ANALYSIS OF A SOLAR SAIL MERCURY SAMPLE RETURN MISSION

摘要

A conventional Mercury sample return mission requires significant launch mass, due to the large Av required for the outbound and return trips, and the large mass of a planetary lander and ascent vehicle. Solar sailing can be used to reduce lander mass allocation by delivering the lander to a low, thermally safe orbit close to the 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 solar sail with an 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 1 year. The total mission launch mass is 2353 kg, on an H2A202-4S class launch vehicle (C_3=0), with a ROM mission cost of 850 M?. Nominal launch is 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.