NASA fires Voyager 1 thrusters after decades-long sleep

Artist's concept of the Voyager 1 spacecraft. NASA's Voyager 1 launched way back in 1977, but it's still in touch with Earth. That's because they rotate so that the spacecraft can communicate with Earth.

In the early days of the mission, Voyager 1 flew by Jupiter, Saturn, and important moons of each.

Ground controllers looked for a solution, and they made a decision to try out a separate rocket pack with four identical MR-103 "trajectory correction maneuver", or TCM, thrusters on the back side of the spacecraft that were used to nudge Voyager 1 and keep it on course during flybys earlier in the mission.

Testing that hypothesis was a job for software developers, as Jet Propulsion Laboratory chief engineer Chris Jones said "The Voyager flight team dug up decades-old data and examined the software that was coded in an outdated assembler language, to make sure we could safely test the thrusters".

The JPL's engineers began to look into alternatives, and found a new way to steer the spacecraft: the probe's trajectory correction maneuver (TCM) thrusters. The last time these thrusters were active was in November 1980, when the probe zipped by Saturn. Yesterday, NASA announced that it has successfully fired up four of Voyager 1's backup thrusters, which haven't been used since 1980, which should extend its life by a couple of years. Now, nearly four decades later, they've come back to life without a hitch to take over for the failing attitude control thrusters. They weren't meant to fire in short bursts to orient its antenna.

"Lo and behold, on Wednesday, Nov. 29, they learned the TCM thrusters worked perfectly - and just as well as the attitude control thrusters", the statement said. The radio waves traveled for 19 hours and 35 minutes before reaching Voyager 1 13 billion miles away; 19 hours and 35 minutes after that, they got the results of their little experiment. And, it seems Voyager's still got a few tricks up its sleeve.

"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", says NASA propulsion engineer Todd Barber.

The team will switch over to the TCM thrusters in January, but there is a drawback: they require heaters to operate, which will draw on the probe's limited power.

The space agency is planning to do a similar thruster test with the twin Voyager 2 spacecraft, which is on track to enter interstellar space within a few years. It was a message from Voyager 1, the only man-made object in interstellar space.

  • Rogelio Becker