The Time History of Events and Macroscale Interactions during Substorms (THEMIS) mission was originally a constellation of five NASA satellites to study energy releases from Earth's magnetosphere known as substorms, magnetic phenomena that intensify auroras near Earth's poles. The name of the mission is an acronym alluding to the Titan, Themis.
Now three of the original satellites remain in the magnetosphere, while two have been moved into orbit near the Moon. Those two have been renamed ARTEMIS for Acceleration, Reconnection, Turbulence and Electrodynamics of the Moon’s Interaction with the Sun, but are also called ARTEMIS P1 (THEMIS B) and ARTEMIS P2 (THEMIS C).
The THEMIS satellites were launched February 17, 2007 from Cape Canaveral Air Force Station Space Launch Complex 17 aboard a Delta II rocket. Each satellite carries identical instrumentation, including a fluxgate magnetometer (FGM), an electrostatic analyzer (ESA), a solid state telescope (SST), a search-coil magnetometer (SCM) and an electric field instrument (EFI). Each has a mass of 126 kg, including 49 kg of fuel.
Launch date 2007-02-17 23:01:00 UTC
