The "powered descent vehicle" of NASA's Mars Science Laboratory spacecraft is being prepared for final integration into the spacecraft's back shell in this photograph from inside the Payload Hazardous Servicing Facility at NASA Kennedy Space Center, Fla. The powered descent vehicle combines the spacecraft's descent stage and the rover Curiosity.

The Mars Science Laboratory spacecraft has been prepared for launch during the period Nov. 25 to Dec. 18, 2011. In a prime mission lasting one Martian year -- nearly two Earth years -- after landing, researchers will use the rover's tools to study whether the landing region has had environmental conditions favorable for supporting microbial life.

NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Mars Science Laboratory Project for NASA's Science Mission Directorate in Washington. Launch management is the responsibility of NASA's Launch Services Program at the Kennedy Space Center in Florida. The Atlas V launch service is provided by United Launch Alliance, Denver, Colo.