NASA selects GIMLI to probe Marius Hills lunar pit
NASA has selected the Planetary Science Institute-led GIMLI project to investigate whether the Marius Hills pit on the Moon connects to an underground cave or lava tube. The team plans to combine ground-penetrating radar, active-source seismic measurements, gravity measurements and cameras on a Commercial Lunar Payload Services lander and rover. The work could clarify the pit’s formation and the volcanic history of the surrounding terrain whether or not a void is found.
The story
NASA has selected a proposal led by the Planetary Science Institute to examine whether the Marius Hills pit, or MHP, is an opening to a larger underground cave or lava tube. The project is called Geophysical Instruments for Marius Lunar pit Investigation, or GIMLI, and is led by PSI associate director and senior scientist Than Putzig. PSI is partnering with Honeybee Robotics, a Blue Origin company, which will provide project-management services and build much of the instrumentation. The equipment is intended to be carried on a lander and rover provided through NASA’s Commercial Lunar Payload Services initiative. The work also involves the Norwegian Space Agency, which is providing the ground-penetrating radar, alongside researchers from Boise State University, Johns Hopkins University, the Lunar and Planetary Institute and the University of Oslo. At MHP, GIMLI will use ground-penetrating radar, an active-source seismic system, a gravimeter and cameras. Radar, seismic and gravity measurements are intended to look below the surface for a void extending away from the pit and, if one is present, help estimate its size. Cameras will document the surface and pit walls. The team will also study exposed layers of regolith and lava flows around the pit to investigate local volcanic processes and the origin of MHP.
Why it matters
Orbital observations have offered evidence that lunar caves and lava tubes may exist, but they cannot provide the direct subsurface measurements proposed for GIMLI. Testing MHP from the surface could help determine whether the pit is linked to a void or reflects another geological process. A confirmed lava tube would provide a clearer comparison with basaltic volcanic caves on Earth, which PSI researcher Gareth Morgan said could help scientists interpret how volcanism operated on the Moon. The results could also identify geological questions for later lunar exploration, while the project itself remains focused on measurement rather than habitat development.
Evidence and context
Marius Hills is described in the supplied report as one of the Moon’s most volcanically diverse regions. Its pit walls expose layers of regolith and lava flows that would otherwise remain underground, giving investigators an opportunity to study the sequence of material deposited there. The report says the broader area has a long volcanic history and that examining the exposed layers may help reveal how lava moved across the Moon and whether eruptions were separated by long intervals. Lava tubes are common in basaltic volcanism on Earth, according to Morgan. That terrestrial comparison is useful but does not establish that MHP contains a tube: the purpose of GIMLI’s combined radar, seismic and gravity observations is to test the lunar case directly. The investigation also revives intentional active-source seismic work on the Moon, which Putzig said has largely not been used since Apollo astronauts conducted early lunar seismic surveys.
Limits and unknowns
The key uncertainty is still whether Marius Hills pit actually connects to a cave or lava tube. The report characterizes orbital observations as compelling evidence for possible underground spaces, not direct confirmation of one at this site. NASA’s selection is also not a completed lunar deployment: the supplied account gives no launch date, landing date, mission duration or expected date for results. The report does not provide a predicted cave size, and the instruments can only estimate one if their measurements identify a subsurface void. A non-detection would still leave the team using the data to investigate how the pit formed and to characterize nearby geology.
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NASA selects GIMLI to probe Marius Hills lunar pit
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Highlights
- A new look at Marius Hills pit
- Three ways to measure below the surface
- Volcanic layers in the pit walls
- Earth’s lava tubes offer a comparison
Transcript
NASA has picked a new investigation to look beneath the Moon’s Marius Hills pit.
Planetary Science Institute’s GIMLI team plans radar, seismic and gravity measurements from a lander and rover.
The pit’s walls expose layers of lunar soil and lava flows from earlier eruptions.
Scientists could compare any confirmed lunar tube with Earth’s basalt caves to study Moon volcanism.
No landing date was provided; whether the pit connects to a cave remains untested.