ESA GNC Conference Papers Repository

PROTEUS development was initiated by CNES and THALES at the end of 1996. The goal was to design and qualify a versatile small satellite bus, as well as a generic ground segment, able to accommodate various payloads for scientific or application missions. As it is an astronomical mission, COROT must comply with stringent constraints on its pointing accuracy, which are not compatible with the PROTEUS generic AOCS capabilities. In order to satisfy the mission needs, the generic PROTEUS Attitude and Orbit Control System (AOCS) has been customised in order to use the measures of the embarked telescope, in other words to include the payload into the control loop. The authors develop in the paper<br> a) the specificities of COROT AOCS wrt generic PROTEUS AOCS for meeting the very stringent requirements, with a focus on the mission Fine Pointing Mode,<br> b) the performances assessed during design studies through comprehensive analyses and simulation campaigns,<br> c) the COROT launch and in-orbit testing activities with a focus on the AOCS behavior,<br> d) the actual AOCS flight performances in routine, compared to requirements and expectations, and correlated to scientist observations and performances,<br> e) finally, the performance of the NOM PROTEUS Mode analyzed in flight with the ecartometry algorithms (shortterm, long term, thermo-elastic deviation).