CAPE CANAVERAL, Fla. -- Technicians prepare to lift the third solid-fueled booster into Launch Complex 17-B at Cape Canaveral Air Force Station in Florida where a United Launch Alliance Delta II is being prepared for launch. The Delta II will carry NASA's Gravity Recovery and Interior Laboratory, or GRAIL, spacecraft into lunar orbit. 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. GRAIL is scheduled to launch September 8, 2011.