Posted: Fri, Mar 21, 2003, 7:50 PM ET (0050 GMT)
NASA announced Thursday that it has selected a mission to study the geomagnetic storms that create aurorae. The Time History of Events and Macroscale Interactions during Substorms (THEMIS) mission was chosen by NASA to be the next Medium-class Explorer (MIDEX) mission. THEMIS, scheduled for launch in 2007, will use five small satellites to measure storms in the Earth's magnetosphere that generate auroral events in arctic regions. THEMIS was selected from a group of four finalists chosen by NASA last April. The total cost of the mission is $173 million. NASA also said it would a "mission of opportunity" on ESA's Extreme Universe Space Observatory (EUSO), a project planned for the International Space Station to study high-energy cosmic particles by observing flashes they generate when they strike the Earth's atmosphere. NASA will provide a Fresnel lens for EUSO for $36 million. NASA also said it will continue studies of a proposed infrared survey mission, the Widefield Infrared Survey Explorer (WISE), with a final decision on proceeding with WISE scheduled for 2004. Two MIDEX missions, Imager for Magnetopause-to-Aurora Global Exploration (IMAGE), launched in 2000, and the Wilkinson Microwave Anisotropy Probe (WMAP), are currently operating, and the third, the Swift gamma-ray burst mission, is scheduled for launch this December.

Related Links:

•  NASA press release