COMMUNICATIONS FOR THE ESA GIOTTO (COMET HALLEY ENCOUNTER) MISSION

Abstract

This space mission will investigate the structure of the comet by passing close to the nucleus. The spacecraft will first be injected into a geostationary transfer orbit where a perigee boost motor will deliver the kick necessary to encounter the comet post perihelion, as it passes through the ecliptic plane at a distance of 0.98 AU from the earth. The spinning spacecraft and the use of a shield for protection from the dust present in the comet atmosphere dictate the use of a despun high gain antenna with inclined beam. The telemetry downlink at 40 KBps is in X Band and will be received on the Parkes (Australia) radio telescope which will be specially adapted for the task. The trade offs leading to the selected communications configuration are described along with the various spacecraft hardware items such as antennas, transponder, decoder and twta.