On October 5, 2026, NASA selected the Planetary Science Institute-led Geophysical Instruments for Marius Lunar pit Investigation (GIMLI) through its Payloads and Research Investigations on the Surface of the Moon (PRISM) program. GIMLI will examine the Marius Hills Pit, a lunar skylight discovered by Japan’s Kaguya orbiter in 2009, to determine whether it opens into an extensive lava tube or cave. The investigation will combine ground-penetrating radar, seismic sensors, gravity measurements, and cameras.[3][5][7]
A confirmed cave could provide a structurally stable environment shielded from much of the Moon’s surface radiation, extreme temperature swings, and micrometeorite impacts. This could materially improve long-duration habitation and preservation by lowering shielding requirements and environmental-control demands, but cave stability, access, illumination, communications, dust control, internal hazards, and usable volume remain unverified. NASA’s broader 2026 investigations also target lunar ice and hazardous surface conditions, linking cave assessment to a wider permanent-base architecture.[3][8]
The Ark team should track GIMLI’s instrument specifications, deployment date, subsurface maps, cave dimensions, roof thickness, seismic stability, radiation measurements, and access geometry. Establish a cave-site qualification standard covering passive shielding, floodable or sealed compartments, redundant entrances, power and communications, contamination control, and emergency egress; integrate candidate caves into trade studies against polar sites and engineered regolith habitats rather than treating a detected void as an immediately habitable base.[3][5]