The Voyager 1 spacecraft just performed another incredible feat after passing into interstellar space in 2012. NASA fired up its thrusters after lying idle for 37 years in the cold vacuum of space.
This was no small feat of engineering. Voyager runs on decades-old computer software and it takes more than 19.5 hours to send a command from Earth to the spacecraft. (Then engineers need to wait another 19.5 hours for Voyager to confirm the signal worked as planned.)
"The Voyager flight team dug up decades-old data and examined the software that was coded in an outdated assembler language, to make sure we could safely test the thrusters," Chris Jones, chief engineer at NASA's Jet Propulsion Laboratory in California, said in a statement.
Voyager 1 — and its twin, Voyager 2 — were originally tasked with mapping the outer solar system when they launched in 1977. Voyager 1 flew by Jupiter and Saturn before zooming away from the orbital plane of our solar system, while Voyager 2 successfully flew by Jupiter, Saturn, Uranus, and Neptune.
The Aerojet Rocketdyne thrusters are needed for both spacecraft to communicate with Earth. Each Voyager spacecraft was equipped with a couple of sets. Attitude control thrusters generally controlled the spacecraft's orientation. Trajectory correction maneuver (TCM) thrusters were used on Voyager 1 up to 1980 to make sure the spacecraft was pointing at the right targets — planets, moons, and the like.
Both thruster types are the same size and perform the same function, but the TCM thrusters were located on the back of the spacecraft and were dormant since November 8, 1980. That is until the attitude control thrusters began degrading in 2014. "Over time, the [attitude control] thrusters require more puffs to give off the same amount of energy," NASA stated. "At 13 billion miles from Earth, there's no mechanic shop nearby to get a tune-up."
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The TCM thrusters on Voyager 1 were tested on Nov. 28 and worked perfectly. Now that the agency know the TCM thrusters work, NASA plans to switch to those thrusters in January. (Voyager 2 may eventually switch over as well, when its attitude control thrusters degrade — but NASA needs to run tests to see how well its TCM thrusters work.)
The change in thruster will extend Voyager 1's mission by two to three years. There's a trade-off, though. Voyager 1 needs to turn on one heater for each of the four TCM thrusters. Heat requires power, and Voyager 1 is running low. Once its power reserves fall too low to operate the TCM thrusters, NASA will switch back to the attitude control thrusters.
This same thruster type — MR-103 — flew on other NASA spacecraft, such as Cassini and Dawn. Cassini was deliberately crashed into Saturn’s atmosphere earlier this year, but Dawn is still mapping out the dwarf planet Ceres after its previous mission at the asteroid Vesta.
In related news, late last month it was announced that Voyager's Golden Record would be released on vinyl to the general public. The genesis was a wildly successful, $1.3-million Kickstarter by Ozma Records that ran earlier in 2017. The plan was to remaster the Golden Record — which featured sounds and music from Earth — and the results finally hit wide public release.
Also in November, music from Voyager 1's data premiered at a supercomputing conference in Denver. The three-minute piece was based on data from an instrument that looks at particles in space. It was composed by Domenico Vicinanza of Anglia Ruskin University and Genevieve Williams of the University of Exeter.
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