After a pause, Voyager 1 contacted the mission team

Tony Gracious, 10/28/2024, NASA Jet Propulsion Laboratory

The tiny dot in the middle of the brownish stripe on the right is the Earth from a distance of 6 billion kilometers. This is one of the last images taken by the Voyager 1 spacecraft between February 14 and June 6, 1990. Credit: NASA

The tiny dot in the middle of the brownish stripe on the right is the Earth from a distance of 6 billion kilometers. This is one of the last images taken by the Voyager 1 spacecraft between February 14 and June 6, 1990. Credit: NASA

On October 24, NASA restored communication with the Voyager 1 spacecraft after a short pause in communication. The spacecraft recently turned off one of its two radio transmitters, and the team is now working to determine what caused the problem.

The transmitter shutdown was apparently caused by the spacecraft's crash protection system, which autonomously responds to problems on board. For example, if a spacecraft overloads its power supply, fault protection will save energy by shutting down systems that are not essential to keeping the spacecraft in flight. But it can take days to weeks before the team is able to determine the underlying problem that caused the failsafe to trip.

When the mission team, which is based at NASA's Jet Propulsion Laboratory in Southern California, transmits instructions to the spacecraft via Deep Space Network agency, Voyager 1 sends back technical data that the mission team evaluates to determine how the spacecraft responded to the command. Typically this process takes a couple of days – almost 23 hours for the control signal to overcome more than 15 billion miles (24 billion kilometers) from Earth to the spacecraft, and another 23 hours for the data to return.

On October 16, the flight team sent a command to turn on one of the spacecraft's heaters. Although Voyager 1 should have had enough power to operate the heater, the failsafe system tripped. The mission team became aware of the problem when the Deep Space Network was unable to detect Voyager 1's signal on October 18.

Typically, a spacecraft communicates with Earth using something called an X-band radio transmitter, named for the specific frequency it uses. The flight team correctly surmised that the crash protection system had reduced the speed at which the transmitter was sending data. This mode requires less power from the spacecraft, but it also changes the X-band signal that the Deep Space Network must listen to. Engineers discovered the signal later that day, and Voyager 1 otherwise appeared to be in a stable condition as the team began investigating what happened.

Then, on October 19, communication seemed to cease completely. The flight team suspected that Voyager 1's failsafe system had tripped twice more and that it had turned off the X-band transmitter and switched to a second S-band radio transmitter. Although S-band uses less power, Voyager 1 has not used it to communicate with Earth since 1981. It uses a different frequency, the signal of which is much weaker than that of the X-band transmitter. The mission team was unsure if S-band could be detected on Earth due to the spacecraft's distance, but Deep Space Network engineers were able to detect it.

Rather than risk turning X-band back on until the cause of the failsafe trip was determined, the team sent a command on October 22 to confirm the functionality of the S-band transmitter. The team is now working to gather information that will help them figure out what happened and return Voyager 1 to normal operation.

Voyager 1 and Voyager 2 have been in flight for over 47 years and are the only two spacecraft operating in interstellar space. Their advanced age means an increase in the frequency and complexity of technical problems and new challenges for the mission engineering team.

More information about the Voyager mission can be found at:
https://science.nasa.gov/mission/voyager

Translation: Alexander Tarlakovsky (blog tay-ceti)

Original: After Pause, NASA's Voyager 1 Communicating With Mission Team

Additional information:
Pale Blue Dot

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