Roving the Red Planet

The Mars Exploration Rover Mission
On January 4, 2004, the first of two Mars Exploration Rovers (shown above in an artist's rendering) landed on the Martian surface. The goal of the rovers was to search for and analyze rocks and soils that yield clues to the planet's watery past. Water, of course, is essential for life — at least as we understand it.

• The Mars Rovers' Fifth Year Anniversary