"At Cape Canaveral Air Force Station's Space Launch Complex 17B in Florida, these spacecraft technicians may be the last persons to glimpse NASA's twin Gravity Recovery and Interior Laboratory, or GRAIL, spacecraft as the sections of the Delta payload fairing close around them. The fairing will protect the spacecraft from the impact of aerodynamic pressure and heating during ascent and will be jettisoned once they are 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 include determining the structure of the lunar interior, from crust to core, and understanding of the thermal evolution of the moon."