The Voyager probes, launched in 1977, have performed spectacularly well over nearly half a century, flying past various planetary bodies and studying them before continuing to the outer reaches of the Solar System. Voyager 1, the first of the two probes to launch, is now 171 astronomical units (AU) from Earth, where 1 AU is the average distance from Earth to the Sun.
On November 13 of this year, Voyager 1 is expected to hit a new landmark for humanity; the first time a human-made object has reached a full light day from Earth. When that happens, it will never be possible to communicate with the probe from Earth without factoring a full day's travel time for the signal.
While a resounding success, the probes are starting to show some signs of wear and tear. A diminishing fuel supply has taken its toll, forcing NASA to shut down scientific instruments to keep the rest of the craft running. There have also been several glitches, with Voyager 1 sending back a garbled pattern of zeros and ones for a time due to corrupted memory, then shutting down its main transmitter entirely. The latter problem was solved in October 2024 by switching temporarily to a transmitter not used since 1981. Since then, communication with the aging spacecraft has been steady, with NASA's Deep Space Network regularly receiving data from both probes. It's no easy feat, given the distances involved.
"The antennas must capture Voyager information from a signal so weak that the power striking the antenna is only 10 exponent -16 watts (1 part in 10 quadrillion)," NASA explains. "A modern-day electronic digital watch operates at a power level 20 billion times greater than this feeble level."
Impressively, the Amateur Radio in Space (AMSAT) group using the Dwingeloo radio telescope have now detected Voyager 1. The group had detected the spacecraft in 2006, but then it was a mere 14.7 billion kilometers (9.1 billion miles) away.
"In all these years, Voyager has traveled a lot of distance," Thomas Telkamp, active volunteer at the historic Dwingeloo Radio Telescope, explained at the AMSAT symposium. "So the signal is really weaker at this point than it was years ago."
Not having NASA's resources, amateurs attempting to detect Voyager have a more difficult job, making the detection even more impressive.
"Since the Dwingeloo telescope was designed for observing at lower frequencies than the 8.4GHz telemetry transmitted by Voyager 1, a new antenna had to be mounted. At these higher frequencies, the mesh of the dish is less reflective, making it extra challenging to receive faint signals," C.A. Muller Radio Astronomy Station (CAMRAS) explained in a blog post following a previous detection in 2024.
"To find the very weak carrier signal in the noise, we used orbital predictions of Voyager 1 to correct for the Doppler shift in frequency caused by motion of Earth and Voyager 1. By doing so, the signal could be seen live in the telescope observation room. Later analysis confirmed that the Doppler shift corresponds to that of Voyager 1."
Despite the telescope being far smaller than those that make up NASA's Deep Space Network, the team was able to receive the signal, making it one of the few telescopes on Earth to have received communication from Voyager 1.
Unfortunately, the spacecraft's mission is slowly coming to a close. With fuel dwindling, Voyager 1 is expected to power down permanently in the early 2030s, making detection – by amateurs or NASA – virtually impossible beyond that timeframe.
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