NASA's twin Gravity Recovery and Interior Laboratory spacecraft are hidden from view as spacecraft technicians secure.

At Space Launch Complex 17B on Cape Canaveral Air Force Station in Florida, NASA's twin Gravity Recovery and Interior Laboratory spacecraft are hidden from view as spacecraft technicians secure the sections of the clamshell-shaped Delta payload fairing around them.

The fairing will protect the spacecraft from the impact of aerodynamic pressure and heating during ascent and will be jettisoned once the spacecraft is outside the Earth's atmosphere. Launch aboard a United Launch Alliance Delta II rocket from Pad 17B is scheduled for Sept. 8. 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. For more information, visit http://www.nasa.gov/grail. Photo credit: NASA/Jim Grossmann