Control of orientation for spacecraft formations in the vicinity of the Sun-Earth L2 libration point

Formation flying in the vicinity of the libration point is an important concept for space exploration and demands reliable and accurate techniques for the control of a spacecraft. On the basis of previous works, this paper addresses the problem of relative orientation control of spacecraft formation flying utilizing the framework of the circular restricted three-body problem (CR3BP) with the Sun and Earth as the primary gravitational bodies. Two specific tasks are accomplished in this study. First, the tangent targeting method (TTM), an efficient two-level differential correction algorithm, is exploited to control the Chief/Deputy architecture to maintain a prespecified orientation. The time spent within the orientation error corridor between successive maneuvers is maximized while the relative separation between the vehicles is held constant at each target point. The second task is to further optimize the maneuver intervals by dropping the constraint imposed on the relative vehicle separation. Numerical investigation indicates that the number of maneuvers can be significantly reduced and the length of time between successive maneuvers can be greatly increased by utilizing the TTM.