In order to keep the spacecraft running, its thrusters have to function properly, but engineers weren't sure if the small devices were going to work considering they hadn't been used since November 1980.
Being able to use the backup thrusters means the lifespan of Voyager 1 has been extended by two or three years, added Suzanne Dodd, project manager for Voyager.
In a blog post, the agency explained that Voyager 1's main attitude control thrusters had been degrading, making it hard to reorient the spacecraft so that its antenna points back towards Earth. At 13 billion miles from Earth, there's no mechanic shop nearby to get a tune-up. However, almost 20 hours after firing up the backup thrusters, engineers received a signal from the Voyager back on Earth, which meant their test was successful.
Voyager 1 was launched in 1977 and flew past Jupiter and Saturn in 1979 and 1980 respectively. Voyager 1, NASA's far away and active spacecraft, is the only human-made object in interstellar space, the environment between the stars.
Aerojet Rocketdyne developed all of the Voyager's thrusters. The probe now uses its attitude control thrusters to make tiny corrections - firing for only milliseconds at a time - to rotate it to point its antenna towards Earth.
Humanity's most distant spacecraft surprised its operators by answering the call to fire up rockets that have not been used in nearly 40 years. They allowed on an exceptional solution: Try giving the job of orientation to a set of thrusters that had been resting for 37 years.
To reawaken these dormant thrusters the team had to go back to the original Voyager documentation.
After reviewing decades-old data and software "that was coded in an outdated assembler language", JPL engineers, led by JPL Chief Engineer Chris Jones, determined it was safe to attempt to fire them.
On the last Tuesday, Voyager engineers fired up the 4 TCM thrusters for the first time in 37 years and examined their capacity to orient the spacecraft using 10-millisecond pulses.
In the early days of the mission, Voyager 1 flew by Jupiter, Saturn, and important moons of each. According to NASA, the re-awakened thrusters were just as effective as the attitude control thrusters. "The mood was one of relief, joy and incredulity after witnessing these well-rested thrusters pick up the baton as if no time had passed at all", Todd Barber, a propulsion engineer, said in the statement. JPL operates Voyager and the Deep Space Network (DSN) that receives the signals.
They will likely also conduct similar tests on the backup thrusters on Voyager 2.