289 / 2023-10-10 20:41:50

GRAIL Gravity Gradients Evidence for a Potential Lava Tube at Marius Hills on the Moon

Lunar; lava tube; gravity gradients; GRAIL

GRAIL Gravity Gradients Evidence for a Potential Lava Tube at Marius Hills on the Moon

Ke Zhu^1,3, Meng Yang^1*,2,3, XingYuan Yan^1,3, WeiKai Li², Wei Feng^1,3, Min Zhong^1,3

1 School of Geospatial Engineering and Science, Sun Yat-Sen University, Zhuhai, 519082, China; yangmeng5@mail.sysu.edu.cn

2 State Key Laboratory of Geodesy and Earth’s Dynamics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan, 430077, China.

3 Key Laboratory of Comprehensive Observation of Polar Environment (Sun Yat-sen University), Ministry of Education, Zhuhai 519082, China



Abstract

Lunar lava tubes are natural underground tunnel-like structures, typically formed during lunar volcanic activity billions of years ago. They offer large, temperature-stable spaces, sheltered from cosmic radiation and minor meteorite impacts, making them potential advantageous locations for future lunar exploration and base construction.      Current lunar exploration missions primarily focus on lunar surface exploration, with relatively limited research on lava tubes. In-depth investigations into lunar lava tubes hold the promise of yielding valuable insights into their distribution, structural characteristics, and formation mechanisms, thus offering essential support for the strategic planning of future lunar missions and the selection of lunar base locations.

This study utilizes the GRGM1200A lunar gravity field model, derived from GRAIL lunar gravity satellite data, to detect anomalous signals indicative of lava tubes beneath lunar basalt in the Marius Hills region. Compared to the classical Hessian matrix, the gravitational gradient method used in this study is capable of detecting anomaly signals both in the north-south and east-west directions. Using this method, we detect a north-south anomaly signal in the Marius Hills region, located at 57.5°W and 14.3°N, indicating a negative density anomaly near the known lunar sinuous rilles and the Marius Hills Hole skylight. This suggests the presence of a potential lava tube, which is confirmed by the results of the forward method and lunar radar echo data. Forward modeling simulations were conducted to further support the presence of the lunar lava tube. When the forward model has dimensions of approximately 60 km in length, 9 km in width, and a center elevation of 55 meters buried 550 meters below the surface, the forward results closely match the observed data.

To further validate the presence of lunar lava tubes, this study conducted a detailed examination of the lunar surface geological features in the Marius Hills region, revealing compelling evidence of volcanic activity. Two sinuous rilles, Rills-A and Rills-B, originating from the local Marius Hills volcanic center and extending westward to young lunar mare basalt, were identified in the eastern part of the lava tube. A skylight (MHH) located in the Rills-A area is likely the result of a penetrating impact on the top of the lava tube, and it is situated less than 15 kilometers east of the newly discovered lava tube. The presence of Marius-B collapse chain to the west and Marius-A collapse chain to the east of the lava tube provides further compelling evidence for the detected lava tube.

Keywords

Lunar; lava tube; gravity gradients; GRAIL