NASA‘s Voyager 1 spacecraft has been in space for nearly 50 years, withstanding the harsh conditions of outer space, while teams on the ground have been figuring out ways to keep its aging equipment from breaking down. In the latest attempt to keep Voyager alive, engineers have managed to bring back to life the spacecraft’s old engines that have been out of service for decades.
NASA engineers have restored a set of engines aboard the Voyager 1 spacecraft to use as a backup while the mission is offline to keep the radio antenna used to communicate with deep space missions up to date, the space agency said this week. Voyager’s main thrusters stopped working in 2004 after losing power to two small internal heaters, but the team managed to restart the engines as the spacecraft flew through interstellar space at a distance of 15.14 billion miles (24.4 billion kilometers).
“Voyager 1 was launched in 1977, less than a month after its twin, Voyager 2, began its journey into space. The twin spacecraft rely on a set of main engines to propel them to keep their antennas pointed at Earth so they can send data and receive commands. The main engines adjust the spacecraft’s orientation – pitch and yaw – while separate engines control its roll. These engines – a set of main and backup units – spin the spacecraft’s antenna like a vinyl record, keeping each Voyager pointed at the star it uses to navigate through space.
Engineers switch between the main and backup engines to prevent them from clogging, but Voyager 1’s main engines broke down 20 years ago, and the spacecraft has relied solely on the backup engines ever since.
“I think at the time the team was willing to accept the fact that the main thrusters were not working because they had a great backup engine,” said Karim Badaruddin, Voyager mission manager at NASA’s Jet Propulsion Laboratory, “and frankly, they had a backup engine. “And, frankly, they probably didn’t think Voyagers would be around for another 20 years.”
Twenty years later, the Voyagers are still traveling, so the team decided to give it another shot at fixing Voyager 1’s main roll thrusters. The engineers in charge of the mission needed to get it done before May 4, when an upgrade to the 230-foot-wide (70-meter) antenna, which is part of NASA’s Deep Space Network, begins in Canberra, Australia. The pause in communications will last until February 2026, with short periods of operation in August and December. This radio antenna is the only antenna with enough signal strength to send commands to Voyagers.
This is a long period of silence, and the mission engineers had to make sure that Voyager 1 could handle it on its own. If the backup thrusters had failed during this time, the spacecraft would have faced significant problems that could have led to the end of the mission. For example, the inoperable engines could have automatically triggered if the spacecraft had deviated too far from its reference star, causing a small explosion.
The team began working to re-examine the problem that could have caused the main thrusters to stop working. “They began to suspect that an unexpected change or disturbance in the circuits that control the power to the heaters had actually moved the switch to the wrong position,” NASA writes. “If they could return the switch to its original position, the heaters could be brought back online, allowing them to reactivate the main thrusters and use them if the backup thrusters, which have been in use since 2004, become completely clogged.”
On March 20, after a long break, the main engines started working again. “These engines were considered dead. And that was a legitimate conclusion,” Todd Barber, the mission propulsion manager at JPL, said in a statement. “It was just that one of our engineers had a hunch that maybe there was another possible cause and it could be fixed. It was another miracle that saved Voyager.”
The Voyager probes, the first spacecraft to cross interstellar space, have been exploring an unfamiliar region for almost 48 years. During its flight past Jupiter and Saturn, Voyager 1 contributed to the discovery of satellites such as Thebes and Metis, as well as a new ring around Saturn. NASA launched Voyager 2 on a trajectory to the gas giants of the Solar System, Jupiter and Saturn, and then continued to explore the ice giants Uranus and Neptune.
All of these journeys have had an impact on the most distant objects created by man, and the days of the spacecraft are numbered. “Voyagers are powered by heat from the decay of plutonium, which is converted into electricity. Every year, aging spacecraft lose about 4 watts of power. In an effort to conserve energy, the mission team turned off all systems that it deemed unnecessary, including several scientific instruments. NASA engineers believe that thanks to the current energy-saving plan, the twin spacecraft will be able to continue operating until the 2030s, just in time for their golden anniversary in space.
