After two years of complete silence, one of the Solar Terrestrial Relations Observatories (STEREO-B spacecraft) has finally made contact. Link
Launched in 2006, it was created to observe the sun. It was launched with its sister, STEREO-A. The STEREO spacecrafts entered an orbit around the sun just ahead of (B) and just behind (A) Earth. The goal, and reasoning behind the slightly different entrances, was to allow them to observe solar phenomena like coronal mass ejections, from multiple angles.
Hold up, what's a coronal mass ejection? Well, basically the sun expels ropes of plasma and magnetic field into space at around 200 miles per second. The interesting part happens when these particles interact with Earth's own magnetic sphere because this interaction can cause major effects on the ground. A small list of their negative effects? They can knock out electrical grids and damage satellites.
But we haven't heard from B since October 2014. Why? and why is it back on now?
Well, it's silence wasn't unexpected. It was originally only supposed to last about two years...and by going from 2006-2014, it far exceeded this expectation. It was given a hard reset after 72 hours of radio silence, but things went a little strange. It let out a weak signal, and then silence...until now.
After several periodic check-ins and a few lucky breaks from the team ever since December, the DSN finally locked on to STEREO-B's signal at 6:27 p.m. EDT on Sunday.
Its health still needs to be determined if it is capable of resuming its scientific duties, but it's sister STEREO-A continues to function normally so there is a lot of hope for this surprisingly resilient machine.