Near-Term Beamed Sail Propulsion Missions: Cosmos-1 and Sun-Diver

Abstract

Next year the Planetary Society plans to launch Cosmos‐1, the first solar sail. We are planning an experiment to irradiate the sail with the Deep Space Network beam from Goldstone. This can demonstrate, for the first time, beamed propulsion of a sail in space. The 450 kW microwave beam from the large 70‐m dish can show direct microwave beam acceleration of the sail by photon pressure, and we can measure that acceleration by on‐board accelerometer telemetry. In addition, we describe a mission scenario called ‘Sun‐Diver’ using a powerful microwave beam on a solar‐driven sail, to both heat and push the sail, accelerating by “boil‐off” of coated materials. Sublimation and desorption work well with the new carbon sail materials which can take very high temperatures (>2000 K), can use promising new materials for mass loss, and promise new classes of missions. These missions make a close pass near the Sun, hence the name, to take advantage of high temperature characteristics of the sail by using the large solar flux at perihelion, yielding high velocities of ∼50 km/s for >40 A.U. missions. Within ∼5 years, the sailcraft flies beyond Pluto, giving high velocity mapping of the outer solar system, the heliopause and interstellar medium.