Inside the mobile service tower workers help guide the Aura spacecraft toward the second stage of the Boeing Delta II rocket.

Inside the mobile service tower, or gantry, at Space Launch Complex 2 on North Vandenberg Air Force Base, Calif., workers help guide the Aura spacecraft toward the second stage of the Boeing Delta II rocket. After mating with the second stage, the fairing will be installed. The latest in the Earth Observing System (EOS) series, Aura is scheduled to launch July 10. Aura’s four state-of-the-art instruments will study the dynamics of chemistry occurring in the atmosphere. The spacecraft will provide data to help scientists better understand the Earth’s ozone, air quality and climate change.