Natural Configurations and Controlled Motions Suitable for Formation Flying G. Gomez, M. Marcote, J.J. Masdemont and J.M. Mondelo Abstract. Assume that a constellation of satellites is required to flight close a given nominal trajectory and that there is some freedom in the selection of the geometry of the constellation. If we are interested in avoiding large variations of the mutual distances between the spacecrafts, we can consider the possible existence of regions of zero relative radial acceleration with respect to the nominal trajectory. The motion along these regions will prevent from the expansion or contraction of the constellation. The goal of this paper is the study of these regions and the controlled motions between them.