Workers guide the suspended upper canister toward the THEMIS spacecraft and upper stage booster at right.

In the high bay at Astrotech Space Operations, workers guide the suspended upper canister toward the THEMIS spacecraft and upper stage booster at right. When the upper and lower canisters are joined, the THEMIS will be completely enclosed and will be transported to Launch Complex 17-B for mating with its launch vehicle. THEMIS consists of five identical probes, the largest number of scientific satellites ever launched into orbit aboard a single rocket. This unique constellation of satellites will resolve the tantalizing mystery of what causes the spectacular sudden brightening of the aurora borealis and aurora australis - the fiery skies over the Earth's northern and southern polar regions. THEMIS is scheduled to launch Feb. 15 from Pad 17-B at Cape Canaveral Air Force Station aboard a Boeing Delta II rocket managed by the United Launch Alliance. Photo credit: NASA/Troy Cryder