Encyclopedia Astronautica
Topex/Poseidon


American earth sea satellite. One launch, 1992.08.10. TOPEX/Poseidon was a co-operative mission between the United States and France designed to provide high-accuracy global sea level measurements.

Data from TOPEX/Poseidon was used to map ocean circulation patterns, help understand how the oceans interact with the atmosphere, and improve our ability to predict the global climate.

NASA provided the satellite bus, five instruments, and was responsible for spacecraft operations. CNES furnished two of the spacecraft's instruments and the mission's Ariane launch vehicle. During its first 3 years on orbit, the satellite measured sea heights to within 4 cm. The spacecraft was based on Fairchild's Multi-Mission Spacecraft bus and was 3-axis stabilized (nadir pointing) via reaction wheels and torque rods. Attitude determination was via Earth sensors, Sun sensors, star cameras, an inertial reference unit, and magnetometers. A single solar array with 1-axis articulation provided 3400W (BOL) and recharged 3 x 50 A-hr batteries. A 1.2 m high gain antenna allowed communications via TDRSS. A hydrazine propellant system allowed orbit maintenance. The GPS antenna was mounted on a deployed boom to minimize multipath noise. The payload included:

  • Dual frequency altimeter (C- and Ku-Band) measured the height of the satellite above the sea.
  • TOPEX Microwave Radiometer (TMR) measured the water vapor along the path viewed by the altimeter to correct the altimeter data for pulse delay due to water vapor.
  • Single-frequency Solid-State Altimeter (SSALT) operates at 13.65 GHz (Ku-Band) to measure the height of the satellite above the sea, wind speed, and wave height.
  • The Laser Reflector Array (LRA) was used with ground-based lasers to track the satellite and to calibrate and verify altimeter measurements.
  • A GPS receiver was used to provide precise orbit ephemeris data.
  • DORIS (Doppler Orbitography and Radiopositioning Integrated by Satellite) was also used for precise orbit determination, as well as to receive signals from ground stations for satellite tracking, make gravity field measurements, and provide ionospheric correction data for SSALT.

Gross mass: 2,402 kg (5,295 lb).
First Launch: 1992.08.10.
Number: 1 .

More... - Chronology...


Associated Countries
See also
  • Ariane First successful European commercial launch vehicle, developed from L3S Europa launch vehicle replacement design. Development of the Ariane 1 was authorised in July 1973, took eight years, and cost 2 billion 1986 Euros. More...

Associated Launch Vehicles
  • Ariane French orbital launch vehicle. First successful European commercial launch vehicle, developed from L3S Europa launch vehicle replacement design. Development of the Ariane 1 was authorised in July 1973, took eight years, and cost 2 billion 1986 Euros. More...
  • Ariane 42P French orbital launch vehicle. Ariane 4 with 2 solid rocket strap-ons. More...

Associated Manufacturers and Agencies
  • JPL American agency;manufacturer of rockets, spacecraft, and rocket engines. Jet Propulsion Laboratory, Pasadena, USA. More...
  • NASA American agency overseeing development of rockets and spacecraft. National Aeronautics and Space Administration, USA, USA. More...
  • CNES French agency overseeing development of spacecraft. Centre National d'Etudes Spatiales, Paris, France. More...
  • Fairchild American manufacturer of rockets, spacecraft, and rocket engines. Fairchild, USA. More...

Bibliography
  • McDowell, Jonathan, Jonathan's Space Home Page (launch records), Harvard University, 1997-present. Web Address when accessed: here.
  • JPL Mission and Spacecraft Library, Jet Propulsion Laboratory, 1997. Web Address when accessed: here.
  • McDowell, Jonathan, Launch Log, October 1998. Web Address when accessed: here.
  • NASA Report, Topex/Poseidon Press Kit, Web Address when accessed: here.
  • NASA Report, Topex/Poseidon Fact Sheet, Web Address when accessed: here.
  • NASA Report, TOPEX/Poseidon science investigations plan, Web Address when accessed: here.
  • NASA Report, Topex/Poseidon: A United States/France mission. Oceanography from space: The oceans and climate, Web Address when accessed: here.

Associated Launch Sites
  • Kourou After the agreement with newly independent Algeria for France to evacuate their launch sites in that country, a location near Biscarosse was selected for French missile testing. However since only launches westwards across the Bay of Biscay could be made from this site, it was unsuitable for France's Diamant orbital launch vehicle. After reviewing 14 potential sites, a location in the South American French colony of Guiana was selected. This would allow over-water launches to a tremendous range of possible orbital inclinations -- from -100.5 deg to 1.5 deg. Being near the equator, it would provide the maximum assist from the earth's rotation for launches into equatorial orbits. The decision was formalized in April 1964 and in July 1966 ELDO chose the site for future launches of the Europa II launch vehicle. More...

Topex/Poseidon Chronology


1992 August 10 - . 23:08 GMT - . Launch Site: Kourou. Launch Complex: Kourou ELA2. LV Family: Ariane. Launch Vehicle: Ariane 42P. LV Configuration: Ariane 42P V52.
  • Topex/Poseidon - . Mass: 2,402 kg (5,295 lb). Nation: France. Agency: JPL; CNES. Class: Earth. Type: Sea satellite. Spacecraft: Topex/Poseidon. USAF Sat Cat: 22076 . COSPAR: 1992-052A. Apogee: 1,344 km (835 mi). Perigee: 1,331 km (827 mi). Inclination: 66.0000 deg. Period: 112.40 min. Summary: Ocean sensing, mapping. Spacecraft engaged in research and exploration of the upper atmosphere or outer space (US Cat B)..

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