NASA - STEREO - The Sun in 3D
STEREO (Solar TErrestrial RElations Observatory) is the third mission in NASA's Solar Terrestrial Probes program (STP). This two-year mission will employ two nearly identical space-based observatories - one ahead of Earth in its orbit, the other trailing behind - to provide the first-ever stereoscopic measurements to study the Sun and the nature of its coronal mass ejections, or CMEs. STEREO's scientific objectives are to: • Understand the causes and mechanisms of coronal mass ejection (CME) initiation. • Characterize the propagation of CMEs through the heliosphere. • Discover the mechanisms and sites of energetic particle acceleration in the low corona and the interplanetary medium. • Improve the determination of the structure of the ambient solar wind.