Voyager 1 spacecraft phones home with transmitter that hasn't been used since 1981

Voyager 1, launched in September 1977, is currently exploring the farthest edges of the solar system.
Artist rendering of Voyager 1 in space. (Image credit: NASA)

Following recent communication issues, NASA's Voyager 1 spacecraft resorted to using a backup radio transmitter that has been inactive since 1981.

The interstellar explorer experienced a brief pause in communications after putting itself in a protective state to conserve power. This was triggered by a command sent on Oct. 16 from NASA's Deep Space Network (DSN) — a global array of giant radio antennas — instructing the spacecraft to turn on one of its heaters.

The mission's flight team first realized there was an issue with Voyager 1 on Oct. 18, when the spacecraft failed to respond to that command. The team later discovered that the spacecraft had turned off its primary X-band radio transmitter and instead switched over to its secondary S-band radio transmitter, which uses less power, according to a statement from NASA.

"The transmitter shut-off seems to have been prompted by the spacecraft's fault protection system, which autonomously responds to onboard issues," NASA officials said in the statement. "The team is now working to gather information that will help them figure out what happened and return Voyager 1 to normal operations."

Related: NASA shuts off Voyager 2 science instrument as power dwindles

Voyager 1's fault protection system can be triggered for a number of reasons, such as if the spacecraft overdraws its power supply. If that happens, the spacecraft will turn off all non-essential systems to conserve power and remain in flight.

After sending instructions to Voyager 1 on Oct. 16, the team expected to receive data back from the spacecraft within a couple of days; it normally takes about 23 hours for a command to travel more than 15 billion miles (24 billion kilometers) to reach the spacecraft in interstellar space, and then another 23 hours for the flight team on Earth to receive a signal back.

However, on Oct. 18, the team was unable to detect Voyager 1's signal on the X-band frequency that the DSN antennas were listening for. This was because, to use less power, the spacecraft's fault protection system lowered the rate at which its radio transmitter was sending back data. The flight team was able to locate a signal later that day – but then, on Oct. 19, communication with Voyager 1 stopped entirely when its X-band transmitter was turned off.

The spacecraft's fault protection system is believed to have been triggered twice more, ultimately causing it to switch to the S-band radio transmitter, which, prior to that date, hadn't been used since 1981. Given the spacecraft is located much farther away in interstellar space today than it was 43 years ago, the flight team was not sure a signal on the S-band frequency could be detected — especially because it transmits a significantly fainter signal while using less power.

However, the team didn't want to risk sending another signal to the X-band transmitter and triggering the fault protection system again. So, instead, a command was sent to the S-band transmitter on Oct. 22. Two days later, on Oct. 24, the team was finally able to reconnect with Voyager 1.

Now, the team will investigate what may have triggered the spacecraft's fault protection system in the first place, given Voyager 1 should have had ample power to operate the heater. However, it may be weeks before operators identify the underlying issue, according to the statement.

Voyager 1, which launched in 1977, ventured into interstellar space in 2012, becoming the first spacecraft to cross the boundary of our solar system. Its time in deep space has taken a toll on its instruments and caused an increasing number of technical issues. Earlier this year, the team had to fix a separate communications glitch that was causing the spacecraft to transmit gibberish.

While spacecraft's advanced age and distance from Earth can make maintenance challenging, Voyager 1 continues to return vital data from beyond the solar system.

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Samantha Mathewson
Contributing Writer

Samantha Mathewson joined Space.com as an intern in the summer of 2016. She received a B.A. in Journalism and Environmental Science at the University of New Haven, in Connecticut. Previously, her work has been published in Nature World News. When not writing or reading about science, Samantha enjoys traveling to new places and taking photos! You can follow her on Twitter @Sam_Ashley13. 

  • Joexo
    Can someone explain me how is it possible that we can send a message from here and Voyager will receive it even if 25 billion km from us?

    There are no interferences in space? I would think that if nothing else at least there should be the chance that planets make some kind of "shadow"?

    I suppose the Voyager is on a different plane than the planet so there's just vacuum?
    Reply
  • George²
    Joexo said:
    1. Can someone explain me how is it possible that we can send a message from here and Voyager will receive it even if 25 billion km from us?

    2. There are no interferences in space? I would think that if nothing else at least there should be the chance that planets make some kind of "shadow"?

    3. I suppose the Voyager is on a different plane than the planet so there's just vacuum?
    1. Answer Much more energy per received and transmitted bit of information. Data is digital not analogue.
    2. Perhaps you imagine the planets very large, like some diagram of the solar system that shows the planets on a scale that in no way corresponds to the real thing. But even the star Sun is tiny compared to billions and tens of billions of miles, and the planets are vastly smaller. Yes, the planets are an obstacle, but when distance now is so big it's so minor* and besides they move and they don't cover their entire orbits in the plane (ecliptic) constantly.

    3.Yes, the trajectory of the Voyagers was slightly above and below eclipse when travelling in solar system between planets with reason to avoid collision with dust and asteroids. After end of planetary part of Voyager 1 mission it's trajectory was set to big angle above ecliptic. Video.
    *Of course, when Voyager was still traveling between the planets and was close to and behind them relative to Earth, the influence of the large planets and their magnetospheres was significant.
    Reply
  • RBruce
    Does planetary gravity affect signal transmission direction and speed?
    Reply
  • Meteoric Marmot
    RBruce said:
    Does planetary gravity affect signal transmission direction and speed?
    All gravity wells warp spacetime, but planets are so small (relatively speaking) that I assume that their effect is minor to negligible.

