NASA engineers have successfully resurrected Voyager 1's half-century-old thrusters, bringing them back to life more than 20 years after they fell silent. This engineering miracle comes just months before a planned communications blackout that could have jeopardized the craft's future. The revival of these crucial backup thrusters has granted Voyager 1 additional operational time, allowing it to maintain contact with Earth until at least next year.
Launched in 1977, Voyager 1 is currently over 15 billion miles (24 billion kilometers) away from Earth, making it the farthest human-made object from our planet. At this distance, it takes approximately 23 hours for any radio signal to travel to and from the spacecraft. However, the Earth-based antenna responsible for sending commands to both Voyager 1 and its twin, Voyager 2, is scheduled for an upgrade. Over the years, the backup thrusters—essential for keeping the spacecraft oriented toward our planet—have been gradually clogging with propellant residue.
Since 2004, these backup thrusters have been in use after two heater circuits, which warm the hydrazine fuel necessary for ignition in the main thrusters, failed. Kareem Badaruddin, Voyager mission manager at NASA's Jet Propulsion Laboratory in Pasadena, California, acknowledged that the team initially accepted the failure of the primary roll thrusters, believing that the backup would suffice. "Frankly, they probably didn't think the Voyagers were going to keep going for another 20 years," he remarked.
Voyager 1 has exceeded expectations, entering interstellar space in 2012 and currently recording conditions beyond the sun's protective magnetic field, known as the heliosphere. As the backup thrusters faced clogging issues and the anticipated antenna blackout loomed, NASA engineers turned to innovative solutions. They theorized that the two faulty heater circuits might have malfunctioned due to a switch disturbance, making the potential fix as simple as flipping the switch back.
However, executing this fix from Earth is a complex task. The thrusters needed to be activated to troubleshoot the heaters, but doing so without the heaters functioning posed a significant risk. Any deviation from Voyager 1's course could trigger an automatic response to fire the thrusters, putting the spacecraft at risk of catastrophic failure.
Compounding the urgency was the status of Deep Space Station 43, a massive 230-foot-wide (70-meter) antenna located in Canberra, Australia. This facility is part of NASA's Deep Space Network and is the only station capable of sending commands to Voyager. Unfortunately, the station went offline on May 4 for upgrades that will last until February 2026. Although it will briefly reactivate in August and December, the engineers needed to ascertain the primary thrusters' functionality before the backup thrusters became completely clogged.
On March 20, the engineering team sent a command signal to Voyager 1 and waited anxiously for 46 hours for a response. When the signal finally reached the spacecraft, data began streaming back, confirming that the thruster heaters were warming up successfully—the fix had worked. "It was such a glorious moment," said Todd Barber, the mission's propulsion lead at JPL. "Team morale was very high that day." The engineers had initially deemed the thrusters non-functional, but one team member's insight led to this unexpected and successful revival.
As both Voyager spacecraft continue their unprecedented journeys through space, their instruments are gradually shutting down, and their power reserves are depleting. While the end of their missions is inevitable, the revival of Voyager 1's backup thrusters has extended their operational life, providing valuable time for continued exploration and data collection from beyond our solar system.
