On Launch Pad 17-B at Cape Canaveral Air Force Station, a third solid rocket booster is lifted into the mobile service tower, joining two others already there. The SRB is one of nine to be attached for the launch of the Dawn spacecraft. Dawn's mission is to explore two of the asteroid belt's most intriguing and dissimilar occupants: asteroid Vesta and the dwarf planet Ceres. Photo credit: NASA/Jim Grossmann