In-orbit repositioning of multiple solar sail spacecraft

Future heliospheric missions will require the Sun to be observed from suitable vantage points and will use multiple spacecraft for guaranteeing a three-dimensional imaging of the entire solar surface. The aim of this paper is to study the repositioning problem of two solar sails whose location must be suitably separated (one ahead of the Earth and one behind it) and placed at the chosen observation points in a given mission time. The use of solar sails for such a maneuver is especially attractive because the sailcraft thrust is obtained from solar photons without using any propellant. In particular, solar sails offer the feasibility of performing rest-to-rest maneuvers, thus giving the opportunity to maintain a fixed value of the azimuthal observation angle to perform long mapping campaigns. The minimum time reorientation maneuver is thoroughly investigated to correlate the maximum value of the separation angle between sailcraft in a given mission time with the technological level required to fulfil the reorientation maneuver.