Workers inside the mobile service tower at Cape Canaveral Air Force Station prepare to remove the canister surrounding the THEMIS spacecraft.

Workers inside the mobile service tower on Launch Pad 17-B at Cape Canaveral Air Force Station prepare to remove the canister surrounding the THEMIS spacecraft. THEMIS consists of five identical probes, the largest number of scientific satellites ever launched into orbit aboard a single rocket. The THEMIS mission is to investigate what causes auroras in the Earth's atmosphere to dramatically change from slowly shimmering waves of light to wildly shifting streaks of color. Discovering what causes auroras to change will provide scientists with important details on how the planet's magnetosphere works and the important Sun-Earth connection. THEMIS is scheduled to launch aboard a Delta II rocket on Feb. 15 during a window extending from 6:08 to 6:27 p.m. Photo credit: NASA/Amanda Diller