Satellites to study geomagnetic storms



NASA's Time History of Events and Macroscale Interactions during Substorms (THEMIS) mission to study geomagnetic substorms over the next two years launched on 17 February from Cape Canaveral Air Force Station, Fla. Substorms are visible in the atmosphere as a sudden brightening of polar auroral ribbons as they split and reorganize, and are thought to form when solar wind overloads the magnetosphere with too much energy. Substorms are closely related to space storms that can disable spacecraft, communications and navigation systems, and power grids and that can expose astronauts to high energy free electrons.

Launched from a single rocket, THEMIS's five satellites will align themselves between the Sun and the Earth to view substorms; simultaneously, ground stations in Alaska and Canada will monitor auroral dynamics.