SILEX Pointing Acquisition and Tracking : ground tests and flight performances

摘要

SILEX (Semi Conductor Inter Satellite Link Experiment) consists of one optical terminal on-board the French LEO observation satellite SPOT 4, and another onboard the European GEO telecommunication satellite ARTEMIS. The mission is to establish optical communications flight performances and to transmit Earth observation data from SPOT 4 to ARTEMIS, which will relay them to ground via Ka band. SPOT 4 has been successfully launched on the 22nd of March 1998. The Pointing Acquisition and Tracking subsystem, designed to meet very challenging performances (in the micro radian range), has been thoroughly tested on ground before launch and in flight for more than one year. Before the ARTEMIS terminal is in orbit, calibrations and star tracking have allowed measuring pointing, acquisition and tracking performances as well as dynamical interactions with the host spacecraft. These in flight measurement results have been correlated with ground measurements performed in the frame of the qualification and acceptance of the terminal. CCD detectors calibrations, acquisition and tracking performances, point ahead performances have been validated and demonstrate the performances in anticipation of the link establishment.