Continuous high-latitude solar observation using sailcraft
摘要
The peculiar characteristics of a photonic solar sail–propelled spacecraft (sailcraft) enable the design of scientific mission scenarios that are difficult to achieve with conventional propulsion systems, whether chemical or electric. In this context, a particularly challenging case, feasible only through the use of a high-performance solar sail, is the creation and maintenance of an equilibrium point in heliocentric space. At this point, the sailcraft’s velocity is zero, and the thrust provided by the photonic solar sail balances the Sun’s gravitational attraction. When a sailcraft reaches such a heliostationary point, thus becoming a statite (a term coined by Robert Forward), it can maintain this condition until the sail membrane degrades. This paper analyzes the transfer trajectories and mission performance of a sailcraft targeting a heliostationary point located above the Sun’s poles, at a given distance from the star’s center of mass. Such a statite would enable both continuous observation of the Sun’s poles and high-latitude regions, as well as uninterrupted communication with ground stations without the risk of radio occultation by the solar disk. The study considers a three-dimensional scenario starting from an elliptical parking orbit and accounts for incomplete reflections of the sail’s thin membrane in modeling the thrust vector. In particular, a new mission strategy is proposed in which the sailcraft’s heliocentric trajectory to the target heliostationary point is divided into two optimized phases.