Geosat Introduction

The US Geodetic Satellite (Geosat) was a pioneering research mission of the US Navy dedicated to radar altimetry. The overall objectives were: Provision of a dense global grid of altimeter data for Navy use in the areas of geodesy (Earth's gravitational models), the study of fronts and eddies, winds, waves, ice topography and physical oceanography.

Background

The GEOSAT mission was originally managed by the Office of Naval Research (ONR), then was transferred to the Naval Electronics Systems Command, now referred to as Space and Naval Warfare Systems Command (SPAWAR). The spacecraft and the payload were designed and built by Johns Hopkins University/Applied Physics Laboratory (JHU/APL) of Laurel, MD. In addition, JHU/APL provided mission operations. The function of data reception, data handling and processing, archiving and distribution were provided by JHU/APL, the Navy Naval Surface Weapons Center (NSWC), and Naval Ocean Research and Development Activity (NORDA) and NOAA.

Mission status

The primary mission was the classified Geodetic Mission (GM) with a mission duration of 18 months (until September 1986). The second mission phase is known as the "Exact Repeat Mission" (ERM), which was unclassified; it started October 1, 1986 and ended in January 1990 (partly due to failures of both on-board tape recorders). The ERM provided more than three years of precise altimeter data - which became also available to the scientific community.

References

1) "The Navy GEOSAT Mission: An Overview", Johns Hopkins APL Technical Digest, Volume 8, No. 2, 1987.

2) "The Navy GEOSAT Mission Radar Altimeter Satellite Program", in Monitoring Earth's Ocean, Land, and Atmosphere from Space, Volume 97, 1985 AIAA, pp. 440-463.

3) J. J. Jensen, F. R. Wooldridge, "The Navy GEOSAT Mission: An Introduction"; McConathy, D. R. and C. C. Kilgus, "The Navy GEOSAT Mission: An Overview", and W. E. Frain, M. H. Barbagallo, R. J. Harvey, "The Design and Operation of GEOSAT", all in Johns Hopkins APL Technical Digest, Volume 8, No. 2, 1987.

4) R. F. Gasparovic, R. K. Raney, R. C. Beal, "Ocean Remote Sensing Research and Applications at APL", Johns Hopkins APL Technical Digest, Vol. 20, No 4, 1999, pp. 600-610.

5) NOAA Report, Vol. IV, No 10, November 1995, URL: http://www.publicaffairs.noaa.gov/nr/pdf/nov1995.pdf

6) D. C. McAdoo, K. M. Marks, "Gravity fields of the Southern Ocean from Geosat data", Journal of Geophysical Research, Vol. 97, 1992, pp. 3247-3260.

7) G. H. Born, J. L. Mitchell, G. A. Heyler, "Geosat ERM-Mission Design", Journal of the Astronautical Sciences, Vol. 35, No 2, April 1987, pp. 119-134.

8) W. H. F. Smith, D. T. Sandwell, "Global Sea Floor Topography from Satellite Altimetry and Ship Depth Soundings", Science 277, 1956-1961, 1997.

9) F. M. Monaldo,"Expected Differences Between Buoy and Radar Estimates of Wind Speed and Significant Wave Height and Their Implications on Buoy-Altimeter Comparisons", Journal of Geophysical Research. Vol. 93, 1988, pp. 2285-2301.

10) L. Miller, R. E. Cheney, B. C. Douglas, "Geosat Altimeter Observations of Kelvin Waves and the 1986-87 El Nino, Science 239, 52-54 1988.

11) D. B. Chelton, M. G. Schlax, D. L. Witter, J. G. Richman, "Geosat altimeter observations of the sea surface circulation of the southern ocean", Journal of Geophysical Research, Vol. 95, 1990, pp. 17,887-17,903.

12) M. J. Gabor, J. C. Ries, "A Systematic Approach to the Precision Orbit Determination of the GEOSAT Exact Repeat Mission Utilizing TRANET Doppler Data", Proceedings of the AAS/AIAA Space Flight Mechanics Meeting, Austin, TX, Feb. 12-15, 1996, Paper: AAS 96-166.

13) J. L MacArthur, P. C. Marth, Jr., J. G. Wall, "The GEOSAT Radar Altimeter", Johns Hopkins APL Technical Digest, Volume 8, No. 2, April-June 1987.

14) D. R. Mantripp, J. K. Ridley, C. G. Rapley, "Antarctic map from the Geosat Radar Altimeter Geodetic Mission", ESA Earth Observation Quarterly, No. 37-38, May-June 1992, pp. 6-10.

15) "GEOSAT-A Data Users/ground system interface control document (ICD)", Johns Hopkins APL, May 1985.