Earth Sensing Missions

The earth sensing satellites carry experiments designed to sense the earth (i.e acquire data on worldwide environmental changes such as the green house effect, ozone layer depletion, tropical rain forest deforestation, and abnormal climatic conditions), in order to contribute to international global environmental monitoring.

These satellites are large, irregular shaped objects. Because of this, these satellites are subject to drag and solar radiation forces which are considerable and to some degree unpredictable.

The TOPEX/Poseidon mission achieved unprecedented orbit accuracies of 2 to 3 centimeters in the radial component. The technology and orbit determination techniques developed during the TOPEX/Poseidon mission have made it possible for other missions to achieve similar levels of accuracy.

Many of the earth sensing satellites are equipped with radar altimeters. SLR is the most accurate technique currently available to determine the geocentric position of an Earth satellite, allowing for the precise calibration of radar altimeters and separation of long-term instrumentation drift from secular changes in ocean topography. In addition, SLR has proven to be a cost-effective means of providing failsafe redundancy to spaceborne radiometric tracking systems such as GPS, PRARE, and DORIS.

Altimetric data from these satellites are making it feasible to study the variations of the height of the surface of the sea, of the snow and ice in polar regions, and hence to obtain information about ocean currents and eddies, and the profile and structure of the ocean floor.

Responsible Government Official: Carey Noll
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