NASA has selected a Planetary Science Institute-led proposal to send a suite of geophysical instruments to the Marius Hills Pit on the Moon. The project, named GIMLI, aims to determine if a deep volcanic cave system extends from the lunar sinkhole to serve as a future shelter for astronauts.
GIMLI Mission Targets Marius Hills Pit for Lunar Subsurface Exploration
Space agencies planning long-term lunar habitats are increasingly focusing on natural geological features rather than entirely surface-level construction. As part of that preparation, NASA selected the Geophysical Instruments for Marius Lunar pit Investigation project to probe a prominent lunar skylight on the nearside’s Oceanus Procellarum according to recent space science reporting. The project is funded through NASA’s Payloads and Research Investigations on the Surface of the Moon program, known as PRISM, and its instruments will travel to the lunar surface aboard a lander and rover provided by the Commercial Lunar Payload Services initiative as detailed in mission announcements.
The target of the investigation, the Marius Hills Pit, is a large hole situated in one of the Moon’s most volcanically diverse regions. Discovered in 2009 by Japan’s SELENE spacecraft, the opening measures about 213 feet in width and descends to an estimated depth between 111 and 131 feet. Orbital observations have long suggested that such pits act as skylights opening into extensive underground lava tubes left behind when the Moon was geologically active. GIMLI will allow researchers to investigate the site directly from the lunar surface for the first time.
The project is led by Than Putzig, an associate director and senior scientist at the Planetary Science Institute, who is partnering with commercial partner Honeybee Robotics—a Blue Origin company—alongside the Norwegian Space Agency.
Active-Source Seismology and Radar Instruments Probe the Subsurface
To find out whether a subterranean cavern extends outward from the pit, the GIMLI payload relies on a multi-instrument approach combining ground-penetrating radar, a gravimeter, and cameras to photograph the pit walls and surrounding surface according to program details. Crucially, the mission will reintroduce an investigative technique that has essentially not been done since the Apollo astronauts conducted the first seismic surveys on the Moon.
Honeybee Robotics is responsible for manufacturing a significant portion of the equipment, including the hardware for the active-source seismic system, gravimeter, and cameras. The company will also manage project integration onto the lander and rover while sharing surface operations leadership with the Planetary Science Institute.
The combination of active-source seismology, radar, and gravity measurements is designed to yield a comprehensive picture of subsurface structures. Researchers anticipate the methods will allow them to detect a lava tube extending away from the Marius Hills pit and map its dimensions as outlined by project scientists.
Volcanic History and Safe Havens for Artemis Astronauts
Confirming the presence of a substantial underground void carries major implications for both planetary science and human spaceflight. On the scientific front, identifying an intact lunar lava tube lets researchers draw direct comparisons to terrestrial basaltic volcanism to better understand how the Moon evolved as explained by Gareth Morgan, PSI Senior Scientist and Deputy Principal Investigator. Even if no cave is discovered, surface measurements around the pit will help explain how the geological feature formed by exposing layers of regolith and ancient lava flows that normally remain buried.
For human exploration, subterranean caves represent potential habitats. The lunar surface experiences extreme environmental hazards, including radiation and extreme temperature swings according to space agency data compiled across mission overviews. Stable underground spaces could protect future crews from these extreme conditions.
The GIMLI selection forms part of a broader NASA push to equip upcoming Artemis missions with essential environmental data. The initiative works to pave the way for future astronaut missions while establishing humanity’s first lunar outpost.