Lunar dust presents a serious challenge to all operations on the Moon, whether human or robotic. It can be especially problematic in applications where it is necessary to make high integrity, gas-tight seals, such as within payloads designed for in situ analysis of lunar ices and volatiles. The challenge has been addressed within the context of the ProSPA instrument being developed for the Luna-27 mission. Soft sealing materials are preferred in order to minimise the required sealing force to enable use of lightweight actuators. JSC-1A simulant was used to test and compare the sealing performance of the elastomer Kalrez® 7075 and of Indium. It was found that both materials were able to seal at dust levels of up to 0.90 mg/cm2 with an applied force of up to 400 N. Indium offers the best sealing performance (better than 10-7 mbar.l.s-1) but Kalrez® is capable of operation at higher temperature, which may be beneficial in applications in which samples are heated to release gases for analysis
