Category: News of the other missions
The Jason-1 satellite will be moved to a new ground track on January 26, 2009 after the end of repeat cycle 259, after more than 7 years of service on the nominal ground track. The OSTM/Jason-2 satellite will continue the long term climate data record
on the primary Topex/Jason-1/OSTM/Jason-2 ground track. Several maneuvers will be performed beginning on January 26, 2009, with the interleaved orbit achieved by February 9, 2009.

The Jason-1 satellite will be moved to the same interleaved orbit that was
used by Topex from 2002-2005 but with a time lag of approximately 5 days with Jason-2. In other words, the start time of the Jason-1 and Jason-2 repeat cycles will differ by approximately 5 days. This new tandem configuration better suits for real-time applications.

<link fileadmin images news mod_actus j1_new_orbit_gmt_pass1_127.png download>	<link fileadmin images news mod_actus j2_j1_interlaced_gmt_zoom_uk.png download>
After February 2009 (cycle 262), ground track coverage for interleaved Jason-1 (green) and OSTM/Jason-2 (red) with a 5-days time lag. When Jason-1 begins a new repeat cycle (n) with the pass 1, OSTM/Jason-2 begins the pass 127 of the same repeat cycle (n).

The first Jason-1 repeat cycle on the new interleaved ground track will be numbered repeat cycle 262. After achieving the new ground track there may be some delay in the availability of the Precise Orbit Ephemeris (POE) for Jason-1, which as a result will delay GDR availability. This is due to the required tuning of the POE orbit determination strategy and models. (e.g. Doris USO correction model).

Further information:

• Duacs updates: <link internal-link>Duacs switches from Jason-1 to Jason-2 as a reference mission.
• Nasa/JPL website: <link http: sealevel.jpl.nasa.gov newsroom features _blank external-link-new-window>Tandem Mission Brings Ocean Currents Into Sharper Focus February 2000