Boosters are positioned beside the first stage of a United Launch Alliance Delta II rocket in preparation for attachment.

Solid-fueled boosters are positioned beside the first stage of a United Launch Alliance Delta II rocket in preparation for attachment. The boosters are being attached to the rocket at Launch Complex 17-B at Cape Canaveral Air Force Station in Florida. 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. For more information visit: http://science.nasa.gov/missions/grail/. Photo credit: NASA/Jim Grossmann