Voyager 1 Signals from Interstellar Space Detected by Amateur Astronomers on 1950s Telescope

'Voyager 1 is currently exploring interstellar space at a distance of 15.5 billion miles (24.9 billion kilometers) away from Earth,' writes Gizmodo.

And yet a team of amateur astronomers in the Netherlands was able to receive Voyager's signals on a 1950s telescope designed to detect weak, low-frequency emissions from deep space:

NASA uses the [Earth-based] Deep Space Network (DSN) to communicate with its spacecraft, but the global array of giant radio antennas is optimized for higher frequency signals. Though NASA's DSN antennas are capable of detecting S-band missives from Voyager — it can also communicate in X-band — the spacecraft's signal can appear to drop due to how far Voyager is from Earth. The Dwingeloo telescope, on the other hand, is designed for observing at lower frequencies than the 8.4 gigahertz telemetry transmitted by Voyager 1, according to the C.A. Muller Radio Astronomy Station... [W]hen Voyager 1 switched to a lower frequency, its messages fell within Dwingeloo's frequency band. Thus, the astronomers took advantage of the spacecraft's communication glitch to listen in on its faint signals to NASA.

The astronomers used orbital predictions of Voyager 1's position in space to correct for the Doppler shift in frequency caused by the motion of Earth, as well as the motion of the spacecraft through space. The weak signal was found live, and further analysis later confirmed that it corresponded to the position of Voyager 1.
Thankfully, the mission team at NASA turned Voyager 1's X-band transmitter back on in November, and is currently carrying out a few remaining tasks to get the spacecraft back to its regular state. Fortunately, radio telescopes like Dwingeloo can help fill in the gaps while NASA's communications array has trouble reaching its spacecraft.

Scientific American shares an interesting perspective on the Voyager probes:
we everyday Earthlings may simplistically think of the sun as a compact distant ball of light, in part because our plush atmosphere protects us from our star's worst hazards. But in reality the sun is a roiling mass of plasma and magnetism radiating itself across billions of miles in the form of the solar wind, which is a constant stream of charged plasma that flows off our star. The sun's magnetic field travels with the solar wind and also influences the space between planets. The heliosphere grows and shrinks in response to changes in the sun's activity levels over the course of an 11-year cycle... [Jamie Rankin, a space physicist at Princeton University and deputy project scientist of the Voyager mission] notes, astronomers of all stripes are trapped within that chaotic background in ways that may or may not affect their data and interpretations. 'Every one of our measurements to date, until the Voyagers crossed the heliopause, has been filtered through all the different layers of the sun,' Rankin says.
On their trek to interstellar space, the Voyagers had to cross a set of boundaries: first a termination shock some seven billion or eight billion miles away from the sun, where the solar wind abruptly begins to slow, then the heliopause, where the outward pressure from the solar wind is equaled by the inward pressure of the interstellar medium. Between these two stark borders lies the heliosheath, a region where solar material continues to slow and even reverse direction. The trek through these boundaries took Voyager 1, the faster of the twin probes, nearly eight years; such is the vastness of the scale at play.

Beyond the heliopause is interstellar space, which Voyager 1 entered in 2012 and Voyager 2 reached in 2018. It's a very different environment from the one inside our heliosphere — quieter but hardly quiescent. 'It's a relic of the environment the solar system was born out of,' Rankin says of the interstellar medium. Within it are energetic atomic fragments called galactic cosmic rays, as well as dust expelled by dying stars across the universe's eons, among other ingredient.

Earlier this month Wired noted ' The secret of the Voyagers lies in their atomic hearts: both are equipped with three radioisotope thermoelectric generators, or RTGs — small power generators that can produce power directly on board. Each RTG contains 24 plutonium-238 oxide spheres with a total mass of 4.5 kilograms...'

But as time passes, the plutonium on board is depleted, and so the RTGs produce less and less energy. The Voyagers are therefore slowly dying. Nuclear batteries have a maximum lifespan of 60 years. In order to conserve the probes' remaining energy, the mission team is gradually shutting down the various instruments on the probes that are still active...

Four active instruments remain, including a magnetometer as well as other instruments used to study the galactic environment, with its cosmic rays and interstellar magnetic field. But these are in their last years. In the next decade — it's hard to say exactly when — the batteries of both probes will be drained forever.

Read more of this story at Slashdot.