SELEX 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 on-board 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 launched on the 22nd of March 1998. ARTEMIS has been launched on the 12th of July 2001. The first SPOT 4 image transmission to Artemis via SILEX has been performed on the 30th of November 2001. The Pointing Acquisition and Tracking subsystem, designed to meet very challenging performances (in the micro radian range) has been validated in real conditions. These in flight measurement results have been correlated with ground measurements performed in the frame of the qualification and acceptance of the SILEX system. This paper describes the verification approach of the terminal and how the ground predictions have been validated by the very successful inflight operations.