A Lockheed Martin technician speaks to NASA Deputy Administrator Lori Garver left about NASA's Gravity Recovery and Interior Laboratory.

A Lockheed Martin technician (right) at Astrotech's payload processing facility in Titusville, Florida, speaks to NASA Deputy Administrator Lori Garver (left) about NASA's Gravity Recovery and Interior Laboratory, or GRAIL, twin spacecraft during Garver's tour of the facility.

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/Jim Grossmann