Skylights, Pits, and Tubes

Lava tube caves are potentially important sites for long-term human presence on the Moon because they provide shelter from surface hazards, including micrometeorites, radiation, extreme temperatures, and dust. The discovery of a lunar lava tube cave opening at the bottom of the Marius Hills Skylight or Pit is compelling motivation for robotic and eventually human exploration missions to this site for in situ investigations and site assessments to determine viability for habitation and utilization of lunar resources. Our LEAP2 program uses the Marius Hills Pit as a case study for determining required technology development needed to access these types of planetary features for exploration and eventual human settlement.

The pit is located in the area of the Moon’s Marius Hills region of Oceanus Procellarum at lunar coordinates 14.2°N, 303.3°E. The Marius Hills Pit is believed to be the opening to a large lunar lava tube cave useful for eventual human habitation. An entrance to a lava tube cave is believed to be indicated by a large overhang at the pit’s northeast side.

Basic scientific understanding of lunar pits is critical for constraining theories about lava-flow thermodynamics and mare emplacement. It is not known whether lunar lava tubes or caves serve as cold traps or reservoirs for the possible accumulation of volatiles, but such potential accumulations—even for more refractory volatiles (e.g., S-bearing minerals)—could yield valuable deposits of water ice. Mineral resources in the surrounding area have been postulated for surface mining operations and the potential for long term habitation and settlement within the protection of the lava tube form the basis for economic development of the site.

These planetary features serve as the basis of our LEAP2 space exploration technology development projects, and also as a framework for our sponsored space-STEM education programs for human habitation on distant worlds. Skylight openings, pits, and lava tubes have been identified on both the Moon and Mars. Over 200 of these features have been discovered on the Moon. Lunar lava tube caverns are believed to be equivalent in size to our largest discovered Earth cave, the Hang Son Doong cave in VietNam which has a floor to ceiling height of over 48 meters. Access for descending and ascending the pits is one of the major technology challenges for exploration of these sites.