An artist's conception of Mars Science Laboratory's Curiosity rover is pictured in this NASA image. With a mixture of tense nerves and confidence, NASA counted down Sunday to the landing of its ... more 

An artist's conception of Mars Science Laboratory's Curiosity rover is pictured in this NASA image. With a mixture of tense nerves and confidence, NASA counted down Sunday to the landing of its largest ever robotic rover on Mars, where it will search for signs that life may once have existed less