Voyager 1 is a long, long way from home. Originally launched by NASA 40 years ago on September 5, 1977, It now travels about 916,000 miles a day. It’s been beyond the limits of our star system five years now, after having left the edge of the heliosphere (called the heliopause). It now travels between the stars, boldy going where no spacecraft has gone before.
In all that time, Voyager 1 has relied on attitude thrusters to provide tiny adjustments so that the transmitting antenna always points back home. Even though the thruster pulse durations are measured in milliseconds, the primary attitude thrusters aboard the tiny craft are wearing out. JPL has been noticing the slow degradation in the thrusters since 2014, so they started pondering a workaround.
The team, made up of Chris Jones, Robert Shotwell, Carl Guernsey and Todd Barber, agreed on an unusual solution: Try giving the job of orientation to a set of thrusters that had been asleep for 37 years.
Jones, chief engineer at JPL, 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The Voyager flight team dug up decades-old data and examined the software that was coded in an outdated assembler language, to make sure we could safely test the thrusters.
They did the forensics on the software, and then on Tuesday, November 28, 2017, issued some simple commands. A bit over 19 hours and 35 minutes later, the commands had reached Voyager 1, and had sent back a return message, received by one of the antennas at the an antenna in part of NASA’s Deep Space Network, at Goldstone, California.
Beyond all rational expectation, it had worked.
Looking for some hot stuff? I fired backup thrusters for the first time in 37 years, and they worked like a champ. This could extend my life 2-3 years. https://t.co/N0pF3nvOkO pic.twitter.com/V35vMbrHCr
— NASA Voyager (@NASAVoyager) December 2, 2017
Amazingly, the test was successful. Now, the Voyager team, based in Pasadena, California, is able to use a set of four backup thrusters, dormant since 1980.
The Voyager team got more excited each time with each milestone in the thruster test.
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.
Suzanne Dodd, project manager for Voyager at NASA’s Jet Propulsion Laboratory said:
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.
The thruster test went so well, the team will likely do a similar test on the TCM thrusters for Voyager 2, which is also on course to enter interstellar space, likely within the next few years.
Voyager is still listening, and still taking commands.
If you think about it, the original Voyager craft is now our Final Front Ear.