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CHAPTER 1 SECTIONS > Background | Mission Objectives | System Capabilities

The Landsat 7 Handbook is out of date. A revised version to bring the information up to date will be developed and posted when complete. Please see the USGS Landsat site at for current information on Landsat 7 ETM+ data and data products.

1.1 Background to the Landsat Program

The Landsat Program has provided over 38 years of calibrated high spatial resolution data of the Earth's surface to a broad and varied user community, including agribusiness, global change researchers, academia, state and local governments, commercial users, military, and the international community. Landsat images provide information meeting the broad and diverse needs of business, science, education, government, and national security.

The mission of the Landsat Program is to provide repetitive acquisition of high resolution multispectral data of the Earth's surface on a global basis. Landsat represents the only source of global, calibrated, high spatial resolution measurements of the Earth's surface that can be compared to previous data records. The data from the Landsat spacecraft constitute the longest record of the Earth's continental surfaces as seen from space. It is a record unmatched in quality, detail, coverage, and value.

The Landsat platforms carry multiple remote sensor systems and data relay systems along with attitude-control and orbit-adjust subsystems, power supply, receivers for ground station commands and transmitters to send the data to ground receiving stations.

The most recent Landsat mission, Landsat 7, offers these features:

  • Data Continuity: Landsat 7 is the latest in a continuous series of land remote sensing satellites spanning 38 years.

  • Global Survey Mission: Landsat 7 data will be acquired systematically to build and periodically refresh a global archive of sun-lit, substantially cloud-free images of the Earth's landmass.

  • Affordable Data Products: Landsat 7 data products will be available through the EROS Data Center at the cost of fulfilling user requests (COFUR).

  • Enhanced Calibration: Data from the ETM+ will be calibrated to better than 5% absolute, providing an on-orbit standard for other missions.

  • Responsive Delivery: Automated request processing systems will provide products electronically within 48 hours of order.

The continuation of the Landsat Program is an integral component of the U.S. Global Change Research Program. Landsat 7 is part of a global research program known as NASA's Earth Sciences Enterprise, a long-term program that is studying changes in Earth's global environment. The goal of Earth Sciences Enterprise is to provide a better understanding of natural and man-made environmental changes. In the Landsat Program tradition, Landsat 7 will continue to provide critical information to those who characterize, monitor, manage, explore, and observe the land surfaces of the Earth over time.

1.1.1 Previous Missions

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Landsat satellites have been providing multispectral images of the Earth continuously since the early 1970's. A unique 38-year data record of the Earth's land surface now exists. This unique retrospective portrait of the Earth's surface has been used across disciplines to achieve improved understanding of the Earth's land surfaces and the impact of humans on the environment. Landsat data have been utilized in a variety of government, public, private, and national security applications. Examples include land and water management, global change research, oil and mineral exploration, agricultural yield forecasting, pollution monitoring, land surface change detection, and cartographic mapping.

Landsat 7 is the latest satellite in this series. The first was launched in 1972 with two Earth-viewing imagers - a return beam vidicon and an 80 meter multispectral scanner (MSS). Landsat 2 and 3, launched in 1975 and 1978 respectively, were configured similarly. In 1984, Landsat 4 was launched with the MSS and a new instrument called the Thematic Mapper (TM). Instrument upgrades included improved ground resolution (30 meters) and 3 new channels or bands. In addition to using an updated instrument, Landsat 4 made use of the multimission modular spacecraft (MMS) which replaced the Nimbus based spacecraft design employed for Landsats 1-3. Landsat 5, a duplicate of 4, was launched in 1984 and even today after 26 years - 21 years beyond its 5 year design life - is still returning useful data. Landsat 6, equipped with a 15 meter panchromatic band, was lost immediately after launch in 1993.

Table 1.1 lists key mission characteristics of the Landsat Program while Table 1.2 compares the sensors carried aboard these satellites. A detailed Landsat Program Chronology is also available.

Table 1.1 Landsat Mission Characteristics
Landsat Mission Characteristics
Table 1.2 Landsat Satellites and Sensors
Comparison of Landsat Sensors

1.1.2 The EOSAT Era

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In the mid 1980's, U.S. Government agencies, including NASA and NOAA, were directed to attain their commercial space objectives without the use of direct federal funding by entering into appropriate cooperative agreements with private sector corporate entities to encourage and advance private sector basic research, development, and operations.

