Protection of lunar structures from micrometeoroid strikes: Behaviour of panels derived from lunar regolith simulant

This paper reports the details and results of an experimental investigation on the impact performance of panel systems that may be used to protect lunar structures from micrometeoroid strikes. The panels investigated were Whipple shields, stuffed Whipple shields and multi-shock shields, formed from aluminium, basalt fibre-reinforced polymer (FRP), and silica FRP plates. The panels also contained a new material (i.e. regolith-resin-composite (RRC)) as derived from a lunar regolith simulant in combination with epoxy resin. The goals of the study were (i) investigate the viability of utilising regolith simulant in panel construction incorporating RRC plates and regolith infill, (ii) minimising internal damage and debris contamination of panels due to projectile impact, and (iii) non-perforation of the panel rear wall. The test panels were designed to withstand the impact energy (2200 J) of a representative 2 mm diameter micrometeoroid with a density of 0.2 g/cm 3 travelling at 72 km/s. This translated to testing in a single-stage gas gun with a 12 mm diameter steel projectile travelling up to 790 m/s. The preferred configurations for the stuffed Whipple shield and multi-shock shields arising from the test results were, respectively (i) aluminium outer layers, a central inner layer of silica and basalt (FRP), as well as regolith infill, and (ii) four layers of silica FRP, an inner layer of basalt FRP and regolith infill. The study has produced a detailed dataset on panel behaviour derived from physical observations and high-speed camera images. The results can serve as important information for in-situ lunar resource utilisation as well as future experimental testing and numerical modelling.