Breakthrough Sun Diving: The Rectilinear Option

Abstract

A near-term possibility for utilization of Breakthrough Initiatives Project Starshot technology is application of the sun diving maneuver as a replacement for laser acceleration of highly miniaturized photon sails to interstellar velocities. This possibility was discussed during the June 2022 Breakthrough Discuss meeting in Santa Cruz California. Here, we consider application of statite-type photon sail probes to achieve rectilinear trajectories to explore outer solar system and near-interstellar destinations. Statite-Type solar photon sails are sufficiently thin and reflective that solar radiation pressure force on the sail exactly balances the solar gravitational force. In such a force-free environment, the spacecraft exits the solar system at its pre-sail-deployment solar-orbital velocity. Here we consider departures from a circular 1 AU solar orbit, the perihelion of a 0.7-1 AU elliptical solar orbit and the perihelion of a 0.3-1 AU solar orbit. Possible outer-solar system destinations of possible interest to Breakthrough Initiatives extraterrestrial-life/artifact -search researchers include Europa, Titan, Enceladus, Methone, and Arrokoth. More distant possible objectives are ‘Oumuamua and the Sun’s inner gravitational focus. To achieve a rectilinear trajectory, the sail must be oriented normal to the Sun and spacecraft areal mass thickness is 1.46 × 10-3 kg/m2. Current sail technology is reviewed to determine whether it can achieve the required areal mass thickness.