Voyager 1, positioned 15.4 billion miles from Earth in interstellar space, is nearing the end of its operational life. NASA engineers initially suspected that the 47-year-old mission may have concluded when the spacecraft recently became silent, having turned off its main radio transmitter used for communication with mission control.
The issue began on October 16, when flight controllers dispatched a routine command to activate a heater on the spacecraft. Upon expecting a response two days later, NASA discovered that Voyager’s fault protection system had been triggered, subsequently turning off its X-band transmitter. By October 19, all communications had ceased.
Prospects appeared bleak for the flight team. Nonetheless, Voyager 1 has a backup transmitter that utilizes a different, albeit much weaker, frequency. The team was uncertain if this secondary transmitter could still operate, considering the spacecraft’s distance and age. After several days, engineers from the Deep Space Network, comprising three large radio dish arrays on Earth, detected a faint signal transmitted over the S-band frequency. This frequency had not been utilized since 1981, according to NASA.
In a recent mission update, NASA stated, “The team is now working to gather information that will help them figure out what happened and return Voyager 1 to normal operations.”
Voyager 1 and its twin, Voyager 2, have been operational for nearly five decades, surpassing their initial life expectancy. Launched in 1977, the pair was originally designed to study Jupiter, Saturn, their moons, and Saturn’s rings, with an expected operational duration of five years.
Following their initial successes, engineers expanded the mission to include Uranus and Neptune. Collectively, the two spacecraft have explored four planets, 48 moons, and various planetary magnetic fields and rings.
In August 2012, Voyager 1 became the first human-made object to enter interstellar space, a region between stars filled with material from long-dead stars. Voyager 1 and 2 remain the only spacecraft to operate beyond the heliosphere, the area of space influenced by the sun’s flow of material.
Voyager 1 is moving away from the solar system at more than 38,000 mph, marking it as the farthest human-made object from Earth. Due to the distance, it takes 23 hours for a command to reach the spacecraft and another 23 hours for a response.
NASA has indicated that the power generated by the Voyagers decreases by about four watts annually, restricting the operational systems onboard. Controllers occasionally deactivate equipment to conserve energy, aiming to maintain functionality beyond 2025.
The reason for Voyager 1’s fault protection system deactivating the main radio transmitter remains unclear. Normally, this system powers down non-essential equipment when issues arise, such as if the spacecraft overdraws its power supply. According to data, Voyager 1 should have had adequate power to activate the heater without complications.
Interstellar space presents a high-radiation environment previously untraversed by human-made objects, leading to a multitude of potential surprises for mission teams. Last month, the team addressed a thruster problem with Voyager 1. Voyager project manager Suzanne Dodd highlighted in a statement that at this stage of the mission, no task is straightforward or assured.
Dodd stated, “All the decisions we will have to make going forward are going to require a lot more analysis and caution than they once did.”
