Regolith textures on Mercury: Comparison with the MoonстатьяИсследовательская статья
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Дата последнего поиска статьи во внешних источниках: 2 декабря 2020 г.
Аннотация:Surfaces of atmosphereless planetary bodies, including the Moon and Mercury, are covered with regolith. Regolith-related processes define surface morphology at scales of meters and tens of meters. We systematically surveyed all available images of the surface of Mercury with image resolution better than 2.5 m per pixel, and compared the observed regolith textures with those on the Moon. In a manner similar to the Moon, a typical surface contains many impact craters of different degrees of degradation, which indicates that regolith gardening smooths all topographic features. Textures characteristic of surfaces of large young craters with thin regolith are similar on both bodies. There are several types of sharp geologically young textures on Mercury that do not have lunar analogs. Hollows are young sharp irregular depressions on Mercury; they were discovered in images of lower resolution and attributed to sublimation of unidentified, moderately volatile material. Our survey reveals small, decameter-size hollows both spatially associated with known large hollow clusters and scattered at great distances from them. The existence of small hollows provides new constraints on the nature of these enigmatic features. Two types of fresh, geologically young regolith textures on Mercury, finely textured slope patches and chevron texture, have no analogs on the Moon, and their formation mechanism is unclear. We propose that sintering of regolith particles due to high peak surface temperatures cause formation of a slightly indurated decimeter-thick crust at the regolith surface on Mercury. We hypothesize that such a crust can play a key role in formation of these uniquely regolith textures of Mercury.