boundary="_000_25CDFAC1A563514A82FC2E7BD9609F2F91A4F463TWMBXP03cnesnet_" ****************************************************************************** dorismail 29-Jun-2016 11:11:51 Message No 1027 ****************************************************************************** Author: Ferrage Pascale Subject: SARAL orbit change / new mission phase starts on July 4h 2016 - Dear IDS users, Please note that SARAL/AltiKa will enter in a new phase named "SARAL-DP".= The orbit altitude will increase by + 1km (from nominal reference altitude= of 800 km) in order to continue the mission based on a drifting orbit. The manoeuver is scheduled on Monday 4 July. Then there will be no more man= oeuver (except debris avoidance manoeuver when necessary). There will be no impact on the DORIS data dissemination to IDS Data Centers. Best regards Pascale Ferrage More information below.... _______________________________________________________________________ From: Guinle Thierry [mailto:Thierry.Guinle@cnes.fr] Wednesday 29th June 2016 Objet : [SARAL] : A new mission phase starts on July 4h 2016 - SARAL-DP Dear OSTST, dear SARAL users, We are pleased to inform you that SARAL/AltiKa mission will enter in a new = phase named "SARAL-DP". Indeed, from July 4th onwards, SARAL satellite will= fly free of station keeping maneuvers; the repetitive ground track will be= no more maintained and with the natural decay of the orbit, the ground tra= ck will drift. "SARAL-DP" stands for SARAL Drifting Phase. This decision - endorsed by CNES and ISRO management - is due to the techni= cal issues we have encountered on the reaction wheels since March 2015 and = was proposed considering 2 key drivers: * fine station keeping maneuvers with thrusters only is very difficul= t to achieve, * there are new science perspectives emerging with drifting orbits on= mean sea surface (MSS), geodesy/ bathymetry and other applications. and implements two recommendations made by the Science Team in 2015 OSTST m= eeting which are recalled hereafter : * RECOMMEND the not-maintained (drifting) orbit for MSS/Gravity/Bathy= metry. * RECOMMEND this phase to start as soon as possible (awaiting 3 years= project meeting in early 2016) Altimetry payload will be operated nominally on the drifting orbit; data pr= ocessing is unchanged as well as data latency. Even no more linked to the g= round track, we keep a "cycle" duration of 35 days with 1002 passes (sub cy= cle ~ 16 days); cycle number will jump to #100 and OGDR, IGDR and GDR produ= cts will be produced as before. Please note also that a semi-major axis inc= rease (+1 km) will be performed just before to start the new phase. This ma= neuver will optimize the sampling for mesoscale applications for the next 2= years. CNES and ISRO share the common objective to continue the SARAL mission as l= ong as possible both for altimetry and ARGOS and we hope that the drifting = phase will be as successful as the first 3 years on the repetitive orbit. O= f course you will be informed on the progress of operational activities. Best Regards and long life to SARAL, T. Guinle, J. Verron, P. Bonnefond, S. Arunan