PROTEUS/JASON1 AOCS FLIGHT RESULTS

摘要

In collaboration with the French National Agency CNES, ALCATEL SPACE has developed PROTEUS (Plate-forme Reconfigurable pour l'Observation, les Telecommunications, et les Usages Scientifiques), a multipurpose LEO platform in the range 500 kg. JASON 1 satellite which is a CNES/NASA-JPL oceanographic mission, is the first PROTEUS application and also the follow-on of the TOPEX-POSEIDON mission. It was successfully launched on December the 7th, 2001 from Vandenberg, California. The PROTEUS Attitude and Orbit Control System has been designed to comply with : 1. inertial, Solar pointing, 2. Earth, Anti-Earth and Nadir pointing. The main selected attitude sensor is a Star Tracker. Associated to a gyro package, it provides the best onboard attitude knowledge for such various missions. A four wheel skewed configuration to avoid zero wheel speed crossing completes the routine mode equipment units, wheel unloading achieved through Magneto-Torquer Bars. Safe Hold Mode is completely autonomous; it does not require any operational conditions. It uses sensors and actuators roughly different from Normal Operating Mode. That makes it, along with the fact that propulsion is not implemented, robust and reliable. Therefore, only low authority units like magnetic torquer bars, magnetometers and coarse sun sensors drive the satellite to the safe attitude. JASON-1, the first PROTEUS application mission, based on this innovative AOCS, appears well on track. The spacecraft, the ground segment and the overall system behave properly and their performance requirements are all met. Regarding the PROTEUS platform, one can praise the robustness and adequacy of its design. As far as the AOCS subsystem is concerned, each functional mode has been reached successfully from Safe Hold Mode to Star Acquisition Mode, then to Normal Operating Mode including Orbit Correction Mode with 2 or 4 Thrusters. All AOCS algorithms are working as expected since the JASON-1's launch. Moreover, all AOCS equipment units have satisfactory in-flight expected performances.