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Ocean Surface Topography from Space
OSTM/Jason-2 Fact Sheet

View the JPL OSTM/Jason-2 Spacecraft Fact Sheet (PDF, 1.61 MB)
View the NASA OSTM/Jason-2 Mission Fact Sheet (PDF, 278 KB)

Science Objectives

  • Extend the time series of ocean surface topography measurements beyond TOPEX/Poseidon (T/P) and Jason to accomplish two decades of observations
  • Provide a minimum of 3 years measurement of global ocean surface topography
  • Determine the variability of ocean circulation at decadal time scales from combined data record with T/P and Jason
  • Improve the measure of the time-averaged ocean circulation
  • mprove the measure of global sea-level change
  • Improve open ocean tide models

Engineering Objectives

  • Launch into the same orbit as Jason
  • Maintain the same measurement accuracy of Jason (3.3 cm) with a goal of achieving 2.5 cm
  • Maintain the stability of the global mean sea level measurement with a drift less than 1 mm/year over the life of the mission
  • Maintain the accuracy of significant waveheight to 50 cm or 10% of the value (whichever is greater)


  • International Collaboration: NASA, NOAA, CNES, EUMETSAT
  • Launch Date: June 15, 2008
  • Launch Vehicle: United Launch Alliance Delta II 7320
  • Launch Site: Vandenberg AFB, California
  • Mission Operations: NOAA, EUMETSAT


  • Altitude: 1336 km
  • Circular, non-sun-synchronous, 66° inclination
  • Global data coverage between 66°N and 66°S latitude
  • 10-day repeat of ground track (±1-km accuracy)
  • Coverage of 95% of ice-free oceans every 10-days


  • Based on Alcatel's Proteus bus
  • Total mass: 510 kg (1124 lbs)
  • Power: 500W
  • Communication through the NOAA Tracking Stations at Alaska, and Wallops Island, Virginia along with a EUMETSAT Station at Usingen, Germany
  • Reaction wheels and magnetic torque rods maintain 3-axis stabilization and nadir-pointing
  • Hydrazine propellant system provides orbital maintenance


  • CNES Poseidon-3 Altimeter (C- and Ku-band) measures height above sea surface
  • NASA Advanced Microwave Radiometer (AMR) Three-frequency radiometer measures total water vapor along altimeter path to correct for pulse delay
  • CNES Doppler Orbitography and Radiopositioning Integrated by Satellite (DORIS) Doppler tracking antenna receives ground signals for precise orbit determination, satellite tracking, and ionospheric correction data for CNES altimeter
  • NASA Global Positioning System Payload (GPSP) receiver provides precise orbit ephemeris data
  • NASA Laser Retroreflector Array (LRA) works with ground stations to track satellite and calibrate the other satellite location systems, and verify altimeter measurements

Data Processing

  • Data Processing, archive and distribution by CNES, EUMETSAT and NOAA depending on type of product

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