Stereo A/B

Solar TErrestrial RElations Observatory

Mission Profile

STEREO (Solar TErrestrial RElations Observatory) A and B are twin NASA spacecraft launched on 26 October 2006 aboard a Delta II 7925-10L, designed to study the three-dimensional structure of coronal mass ejections (CMEs) and their propagation through the solar wind using stereoscopic imaging from two different vantage points in Earth's orbit. Over time STEREO-A and B have drifted to opposite sides of the Sun, providing the only continuous solar imaging from multiple perspectives and enabling the first complete 360-degree view of the Sun's surface in 2011. STEREO's stereo perspective fundamentally transformed space weather forecasting by allowing the direction and speed of CMEs to be measured before they reach Earth. STEREO-B contact was lost in 2016 but STEREO-A continues to operate, providing valuable data from its unique solar vantage point.