Dynamical performance for science-mode stationkeeping with an external occulter

An external occulter flown in precise formation with a telescope is being considered for high-contrast direct imaging of exoplanets as a viable mission scenario. In this paper, the dynamics about the Sun-Earth L2 region for an occulter-telescope constellation are considered in conjunction with fourth-body and solar radiation pressure acting as disturbing forces. An optimal observation window is defined in terms of both thrust required and the Sun-constellation geometry. By simulation, the effects of the stellar latitude and distance, the spacecraft separation, the magnitude of the disturbing forces, and on-off versus continuous thrusting are quantified on the thrusting profile needed to maintain precise alignment.