Workers on Pad 17-A, Cape Canaveral Air Force Station, work on the bottom of the first stage of the Delta II rocket being lifted up the launch tower. The Delta will launch the Mars Exploration Rover (MER-A) vehicle. The MER Mission consists of two identical rovers designed to cover roughly 110 yards each Martian day over various terrain. Each rover will carry five scientific instruments that will allow it to search for evidence of liquid water that may have been present in the planet's past. Identical to each other, the rovers will land at different regions of Mars. Launch date for this first of NASA's two Mars Exploration Rover missions is scheduled no earlier than June 6.