Asteroid bombardment may have brought water to Mars

New Scientist : Cracks and other geological features on Mars’s surface indicate it once had extensive reservoirs of liquid water. Yet according to models of the Red Planet’s ancient climate, the atmosphere would have been too thin to allow liquid water to remain on the surface for long. Now Tim Parker of NASA’s Jet Propulsion Laboratory says that rather than having a primordial ocean, Mars may have imported its water from asteroids that struck the planet during the Late Heavy Bombardment some 4 billion years ago. The asteroid barrage would also have heated the planet’s surface, which would have allowed the water to remain for a few hundred million years—long enough to carve up the surface, but probably not long enough for life to evolve. Parker presented his findings at the Lunar and Planetary Science Conference held last week in The Woodlands, Texas.