Ice caves on Mars: Hoarfrost and microclimates

Abstract

Caves on planet Mars could potentially contain water ice deposits. Here, the physical processes responsible for the growth and preservation of spelean ice formations on Mars are assessed. Martian caves are situated in environments where phase transitions of water are only by sublimation. The predominant type of cave ice is expected to be perennial hoarfrost that slowly grows in supersaturated cavities. The role of cave microclimates for maintaining ice bodies is evaluated comparatively. Free and forced convection transport less sensible heat than in the denser terrestrial atmosphere. Cooling through sublimation is also expected to be far weaker in Martian caves than in terrestrial caves. Hence, the cooling of ice deposits by flow through the cave, often a crucial factor in terrestrial ice caves, is insignificant on Mars, which limits the geographic extent where cave ice deposits can be expected.