Reactivating Old Systems
In order to pull off this seemingly miraculous feat, the team had to dig through a huge archive of old Voyager data for the information they needed to test the feasibility of firing up the thrusters. After studying the code, which was written in “an outdated assembler language,” the team decided it was worth a shot, and gave the thrusters a wake-up call.
On Nov. 28, 2017, Voyager engineers fired up the four backup thrusters for the first time and tested their ability to orient the spacecraft using short 10-millisecond pulses. The team then waited eagerly as the test results travelled through space, taking over 19 hours to arrive back on Earth. With much celebration, on Wednesday, Nov. 29, the NASA team learned the thrusters worked perfectly, and just as well as the attitude control thrusters.
“With these thrusters that are still functional after 37 years without use, we will be able to extend the life of the Voyager 1 spacecraft by two to three years,” Suzanne Dodd, project manager for Voyager at NASA’s Jet Propulsion Laboratory, Pasadena, California. 
The backup thrusters on Voyager 1 worked so well, the plan is to conduct a similar migration over to the backup thrusters on Voyager 2 once it’s attitude control thrusters also start to degrade.