SMALL LASER TERMINAL FOR OPERATIONAL INTERSATELLITE LINKS

Applications for line-of-sight communications links between spacecraft include data relay from LEO spacecraft, telecommunications between sa tellites in GSO or LEO orbits, secure communications in military satel lite constellations, and links to manned spacecraft. Optical technolog y will be the preferred choice for many such applications due to poten tial advantages of small antenna (telescope) size and low mass and pow er. MMS has been leading the development of the technologies needed fo r such terminals under the ESA funded SILEX(1) programme and two fligh t models are now under integration. In parallel, a second generation t erminal known as the Small Optical User Terminal (SOUT) has been devel oped to elegant breadboard level under ESA funding. The advantages of low mass and power can now be realised due to recent advances in semi- conductor laser technology. MMS has combined its experience in SILEX a nd SOUT to produce a concept for a small terminal which will be attrac tive to users in the near-term. This retains essential features of the SOUT such as the softmount interface, combined acquisition and tracki ng sensor, and fibre coupled lasers. It also minimizes cost by re-usin g SILEX derived electronics and other space qualified elements. The te rminal has a 7 cm diameter telescope, a mass below 50 kg, and will pro vide a 50 Mbps data link with SILEX. The main features of the terminal are presented in this paper together with the chief applications whic h are envisaged.