Scientists are back in touch with a NASA spacecraft that has been silent since October 2014.

NASA re-established contact with the STEREO-B spacecraft, one of two twin Solar Terrestrial Relations Observatories, on Sunday evening.

After 22 months of unanswered calls, the U.S. space agency managed to get in touch using the Deep Space Network, which tracks and communicates with its space missions.

We have re-established contact with STEREO-B! DSN locked on at 6:27pm ET on Aug. 21. More: <a href="https://t.co/hpwfJCzmXH">https://t.co/hpwfJCzmXH</a> <a href="https://t.co/3Zuwd5b7es">pic.twitter.com/3Zuwd5b7es</a> —@NASASunEarth

Communications with STEREO-B were lost on Oct. 1, 2014, during a test of a system that's triggered when the spacecraft can't communicate with Earth for 72 hours — something that was about to happen at that time due to the relative positions of the sun, the Earth and the satellite.

The twin STEREO spacecraft are designed to measure and study the sun and its coronal mass ejections — powerful eruptions of plasma from the sun's surface that can cause geomagnetic storms and auroras when they hit Earth's atmosphere.

This graphic shows the positions of the two STEREO spacecraft and their orbits in relation to Earth, Venus, Mercury and the sun. They were designed to each provide slightly different views of the sun that would generate a 3D or 'stereoscopic' images and data when combined (NASA)

The STEREO spacecraft were launched on Oct. 25, 2006, and orbit the sun with the Earth. STEREO-A travels ahead of Earth in its orbit and STEREO-B behind. They were designed to each provide slightly different views of the sun that would generate 3D or "stereoscopic" images when combined — something that was not possible when STEREO-B lost touch.