||The STEREO mission is a strategic element of NASA's Sun-Earth Connection program, a multi-institutional and international collaboration involving participants from France, Germany, the Netherlands, Belgium, Switzerland, the United States, and the United Kingdom. STEREO is the third mission NASA's Solar Terrestrial Probes program. The overall objective is to increase the understanding of the origin and consequences of CMEs (Coronal Mass Ejections).
The mission consists of two nearly identical spacecraft in heliocentric elliptical orbit in the ecliptic plane at approximately 1 AU from the sun: one drifting ahead of the Earth and one behind. Simultaneous measurements are obtained by the satellites instruments at gradually increasing separations over the course of the two-year mission. The STEREO mission observation capabilities are:
* First stereo viewing of Sun from out-of-Earth-orbit vantage points
* First imaging and tracking of space disturbances from Sun to Earth
* First continuous determination of interplanetary shock positions by radio triangulation
* First simultaneous imaging of solar activity with in-situ measurement of energetic particles at 1 AU.