After almost four decades of dormancy, NASA has successfully ordered the Voyager 1 deep space probe to fire a set of thrusters that have been inactive for 37 years. The November 28 test was carried out by mission control at the Jet Propulsion Laboratory (JPL) in Pasadena, California, as part of an effort to keep the unmanned explorer functional for up to an additional three years as it speeds into interstellar space.
Launched 40 years ago, Voyager 1 is the most distant and fastest manmade object ever to leave the Earth, and at a distance of 13 billion mi (22 billion km) away a signal from the nuclear-powered spacecraft takes 19 hours and 35 minutes to reach one of NASA’s Deep Space Network antennae at Goldstone, California. In 2013, it became the first probe to enter interstellar space and the space agency hopes that its failing radioactive batteries will continue to function until 2025.
However, how long Voyager’s nuclear power source operates will be irrelevant if it’s unable to keep its main antenna pointed at Earth. If its attitude starts to drift, there is the danger of contact being lost forever and the spacecraft shutting itself down automatically. To prevent this from happening, the probe is equipped with a set of gyroscopes and 16 hydrazine MR-103 thrusters (eight primary and eight backup) built by Aerojet Rocketdyne.