Several upcoming European and American space missions will be operated using a number of spacecraft flying in formation. The associated scientific challenges are demanding, both with respect to the construction of the spacecraft as well as to the mission design. For instance, energy efficient trajectories and corresponding control laws that enable precision formation flying over long periods of time have to be con- structed. The stabilization of the group on its nominal trajectory has to be made robust with respect to failures of individual spacecraft. Correspondingly, robust and efficient inter-spacecraft communication topologies have to be designed. Finally, in view of visionary missions with hundreds of participating micro- or nano-satellites, geometric configurations have to be found which enable these communication topologies and which scale well with an increasing number of spacecraft. In this contribution we report on our investigations concerning these questions, in particular with respect to the design of energy efficient trajectories and robust communication topologies