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9th November 2024
10:41am GMT
NASA has announced it has reconnected with the Voyager 1 spacecraft after a period of radio silence.
Voyagers 1 and 2 have been flying for more than 47 years and are the only two spacecraft to operate in interstellar space.
Voyager 1 is currently 15 billion miles from Earth.
The spacecraft recently turned off one of its two radio transmitters - and experts are now trying to discover what happened.
“The spacecraft recently turned off one of its two radio transmitters, and the team is now working to determine what caused the issue,” according to a NASA blog post.
Their age means that an increase in the frequency and complexity of technical issues is more likely and raises new challenges for the mission engineering team.
The team believes that the transmitter shut-off was caused by the spacecraft’s fault protection system, which autonomously responds to onboard issues.
For example, if the spacecraft overdraws its power supply, fault protection will conserve power by turning off systems that aren’t essential for keeping it flying.
However, it may take weeks for the team to identify the underlying issue that triggered the fault protection system.
When the flight team, which is based at NASA’s Jet Propulsion Laboratory in Southern California, beams instructions to the spacecraft via the agency’s Deep Space Network, Voyager 1 sends back engineering data that the team assesses to determine how the spacecraft responded to the command.
This process takes a couple of days — almost 23 hours for the command to travel more than 15 billion miles (24 billion kilometres) from Earth to the spacecraft, and another 23 hours for the data to travel back.
On October 16, the flight team sent a command to turn on one of the spacecraft’s heaters.
While Voyager 1 should have had ample power to operate the heater, the command triggered the fault protection system.
The team only became aware of the issue when the Deep Space Network couldn’t detect Voyager 1’s signal on October 18.
The spacecraft typically communicates with Earth using what’s called an X-band radio transmitter, named for the specific frequency it uses.
The flight team correctly theorised that the fault protection system had lowered the rate at which the transmitter was sending back data because it requires less power from the spacecraft. However, this also changes the X-band signal that the Deep Space Network needs to listen out for.
Engineers found the signal later that day, and Voyager 1 otherwise seemed to be stable as the team began to investigate what had happened.
However, on October 19, communication appeared to stop entirely.
The team suspected that Voyager 1’s fault protection system was triggered twice more and that it turned off the X-band transmitter and switched to a second radio transmitter called the S-band.
Voyager 1 had not used the S-band to communicate with Earth since 1981.
The team were worried that the S-band would not be detected on Earth due to the spacecraft’s distance, but engineers with the Deep Space Network were able to find it.
They then sent a command on October 22 to confirm the S-band transmitter was working and will gather information that will help them figure out what happened before returning Voyager 1 to normal operations.
