April 29, 2009--The relatively flat expanse of the Martian valley known as Mawrth Vallis is among four places NASA may land its next big thing: the roving Mars Science Laboratory.

Slated for launch in 2011, the SUV-size rover will carry a fleet of advanced equipment for studying the red planet--enabling, among other things, tests for whether Mars ever gave rise to life and whether the planet could ever be suitable for human habitation. Mawrth Vallis interests researchers because of its different clay layers, which might offer new clues to Mars's watery past.