Solid rocket boosters are clustered around the base of the United Launch Alliance Delta II rocket. A total of nine will assist in the launch of the THEMIS integrated spacecraft. 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 Cape Canaveral Air Force Station. Photo credit: NASA/Jack Pfaller