On this day in 2006 – October 25th – NASA launched STEREO.

STEREO was a solar observation mission using two identical spacecraft in two slightly different orbits. That permitted stereoscopic imaging of the Sun. The mission lasted longer than the two years for which it was planned, but in 2014 STEREO-B malfunctioned and couldn't be recovered. STEREO-A is still operational.

Mona Evans
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