On Launch Pad 17-B at Cape Canaveral Air Force Station, the Dawn spacecraft arrives at the upper level of the mobile service tower. It will be moved inside and prepared for mating with the awaiting Delta II rocket. Dawn is scheduled for launch in a window from 7:25 to 7:54 a.m. Sept. 26 from CCAFS. During its nearly decade-long mission, the Dawn mission will study the asteroid Vesta and dwarf planet Ceres, celestial bodies believed to have accreted early in the history of the solar system. To carry out its scientific mission, the Dawn spacecraft will carry a visible camera, a visible and infrared mapping spectrometer, and a gamma ray and neutron spectrometer, whose data will be used in combination to characterize these bodies. In addition to the three instruments, radiometric and optical navigation data will provide data relating to the gravity field and thus bulk properties and internal structure of the two bodies. Data returned from the Dawn spacecraft could provide opportunities for significant breakthroughs in our knowledge of how the solar system formed. Photo credit: NASA/Jack Pfaller