NASA's twin Gravity Recovery and Interior Laboratory (GRAIL) spacecraft are lowered onto the second stage of their Delta II launch vehicle at Space Launch Complex 17B at Cape Canaveral Air Force Station in Florida (8/18/2011). At the top of the image is the spacecraft adapter ring which holds the two lunar probes in their side-by-side launch configuration. The adapater ring and the probes are wrapped in plastic to prevent contamination outside the clean room in the Astrotech Space Operation's payload processing facility in Titusville, Fla. The spacecraft will fly in tandem orbits around the moon for several months to measure its gravity field. GRAIL's primary science objectives are to determine the structure of the lunar interior, from crust to core, and to advance understanding of the thermal evolution of the moon.

NASA's Jet Propulsion Laboratory, Pasadena, Calif., manages the GRAIL mission. The Massachusetts Institute of Technology, Cambridge, is home to the mission's principal investigator, Maria Zuber. The GRAIL mission is part of the Discovery Program managed at NASA's Marshall Space Flight Center in Huntsville, Ala. Lockheed Martin Space Systems, Denver, built the spacecraft. Launch management for the mission is the responsibility of NASA's Launch Services Program at the Kennedy Space Center in Florida. JPL is a division of the California Institute of Technology in Pasadena.

For more information about GRAIL, please visit http://solarsystem.nasa.gov/grail.