Geosat was a US Navy satellite designed to measure sea surface heights to within 5 cm. After a one-and-a-half year long classified mission for the Navy, Geosat's scientific Exact Repeat Mission (ERM) began on November 8, 1986. When the ERM ended in January 1990 (due to failures of both on-board tape recorders), more than three years of precise altimeter data were available to the scientific community. Spacecraft: Gravity gradient stabilised. Two tape recorders. Payload: Radar altimeter to measure sea surface height.

Design Life: 3 years. Total Mass: 635 kg.

Ocean sea height mapping. Spacecraft engaged in practical applications and uses of space technology such as weather or communication (US Cat C).

• 2 - McDowell, Jonathan, The United Nations Registry of Space Objects, Harvard University, 1997. HTML when accessed: http://hea-www.harvard.edu/QEDT/jcm/space/un/un.html
• 6 - JPL Mission and Spacecraft Library, Jet Propulsion Laboratory, 1997. HTML when accessed: http://msl.jpl.nasa.gov/home.html
• 279 - McDowell, Jonathan, Launch Log, October 1998. HTML when accessed: http://hea-www.harvard.edu/~jcm/space/log/launch.html