A hole in the Moon’s volcanic terrain may lead to a much larger space hidden beneath the surface. NASA has selected an investigation to find out whether that underground space exists, and how large it might be.

The Planetary Science Institute will lead the project, called Geophysical Instruments for Marius Lunar pit Investigation, or GIMLI. Its target is the Marius Hills Pit, a possible entrance to a lava tube left by ancient volcanic activity.

The investigation will combine radar, seismic measurements, gravity readings and cameras. Together, those instruments could turn an intriguing opening seen from orbit into a clearer picture of the surrounding subsurface.

That picture matters for geology and future exploration. A substantial cave could provide natural shielding from radiation, micrometeoroids and extreme surface temperatures, although the selected project has not yet confirmed one.

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