At an astonishing distance of 15.4 billion miles from Earth, Voyager 1 is meandering through interstellar space, yet its expedition may soon reach a conclusion. Recently, NASA’s flight engineers expressed concern that the 47-year-old spacecraft had potentially gone silent after unexpectedly halting communication. The primary radio transmitter of the probe, crucial for connection with mission control, had ceased functioning.

The problem began on October 16, when flight controllers issued a standard command to activate a heater. However, two days later, upon anticipating a reply, they found that Voyager 1’s fault protection system had been activated, resulting in the shutdown of its X-band transmitter. By October 19, all communication had stopped completely.

The flight team was not optimistic. Nonetheless, Voyager 1 possessed a backup transmitter, although it operated on a significantly weaker frequency. Considering the great distance and age of the spacecraft, there was uncertainty about whether this secondary transmitter would still be operational. Days later, engineers from NASA’s Deep Space Network—a network of three enormous radio dish arrays on Earth—picked up a faint signal from the S-band transmitter, which had not been utilized since 1981.

“The team is currently working to collect information that will assist in understanding what occurred and in restoring Voyager 1 to normal functioning,” NASA stated in a recent mission update.

Both Voyager 1 and its counterpart, Voyager 2, have been functioning for nearly 50 years, far surpassing their original operational timeline. Launched in 1977, the spacecraft were initially intended to investigate Jupiter, Saturn, their moons, and Saturn’s rings. The mission was projected to endure just five years. However, following their initial achievements, engineers broadened the mission to encompass Uranus and Neptune. Together, the two spacecraft have explored four planets, 48 moons, and numerous planetary magnetic fields and rings.

In August 2012, Voyager 1 made history by crossing into interstellar space—the area between stars filled with remnants from stars that perished millions of years ago. Both Voyagers are the sole spacecraft that have ventured beyond the heliosphere, the region of space affected by the Sun’s solar wind.

Currently, Voyager 1 is hurtling away from the solar system at speeds exceeding 38,000 mph, making it the most distant human-made object from Earth. Due to its vast distance, a command takes 23 hours to reach the spacecraft, with another 23 hours required for mission control to receive a reply.

NASA has previously indicated that the Voyagers lose approximately 4 watts of power annually, which restricts the number of systems they can operate. To save power, flight controllers have occasionally powered down non-essential devices. The aim is to maintain both spacecraft’s functionality beyond 2025.

The specific reason for Voyager 1’s recent difficulties remains uncertain. The fault protection system is programmed to deactivate non-essential systems when the spacecraft encounters challenges, such as excessive power consumption. However, data suggests that Voyager 1 should have had sufficient power to activate the heater without issue.

Interstellar space presents a high-radiation environment that no human-made object has navigated previously, meaning the mission team continuously confronts new obstacles. Just last month, the team tackled a thruster issue on Voyager 1. At this juncture of the mission, nothing is straightforward or assured, stated Suzanne Dodd, Voyager project manager.

“All decisions we must make moving forward will necessitate significantly more analysis and caution than they did in the past,” Dodd remarked.