NASA selected three new uncrewed scientific missions to the moon as part of its Artemis programme. The third mission stands out because it will investigate a subterranean lava tube at the Marius Hills pit on the moon's nearside.
The robot, named GIMLI (Geophysical Instruments for Marius Lunar pit Investigation), is a joint effort between the Planetary Science Institute, NASA, the Norwegian Space Agency and US tech firm Honeybee Robotics, a subsidiary of Blue Origin. Nathaniel Putzig at the Planetary Science Institute leads the project.
Lava tubes form when molten lava flows through a channel. The top cools and hardens into a roof while the lava drains away, leaving hollow cavities behind. The Marius Hills pit appears to be a natural skylight into one of these tubes.
GIMLI will not enter the pit. Instead, it will land nearby and use ground-penetrating radar, seismic sensors and gravitational field measurements to map the subsurface. Its cameras will photograph the pit and its walls.
NASA notes that lava tubes offer "natural, ready-made shelters that provide crucial thermal stability and shielding from deadly ionizing radiation and micrometeoroid bombardment". The moon experiences extreme temperatures, with daytime reaching 120°C and craters dropping to -245°C. Pebble-sized asteroids travel at tens of thousands of kilometres per hour, functioning as hypersonic projectiles. Solar storms can expose astronauts on the surface to fatal radiation doses.
GIMLI will help NASA determine whether lava tubes could shelter astronauts and habitats during future crewed missions to the moon.