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Ocean Surface Topography from Space
Jason-1 - Fact Sheet

There is also a PDF (PDF, 1 MB) version of the Fact Sheet.


  • Extend ocean surface topography into the 21st century
  • Provide a 5-year view of global ocean surface topography
  • Increase understanding of ocean circulation and seasonal changes
  • Improve forecasting of climate events like El Niño
  • Measure global sea-level change
  • Improve open ocean tide models
  • Provide estimates of significant wave height and wind speeds over the ocean


  • Joint NASA-CNES program
  • Launched: December 7, 2001
  • Launch Vehicle: Boeing Delta II 7920; shared with NASA TIMED mission, with Jason-1 separating first
  • Launch Site: Vandenberg AFB, California
  • Operations for 5-year prime mission: JPL
  • Orbit: 1336 km, circular, 66° inclination
  • 10-day repeat of ground track (±1-km accuracy)
  • Covers 95% of ice-free oceans every 10-days


  • Based on Alcatel's Proteus bus
  • Total mass: 500 kg (1102 lbs)
  • Twin solar panels provide 1.0 kW of power
  • Satellite communicates through the Wallops Ground Network Tracking Stations at Poker Flats, Alaska and Wallops Island, Virginia
  • Reaction wheels and magnetic torque rods maintain 3-axis stabilization and nadir-pointing
  • Hydrazine propellant system provides orbital maintenance


  • CNES Poseidon-2 Altimeter (C- and Ku-band) measures height above sea surface
  • NASA Jason Microwave Radiometer (JMR) measures water vapor along altimeter path to correct for pulse delay
  • CNES DORIS Doppler tracking antenna receives ground signals for precise orbit determination, satellite tracking, and ionospheric correction data for CNES altimeter
  • NASA BlackJack Global Positioning System receiver provides precise orbit ephemeris data
  • NASA laser retroreflector array works with ground stations to track satellite and calibrate and verify altimeter measurements.


  • Sea-level measurement accuracy <4.2 cm (1.7 inch) required, <2.5 cm (1.0 inch) goal
  • Data rate: 613 kb/s in S-band
  • Data turn-around 3-hour data product within 1 hour of data reception
  • Global data coverage between 66°N and 66°S latitude
  • Data availability through NASA/JPL and CNES

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