In a remarkable display of ingenuity and precision, engineers at NASA’s Jet Propulsion Laboratory (JPL) have successfully reactivated a set of thrusters aboard the Voyager 1 spacecraft that had been dormant since 2004.
NASA’s twin Voyager spacecraft, launched in 1977, are now traveling through interstellar space at around 35,000 mph (56,000 kph). This artist’s concept depicts one of the probes speeding away. Credit: NASA/JPL-Caltech
The mission team undertook the high-stakes effort to restore the spacecraft's primary roll thrusters—crucial for maintaining orientation—before a critical communications antenna on Earth temporarily goes offline for months of upgrades. The antenna, Deep Space Station 43 in Canberra, Australia, is the only one capable of sending commands to the distant Voyager probes and began its extended downtime on May 4.
Voyager 1, now over 15 billion miles from Earth and traveling through interstellar space at roughly 35,000 mph (56,000 kph), relies on thrusters to keep its antenna precisely pointed at Earth. In 2004, the spacecraft's primary roll thrusters were deemed unusable due to failed heaters. Since then, Voyager 1 has depended on its backup roll thrusters to stay aligned with its guide star. However, those backup thrusters are now threatened by a residue buildup in their fuel lines—potentially rendering them inoperable by fall 2025.
Facing the risk of losing the ability to maintain spacecraft orientation, JPL engineers decided to investigate the original failure. They hypothesized that the heaters had shut down not due to hardware failure, but possibly because of a flipped switch in the power control circuits. If they could reset that switch, the heaters might power back on, making the roll thrusters usable again.
The challenge was steep: If the heaters remained off and the roll thrusters activated, it could cause a small explosion. The team had to ensure Voyager’s star tracker was locked precisely on its guide star before issuing the remote commands. And with a 23-hour signal delay between Earth and the spacecraft, they had to wait almost a full day to confirm the outcome.
Their gamble paid off. On March 20, telemetry showed the temperature of the thruster heaters rising—signaling a successful revival. “It was such a glorious moment,” said Todd Barber, Voyager’s propulsion lead at JPL. “These thrusters were considered dead. It was yet another miracle save for Voyager.”
The timing was critical. NASA’s DSS-43 antenna, responsible for sending commands to the Voyagers, will only briefly come back online in August and December during the overhaul, limiting opportunities for mission updates.
“These antenna upgrades are essential for future lunar missions and deep space science,” said Suzanne Dodd, Voyager project manager and director of the Interplanetary Network at JPL. “But with Voyager, we’re doing all we can in advance to safeguard the mission.”
Voyager 1 and its twin, Voyager 2—launched in 1977—are the only spacecraft to have returned data from interstellar space, having long since passed beyond the protective bubble of particles and magnetic fields generated by the Sun. Now, nearly five decades later, NASA’s oldest explorers continue to push the boundaries of space—and engineering.
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The little spacecraft that could.