Voyager's Thruster Revival: A Spacecraft's Second Wind

Voyager 1 has been a space traveler for nearly 50 years, braving the tough conditions of outer space. It is a marvel of engineering that has kept going despite its age. The latest challenge for the team on the ground was to bring back to life a set of thrusters that had been out of action for decades. This was necessary because the spacecraft's main communication tool was going offline for upgrades. The Voyager 1 spacecraft has a twin, Voyager 2. Both spacecraft have primary and backup thrusters. These thrusters help the spacecraft stay pointed in the right direction. They adjust the spacecraft's position and keep the antenna aimed at Earth. The primary roll thrusters on Voyager 1 stopped working in 2004. Since then, the spacecraft has been relying on its backup thrusters. The team had accepted that the primary thrusters were no longer working. They did not expect the Voyagers to keep going for another 20 years. However, the Voyagers kept going, so the team decided to try and fix the primary roll thrusters. They needed to do this before the spacecraft's communication tool went offline. This tool is a radio antenna in Canberra, Australia. It is part of a network that communicates with deep space missions. The antenna will be undergoing upgrades until February 2026. During this time, the Voyagers will be on their own. If the backup roll thrusters fail, the spacecraft could face serious problems. The dormant thrusters could automatically fire if the spacecraft drifts too far from its guide star. This could cause a small explosion and end the mission.

The team suspected that a change in the circuits controlling the heaters' power supply had caused the primary roll thrusters to stop working. They thought that if they could fix this, the heaters might work again. This would allow them to reactivate the primary roll thrusters. On March 20, the primary roll thrusters turned back on after a long break. It was a surprising success. The thrusters were considered dead, but an engineer had an insight that maybe there was another possible cause and it was fixable. The Voyager probes are the first spacecraft to cross into interstellar space. They have been exploring this unfamiliar region for nearly 48 years. During its flybys of Jupiter and Saturn, Voyager 1 contributed to the discovery of moons including Thebe and Metis, and a new ring around Saturn. Voyager 2 was launched on a trajectory toward the solar system’s gas giants, Jupiter and Saturn, before going on to explore the icy giants Uranus and Neptune. All that traveling has taken a toll on the farthest human-made objects, and the spacecraft’s days are numbered. The Voyagers are powered by heat from decaying plutonium, which is converted into electricity. Each year, the aging spacecraft lose about 4 watts of power. In an effort to conserve power, the mission team has turned off any systems that were deemed unnecessary, including a few science instruments. With the current energy-conserving plan, NASA engineers believe the twin spacecraft could continue operating into the 2030s, just making it past their golden anniversary in space.

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