Workers prepare one of the THEMIS probes for installation of bolt cutters that will separate each probe from the payload carrier.

At Astrotech Space Operations in Titusville, Fla., workers prepare one of the THEMIS probes for installation of bolt cutters that will separate each probe from the payload carrier. The probes will undergo weeks of testing and launch preparations. This includes a functional performance test to verify the state of health of each of the five probes and pressurization and leak checks of the reaction control systems. 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. These lights are the visible manifestations of invisible energy releases, called geomagnetic substorms, in near-Earth space. THEMIS will not only seek to answer where and when substorms start, but will also provide clues as to how and why these space storms create havoc on satellites, terrestrial power grids, and communication systems. THEMIS is scheduled to launch Feb. 15 from Cape Canaveral Air Force Station. Photo credit: NASA/Jack Pfaller