to opti-
mize swamp ecology and balance Miami's urban water needs. Run-off predic-
tion models were augmented by monitoring the geographic extent and depth of
river basin snow levels, and temporal dynamics of major floods such as those that
occurred along the Mississippi River and Cooper's Creek (Australia) in 1973
were examined in the context of disaster assessment.
Other time-sensitive applications were also advanced. In agriculture, MSS
imagery was used to improve an existing production estimation model for wheat
in western Kansas, thus proving the concept that satellite-acquired data could
provide accurate and timely crop predictions (Morain and Williams, 1975~. For-
est clear-cuts in Oregon and Washington were monitored, and in Washington,
remote observations were actually used to assess lessee compliance. Rangeland
studies included spectral responses through time for the assessment of biomass
production and general range condition.
Landsat MSS and TM data have also become important in global and local
studies of biodiversity and biogeography, and have become key to the emerging
framework of "landscape ecology," whereby remote sensing is used to identify
vegetation gaps and patterns in the landscape that influence habitats and ecosys-
tem functioning and dynamics.
These early modeling efforts evolved into satellite applications that address
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STANLEY A. MORAIN
41
today's social and environmental issues (e.g., food security, deforestation im-
pacts, desertification trends, resource sustainability, and news gathering). Yet
none of them led directly to these more profound applications. They all required
iterations that included many false starts. Early applications, therefore, were
important as pioneering efforts and for what they taught the scientific community
about future satellite requirements and collateral inputs for problem solving. All
of the Landsat- 1 results relied on collateral, ground-based data (today's relational
database or geographic information system [GIS] technology) and suffered from
gaps in temporal data that would have made them more robust. Further, the
spectral data were often too coarse. If satellite earth observations were to deliver
on their early promise, more spectral channels with narrower bandwidths would
have to be acquired from a larger number of platforms providing more frequent
observations. It was believed that if this could be achieved, the data and imagery
would have commercial as well as public value.
Pri vatiz ation/C ommerci al iz all on
As the nation's civilian space research and development agency, NASA
successfully executed its role by launching Landsat-l. The handoff of responsi-
bility for data dissemination from NASA to USGS/EDC had already been com-
pleted by the time Landsat-1 was launched. The plan was for EDC to serve as the
supplier of Landsat products, while NASA would continue to develop future
sensors and platforms. Differing agency responsibilities and management agen-
das, however, plagued the Landsat program from its inception. To resolve these
issues, the Carter Administration undertook an extensive review of both the
military and civilian space policies. By 1979, new policies had been formulated
by which the civilian program was to be made operational, administered by
NOAA, and eventually privatized. At about this same time, Congress merged
land-, ocean-, and weather-sensing systems under the administration of NOAA.
A crisis ensued (National Research Council, 1985~. Among the major play-
ers in this crisis were an ever-growing community of Landsat data users, includ-
ing the news-gathering media, which wanted inexpensive, publicly accessible
data; an increasingly vociferous industrial sector that was concerned about pend-
ing international competition and believed privatization would preserve
America's niche in commercial earth observations; and a federal establishment
disinclined to privatize all land, ocean, and weather satellite data systems.
In its effort to reduce the size of government, the first Reagan Administration
moved quickly to privatize the Landsat program. What resulted was the Land
Remote-Sensing Commercialization Act of 1984 (P.L. 98-965~. NOAA solic-
ited bids to manage the existing Landsats and civilian meteorological satellites
and, aided by large government subsidies, to build and operate future systems.
Bids were received from aerospace companies, an insurance company in New
York, a small geoscience firm in Michigan, and a farmer in North Dakota (U.S.
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42
A BRIEF HISTORY OF REMOTE SENSING APPLICATIONS
Department of Commerce, 1984~. In 1985, a contract was signed with EOSAT
Corporation (now Space Imaging/EOSAT Corporation), and the transfer was
complete (U.S. Department of Commerce, 1985~.
A history of the national debate leading up to and following privatization is
provided by Morain and Thome (1990~. It is interesting that the most compelling
arguments made to Congress for Landsat privatization focused on data and pro-
gram continuity not spectral analyses and fine-resolution time-sequential data.
