Jason 1

spacer spacer spacer spacer  
spacer News and Announcements spacer  DATA Links  
spacer

Jason-1 is a follow-on altimetric mission to the very successful TOPEX/Poseidon mission. It is a joint mission between NASA and CNES (French space agency). It launched December 7, 2001 and began data collection at January 15, 2002. Jason-1 is capable of measuring significant wave height, sigma0, dry and wet troposphere and ionosphere, which can be used to calculate sea surface height and anomalies and total electron content.

Jason-1 has a repeat period of approximately 10 days with 254 passes per cycle. A list of cycle start times can be found here.

Sometimes there maybe anomalous or missing data. Occasionally Jason-1 must perform maneuvers to maintain orbit. This may cause anomalous values so a list of maneuvers is available here. When the satellite detects something abnormal it will go into safehold and will turn off all instruments and no data will be collected. A list of safeholds and periods of no data collection can be found here.

 spacer spacer spacer  
  Orbits and Auxilary Day    
  Semi-major axis 7,714.43 km  
spacer Eccentricity 0.000095  
spacer Inclination 66.04°  
spacer Argument of periapsis 90.0°  
spacer Inertial longitude of the ascending node 116.56°  
spacer Mean anomaly 253.13°  
spacer Reference altitude 1,336 km  
spacer Nodal period 6,745.72 sec  
spacer Repeat period 9.9156 days  
spacer Number of revolutions within a cycle 127  
spacer Number of passes within a cycle 254  
spacer Equatorial cross track separation 315 km  
spacer  
spacer Interleaved Mission  
spacer Ground track control band +1 km  
spacer spacer Acute angle at Equator crossings 39.5°  
spacer

After the launch of OSTM/Jason-2 and several successful months of data collection Jason-1 was moved to a new interleaved orbit in relation to OSTM. Originally they were in tandem. Jason-1 began maneuvering to the new orbit January 26, 2009 (cycle 260) and the altimeter was placed in standby, i.e. no altimeter data collection. Feburary 10, 2009 the altimeter was turned back on, but Jason-1 was still maneuvering to the new orbit. The maneuver was completed February 14, 2009 and cycle 263 was the first complete cycle for the new orbit.

  
spacer Longitude of Equator crossing of pass 1,
cycles 1-365		 99.9249°  
spacer Longitude of Equator crossing of pass 1,
cycles 369-onward		 98.5°  
spacer Inertial nodal rate -2.08°/day  
spacer  
spacer Instruments spacer Orbital speed 7.2 km/s  
spacer Ground track speed 5.8 km/s  
spacer  
spacer
Poseidon-2 – 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.

JMR – Jason-1 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.

TRSR – Turbo Rogue Space Receiver is a type of GPS receiver. It provides supplementary position data to support the POD function and to improve gravity field models. However the TRSR has degraded in performance since April 2009. There is no major impact to the mission, but be aware of this if you are expressly using the GPS data from Jason-1.

 spacer  
spacer spacer  
spacer Additional information about instruments, orbit or other properties of Jason-1 can be found in the Handbook.  
spacer  
spacer Links  
spacer  
spacer - Cycle list
- Maneuver list
- Safe hold list
- Jason-1 handbook
- Ocean Surface Topography from Space
- JPL's Global Climate Change Site
- Jason-1 Mission
- NASA's Ocean Motion Site
- AVISO (French Data Archive)		 spacer  
spacer  
spacer Citations/References  
spacer spacer