Cited research: Icarus doi:10.1016/j.icarus.2010.03.039 (2010)

On Earth, caves can shelter ice, allowing it to persist all year round, even when temperatures outside rise above freezing. This may well happen on Mars too, according to Kaj Williams of NASA Ames Research Center in Moffett Field, California, and his colleagues.

Extinct volcanoes on Mars are likely to have developed hollow lava tubes that could today function as ice caves. The researchers modelled the growth and loss rates of frost for a subterranean room connected by a small chimney to the planet's surface. They suggest that ice can remain stable for 100,000 years or more. The volcanic 'cave' terrains on Mars, the authors add, could thus be important regions to target in the search for extraterrestrial life.