Ka-band altimeter for future AltiKa oceanography missions
Nathalie Steunou(1) , Pierre SENGENES(1) , Eric THOUVENOT(1) , and Laurent REY(2)
18 avenue Edouard Belin,
31401 Toulouse CEDEX 9,
(2) ALCATEL ALENIA SPACE, 26 avenue Champollion, 31037 Toulouse CEDEX1, France
In partnership with scientific laboratories and industry, and for several years, CNES has studied the feasibility of a high-resolution ocean topography mission named AltiKa, based upon a new class of wide-band Ka-band altimeter in preparation of the post-ENVISAT mission and in order to complement the OSTM/Jason-2 mission. The central objective is the retrieval of the ocean mesocale circulation and data assimilation in global or regional ocean models. Moreover, other applications of the mission have been identified: coastal altimetry, continental water studies, ice sheet monitoring, low-rain systems characterization are the main “secondary” objectives identified so far.
The proposed architecture for the Ka-band altimeter is based on the classical deramp technique for pulse compression and takes benefits of Alcatel and CNES experience from the realisations of Poseidon1, 2 & 3 and SIRAL (Cryosat mission). A bi-frequency radiometer is part of the compact Ka-band payload. Both altimeter and radiometer share the same antenna.
Apart from the combined altimeter and radiometer, the AltiKa payload also consists of a DORIS plus LRA (Laser Retroreflector Array) orbitography system that will ensure a high level of accuracy in terms of orbitography.
A preliminary definition study of a coupled altimeter-radiometer instrument has been performed in 2001-2003 with the support of Alcatel Space. At the present time, a delta phase B is being conducted, with an expected phase C/D at the beginning of 2006. Indeed, AltiKa payload could be embarked in the frame of a cooperation with ISRO (Indian Space Research Organisation) with an expected launch in 2009.