Comet bombardment may have supported life on Mars

New York: If early Mars was as barren and cold as it is today then the bombardment of the Red Planet some four billion years ago by comets and asteroids may have made its climate more conducive to life, according to a study.

The impacts would have produced regional hydrothermal systems on Mars similar to those in Yellowstone National Park, which today harbour chemically powered microbes, some of which can survive boiling in hot springs or inhabiting water acidic enough to dissolve iron nails, said study co-author Stephen Mojzsis from the University of Colorado at Boulder.

Scientists have long known there was once running water on Mars, as evidenced by ancient river valleys, deltas and parts of lake beds, Mojzsis added.

In addition to producing hydrothermal regions in portions of Mars' fractured and melted crust, a massive impact could have temporarily increased the planet's atmospheric pressure, periodically heating Mars up enough to "re-start" a dormant water cycle.

Published recently in the journal Earth and Planetary Science Letters, the study took into consideration temperatures beneath millions of individual craters on Mars.