The first time I heard sounds from space was in 2001. I was in western Latvia working with a 32-metre parabolic dish called RT32. It had been used by the Soviets to intercept communications between Europe and America during the cold war. The Russians wanted to blow the site up after the collapse of the Soviet Union but the scientific community was able to convert it into a radio telescope, to focus on celestial, rather than earthly, signals.
While our project uses what we describe as “sounds from space”, stars and planets are not directly audible. Sound waves cannot propagate in the vacuum of space. However, radio waves emitted from celestial bodies, such as Jupiter and the sun, can be converted into sound waves that we can hear, using radios and amplifiers.
In our galaxy, the sun is the strongest source of radio waves – the most powerful transmitter in our radio sky. Jupiter also sends us strong radio signals. What we hear – unsurprisingly, given the technology – is similar to our experience of radio here on Earth. The sounds are a bit like the sound of static between the stations.
Contemporary radio telescopes let you listen to all kinds of weird and wonderful phenomena. You can tune in to solar flares on the surface of the sun, listen to the regular beat of a pulsar in deep space, or the sizzling radio noise storms that occur between Jupiter and its volcanic moon Io. At the moment, the sounds that excite me most are Nasa’s Voyager 1’s plasma waves. The spacecraft was launched in 1977 and it has a plasma receiver designed by Don Gurnett and his team at the University of Iowa. What it detects is transmitted back to Earth, and Gurnett’s team turn these plasma waves into beautiful sounds using a process called sonification. There is a magical and somewhat spooky quality to these sounds that I find mesmerising. Perhaps it is what we should expect from the first man-made object to reach interstellar space, billions of miles away.
Of all the sounds I’ve encountered, the one that stays with me is the oldest and most significant – the “cosmic microwave background” radiation that survives from the birth of the universe 13.8 billion years ago. That we can still actually listen to the very beginning of all things – the Big Bang – is something I find extraordinary.