STEREO-A
STEREO-A — the "Ahead" spacecraft of NASA's twin STEREO solar observatories, launched on 26 October 2006 into an orbit around the Sun that carries it slowly ahead of Earth. Seeing the Sun from beside Earth's line of sight, the pair gave 3-D views of eruptions from the Sun, and on 6 February 2011 the two, then 180° apart, saw the whole Sun at once. STEREO-A is still working.
Key facts
Mission & specifications
Mission
- Operator
- NASA
- Launched
- October 26, 2006
- Status
- Active
Trajectory
- Current speed
- 30.2 km/s
- Computed from the cached state vector
- Distance from the Sun
- 0.967 AU
- Computed from the cached position
- Distance from Earth
- 1.14 AU
- Computed from cached positions
- Distance from Mars
- 0.616 AU
- Computed from cached positions
Mission
STEREO — the Solar TErrestrial RElations Observatory — was the third mission of NASA's Solar Terrestrial Probes programme: two nearly identical observatories, launched together on a Delta II on 26 October 2006. For their first months they flew long, looping orbits out past the Moon; lunar flybys then sent one into an orbit around the Sun ahead of Earth (STEREO-A, "Ahead") and the other behind it (STEREO-B, "Behind"). Drifting away from Earth in opposite directions, the two watched the Sun and the eruptions leaving it from two directions at once, giving 3-D views of coronal mass ejections — the clouds of solar plasma that drive geomagnetic storms at Earth. On 6 February 2011 they were 180° apart, and for the first time the whole Sun was in view at once. STEREO-B fell silent in 2014; STEREO-A has continued alone and is still observing.
- 2006Launch with STEREO-BLaunch
Two nearly identical observatories on one Delta II.
- 2011The whole Sun at onceMilestone
STEREO-A and STEREO-B are 180° apart, seeing all of the Sun between them.
- 2014On its ownMilestone
Contact with STEREO-B is lost; STEREO-A carries on alone.
Images
Images from open archives · credit shown per image