Dwingeloo telescope receives signals from Voyager 1

© CC-BY-SA 4.0 Tammo Jan Dijkema / CAMRAS

We have used the Dwingeloo radio telescope to receive signals from the Voyager 1 spacecraft. Only a few telescopes in the world have received these signals, which are very faint due to the distance of Voyager 1: almost 25 billion kilometers, more than four times the distance to Pluto.

Voyager 1 was launched in 1977 to visit the outer planets in the Solar system. After its primary mission ended, it was sent on a journey out of the Solar system. It is currently the most distant and fastest human-made object, traveling in interstellar space. Its radio signals, traveling at the speed of light, currently need 23 hours to reach Earth.

Since the Dwingeloo telescope was designed for observing at lower frequencies than the 8.4GHz telemetry transmitted by Voyager 1, a new feed had to be mounted in the focus (see https://www.astron.nl/dailyimage/main.php?date=20241118 ). At these higher frequencies, the mesh of the dish is less reflective, making it extra challenging to receive faint signals.

In October this year, Voyager 1 turned off one of its two transmitters. The NASA JPL flight team has been able to recover the spacecraft, which is now operating nominally again.

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.

NASA uses dishes in the Deep-Space Network (DSN) to communicate with Voyager 1. These dishes, located around the globe in Goldstone, Canberra and Madrid, are optimized for these higher frequencies and have a diameter of 70m, much larger than the 25m Dwingeloo Telescope.