Voyager 1 breaks the silence towards NASA via a radio transmitter that has not been used since 1981

In 1977, NASA launched Voyager 1 and 2: a pair of spacecraft that would circumnavigate Jupiter, Saturn, Uranus and Neptune using a rare alignment of the outer planets that only happens once every 175 years. The two probes had both completed their encounters with these worlds by 1989and since then they have traveled to the outer limits of our solar system and beyond, sending critical scientific data back to Earth.

Recently, however, Voyager 1 went silent for a while. It cut communications with NASA in mid-October, then reestablished contact in an unexpected way: a spare radio transmitter that had been inactive since 1981.

“The spacecraft recently disabled one of its two radio transmitters and the team is now trying to determine what is causing the problem,” a NASA official said. blog post.

NASA’s twin Voyager probes have been flying for 47 years, meaning the agency’s scientists and engineers on Earth are increasingly encountering age-related maintenance issues, per Space.com‘s Samantha Mathewson. For example, last December Voyager 1 started sending nonsensical messages. Engineers solved the problem five months later, restoring the craft at full capacity this summer.

On October 16, Voyager 1 experienced another hiccup. Scientists sent the probe a command to turn on one of the heating elements, but for some reason the command activated the fault protection system, which is built to autonomously respond to problems on board. To save energy, the failsafe system occasionally shuts down non-essential processes, but Voyager 1 should have had enough energy to run the heater.

Because the probe is currently more than 15 billion miles away– making it the farthest spacecraft from Earth – it takes almost 23 hours for a command to reach the craft and another 23 hours for the response to reach scientists. That means the NASA team didn’t notice anything was wrong until two days later, when they detected no response from the probe.

Scientists communicate with both Voyager probes using a radio transmitter that works on X band frequencies, within a range of 8 to 12 gigahertz, via NASA’s Deep space networka web of giant radio antennas that form part of the world’s largest and most sensitive scientific telecommunications system. However, NASA soon realized that to save energy, Voyager 1 had started sending signals at a lower speed on the transmitter, and teams had successfully found the new signal.

Then, on October 19, Voyager 1 stalled again. The team speculated that the probe may have disabled its X-band transmitter completely in favor of a backup S band radio transmitter, which operates at a much lower frequency of two to four gigahertz, an instrument it has not used for 43 years. Communicating via the S-band uses less power, but the signal is also weaker. If that were the case, NASA scientists weren’t sure they would be able to detect it from Earth. Combined with the fact that Voyager 1 is now much further away than when it last used S-band in the 1980s, finding the signal could have been a difficult task.

Fortunately, the Deep Space Network was indeed able to pick up the new, weaker signal, and scientists are now trying to understand what caused Voyager 1 to turn off its X-band transmitter.

The agency’s engineers will proceed cautiously because they don’t want to risk the well-being of the spacecraft by trying to turn the X-band back on prematurely, as Bruce Waggoner, the Voyager mission assurance manager, tells us. CNN“Ashley Strickland. But if they can get the channel back online, it might be able to tell them what went wrong.

“The S-band signal is too weak to use in the long term,” Wagoner told CNN. “So far, the team has not been able to use it to obtain telemetry (information about the health and status of the spacecraft), let alone scientific data. But it allows us to at least send commands and make sure the spacecraft is still aimed at Earth.”

Despite how long ago the twin probes were launched, the Voyager spacecraft are built to last. “A profound insight gained during Voyager 1’s odyssey is the importance of redundancy in mission-critical hardware,” writes Eric Ralls for Earth.com. “The foresight to build in a backup radio transmitter decades ago underscores the need to plan for the contingency in space exploration.”

“We didn’t design them to last thirty or forty years, we designed them not to fail,” Johannes CasaniVoyager project manager from 1975 to 1977, says in a NASA statement.

In 2012, Voyager 1 became the first spacecraft to leave space heliosphere– a kind of bubble that surrounds the solar system, filled with the sun’s magnetic field and the solar wind – making it the first spacecraft to enter interstellar space. Voyager 2 reached the cosmic milestone six years later.

Voyager 1 will likely have enough power to run its scientific instruments until 2025 Newsweek‘s Tom Howarth, but NASA should be able to maintain communications with the spacecraft into the 2030s.