NASA has selected a Planetary Science Institute-led project, GIMLI, to investigate the Marius Hills Pit on the Moon. The mission aims to determine if the lunar hole serves as an entrance to a subsurface lava tube, potentially providing a radiation-shielded habitat for future astronauts as part of the Artemis program.
GIMLI Mission Objectives at Marius Hills Pit
The Geophysical Instruments for Marius Lunar pit Investigation (GIMLI) project is set to explore the Marius Hills Pit (MHP), a large skylight located on the Moon. First identified by Japan’s Kaguya spacecraft in 2009 and later studied by NASA’s Lunar Reconnaissance Orbiter, the pit measures approximately 34 meters deep and spans roughly 65 by 90 meters. While orbiters have confirmed the pit’s existence, scientists currently lack the data to verify if it connects to an extensive underground lava tube system.
The mission, funded through NASA’s Payloads and Research Investigations on the Surface of the Moon (PRISM) program, will utilize a lander and rover provided by the Commercial Lunar Payloads Services (CLPS) initiative. The project team is led by Than Putzig, an associate director and senior scientist at the Planetary Science Institute (PSI), with Honeybee Robotics serving as a commercial partner for instrument development and project management.
GIMLI Uses Sensors to Probe the Lunar Surface
To probe beneath the lunar surface, GIMLI will deploy a multi-sensor suite designed to gather data on subsurface properties. The team plans to combine ground-penetrating radar, a gravimeter, and seismic sensors. The mission will reintroduce active-source seismic methods, a technique not utilized on the Moon since the Apollo era.
“It’s long been a desire of mine to reintroduce intentional active-source seismic methods to planetary science, as it has essentially not been done since the Apollo astronauts conducted the first seismic surveys on the Moon. Combining that method with ground-penetrating radar and gravity measurements makes it all the more exciting, as these methods together will allow us to get a much better understanding of subsurface properties, including the anticipated detection of a lava tube extending away from the Marius Hills pit.”
Than Putzig, PSI Associate Director and Senior Scientist
In addition to these sensors, the rover will carry cameras to capture imagery of the surface and the exposed walls of the pit. The Norwegian Space Agency is also contributing to the effort.
Potential for Lunar Habitats and Geological History
The search for lava tubes is driven by the need for stable environments on the lunar surface. Astronauts currently face extreme conditions, including temperature swings from approximately 127°C during the day to minus 173°C at night, as well as constant exposure to solar radiation and micrometeorites. NASA research indicates that the interior of lunar pits may maintain more stable temperatures, roughly 17°C, potentially offering natural, structurally sound shelter for future long-term outposts.
Even if GIMLI does not locate an extended lava tube, the mission aims to clarify how the Marius Hills Pit formed. By examining the regolith and lava flow layers exposed in the pit walls, scientists hope to gain insights into the Moon’s ancient volcanic activity. PSI Director and CEO Amanda Hendrix emphasized the project's scope.
“GIMLI represents the type of ambitious planetary science that PSI was built to pursue. Than and his team are taking a scientific question we’ve been studying from orbit and have developed a way to investigate it directly on the Moon. We’re excited to have PSI leading this effort and to be partnering with NASA and Honeybee Robotics to learn more about the Moon and its volcanic past.”
Amanda Hendrix, PSI Director and CEO
Confirming a substantial lava tube would allow researchers to compare lunar basaltic volcanism with similar terrestrial formations, providing a clearer record of the thermal and geological processes that shaped the Moon. The data gathered by the GIMLI mission will directly support the Artemis program’s stated goal of establishing a sustained presence on the lunar surface.
