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TOPEX/Poseidon (TOPEX)

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Status: Completed
Mission Category: Earth Observing System (EOS)
Launch Date: August 10, 1992

Topography Experiment (TOPEX)/Poseidon monitored global ocean circulation, improved global climate predictions, and tracked El Niño conditions and ocean eddies. After over 62,000 orbits, the satellite has ceased operations. TOPEX/Poseidon remains in orbit 830 miles above the Earth, posing no threat to the planet.

The mission’s most important achievement was to determine the patterns of ocean circulation - how heat stored in the ocean moves from one place to another. Another of the mission’s major accomplishments was the development of the most accurate global ocean tide models ever produced.

Furthermore, TOPEX/Poseidon was the first mission to demonstrate that the Global Positioning System Payload (GPS) could be used to determine a spacecraft’s exact location and track it in orbit. Knowing the satellite’s precise position to within 2 centimeters (less than 1 inch) in altitude was a key component in making accurate ocean height measurements possible.

TOPEX/Poseidon used the global perspective available only from space to develop maps of ocean topography showing the barely perceptible hills and valleys of the sea surface. This effort significantly expanded the knowledge developed from shipboard research, which is limited to specific locations. From TOPEX/Poseidon data, scientists calculated speed and direction of ocean currents worldwide to better understand how the oceans transport heat from the Earth’s equatorial region toward the poles, thus regulating global climate.

Key TOPEX/Poseidon Facts

Mission/Portal Page: http://science.nasa.gov/missions/topex-poseidon/
Instruments: AMR (Advanced Microwave Radiometer)
DORIS (Doppler Orbitography and Radio-positining Integrated by Satellite)
GPSP (Global Positioning System Payload)
LRA (Laser Retroreflector Array)
Poseidon-3 Altimeter

Related Publications:

Relevant Science Focus Areas:

  • Climate Variability and Change
  • Water and Energy Cycles

Relevant Science Questions:

  • How is the global Earth system changing?

Science Goals:

  • Coastal Management
  • Disaster Management