Fiftyfive years after the Apollo 11 landing, the Moon continues to reveal its dark side to scientists still studying Earth's natural satellite: for the first time, international research has identified more than 20 structures linked to now-buried craters and various inclined stratifications in the regolith, which is the layer of material composed of dust, rock and debris that lies on the Moon's surface and is the result of millennia of meteorite impacts and erosive processes. 

Coordinating the team of researchers is the Applied Geophysics group of Professor Michele Pipan from the Department of Mathematics, Computer Science and Geosciences at the University of Trieste.

Scientists interpreted geological structures at a depth of more than 30 metres from the lunar surface by analysing radar data collected by the Chinese Chang'E-4 mission from 2019, through the first rover landed on the moon's hidden face and integrating them with measurements from remote sensors.

The investigation involved part of the Van Kármán crater, located within the South Pole-Aitken Basin, an unexplored area of the satellite with a diameter of more than 180 km now at the centre of new geological revelations. For the first time, the researchers used deep learning algorithms based on artificial intelligence to collect and process the data, which allowed them to examine the radar data much more precisely and objectively than before, uncovering features and evolution of the hidden side of the lunar surface and revealing a complexity in the geometry of the regolith that was previously unknown. In fact, the regolith in the area observed does not have a constant thickness, contrary to previous assumptions, but varies between 5 and 15 metres.

‘These results demonstrate the importance of multidisciplinary analyses, which not only provide crucial information from a scientific point of view, but are also the essential starting point for the evaluation of potential lunar subsurface resources and for the planning of future missions and permanent lunar bases’, explains Michele Pipan, Professor of Applied Geophysics at the University of Trieste.

The research, published in the scientific journal Icarus, involved scientists from the University of Trieste, the INAF - National Institute of Astrophysics in Rome, Purdue University (USA), the Chinese Academy of Sciences and Zhejiang University (China). 

In January 2024, the same research team corrected and validated the radar data collected by the mission, available on the Lunar and Planetary data release system site of the National Astronomical Observatory of China and made them available to the international community through publication in the journal Scientific Data.

Currently, the University of Trieste research group that led this study is involved in a project selected by the European Space Agency (ESA) to send a magnetometer and radar system to the Moon for geophysical surveys of the lunar subsurface.

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Full study published in Icarus

Deep learning driven interpretation of Chang’E – 4 Lunar Penetrating Radar

G. Roncoroni a, E. Forte a, I. Santin a, A. ˇCernok a, A. Rajˇsi´c b, A. Frigeri c, W. Zhao d, G. Fang e,f,g, M. Pipan a

a Department of Mathematics, Informatics and Geosciences, University of Trieste, Italy
b Department of Earth, Atmospheric and Planetary Sciences, Purdue University, West Lafayette, IN, USA
c Istituto di Astrofisica e Planetologia Spaziali (IAPS), Istituto Nazionale di Astrofisica (INAF), Rome, Italy
d Key Laboratory of Geoscience Big Data and Deep Resource of Zhejiang Province, School of Earth Sciences, Zhejiang University, Hangzhou 310058, China
e Aerospace Information Research Institute, Chinese Academy of Sciences, Beijing 100190, China
f Key Laboratory of Electromagnetic Radiation and Sensing Technology, Chinese Academy of Sciences, Beijing 100190, China
g School of Electronic, Electrical and Communication Engineering, University of Chinese Academy of Sciences, Beijing 100049, China