The GFO Spacecraft and Mission Design

The GFO satellite includes all the capabilities necessary for the precise measurement of both
mesoscale and basin-scale oceanography. A water vapor radiometer has been added to the
basic GEOSAT measurement capability. GFO also included GPS receivers but these are not

GFO was launched aboard a TAURUS launch vehicle on 10 February 1998 from Vandenberg
Air Force Base in California. The launch was near the minimum of the solar cycle. The satellite
was accepted by the Navy on 29 November 2000. During its mission life, the satellite will be
retained in the GEOSAT Exact Repeat Mission (ERM) orbit (800 km altitude, 108 degree
inclination, 0.001 eccentricity, and, 100 min period). This 17-day Exact Repeat Orbit (ERO)
retraces the ERM ground track to +/-1 km. As with the original GEOSAT ERM, the data will
be available for ocean science through NOAA/NOS and NOAA/NESDIS.

The 300-kg spacecraft is approximately 3-m long and supports the following payloads:

  1. Radar Altimeter - single frequency (13.5 GHz) with 3.5-cm height precision.
  2. Water Vapor Radiometer - dual frequency (22 and 37 GHz) nadir-looking with a path
    correction accuracy of 1.9 cm rms.
  3. GPS Receivers Not working
  4. Doppler Beacon - GEOSAT performance-stable oscillators and doppler beacons will
    allow operational orbits to be determined with 1.8-cm rms radial orbit error for mesoscale
    oceanography (after tilt and bias removal along a 3000-km arc-filter length.

The payloads will feature complete redundancy, light weight (47 kg total), and low power
consumption (121 W total).

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