ESA Science & Technology - Sample return from Mercury and other Terrestrial Planets using Solar Sail Propulsion

Publication date: 02 June 2006

Authors: Hughes, G.W., et al.

Journal: Journal of Spacecraft and Rockets
Year: 2006

A conventional Mercury sample return mission requires significant outbound and return trips, and the large mass of a planetary lander and ascent vehicle. In this paper, it is shown that solar sailing can be used to reduce lander mass allocation by delivering the lander to a low, thermally safe orbit close to the planetary terminator. In addition, the ascending node of the solar sail parking orbit plane can be artificially forced to avoid out-of-plane manoeuvres during ascent from the planetary surface. Propellant mass is not an issue for solar sails, so a sample can be returned relatively easily, without resorting to lengthy, multiple gravity assists. A 275 m square solar sail with a sail assembly loading of 5.9 g m-2 is used to deliver a lander, cruise stage and science payload to a forced Sun-synchronous orbit at Mercury in 2.85 years. The lander acquires samples, and conducts limited surface exploration. An ascent vehicle delivers a small cold gas rendezvous vehicle containing the samples for transfer to the solar sail. The solar sail then spirals back to Earth in one year. The total mission launch mass is 2353 kg, on an H2A202-4S class launch vehicle (C3=0). Extensive launch date scans have revealed an optimal launch date in April 2014 with sample return to Earth 4.4 years later. Solar sailing reduces launch mass by 60% and trip time by 40%, relative to conventional mission concepts. In comparison, mission analysis has demonstrated that solar sail Mars and Venus sample return appears to have only modest benefit in terms of reduced launch mass, at the expense of longer mission durations than conventional propulsion systems.