In the upcoming years, significant changes in the profile of satellite missions are expected as scientists and managers want to benefit from multi-satellite missions. Among others, distributed or virtual satellite platforms will create a completely new class of space missions, where not one single spacecraft or payload segment has to be operated but a formation or constellation of satellites. A “formation” designates multiple satellites in close proximity and is typically characterized by demanding guidance, navigation and control requirements. In comparison to perform these tasks by a ground control approach, on-board autonomy can guarantee superior performance with respect to control accuracies and cost efficiency. A dedicated research and development program on “Autonomous Spacecraft Navigation and Formation Flying” was initiated at DLR/GSOC in 1998. Numerous contributions in the area of space-borne GPS receiver technology, precision relative navigation and autonomous orbit control of satellite formations as a prerequisite for spacecraft autonomy have been made. Practical experience in the operations of a two-satellite formation has been gained by the GRACE mission. Next, GSOC is supporting Swedish Space Cooperation (SSC) in the implementation of the PRISMA formation flying demonstration mission, where a fully autonomous, robust and precise formation flying of spacecraft will be conducted by experiment. Finally, the German TerraSAR-X/TanDEM-X radar satellites will be Europe’s first space mission equipped and operated routinely with an autonomous formation flying system.