Exomars Radar Doppler Altimeter (A Doppler radar for accurate attitude measurements in support to landing phase)

ExoMars programme, led by the European Space Agency, consists in two missions scheduled in the year 2016 and 2018. Thales Alenia Space Italy (TAS-I) is the Industrial Prime Contractor for both missions. TAS-I is also responsible of the Mission 2016 Entry Descent Landing Demonstrator Module (EDM) designed to demonstrate key technologies for Entry Descent and Landing (EDL) capability. Among these key technologies, TAS-I has specifically designed and manufactured a Ka-band Radar Doppler Altimeter (RDA) that is capable to support during the landing phase the autonomous determination by the EDM of its velocity and altitude with respect to the Mars surface. The RDA is requested to provide range and velocity measurement with a very high accuracy during the landing phase at 20Hz rate. In order to exploit to the maximum extent the capabilities of the RDA and its performance during its development, several verification stage have been planned at different level and on different model stage to provide the full evidence and confidence that instrument is able to operate as expected. The performance verification has been conducted at radar electronic equipment level and at radar system level using dedicated Electrical Ground Support Equipment (EGSE) which included a dedicated MARS environment simulator and outdoor tests to exploit the verification and validation tasks in real environment to cope with the need to investigate measure conditions not fully reproducible by the ground simulation equipment. The present paper aims to describe the key performance parameters and the related design drivers, the overall radar design, its development process up to PFM delivery to EDM, and most of all the tests campaign conducted to show the evidence of the radar full compliance to the measure's performances. Finally an outlook to the possible uses of such a kind of design to other applications is presented.