Voyager 1 is currently exploring interstellar space at a distance of 15.5 billion miles (24.9 billion kilometers) from Earth. Communicating with the most distant human-made object can be challenging, but not for a telescope that is designed to listen to low frequencies emanating from space.
A team of amateur astronomers used the Dwingeloo radio telescope in the Netherlands to receive signals from Voyager 1 after a communication failure forced the spacecraft to rely on a backup transmitter. Dwingeloo, built in the 1950s, belongs to an elite group of telescopes capable of detecting Voyager’s weak radio signals from deep space, which is crucial when NASA’s antennas are unable to communicate with the spacecraft.
In late October, Voyager 1 suddenly turned off one of its radio transmitters, forcing the mission team to rely on a backup device, a weaker transmitter that had not been used since 1981. Voyager’s second radio transmitter, operating in the S-band, transmits a much weaker signal than the X-band transmitter. The NASA team was not sure that the S-band signal could be detected because the spacecraft is much further away today than it was 43 years ago. NASA uses the Deep Space Network to communicate with its spacecraft, but the global array of giant radio antennas is optimized for higher-frequency signals.
The Dwingeloo telescope, on the other hand, is designed to observe at lower frequencies than the 8.4 gigahertz telemetry transmitted by Voyager 1, according to the K.A. Muller Radio Astronomy Station. Normally, Dwingeloo would not have been able to detect the signals transmitted by Voyager 1 because the dish’s grid has less reflectivity at higher frequencies. However, when Voyager 1 switched to a lower frequency, its messages fell into the Dwingeloo’s frequency range. Thus, astronomers took advantage of the spacecraft’s communication failure to listen to its faint signals for NASA.
The astronomers used orbital predictions of Voyager 1’s position in space to correct for the Doppler frequency shift caused by the Earth’s motion as well as the spacecraft’s motion in space. A faint signal was found on the air, and further analysis later confirmed that it corresponded to the position of Voyager 1.
Fortunately, NASA’s mission team turned Voyager 1’s X-band transmitter back on in November, and is now completing the few remaining tasks to return the spacecraft to normal. Fortunately, radio telescopes such as Dwingeloo can help fill in the gaps while NASA’s communications network has trouble accessing the spacecraft.
The iconic Voyager 1 has provided scientists with invaluable data about the solar system and beyond for decades. On its way to interstellar space, the probe had close encounters with Jupiter and Saturn and discovered two of Jupiter’s moons, Phebe and Metis, as well as five new moons and a new ring called the G-ring around Saturn.
