The circumference of moon it has shrunk by about 46 meters over the last hundreds of millions of years, while its core appears to have gradually cooled, which has increased the risk of landslides and instability at its southern pole. These, in a nutshell, are the results of a study published in The Planetary Science Journalconducted by scientists fromUniversity of Maryland.
The team, led by Thomas R. Watters, examined measurements and data available for our natural satellite to understand its evolution over the past millennia. The Moon, experts explain, seems to have developed small folds, just like raisins wrinkle when drying.
Unlike the fruit, however, the celestial body does not have a “flexible peel”, but a rather fragile surface, vulnerable to the formation of faults when sections of the crust meet. The researchers found that the shrinking of the Moon causes significant surface deformation in its southern polar region, including regions proposed as landing sites for the Artemis III mission crew.
The emergence of faults, the researchers add, often occurs in conjunction with seismic activity and lunar earthquakes. For this reason, locations adjacent to fault zones may not represent the ideal location for human exploration. As part of the new work, the research team linked a group of faults located in the southern polar region of the Moon to one of the most powerful earthquakes recorded by Apollo seismometers over 50 years ago.
Scientists used a series of models to simulate the stability of surface slopes in the region. According to what emerges from the investigation, some areas are particularly vulnerable to landslides due to seismic shocks. «Our work – comments Watters – suggests that surface earthquakes capable of producing strong ground shaking in the region of the lunar south pole can cause slip events and the formation of new faults. This information should be taken into account when designing permanent outposts on our satellite.”
Shallow earthquakes occur near the surface of the Moon, about 160 kilometers deep in the crust. While generally very short, these events are powerful enough to damage buildings, equipment and man-made structures.
«The surface of the Moon – adds Nicholas Schmerr, another author of the article – can be compared to a terrain of gravel and dust. Over billions of years, impacts with comets and asteroids have changed the structure and size of various fragments of lunar material. The resulting sediments then pose the risk of shaking and landslides.”
The research team now aims to continue monitoring the Moon and its seismic activity, in the hope of identifying regions potentially dangerous for human exploration. «In view of the manned Artemis missions – concludes Schmerr – it is essential to safely decide how to approach the work necessary for the establishment of outposts and infrastructures».