A control device (D) for a spacecraft of a group of spacecraft intended to travel in a chosen formation comprises i) a set of at least three send/receive antennas (A1-A3) installed on at least three differently oriented faces of its spacecraft and adapted to send/receive radio-frequency signals, ii) first measuring means (M1) responsible for determining the power of the signals received by each of the antennas (A1-A3) and for delivering sets of powers each associated with one of the other spacecraft of the group, iii) storage means (BD) responsible for storing sets of cartographic data each representative of the normalized powers of the signals received by each of the antennas (A1-A3) as a function of chosen send directions, and iv) processor means (MT) responsible for comparing each set of powers delivered by the first measuring means (M1) to the stored sets of cartographic data in order to estimate each send direction of the signals sent by the other spacecraft of the group with respect to a system of axes fixed with respect to their spacecraft.