Although data continuity has never been defined, and program continuity re-
mains a political question, Congress continues to legislate most aspects of
America's space remote sensing activities.
Following another series of program reviews, the National Space Council
released its National Space Policy Directive #5, which established new goals and
implementation guidelines for the Landsat program (Office of the President,
1992~. The directive called for a joint DOD/NASA effort to build, launch, and
operate Landsat-7. In October 1992, the Land Remote Sensing Policy Act (P.L.
102-55) was signed into law. It reversed the 1984 decision to commercialize the
Landsat system and recognized the scientific, national security, economic, and
social utility of land remote sensing from space (Scheffner, 1994~. It mandated
that DOD and NASA (1) establish a management plan, (2) develop and imple-
ment an advisory process, (3) procure Landsat-7, (4) negotiate with EOSAT for a
new data policy regarding existing systems, (5) assume program responsibility
from the Department of Commerce, (6) conduct a technology demonstration
program, and (7) assess options for a successor system.
Scarcely a year had passed before the Landsat program was evaluated for a
third time, principally because of severe budget constraints surrounding the High
Resolution Multispectral Stereo Imager instrument proposed by DOD for
Landsat-7. The National Science and Technology Council (NSTC) recommended
that Landsat-7 be developed only with an improved TM instrument and that a
new management structure be established so DOD could withdraw from the
program. The result was Presidential Decision Directive/NSTC-3, dated May 5,
1994, which reconfirmed the administration's support for the program, but gave
NASA, NOAA, and USGS joint management responsibility (Office of the Presi-
dent, 1994~. These three agencies negotiated with EOSAT for new Landsat-4
and -5 product prices for the U.S. government and its affiliated users, and are
proceeding to develop Landsat-7. Meanwhile a tired but operable Landsat-5
(into its fourteenth year) remains aloft, transmitting consistent and reliable im-
ages of the earth to the U.S. ground station and its foreign counterparts.
It has been argued that government policies designed to transfer the Landsat
program from the public to the private sector were seriously flawed. These
policies did not result in market growth, were more costly to the federal govern-
ment than would have been the case if the system had been federally operated, did
not significantly reduce operating costs, and significantly inhibited applications
of the data (Lauer, 1990~. Costs of imagery increased from about $200 for an
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STANLEY A. MORAIN
43
MSS scene in 1972 to more than $4,500 for a TM scene in 1997, a rate much
greater than inflation and prohibitive to many users. Nevertheless, the program
continued to provide a flow of high-quality, well-calibrated, synoptic imagery of
the earth.
Whether or not Landsat privatization was premature given existing and an-
ticipated markets, it can be argued that a global groundswell of government and
academic users, particularly within developing nations in Africa, Latin America,
and Asia, stimulated a proliferation of international Landsat look-alike satellites.
After 1986, these systems augmented Landsat data around the world, further
verifying proof-of-concept applications and elevating overall space-based capa-
bilities to a new plane.
The proposed series of NASA's Earth Observing System (EOS) satellites is
designed to provide information on a wider range of variables and at a more
detailed resolution than that provided by Landsat, and a number of other nations
have launched satellites to provide information of relevance to land-use and other
applications. For example, the French Systeme pour ['Observation de la Terre
(SPOT) satellite has a higher resolution (10 m) than that of the latest Landsat
satellites and has been used in a variety of applications, including observation of
the Chernobyl accident and agricultural monitoring (Sadowski and Covington,
1987~. The primary constraint on widespread use of SPOT data is the cost,
especially for studies over large areas. India has launched two satellites with
sensor systems similar to the Landsat TM, which are being used for natural
resources management. Japan and Europe have launched Earth Resources Satel-
lites, which use synthetic aperture radar to provide information on the physical
and electrical conditions of terrain. These radar satellites are beginning to pro-
vide information of relevance to studies of fire, deforestation, crop monitoring,
and urbanization (Consortium for International Earth Science Information Net-
work, 1997; Office of Technology Assessment, 1993~.