The implementation of this policy required the transfer of government-developed space technology to the private sector in such a manner as to protect its commercial value, which included retention of technical data rights by the private sector. Commercial sector space activities developed under this mandate were to be supervised or regulated by federal agencies only to the extent required by law, national security, international obligations and public safety.

With the passage of Public Law 98-365, the "Land Remote Sensing Commercialization Act of 1984", NOAA was directed to delegate management of the Landsat 4 and 5 satellites and their data distribution to the private sector. In addition, NOAA was to pursue procurement of future remote sensing Landsat products and services from the private sector.

In 1985, NOAA solicited bids to manage the existing Landsat satellites and to build and operate future systems. The Earth Observation Satellite Company (EOSAT), a joint venture between RCA and Hughes Aircraft, now called Space Imaging Corporation, won the competitive bidding process in August 1984 and took over operation of the Landsat system on September 27, 1985.

From 1985 to 1994, EOSAT retained exclusive sales rights to all Landsat 4 and 5 Thematic Mapper (TM) data until July 1994, at which time Landsat data over ten years old became available from the National Archive at the EROS Data Center (EDC). This agreement between Landsat Program management and EOSAT Corporation on cost and reproduction rights for Landsat 4 and 5 Thematic Mapper data remains in effect and was last updated in October 1996. EOSAT also won competition to produce the next satellite in the series, Landsat 6.

1.1.3 Basis in Law for Landsat

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By 1992, it had become clear that the high cost of commercially-provided Landsat data had greatly restricted its use in research and other public sector applications. In response, the U.S. Congress passed H.R. 6133, the "Land Remote Sensing Policy Act of 1992", into law in September of that year. This law established a new national land remote sensing policy which:

  • Abandoned full commercialization of the Landsat Program.

  • Returned management of the Program to the Government.

  • Established a data policy of distributing Landsat data at the cost of fulfilling a user request (COFUR).

  • Directed that preliminary work begin on a new Landsat 7.

  • Foster development of advanced land remote sensing systems and opportunities for commercialization.

The loss of Landsat 6 in October, 1993 suddenly made the new Landsat 7 mission imperative. A May 5, 1994 Presidential Decision Directive (NSTC-3) defined the new Landsat 7 data policy, program management strategies and implementation guidelines. Subsequent NASA and NOAA memoranda later that summer brought the current Landsat 7 mission into existence.

Other, recent legislation relevant to Landsat:

  • HR1275
    Short title: "Civilian Space Authorization Act, Fiscal Years 1998 and 1999"

  • HR1278
    Short title: "National Oceanic and Atmospheric Administration Authorization Act of 1997"

  • HR1702
    Short title: "Commercial Space Act of 1997"

Visit Recent and Pending Legislation Affecting the Landsat Program for detailed public law information.

1.1.4 System Operation and Management

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The Landsat 7 Program management structure changed repeatedly from 1992 through 1998, from NASA/USAF/USGS to NASA/NOAA/USGS to a bi-agency NASA/USGS partnership. As described in the Landsat 7 Management Plan, NASA is responsible for the development and launch of the Landsat 7 satellite and the development of the ground system. The Landsat Project at Goddard Space Flight Center manages these responsibilities with Hughes Santa Barbara Remote Sensing building the sensor and Lockheed Martin Missiles and Space developing the spacecraft. The USGS is responsible for operation and maintenance of the satellite and the ground system for the life of the satellite. In this role the USGS captures, processes, and distributes the data and is responsible for maintaining the Landsat 7 data archive. The following web sites should be visited for additional information:

  • NASA Landsat 7 Project developed the Landsat 7 System. Specifically, it meant designing, developing, and testing the Landsat 7 spacecraft, ETM+ instrument, and the end-to-end ground system. NASA was also responsible for the satellite launch and performing a 60 day in-orbit check out before handing operations to the USGS. NASA is still responsible for verifying data processing integrity and assuring high image quality.

  • The USGS Center for Earth Resources Observation and Science (EROS) manages the overall Landsat 7 Mission Operations. In this capacity EDC directs on-orbit flight operations, implements mission policies, directs acquisition strategy, and interacts with International Ground Stations. EDC captures Landsat 7 data and performs pre-processing, archiving, product generation, and distribution functions. EDC also provides a public interface into the archive for data search and ordering and handles billing and accounting procedures.

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