The Sounds of Space, in Indie Music

A new compilation of indie rock music includes sounds collected from the Voyager space missions.

ea139c80The universe may sound silent to human ears, but a new compilation curated by Portland, Oregon’s Lefse Records has found a way to make space a musical collaborator. All 14 tracks on Space Project, to be released on Record Store Day on April 19, use samples of “sounds” collected by the Voyager 1 and Voyager 2 spacecraft, which launched in 1977 to explore the outer solar system from Jupiter and beyond.

“Oftentimes, people think that space is a vacuum with nothing there,” says Don Gurnett, a professor in the department of physics and astronomy at the University of Iowa and the principal investigator for the Voyager radio and plasma wave instrument. But space contains a significant amount of ionized gas, generally referred to as plasma—and “it turns out, there’s just a huge variety of sounds that occur in a plasma,” says Gurnett. The Voyager probes’ antennae can detect those sounds in the form of plasma waves, which are oscillations in plasma that act similarly to sound waves here on earth.

There are several ways that plasma waves occur and create sound. For example, lightning on a planet with a magnetic field can cause plasma waves called “whistlers,” or tones that drop in frequency, according to Gurnett. Or, when electrons rotate around a magnetic field in a radiation belt, they can create another plasma wave known as a “dawn chorus,” because it resembles morning bird chirps.

So many different kinds of waves can exist in plasma that “we sometimes call it the plasma wave zoo,” says Gurnett.

The Voyager probes captured the sounds heard on Space Project with V-shaped antennae made out of beryllium-copper tubes that are attached externally to the spacecraft, according to Gurnett. They’re hooked up to electronic amplifiers, which NASA uses to convert incoming plasma waves into digital waveforms. Gurnett likens the process to a car radio receiver translating radio waves to sounds that humans can hear.

Voyager 1 first detected sounds in 1979 as it approached Jupiter. Particles streaming out from a shockwave created in the planet’s magnetic field caused plasma waves, says Gurnett.

As the probe came within Jupiter’s reach, Gurnett’s team began detecting the dawn chorus. “Then we detected whistlers, which was the first discovery of lightning on a planet other than earth. That was pretty dramatic. And there were these electron cyclotron harmonics and electron plasma oscillations [both are types of plasma waves]. There was just a whole menagerie of sounds,” says Gurnett.

This trove of noises inspired Lefse Records’ Matt Halverson to create Space Project. He says he first heard about the Voyager sounds from his scientist brother-in-law.

“I was shocked [by] how much the recordings sounded like minimal, drone-like, electronic music,” Halverson wrote in an email. “Immediately my wheels started turning.”

He recruited some of his favorite artists, including Spiritualized, Beach House, Youth Lagoon, and The Antlers, to take those sounds and get creative musically. For instance, Halverson assigned Jordan Lee of the band Mutual Benefit sounds from Uranus’s smallest moon, Miranda.

“I ended up really falling in love with the sample,” wrote Lee in an email. “The clip I had was about 10 minutes long, and I left it on repeat for a couple days until I felt familiar with it as a whole.” He also noticed “certain parts that popped out as being textures that would be nice going throughout the entire song.”

“Working with material that doesn’t always fit into conventional tonality or timing can make things a bit tricky,” he wrote, adding jokingly, “but I guess it would be a bit unrealistic to expect the universe to sing in a C major scale in 4/4 time.”

The resulting composition, “Terraform,” fits in seamlessly with the rest of Mutual Benefit’s discography of lovesick folk.

About a year ago, measurements of plasma waves around Voyager 1 revealed that it had reached interstellar space. The noise it recorded at that milestone was “kind of a squeaky sound. It wasn’t very impressive, but it was impressive to us,” Gurnett says. “We built this instrument almost 40 years ago, put it on the spacecraft, and here it is, 36 years after launch. [That Voyager went so far] was something I guess I never anticipated.”

It will take Voyager 1 about 30,000 years to go the distance of the nearest star, says Gurnett—and there’re bound to be some interesting tunes along the way.

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About Chau Tu

Chau Tu is an associate editor at Slate Plus. She was formerly Science Friday’s story producer/reporter.