The GEOSAT was a U.S. Navy Earth observation satellite, launched on March 12, 1985 into an 800 km, 108° inclination orbit, with a nodal period of about 6040 seconds. The satellite carried a radar altimeter capable of measuring the distance from the satellite to sea surface with a relative precision of about 5 cm. Its 18-month initial phase was a classified Geodetic Mission with a near-23-day repeat that was intended to replicate the orbit of the short-lived Seasat. After this, the satellite was maneuvered into a near-17-day exact repeat for oceanographic research.