Voyager 1 Fires Up Its Old Thrusters After 37 Years

Saturday, 02 December 2017 - 11:45AM
Space
NASA
Saturday, 02 December 2017 - 11:45AM
Voyager 1 Fires Up Its Old Thrusters After 37 Years
NASA/JPL-Caltech
NASA's Voyager 1 spacecraft, the only probe we've sent into interstellar space (the empty space between solar systems), is tough to repair when it needs a tune up. Once it left our solar system in 2012, it became pretty clear that we'd never get our hands on it again, although we still keep in contact with it.

Which makes it an even more impressive feat that NASA's Voyager team was just able to activate a set of backup thrusters on the probe which haven't been used since 1980, three years after its launch. According to a press release from the agency, activating the dusty old backup thrusters for the first time in 37 years was a surprising but necessary victory, as the satellite's primary thrusters are starting to decay. 

Voyager's thrusters are less important for propelling it forward, and more important for reorienting the probe so that its antenna is always pointing in Earth's direction - otherwise, we couldn't communicate with it. These are called "attitude control thrusters," and they fire out tiny pulses that last only milliseconds, but which constantly rotate the probe so it's never pointing its antenna off in some random direction.


It was around 2014 that engineers noticed the primary thrusters were showing signs of decay, and would probably be on their way out before too long. They eventually came to an agreement that testing out the backup thrusters, shaky as that test might be, was the best option for keeping the probe alive.

On top of the the backups sitting idle for so long, while being 13 billion miles from Earth, there was a third problem: the backups weren't used for "attitude control." They were for "trajectory correction maneuvers" (TCM), and while similar, they were supposed to be used continuously in order to change Voyager's direction as it maneuvered around Jupiter and Saturn. They weren't meant to fire in short bursts to orient its antenna.

So, to recap: these thrusters have sat in disuse since Jimmy Carter was president, they aren't designed for this sort of task, and they're a baker's dozen billion miles away. But this past Tuesday, engineers fired them up anyway, and after 19 hours of waiting for the results to transmit from Voyager's antenna to Earth, they learned that it actually worked. The backups were up and running without any trouble.

According to Chris Jones, chief engineer at NASA's Jet Propulsion Laboratory in Pasadena, California:

Opening quote
"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."
Closing quote
 

It's expected that once the primary thrusters are completely shot, the backups will give Voyager 1 a few extra years of life before its data becomes too fuzzy to read. But even when that finally happens, Voyager 2 is expected to hit interstellar space within a few years. So it won't be completely alone out there, especially if the science fiction dream comes true and it gets intercepted by someone else.

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