Two solid rocket boosters in the mobile service tower wait for a third below.

Two solid rocket boosters in the mobile service tower on Launch Pad 17-B at Cape Canaveral Air Force Station wait for a third, below. They will all be mated to the Delta II first stage for launch of the Dawn spacecraft. Dawn's goal is to characterize the conditions and processes of the solar system's earliest epoch 4.5 billion years ago by investigating in detail two of the largest asteroids, Ceres and Vesta. They reside between Mars and Jupiter in the asteroid belt. Launch is targeted for July 7. Photo credit: NASA/Jim Grossmann