Geologic Modeling for Resource Mapping in Planetary Exploration

Geological modelling refers to developing models of geologic units and structures in the underground,  starting from information from geological maps, geophysical surveys, or borehole logs.    On Earth, geologic information from the subsurface, such as borehole observation data and geophysical surveys, is the key element for the development of models of the underground at various scales for the purpose of scientific investigation, urban planning, water resources, geothermal, and mineral resources.    

Besides Apollo missions, which included drilling and geophysical prospecting, planetary exploration in the last 50 years has mainly returned data from the surfaces.  However, over the past 20 years, a new wave of orbital and rover-mounted planetary subsurface radar sounders has unveiled the subsurface of the first hundreds of meters at various vertical resolutions.  On Mars, the shallow subsurface of the first few meters represents the primary target for both biosignatures and access to ice/water resources, and drilling is the most practical way to access this underground world.  Within the payload of the latest generation of missions to the Moon, we found radar sounders and drills to explore the shallow underground. 

Geologic models of extra-terrestrial undergrounds have started to be developed in the last decade.  Yuan et al. (2017) developed a model to explain the dynamics of the emplacement of a sequence of lava flows on the Moon starting from the radar sounder data. Another geologic model has been developed  from the combination of the geologic context and the analysis of the seismometer data from InSight mission on Mars.   Katayama and Akamatsu (2024) interpreted a seismic discontinuity as being generated from the volume of rock cracks filled by liquid water at a depth of a few tens of meters.  

These examples prove how we can apply the geologic modeling techniques we use on Earth also to other worlds, where resource mapping is becoming of primary importance for future robotic and human exploration.   We have to adapt to different balances between the quantity and quality of surface and subsurface data, and concentrate on the specific scale imposed by the information returned by a particular mission or series of missions. The interoperability of data, reference systems, and open formats represents a critical point for developing models that are not only accessible to other scientists but also to engineers and personnel involved in mission operations.

Acknowledgements: This study is supported by the Space It Up project funded by the Italian Space Agency, ASI, and the Ministry of University and Research, MUR, under contract n. 2024-5-E.0 - CUP n. I53D24000060005.

Bibliographic References:  Ikuo Katayama, Yuya Akamatsu, 2024. Seismic discontinuity in the Martian crust possibly caused by water-filled cracks. Geology 52 (12), 939–942;  Yuan, Y., Zhu, P., Zhao, N., Xiao, L., Garnero, E., Xiao, Z., Zhao, J., Qiao, L., 2017. The 3‐D geological model around Chang’E‐3 landing site based on lunar penetrating radar Channel 1 data. Geophysical Research Letters 44, 6553–6561.