You are here



The Ocean Surface Topography Mission (OSTM)/Jason-2 was a follow-on altimetric mission to the very successful TOPEX/Poseidon mission and Jason-1. It was a joint mission between NASA and CNES (French space agency). It launched 20 June 2008 and began data collection on 12 July 2008. OSTM measured significant wave height, sigma naught (sigma0), dry and wet troposphere and ionosphere, which can be used to calculate sea surface height and anomalies and total electron content.

OSTM had a repeat period of approximately 10 days with 254 passes per cycle. Lists of cycle start times, maneuvers performed to maintain orbit, sateholds and periods of no data collection are provided in the "Related Links" sidebar.

After more than 11 years in orbit, the Ocean Surface Topography Mission (OSTM) on Jason-2 permanently ceased acquisition of scientific data at 06:48 UTC on 1 October 2019 due to aging-related issues onboard the spacecraft.  Approximately three hours later, the final pass 147 for science cycle 644 was produced as an OGDR product and disseminated to operational users.  IGDR production ceased about 2.5 days later, GDR production approximately 2 months later. The OGDR, IGDR and GDR data can be found at NOAA.

The operation of the Jason-3 reference mission remains nominal and its continued data production will not be affected in any way.

  • Poseidon-3 – Dual frequency radar altimeter that measures in the Ku (13.575 GHz) and C (5.3 GHz). It measures altimeter range, sigma0, significant wave height and ionospheric correction
  • DORIS – Doppler Orbitography and Radiopositiong by Satellite is a Precise Orbit Determination (POD) system. It receives at the 401.25 MHz and 2036.25 MHz frequencies. It is used for the all weather global tracking and calculates the orbit ephemeris.
  • AMR – Advance Microwave Radiometer measures the 18.7 GHz, 23.8 GHz and 34.0 GHz sea surface microwave brightness temperatures. The 18.7 GHz channel provides the wind induced effects in the sea surface background emissions correction. The 23.8 GHz channel measures water vapor. The 34.0 GHz channel measures the cloud liquid water to be corrected. All together the three frequencies provide the error in the satellite range measurement caused by pulse delay due to water vapor.
  • LRA – Laser Retroreflector Array supports the calibration and validation for the POD.
  • GPSP – GPS Payload receiver. It provides supplementary position data to support the POD function and to improve gravity field models.
  • CARMEN-2 Radiation Detectors – CNES instrument that measures high energy particles that could disrupt the DORIS oscillator and create drifts.
  • LPT – Light Particle Telescope. Provided by JAXA, measures radiation to complement that measured by DORIS.
  • T2L2 – Time Transfer by Laser Link. CNES instrument for precise time transfer used to monitor the clock in DORIS.