Downpours on Ancient Mars? Sky and Telescope

The red planet does not lack for water in its frozen state. Great swaths of the Martian surface appear to be underlain by ice-impregnated dirt, and a fresh look at data returned by NASA’s 2001 Mars Odyssey spacecraft concludes that the planet may have stashed even greater amounts of ice than first thought. According to investigator William V. Boynton (University of Arizona), subsurface regions surrounding Mars’s polar caps may contain at least 70 percent ice by volume