The Legacy
Landsat-7
Landsat-7 is scheduled for launch in mid-1998. Its payload will be an En-
hanced Thematic Mapper (Plus) instrument designated the ETM+. The ETM+
has the same basic design as the TM sensors on Landsats-4 and -5, but includes
some conservative advances (Obenschain et al., 1996~. It will provide 60-m (as
opposed to 120-m) spatial resolution for the thermal band and a full-aperture
calibration panel that will result in improved absolute radiometric calibration (5
percent or better). The geodetic accuracy of systematically corrected ETM+ data
should be comparable to that characterizing Landsat-4 and -5 TM data, with a
specific uncertainty of 250 m (1 sigma) or better. Other features have been added
to the Landsat-7 program to facilitate use of the data, particularly by private
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44
A BRIEF HISTORY OF REMOTE SENSING APPLICATIONS
industry. For example, Landsat-7 will directly downlink ETM+ data to domestic
and international ground receiving stations at 150 megabits per second using
three steerable X-band antennae. Although transmissions to international ground
stations will continue, the system is being designed so that the United States can
capture and refresh a global archive to be located at EDC. To make it possible for
ETM+ to capture data over regions beyond the range of EDC's receiving antenna,
Landsat-7 will use a 378 gigabits per second solid-state recorder capable of
storing approximately 40 minutes or 100 scenes of ETM+ data. A second North
American receiving station is being added near Fairbanks, Alaska, so that 250
scenes of data per day can be collected. Thus, the recorder will downlink re-
corded data when the satellite is within range of either EDC or the Alaskan
station, and EDC will receive and archive 250 ETM+ scenes per day. These
features will provide the capability for global coverage of continental surfaces on
a seasonal basis.
On the other hand, Landsat-7 does not include some useful technologies,
such as the ability to "point," and its 15 x 15-m spatial resolution may be rapidly
overtaken by the 1 x 1-m resolution of the Space Imaging EOSAT system in
1998.
Beyond Landsat-7
The 1992 Land Remote Sensing Policy Act called for developing cost-
effective advanced-technology alternatives for maintaining data continuity be-
yond Landsat-7 (Scheffner, 1994~. To address this requirement, NASA plans to
launch EO-1 as part of its New Millennium Program (Ungar,1997~. This mission
will be devoted to testing new technologies for use beyond Landsat-7. Some
concepts for an advanced sensor are described by Salomonson et al. (1995) and
Williams et al. (1996~. In essence, advanced Landsat concepts use solid-state,
push-broom, multispectral linear arrays, and hyperspectral area arrays that em-
ploy grating and wedge filter technologies.
Exactly how an advanced Landsat observing capability will be implemented
is still under study. One option is to fly the advanced-technology Landsat sensor
on one of the NASA EOS satellites, such as the AM-2 mission. This option
would reduce launch costs. Other possibilities include flying the sensor on a
separate, smaller and less expensive advanced-technology spacecraft. A third
possibility is for the advanced-technology capabilities and Landsat continuity
requirements to be incorporated in a capability provided by a commercial entity.
In any case, it is clear that the earth science and applications community needs
the Landsat TM quality and type of data to be provided and continuity to be
ensured so that the integrity of the databases inaugurated by Landsat-1 can be
preserved. It appears clear that advanced technology can be used to meet these
requirements and possibly provide highly desirable enhancements.
