DORIS role in the next years P Escudier

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DORIS role in the next years P. Escudier CNES DORIS Days May 2 -3,

DORIS role in the next years P. Escudier CNES DORIS Days May 2 -3, 2000

Next years evolution êPrediction : l theoretical exercise l limited to tendencies êmain parameters

Next years evolution êPrediction : l theoretical exercise l limited to tendencies êmain parameters : l today situation l extrapolation of tendencies observed over the last years l anticipation of breakthrough êexercise to be conducted on : l user needs l DORIS technical aspects l external environment DORIS Days May 2 -3, 2000

DORIS present situation : Applications êUnique Precise Orbit Determination technique l More than 10

DORIS present situation : Applications êUnique Precise Orbit Determination technique l More than 10 years of operations l operationality, robustness l accuracy l only technique able to provide real time on board decimetric accuracy orbit êImportant station positioning technique l first technique having provided Antarctica and Africa tectonic plate precise motion measurements l accurate vertical motion measurement l complementary from other techniques : cross calibration l uplink system : system provides transmission of measurements to distant users DORIS Days May 2 -3, 2000

DORIS present situation : programmatics êDORIS on board SPOT 2, SPOT 4 and TOPEX/POSEIDON

DORIS present situation : programmatics êDORIS on board SPOT 2, SPOT 4 and TOPEX/POSEIDON to be operated till end of each satellite lifetime êJason 1, ENVISAT and SPOT 5 will be launched within the next 18 months Significant increase of the number of in flight receivers êDORIS Pilot Experiment to begin Frame for efficient interactions between the various DORIS partners : l l host agencies (stations) l DORIS Days May 2 -3, 2000 data users project team

DORIS present situation : technical aspects êOn board equipment new generation l dual channel

DORIS present situation : technical aspects êOn board equipment new generation l dual channel : ability to track simultaneously 2 beacons l phase measurement : u precise synchronization of dual channel measurements : relative positioning improvement u precise synchronization of 2 GHZ & 400 MHz channels : ionospheric correction improvement l error budget improvement êStation network will be renewed with 3 rd generation beacons : l shifted frequencies : u denser u ability u new network to have a more open management of the network : IDS group applications : precise time tagging DORIS Days May 2 -3, 2000

Anticipated evolutions : POD applications ê Precise Orbit Determination for altimetry missions : l

Anticipated evolutions : POD applications ê Precise Orbit Determination for altimetry missions : l long term commitment, decisions to be taken Jason 2, post ENVISAT, ALTIKA, … l need for continuous performance improvements u l accuracy, quasi real time products new mission for ice altimetry : CRYOSAT (ESA) ê Precise on board orbit determination : l exact need to be further analyzed considering DORIS performances : u radar interferometry, high resolution imagery u navigation system (GALILEO) u . . . ê Gravity missions : l DORIS will benefit from these missions but not presently included in there definition DORIS Days May 2 -3, 2000

Anticipated evolutions : Precise Positionning applications êTerrestrial reference system definition will continue to require

Anticipated evolutions : Precise Positionning applications êTerrestrial reference system definition will continue to require multiple technique for cross calibration l need for continuous performances improvement considering u other techniques evolution u accuracy demand êvertical motion measurement is a developing need : l in situ sea level monitoring complementary to satellite altimetry, u needs for measurements using the same reference êdenser network will open new application DORIS Days May 2 -3, 2000

Evolution : programmatics êFuture decisions anticipated within the next years : l DORIS/CRYOSAT l

Evolution : programmatics êFuture decisions anticipated within the next years : l DORIS/CRYOSAT l Jason 2 l PLEIADES (SPOT follow on) l other programs still at very preliminary stage : u cooperation with NASDA u NPOESS l … to be discussed IDS may be a frame for new proposals to be submitted to the different Space Agencies DORIS Days May 2 -3, 2000

Evolution : technical aspects 1 instrumentation êBeyond already decided evolutions, R & T actions

Evolution : technical aspects 1 instrumentation êBeyond already decided evolutions, R & T actions are going on : u mass, power reduction to make accommodation easier and increase the number of in flight receivers u on board processor change u performances u instruments improvements : ie USOs adapted to high altitude orbits (MEO) Considering the time to develop a new spacecraft, those changes will affect the users in the mid term and not in the short term êImportant activity to be conducted in the next years l network survey for stations monument stability improvement DORIS Days May 2 -3, 2000

Evolution : technical aspects 2 Processing ê Analysis of past years situation shows that

Evolution : technical aspects 2 Processing ê Analysis of past years situation shows that the basis for system performances evolution is data processing improvement l T/P Orbit precision accuracy as improved from 10 to 2 cm within 8 years using the same instrument system ê Further improvements still possible l modeling algorithms and estimation strategy tuning l taking advantages of technical evolution l u measurement accuracy improvement u phase measurement u dual channel measurements taking advantage of simultaneous multiple receivers u this is probably the major breakthrough l taking advantage of multiple technique combination l taking advantage of external improvements u gravity missions for more accurate and time varying earth gravity field DORIS Days May 2 -3, 2000

DORIS EVOLUTION Main tendancies (to be discussed) êDORIS role in POD and precise positioning

DORIS EVOLUTION Main tendancies (to be discussed) êDORIS role in POD and precise positioning should continue and develop in the next years êStrong need for continuous performance improvements l elements in place to support this effort : u increase u new l of the number of in-flight receivers generation of stations and on board receivers will basically rely on efforts made by data users u to benefit from the system evolution – number of receivers, instrumentations changes u to benefit from external improvements (ie gravity field missions) u to develop new strategies for improving POD or positioning accuracy IDS will play a key role to facilitate this process DORIS Days May 2 -3, 2000