NASA’s Voyager 1 spacecraft is one of the greatest achievements in space exploration, becoming the first probe to reach interstellar space, after epic flybys of Jupiter and Saturn in 1979 and 1980. Since then, Voyager 1 has remained healthy although its thrusters have been dormant for the past 37 years; the last time they needed to be used was Nov. 8, 1980. But now, the thrusters have been successfully fired up once again, not bad for such an aging spacecraft.
“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 Suzanne Dodd, project manager for Voyager at NASA’s Jet Propulsion Laboratory, Pasadena, California.
The thrusters, called “attitude control thrusters,” are used to help keep the spacecraft oriented so it can communicate with Earth. They fire in small pulses or “puffs” lasting only milliseconds each. The four backup thrusters just fired up hadn’t been used since 1980. While they had not been needed, engineers noticed that they were beginning to degrade. The engineers decided to try to address the problem by firing up the four backup thrusters on Nov. 28, 2017, and it worked.
“The Voyager flight team dug up decades-old data and examined the software that was coded in an outdated assembler language, to make sure we could safely test the thrusters,” said Jones, chief engineer at JPL.
The “trajectory correction maneuver” (TCM) thrusters are used to point the spacecraft at various targets, such as Jupiter, Saturn and their moons during the flybys. They were not needed for the smaller pulses to orient the spacecraft.
For the test firing of the backup thrusters, they were fired in very brief 10-millisecond pulses, and they functioned perfectly.
“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,” said Barber, a JPL propulsion engineer.
In January, engineers will try switching to the TCM thrusters. They will try turning on one heater per thrusters although there is no longer enough power to turn on all the heaters. A similar test is also now being planned for Voyager 2; its thrusters are not yet as degraded as those of its twin. It is also expected that Voyager 2 will also enter interstellar space within the next few years. The Hubble Space Telescope is also being used to measure interstellar material along the trajectories of both Voyager spacecraft.
Last August, Voyager 2 celebrated 40 years of exploration, long after the flybys of Jupiter and Saturn, as well as Uranus and Neptune, in the late 1970s and 1980s. Both Voyagers provided incredible glimpses of the planets in the outer Solar System, and they even carried a “Golden Record,” a 12-inch, gold-plated copper phonograph record, which contained images and sounds of life on Earth, just in case they were to be found by any alien civilizations.
Voyager 1 is now about 13 billion miles from Earth, the farthest any spacecraft has traveled so far.