NASA Selects GIMLI Mission to Check if a Lunar Pit Hides a Cave for Astronauts

NASA has selected a mission called GIMLI — Geophysical Instruments for Marius Lunar pit Investigation — to investigate a pit on the Moon's surface and test whether it is the entrance to a much larger underground lava tube, according to NASA and the Planetary Science Institute (PSI), which leads the project.

What was announced

NASA said the selection is part of its PRISM program, short for Payloads and Research Investigations on the Surface of the Moon, which funds science instruments that fly to the lunar surface on commercial landers under NASA's Commercial Lunar Payload Services (CLPS) initiative. NASA's announcement, dated September 30 and updated October 2, 2026, described GIMLI as one of several new science investigations meant to support NASA's planned Moon base.

PSI identified Than Putzig, the institute's associate director and a senior scientist, as the mission's principal investigator. Gareth Morgan, a PSI senior scientist, is deputy principal investigator, and PSI director and CEO Amanda Hendrix is also named on the team, according to the PSI announcement. NASA's own release instead refers to the principal investigator as Dr. Nathaniel Putzig; the two names appear to refer to the same person, with sources differing on whether to use his full first name or a shorter form.

The target: a pit in the Marius Hills

The mission's target is a known depression called the Marius Hills Pit, located in the Marius Hills, a volcanic field in Oceanus Procellarum on the Moon's near side, according to the English Wikipedia entry on the Marius Hills used here for background orientation. The region has one of the highest concentrations of volcanic domes on the Moon, formed by relatively viscous lava.

Coverage of the GIMLI selection reported by Indonesian outlet detik.com described the pit as measuring roughly 65 by 90 meters across with an estimated depth of 34 to 45 meters. The Wikipedia entry on the Marius Hills instead cites an older depth estimate of 80 to 88 meters for the same feature, illustrating that published figures for the pit's depth vary depending on the source and measurement method.

Scientists believe the pit, first spotted by Japan's SELENE orbiter and later imaged by NASA's Lunar Reconnaissance Orbiter, is a 'skylight' — a collapsed section of roof — that could open into an intact lava tube running beneath the surface, according to the Wikipedia summary and the PSI mission description.

How GIMLI will search for a cave

GIMLI will not land directly in the pit. Instead, PSI said a lander and rover delivered by a CLPS provider will carry a suite of instruments to the area to probe what lies beneath and around it.

• Ground-penetrating radar to map subsurface structures
• Active-source seismic sensors, similar in concept to instruments used during the Apollo program
• A gravimeter to detect density differences consistent with a void underground
• Cameras to photograph the surface and the exposed walls of the pit

PSI said the equipment will be built largely by Honeybee Robotics, a Blue Origin company, with mission partners including the Norwegian Space Agency, Boise State University, Johns Hopkins University, the Lunar and Planetary Institute and the University of Oslo. Neither NASA nor PSI disclosed a specific funding figure or a launch date for the hardware in the materials reviewed for this article.

Why a cave matters for a future Moon base

NASA and PSI both frame the search in terms of future human presence on the Moon. An intact lava tube could offer natural shielding from cosmic radiation, solar particle events and micrometeorite impacts, as well as more stable temperatures than the open lunar surface, according to the PSI mission description.

Than Putzig, the mission's principal investigator, said combining seismic methods with ground-penetrating radar and gravity measurements should allow the team to better understand what lies beneath the pit, including whether a lava tube extends away from it, according to the same Universe Today report.

NASA's Science Mission Directorate associate administrator, Nicky Fox, described the broader round of PRISM selections, which includes GIMLI, as part of an effort to map lunar resources and hazards ahead of any sustained human presence, saying NASA Science aims to build a comprehensive guide to surviving on other worlds so that scientific reconnaissance precedes astronauts to the lunar surface, according to NASA's announcement.

What is still unknown

No source reviewed confirms that a habitable cave has actually been found. GIMLI's purpose is to test the hypothesis that one exists beneath the Marius Hills Pit and, if so, to estimate its size — a result that will only come once the instruments are delivered and operated on the lunar surface. NASA and PSI have not published a confirmed delivery or launch date for the mission's lander and rover.