NASA regains contact with Sun probe lost 2 years ago

NASA has reestablished contact with one of its solar-probing spacecrafts - which captures stereoscopic images of the Sun - almost two years after communications were lost.

The Solar Terrestrial Relations Observatory (STEREO) is a solar observation mission which captures stereoscopic images of the Sun and solar phenomena, such as coronal mass ejections.

Two nearly identical spacecraft were launched in 2006 into orbits around the Sun.
On Sunday, contact was reestablished with one of the Solar Terrestrial Relations Observatories, known as the STEREO-B spacecraft, after communications were lost on October 1, 2014. Over 22 months, the STEREO team has worked to attempt contact with the spacecraft.

Most recently, the team attempted a monthly recovery operation using NASA's Deep Space Network (DSN) which tracks and communicates with missions throughout space.

The DSN established a lock on the STEREO-B downlink carrier. The downlink signal was monitored by the STEREO Mission Operations team over several hours to characterise the attitude of the spacecraft and then transmitter high voltage was powered down to save battery power.

The team plans further recovery processes to assess observatory health, re-establish attitude control and evaluate all subsystems and instruments.

Communications with STEREO-B were lost during a test of the spacecraft's command loss timer, a hard reset that is triggered after the spacecraft goes without communications from Earth for 72 hours.

The STEREO team was testing this function in preparation for something known as solar conjunction, when STEREO-B's line of sight to Earth - and therefore all communication - was blocked by the Sun.