NASA Greenlights Mission to Probe a Mysterious Hole That Could House Future Astronauts

A Hole in the Moon With Big Implications

There is a roughly 65-meter-wide opening on the lunar surface that scientists have stared at from orbit for years, wondering what lies beneath. Now, they are finally going to find out. NASA has selected a Planetary Science Institute–led proposal to investigate whether a potentially large underground cave extends beyond the opening of a lunar pit. The target is the Marius Hills Pit, and the stakes couldn't be higher for the future of human spaceflight.

Such a cave may one day provide a safe haven for astronauts to escape the radiation and extreme temperature swings present at the lunar surface. That tube could one day shelter astronauts from the Moon's brutal radiation, temperature swings exceeding 250°C (482°F) between day and night, and micrometeoroid impacts — providing a natural ready-made habitat that no constructed shield has ever matched. In other words, the Moon may already have built the shelter humanity needs — scientists just have to confirm it exists.

Meet GIMLI: The Mission With a Fitting Name

Led by PSI Associate Director and Senior Scientist Than Putzig, the selected project is the Geophysical Instruments for Marius Lunar pit Investigation, or GIMLI. The name, a nod to the famous fictional dwarf who ventured deep into underground caverns, suits the mission perfectly. GIMLI's research will focus on the Marius Hills Pit, a large hole in one of the Moon's most volcanically diverse regions. For years, orbital observations have suggested that some lunar pits may be skylights created when sections of ancient lava tubes collapsed, exposing openings into underground cavities.

GIMLI will send ground-penetrating radar, seismic equipment, and a gravimeter to Marius Hills Pit — the first intentional seismic survey on the Moon since Apollo 17 in 1972 — to confirm whether a vast underground cave could shelter future astronauts. Putzig himself has long championed a return to this kind of hands-on lunar science. "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," he said, adding that combining the method with ground-penetrating radar and gravity measurements "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."

A Team Built for the Task

Honeybee Robotics, a Blue Origin company, will provide project management services, build instrumentation for the active-source seismic system, gravimeter, and cameras, and integrate all instruments onto the lander and rover. The project will be funded through NASA's Payloads and Research Investigations on the Surface of the Moon (PRISM) program, which sends scientific instruments to the Moon on spacecraft provided by the Commercial Lunar Payload Services (CLPS) initiative providers. The PSI work will also be carried out in partnership with the Norwegian Space Agency.

"Confirming a substantial lava tube would give us an insight into how volcanism operated on the moon," noted Gareth Morgan, a senior scientist at PSI and the program's deputy principal investigator. Measurements and imagery will also help constrain the pit's origin and the region's volcanic history, whether or not a cave is detected. That means even a null result will advance science — a rare and welcome quality in deep-space exploration.

What Discovery Could Mean for Moon Base Planning

GIMLI will scan beneath the surface to determine whether the pit connects to a large void. If confirmed, such a discovery could reshape Moon Base planning by identifying natural locations for long-term habitation. NASA said the payloads are designed to help researchers understand lunar resources, map natural shelters, and assess environmental hazards to support sustained human activities on the Moon.

The simplest ideas are often the most powerful. Rather than engineering elaborate radiation shields and temperature-controlled habitats from scratch, humanity might simply move underground — into tunnels carved by ancient volcanoes billions of years ago. GIMLI won't send astronauts into that darkness, but it will shine the first real light into it. What it finds could determine not just where humans live on the Moon, but whether long-term lunar settlement is feasible at all.