Earth resources satellites

DEFINITION: Unmanned scientific satellites that collect information about the earth and its resources and relay it to land-based scientific stations

Earth resources satellites provide scientists with systematic, repetitive measurements of the surface conditions of the earth, including atmospheric and oceanic conditions. The data the satellites collect help scientists understand phenomena such as climate change and how events such as deforestation, coastal erosion, and pollution affect the earth as a whole.

The first earth resources satellite was launched on July 23, 1972, from Vandenberg Air Force Base in California. Earth Resources Technology Satellite 1, which became better known as Landsat 1, was placed in an orbit in which it passed over the North and South Poles to provide scientists with information about those areas. Since that first launch, earth resources satellites have provided scientists with a wealth of data about the earth. They accurately measure and transmit values for atmospheric water vapor, cloud cover, ocean currents and temperatures, ozone distribution, surface altitude and temperatures, wave height, wind speed and direction, and a variety of other atmospheric, geological, and oceanic information. By tracking the fluctuations in these measurements, scientists can study how various events affect the earth’s surface and climate. They can also use this information to observe and monitor the earth’s limited resources, document the spread of and changes in climate, and better understand how the earth’s limited resources can be used and conserved in the best ways possible.

Earth resources satellites also document events such as earthquakes, fires, floods, oil spills, and volcanic eruptions, giving scientists a clearer picture of how these events interact across the planet. For example, scientists came to a better understanding of the El Niño weather phenomenon by using satellite-gathered data to track the ocean’s surface currents, temperatures, and winds through several El Niño cycles. During the 1991 Persian Gulf War, images from these satellites were used to document and monitor the damage caused to Kuwait’s oil fields during the Iraqi occupation. Since Russia's invasion of Ukraine in 2022, Ukraine's allies have provided information from satellites indicating the location of Russian troops and destroyed Ukrainian buildings.

Information gathered by earth resources satellites may also be used to locate deposits and monitor the condition of forests, fisheries, and farms. Agricultural uses include finding underutilized areas of both sea and land and determining whether plots of land can be irrigated to produce new farming areas or whether aquaculture could be a fitting use for particular areas in the sea. Satellite-gathered information has also been used to pinpoint the origins of crop diseases and to monitor the spread of such diseases.

History

During the 1960’s weather satellites and photographs from high-flying aircraft provided scientists with some information about the earth’s surface. These information sources were relatively inefficient, however; the black-and-white images from weather satellites did not provide significant detail, and it was impossible to take enough aerial photographs to provide sufficient information (it was estimated that some thirty thousand photographs would need to be taken to cover the United States alone). William T. Pecora, who worked for the U.S. Geological Survey, became interested in developing a type of orbiting platform that would carry scientific recording devices and provide better information. This type of equipment was already being developed for space exploration and for possible military applications, and he saw its potential for providing detailed maps of the earth. At the same time, Archibald B. Park, who worked in the U.S. Department of Agriculture, was interested in the same type of information; he believed that if the world’s crops and forests could be mapped and surveyed, farmers and ecologists could use the information to help them better manage land resources.

For about ten years, what became the Landsat program was managed by a private-sector company (the Earth Observation Satellite Company, a partnership between Hughes Aircraft Company and the RCA Corporation), but throughout most of the history of these satellites, the U.S. government has managed Landsat through a joint program of the National Aeronautics and Space Administration (NASA) and the U.S. Geological Survey. Other countries also have earth resources satellites circling the globe, either through their own national programs or joint ventures; these include Australia, Brazil, China, Canada, Japan, and various European nations.

The first five U.S.-based earth resources satellites were launched in 1972, 1975, 1978, 1982, and 1984. The sixth satellite, launched in 1993, failed to achieve orbit, but a seventh, known as Landsat 7, was successfully launched in 1999. All of the satellites have carried various types of cameras, including infrared cameras. The older models collected photographic images of the earth’s surface; the later models (1982, 1984, and 1999) also carried additional sensors and a scanning radiometer capable of providing scientists with high-resolution images of the earth’s surface.

Bibliography

Bukata, Robert P. Satellite Monitoring of Inland and Coastal Water Quality: Retrospection, Introspection, Future Directions. Boca Raton, Fla.: CRC Press, 2005.

China Remote Sensing Satellite Ground Station. The Majestic Earth: A Selection of Earth Resources Satellite Images. Hong Kong: Science Press, 1996.

Chuvieco, Emilio, ed. Earth Observation of Global Change: The Role of Satellite Remote Sensing in Monitoring the Global Environment. New York: Springer, 2008.

Dickey, Robin and Michael P. Gleason. "Space and War in Ukraine: Beyond the Satellites." Aether, 3 Apr. 2024, www.airuniversity.af.edu/Portals/10/AEtherJournal/Journals/Volume-3‗Number-1/Dickey‗Gleason.pdf. Accessed 16 July 2024.

"How Earth Observation Helps Natural Resources Management." Dragonfly Aerospace, 5 Apr. 2022, dragonflyaerospace.com/earth-observation-and-natural-resource-management/. Accessed 16 July 2024.

Kramer, Herbert J. Observation of the Earth and Its Environment: Survey of Missions and Sensors. New York: Springer, 2002.

Mack, Pamela E. Viewing the Earth: The Social Construction of the Landsat Satellite System. Cambridge, Mass.: MIT Press, 1990.

Maul, G. A. Introduction to Satellite Oceanography. Dordrecht, Netherlands: Martinus Nijhoff, 1985.

Short, Nicholas M. Mission to Earth: Landsat Views the World. Washington, D.C.: National Aeronautics and Space Administration, 1976.