NASA’s Voyager 1 spacecraft is the only human-made object in interstellar space. The spacecraft, which has been flying for 40 years, relies on small devices called thrusters to orient itself so it can communicate with Earth. Now, the Voyager team is able to use a set of four backup thrusters, dormant since 1980.
Voyager 1 launched from Florida’s NASA Kennedy Space Center on September 5, 1977, 16 days after its twin, Voyager 2. This artist concept depicts one of NASA’s twin Voyager spacecraft. Image credit: NASA / JPL-Caltech.
Since 2014, NASA’s engineers have noticed that the thrusters Voyager 1 has been using to orient the spacecraft, called ‘attitude control thrusters,’ have been degrading. Over time, the thrusters require more ‘puffs’ to give off the same amount of energy.
The Voyager team assembled a group of propulsion experts at NASA’s Jet Propulsion Laboratory to study the problem.
The experts analyzed options and predicted how the spacecraft would respond in different scenarios. They agreed on an unusual solution — try giving the job of orientation to a set of ‘trajectory correction maneuver’ (TCM) thrusters that had been asleep for 37 years.
“In the early days of the mission, Voyager 1 flew by Jupiter, Saturn, and their moons,” the researchers said.
“To accurately fly by and point the spacecraft’s instruments at a smorgasbord of targets, we used TCM thrusters that are identical in size and functionality to the attitude control thrusters, and are located on the back side of the spacecraft.”
“But because Voyager 1’s last planetary encounter was Saturn, we hadn’t needed to use the TCM thrusters since November 8, 1980.”
“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,” said Dr. Suzanne Dodd, project manager for Voyager at NASA’s Jet Propulsion Laboratory.
On November 28, 2017, the Voyager team fired up the four TCM thrusters and tested their ability to orient the spacecraft using 10-millisecond pulses.
The engineers waited eagerly as the test results traveled through space, taking 19 hours and 35 minutes to reach NASA’s Deep Space Network.
The next day, they learned the TCM thrusters worked perfectly — and just as well as the attitude control thrusters.
The test went so well, the team will likely do a similar test on the TCM thrusters for Voyager 2, the twin spacecraft of Voyager 1. The attitude control thrusters currently used for Voyager 2 are not yet as degraded as Voyager 1’s, however.
