Concept of formation flyer for the ASPICS solar coronagraphic mission

This paper describes a concept of a formation flyer for ASPICS (Association de Satellites Pour l'Imagerie et la Coronagraphie Solaire), a giant 100 m based, externally occulted coronagraph aimed at observing the inner corona (and the solar disk) in the visible and ultra-violet. The two-satellite formation approach, based on existing space systems, is composed of a Myriade micro-satellite supporting the occulter and a Proteus platform as the main system carrying the coronagraph and imager scientific instruments. Both spacecrafts are launched as a single composite and deployed once on orbit, preferably a 3-day orbit or at the L1 Lagrange point. The coronagraph satellite acts as the "master" and provides the main functions of the mission (data handling, communication, propulsion, Guidance Navigation and control) while the Myriade acts as the "slave". The control of the formation is performed in two steps: i) RF metrology for deployment and preliminary pointing, ii) classical optical attitude sensors and metrology based on diverging laser beams. This will insure the nominal requirement of a lateral positioning with an accuracy of 1 mm and a longitudinal positioning with an accuracy of 500 mm