The National Aeronautics and Space Administration (NASA) announced this week that on October 24, the farthest spacecraft from Earth, Voyager 1, reestablished contact with NASA from 15 billion miles away in space through a channel that had not been used in 43 years after a few days of loss of communication. However, the spacecraft has not yet been freed from its predicament, as the ground team is still working to identify the cause of the malfunction.
Voyager 1 is currently using a radio transmitter that has not been used since 1981 to communicate with the team on Earth. At the same time, NASA engineers are striving to determine what went wrong with this spacecraft, which has the longest operational history among NASA’s missions. The legendary spacecraft recently shut down one of its two radio transmitters.
NASA stated that the shutdown of the radio transmitter appears to have been triggered by the spacecraft’s fault protection system. This system can autonomously respond to onboard issues. For example, if Voyager 1 is experiencing power constraints, the fault protection system will shut down non-essential systems to conserve power needed for the spacecraft’s flight. It may take the ground team several days to weeks to identify the root cause that triggered the fault protection system.
When the team at NASA’s Jet Propulsion Laboratory sends commands to Voyager 1 through the Deep Space Network, the spacecraft responds by transmitting engineering data, which helps the ground team assess its response to the commands. This process typically takes two days because the commands have to travel over 15 billion miles from Earth, taking almost 23 hours to reach Voyager 1, and the spacecraft’s data transmission back to Earth also takes 23 hours.
According to CNN, Voyager Mission Assurance Manager Bruce Waggoner mentioned that engineers occasionally send commands to Voyager 1 to activate some heaters to warm up components that have suffered radiation damage over the past few decades. Heating can help reverse radiation damage, which can degrade spacecraft components’ performance.
On October 16, the ground team sent a command to activate one of Voyager 1’s heaters. Although the spacecraft should have had enough power to operate the heater, this command triggered the fault protection system. It was not until October 18 when the team realized the issue as the Deep Space Network failed to detect Voyager 1’s signal.
Voyager 1 usually uses X-band radio transmitters to communicate with NASA. The team speculates that the fault protection system reduced the rate at which the transmitter sent back data, a mode that consumes less power for Voyager 1 but also alters the X-band signal that the Deep Space Network needs to listen to. The ground team began investigating what was happening.
By October 19, communication seemed to have completely ceased. The ground team suspected that Voyager 1’s fault protection system was triggered twice more, causing it to shut down the X-band transmitter and switch to the S-band radio transmitter. Although the S-band uses less power, Voyager 1 has not used the S-band transmitter to communicate with Earth since 1981. The frequency used by the S-band transmitter is different from the X-band, resulting in a much weaker signal. Due to the spacecraft’s distance from Earth, the ground team could not be certain if the S-band signal could be detected on Earth, but the Deep Space Network engineers eventually located it.
On October 22, NASA sent a command to confirm that the S-band transmitter was functioning. The team is currently working to gather information to help them understand what occurred and to return Voyager 1 to normal operation.
Voyager 1 is currently approximately 15 billion miles away from Earth, making it the farthest spacecraft from humanity. Voyager 2 is over 12 billion miles away from Earth. Launched in 1977, these two spacecraft have been traveling in space for 47 years, conducting direct sampling of interstellar space. The information collected by both spacecraft is aiding scientists in understanding the heliosphere’s comet-like shape and how it shields Earth from high-energy particles and radiation in interstellar space.
They are NASA’s longest-operating and farthest-traveling spacecraft. They have both flown by Jupiter and Saturn, with Voyager 2 also passing Uranus and Neptune.
Last November, Voyager 1 was unable to transmit readable data to Earth due to a computer malfunction. NASA’s team creatively restored communication with the spacecraft and announced in June of this year that the spacecraft had resumed scientific research.
The advanced age of Voyager 1 and Voyager 2 means an increase in the frequency and complexity of technical issues, presenting new challenges for the mission engineering team.
Suzanne Dodd, the Voyager program manager at NASA’s Jet Propulsion Laboratory (JPL), once told CNN, “We can never be sure what Voyager will do next, but they just keep on going, and that continues to amaze me.”