In Oceanus Procellarum, on the flank of the volcanic Marius Hills, there is a collapse tens of meters across: the Marius Hills Pit. From orbit it looks like a skylight into an ancient lava channel. If a tube really runs beyond it—formed roughly 3 to 3.8 billion years ago—it would be a ready-made shelter. A rock roof could shield a future base from radiation and from the Moon’s extreme day–night temperature swings. That is the target of GIMLI, the Geophysical Instruments for Marius Lunar pit Investigation. The project is led by Nathaniel (Than) Putzig of the Planetary Science Institute, with the Norwegian Space Agency as a partner and Honeybee Robotics building the instruments. A lander and rover will be supplied through NASA’s CLPS program; funding comes through PRISM. The selection was announced in late September 2026, alongside two other lunar payload suites. On board are ground-penetrating radar, an active-source seismic system, a gravimeter, and cameras. The seismic part matters: no one has deliberately generated seismic waves on the Moon since Apollo 17 in 1972. Together the instruments are meant not only to search for a void but to estimate its size, while the cameras image the pit walls and the exposed lava layers. Even if there is no long tunnel, the pit will still show how lunar volcanism worked. No launch date is set yet; that will be fixed closer to the CLPS flight






