Gravity Modeling of Lunar Lava Tubes: Insights From a Terrestrial Analog

Abstract The exploration of lunar lava tubes can address challenges of human habitation on the Moon by identifying natural shelters against radiation, temperature extremes, and micrometeoroid impacts. This study shows the feasibility of detecting lunar lava tubes with gravimetry using Ape Cave in Washington State, USA, as a terrestrial analog. Ape Cave's unique features, including its 3.5 km length, irregular geometry, and minimal surface expression, make it an ideal model for simulating lunar conditions. A high‐resolution 3D model of the cave enabled the creation of forward gravity models, incorporating density and geometric variations of realistic terrestrial and lunar conditions. These models show significant negative gravity anomalies that closely fit field measurements along transects above Ape Cave, validating their use in predicting anomalies from lava tubes with comparable dimensions and complexity. Extending this to the Moon, two forward models simulated lunar lava tubes: one with Ape Cave's dimensions and another scaled to five times larger. Results show that while lunar anomalies are weaker due to lower surface gravity, instruments with resolutions of <25 μ Gal can nevertheless reliably detect tubes even at burial depths reaching >26 m. However, larger and more realistic lunar lava tubes produce detectable signals even with lower reading resolution instrument thresholds. This study underscores the benefit of integrating analog models with advanced gravimetric technologies for lunar exploration and highlights the importance of refining sensor capabilities to optimize the detection of lunar subsurface features. These findings contribute to the development of geophysical exploration strategies for future lunar missions to identify habitable environments.