59th International Astronautical Congress 2008 Paper ID: 415 SPACE COMMUNICATIONS AND NAVIGATION SYMPOSIUM (B2) Advanced Technologies (4) Author: Mr. Michael Schiffner OHB System AG-Bremen, Germany, M.Schiff[email protected] Mr. J¨urgenLetschnik Technical University of Munich, Germany, [email protected] Mr. Jan Harder Technical University of Munich, Germany, [email protected] Mr. Matthias Pfeiffer Technical University of Munich, Germany, matthias.pfeiff[email protected] Prof. Ulrich Walter Technical University of Munich, Germany, [email protected] A COMPACT, LIGHT-WEIGHT, HIGH DATA-RATE ANTENNA SYSTEM FOR REMOTE-SENSING ORBITERS AND SPACE EXPLORATION Abstract Upcoming space missions utilizing multispectral or high-resolution SAR sensors will generate a huge amount of data in orbit. On the other hand, the average communication duration between a spacecraft in low Earth orbit (LEO) to a dedicated groundstation is only about seven minutes. The short acquisition time in addition to the high downlink data-rate make a high-performance communication system on board of the satellite indispensable. Similar constraints can be found on space exploring missions like the intended German Lunar Ex- ploration Orbiter mission to the Moon. The experiments on board of this spacecraft generate a data downlink of several TeraBit per orbit. An alternative to this problem for an Earth orbiting spacecraft is to provide longer acquisition times with the ground station which can be achieved by employing an inter-satellite link to a geostationary relay satellite. For satellites on a mission to Moon or Mars the antenna should be just steerable to the ground station. For both cases a flat, compact, steerable, light-weight yet robust antenna is needed. Such an antenna system (antenna plus steering mechanism) for S-Band was developed at the Institute of Astronautics, Technische Universit¨atMunich, in the last years in cooperation with German space companies, research institutes and the German Aerospace Center (DLR). Its successful operation via the European GEO relay satellite Artemis was demonstrated in cooperation with ESA in particular for telepresence activities. This paper describes the evaluation of an antenna system in the Ka-Band, as a successor to be developed in the next two years for high data-rates and the various applications of such an antenna system. It will be shown how this flat, compact, light-weight, high data-rate antenna system can improve space missions due to the extended communication link-time via geostationary relay satellites. 1.