Table 2-4 is a chronology of Landsat and similar international satellite sys
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STANLEY A. MORAIN
TABLE 2-4 Chronology of Landsat and Landsat-like Launches, 1972-2007
45
Year Platform (Nationality) Sensor
1972 Landsat-1 (United States) MSS; RBV
1975 Landsat-2 (United States) MSS; RBV
1978 Landsat-3 (United States) MSS; RBV
1982 Landsat-4 (United States) MSS; TM
1984 Landsat-5 (United States) MSS; TM
1986 SPOT-1 (France) HRV
1988 RESURS-01 (Russia) MSU-SK
1988 IRS- 1A (India) LISS- 1
1990 SPOT-2 (France) HRV
1991 IRS-1B (India) LISS-2
1992 JERS-1 (Japan) OPS
1993 Landsat-6 (United States) ETM
1993 SPOT-3 (France) HRV
1993 IRS-PI (India) LISS-2; MEOSS
1994 IRS-P2 (India) LISS-2; MOS
1994 RESURS-02 (Russia) MSU-E
1995 IRS-1C (India) LISS-3
1996 ADEOS (Japan) AVNIR
1996 PRIRODA (Germany/Russia) MOMS
1997 IRS-ID (India) LISS-3
1998 CBERS (China/Brazil) LCCD
1998 SPOT-4 (France) HRVIR
1998 Landsat-7 (United States) ETM+
1998 EOS AM-1 (United States/Japan) ASTER
1998 IRS-P5 (India) LISS-4
1999 Resource 21 (United States) Resource 21
2000 IRS-2A (India) LISS-4
2002 ALOS (Japan) AVNIR-2
2002 SPOT-5A (France) HRG
2004 IRS-2B (India) LISS-4
2004 SPOT-5B (France) HRG
2004 ALOS-A1 (Japan) AVNIR-3
2007 ALOS-A2 (Japan) AVNIR-4
NOTE: The acronyms in this table are the terms by which the platforms and sensors listed are
commonly known; for the full names, see Morain and Budge (1996).
SOURCE: From Morain and Budge (1996) and Stoney et al. (1996).
tems. It lists only so-called earth resources satellites having sensors operating in
the visible and near infrared spectrum, and channels roughly equivalent to those
of the Landsat MSS or TM sensors. In the past 25 years there have been nearly
20 launches and 4 distinct international systems (a fifth will become operational
with the launch of the China/Brazil Earth Resources Satellite). Data from these
satellites are used daily by international donor agencies, government agencies at
all levels, oil and mineral exploration companies, environmental consultants,
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46
A BRIEF HISTORY OF REMOTE SENSING APPLICATIONS
value-added commercial firms, academia, and the general public. The first-order
land-cover categories predictable in 1972 have expanded to include rather so-
phisticated higher-order applications. Continuity has been achieved in more than
one sense (Morain and Budge, 1995~. Use of time as a discriminant has envel-
oped the user community in ways that were not foreseen, and will be integral to
future applications in ways that are not yet perceived. Spectral analytical proce-
dures have evolved around the time dimension and will also be stimulated by
future hyperspectral data collectors. It can truly be said that even if the Landsat
program heads toward extinction, its progeny will continue to support the tech-
nology it has created.
CONCLUSIONS
The earliest visionaries, such as Jules Verne, Arthur C. Clarke, Robert
Alexander, William Fisher, Archibald Park, and William Pecora, predicted great
things to come as humans took their first steps into space. Of all the ventures to
date, the U.S. Landsat program ranks among the most successful. Interestingly,
most of the problems that have plagued this national program have not been
technical, but administrative and political. Despite the difficulties related to
national security issues, agency roles, delays in data delivery, funding uncertain-
ties, and a shaky attempt to privatize a federal program, the accomplishments of
the Landsat program have been extraordinary. For the 25 years from 1972 to
1997, synoptic, high-quality data have been routinely acquired, processed into an
ever-improving array of digital and photographic products, and used to better
measure and monitor earth resources. The Landsat series has provided new
insights into geologic, agricultural, and land-use surveys, and opened new paths
in the exploration of new resources. Understanding of the earth, its terrestrial
ecosystems, and its land processes has been advanced remarkably through the
Landsat program. Of equal importance, this program has stimulated new ap-
proaches to data analysis and academic research, and provided opportunities for
the private sector to develop spacecraft, sensors, and data analysis systems and
provide value-added services. It has also fostered strong international participa-
tion and a whole new generation of Landsat-like systems around the world. The
political, scientific, and commercial currents over the next 25 years of earth-
observing systems will be no easier to chart than were those of the first 25, but the
systems that result are certain to advance human understanding and use of the
planet's resources.
NOTES
1 A related, longer version of this paper appeared in Photogrammetric Engineering and Remote
Sensing (Lauer et al., 1997).
2 The "S" in EROS was subsequently changed to stand for "System" rather than "Satellite."
3 Routine collection of MSS data was terminated in late 1992.
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STANLEY A. MORAIN
47
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Representative terms from entire chapter:
sensing applications