    The "speed of transmission" is an inexact term. The signal itself travels at the speed of light (because it is electromagnetic radiation just as light is) and it is not affected by gravity, only by changes in the medium it is traversing.

    The speed of data transmission is a different animal and depends on a variety of factors -- predominantly on the technology used. I can't think of anything that gravity could affect, but I could be wrong.
    Reply
  • BrianR
    What happened to voyager 2? Is that still functioning?
    Reply
  • billslugg
    EM waves respond to gravity. The Sun's gravity will bend the light of a star behind it.
    Gravity warps spacetime. Everything follows spacetime, whether massive or not.
    Reply
  • RBruce
    Meteoric Marmot said:
    All gravity wells warp spacetime, but planets are so small (relatively speaking) that I assume that their effect is minor to negligible.

    The "speed of transmission" is an inexact term. The signal itself travels at the speed of light (because it is electromagnetic radiation just as light is) and it is not affected by gravity, only by changes in the medium it is traversing.

    The speed of data transmission is a different animal and depends on a variety of factors -- predominantly on the technology used. I can't think of anything that gravity could affect, but I could be wrong.
    Let me restate. Assume signal travels at the speed of light. Does gravity affect the distance travelled which would lengthen the time from the point-of-view of someone on Earth. Rough calculations shows a signals takes 22hours to be received. A lot can alter the signal's course. Is there a time synchronization code between Voyager and receiver to calculate distance? Is there a second distance measurement to compare the receiving times?
    Reply
  • bolide
    billslugg said:
    EM waves respond to gravity. The Sun's gravity will bend the light of a star behind it.
    Gravity warps spacetime. Everything follows spacetime, whether massive or not.
    Not an issue in the present case. There's no gravitational force between us & the satellite that would have a meaningful effect on signals sent or received.
    Reply
  • billslugg
    The gravitational field of the Sun will affect EM waves slightly. The effect on the outgoing signal is exactly balanced by the effect on the incoming signal.
    Reply
  • Torbjorn Larsson
    It 's both heroic and nail biting worthy, but every little holdup interferes with and cuts down on the remaining science.
    Voyager 1's extended mission is expected to continue to return scientific data until at least 2025, with a maximum lifespan of until 2030.
    https://en.wikipedia.org/wiki/Voyager_1
    BrianR said:
    What happened to voyager 2? Is that still functioning?
    The spacecraft is now in its extended mission of studying the interstellar medium. It is at a distance of 138.05 AU (20.7 billion km; 12.8 billion mi) from Earth as of October 2024.
    The probe entered the interstellar medium on November 5, 2018, at a distance of 119.7 AU (11.1 billion mi; 17.9 billion km) from the Sun and moving at a velocity of 15.341 km/s (34,320 mph) relative to the Sun. Voyager 2 has left the Sun's heliosphere and is traveling through the interstellar medium, though still inside the Solar System, joining Voyager 1, which had reached the interstellar medium in 2012. Voyager 2 has begun to provide the first direct measurements of the density and temperature of the interstellar plasma.
    https://en.wikipedia.org/wiki/Voyager_2
    billslugg said:
    EM waves respond to gravity. The Sun's gravity will bend the light of a star behind it.
    Gravity warps spacetime. Everything follows spacetime, whether massive or not.
    The non-reciprocal gravitational time dilation differences in climbing out of Sun's gravity well at large distances doesn't seem to interfere with the signal decoding timing, and for radial signals the space curvature lensing will be insignificant.

    Radio astronomy can currently look back to the early universe, whether for strong radio bursts or for weak gas cloud emissions. (Admittedly in the latter case with the cheat of precisely strong gravitational lensing amplification of 30 times with the help of a foreground object. We need at least 100 - 1000 times better radio telescopes!).

    This 'fast radio burst' (FRB) is the most distant ever detected. Its source was pinned down by the European Southern Observatory’s (ESO) Very Large Telescope (VLT) in a galaxy so far away that its light took eight billion years to reach us. The FRB is also one of the most energetic ever observed; in a tiny fraction of a second it released the equivalent of our Sun’s total emission over 30 years.
    https://www.eso.org/public/news/eso2317/
    Using GMRT data, Arnab Chakraborty, postdoctoral researcher at the Department of Physics and Trottier Space Institute of McGill University, and Nirupam Roy, Associate Professor, Department of Physics, IISc have detected a radio signal from atomic hydrogen in a distant galaxy at redshift z=1.29.

    "Due to the immense distance to the galaxy, the 21 cm emission line had redshifted to 48 cm by the time the signal traveled from the source to the telescope," says Chakraborty. The signal detected by the team was emitted from this galaxy when the universe was only 4.9 billion years old; in other words, the look-back time for this source is 8.8 billion years.

    This detection was made possible by a phenomenon called gravitational lensing, in which the light emitted by the source is bent due to the presence of another massive body, such as an early type elliptical galaxy, between the target galaxy and the observer, effectively resulting in the "magnification" of the signal. "In this specific case, the magnification of the signal was about a factor of 30, allowing us to see through the high redshift universe," explains Roy.
    https://phys.org/news/2023-01-record-breaking-radio-atomic-hydrogen-extremely.html
    Reply