An Air Force cargo plane arrives carrying the space agency's Gravity Recovery and Interior Laboratory or GRAIL spacecraft.

An Air Force C-17 cargo plane arrives on the Shuttle Landing Facility at NASA's Kennedy Space Center in Florida carrying the space agency's Gravity Recovery and Interior Laboratory, or GRAIL, spacecraft. The spacecraft traveled from the Lockheed Martin plant in Denver, Colo., and will undergo further processing in the Astrotech payload processing facility in Titusville, Fla. The United Launch Alliance Delta II rocket that will carry GRAIL into lunar orbit already is fully stacked at NASA's Space Launch Complex 17B and launch is scheduled for Sept. 8.

The GRAIL mission is a part of NASA's Discovery Program. GRAIL will fly twin spacecraft in tandem orbits around the moon for several months to measure its gravity field. The mission also will answer longstanding questions about Earth's moon and provide scientists a better understanding of how Earth and other rocky planets in the solar system formed. For more information, visit http://science.nasa.gov/missions/grail/. Photo credit: NASA/Dimitri Gerondidakis