The sound of space and beyond


Need some unearthly sounds for your next ambient adventure or do you simply want to stay in tune with what is happening in our solar system. Whether you will detect some alien communications going on or if you are a producer of obscure electronic music, the latest arrivals from NASA on SoundCloud will surely get you in an inspirational mode. NASA has assembled a playlist of unusual sounds – from electromagnetic tones to the glitchy radar echoes off Titan. And that means you can listen in for sonic inspiration, or download for sampling, remixing, and sound design.

Just a thought: The deepest sound you’ve ever heard has a cycle of about one oscillation every twentieth of a second. The drone of Perseus’ black hole has a cycle of about one oscillation every 10 million years. That’s sound on a massive scale, played across deep time.

Soaring to the depths of our universe, gallant spacecraft roam the cosmos, snapping images of celestial wonders. Some spacecraft have instruments capable of capturing radio emissions. When scientists convert these to sound waves, the results are eerie to hear.

NASA has provided explanations for some of these sounds:

Juno Captures the ‘Roar’ of Jupiter: NASA’s Juno spacecraft has crossed the boundary of Jupiter’s immense magnetic field. Juno’s Waves instrument recorded the encounter with the bow shock over the course of about two hours on June 24, 2016.

Plasma Waves: Plasma waves, like the roaring ocean surf, create a rhythmic cacophony that — with the EMFISIS instrument aboard NASA’s Van Allen Probes — we can hear across space.

Saturn’s Radio Emissions: Saturn is a source of intense radio emissions, which were monitored by the Cassini spacecraft. The radio waves are closely related to the auroras near the poles of the planet. These auroras are similar to Earth’s northern and southern lights. More of Saturn’s eerie-sounding radio emissions.

Sounds of Jupiter: Scientists sometimes translate radio signals into sound to better understand the signals. This approach is called “data sonification”. On June 27, 1996, the Galileo spacecraft made the first flyby of Jupiter’s largest moon, Ganymede, and this audio track represents data from Galileo’s Plasma Wave Experiment instrument.

Sounds of a Comet Encounter: During its Feb. 14, 2011, flyby of comet Tempel 1, an instrument on the protective shield on NASA’s Stardust spacecraft was pelted by dust particles and small rocks, as can be heard in this audio track.

On the subject of space music and sounds. A lot of artists has taken the opportunity to incorporate sounds from space into their music. One example is the Italian scientist Domenico Vicinanza who has taken 37 years worth of data from both Voyager space probes and turned it into music. The result is surprisingly good. The composer is a project manager at Géant — Europe’s high-speed data network that powers Cern and the Large Hadron Collider. He used 320,000 individual measurements of cosmic particle data taken at one-hour intervals using the spacecrafts’ cosmic ray detector.

To make this data sound musical, Vicinanza mapped different frequencies, or detections, to different frequencies of a note. And to distinguish between the two spacecraft, he created a kind of duelling duet by giving each probe its own arrangement and sound texture.

 “I wanted to compose a musical piece celebrating the Voyager 1 and 2 together, so used the same measurements (proton counts from the cosmic ray detector over the last 37 years) from both spacecrafts, at the exactly same point of time, but at several billions of kilometres of distance one from the other,” said Vicinanza in a Guardian article.
As the video below  from NASA’s Jet Propulsion laboratory explains, the “sounds” you hear reflect the detection of dense, ionized gas (the “interstellar plasma” that fills the space between star systems like ours and, say, Alpha Centauri) by Voyager’s plasma wave instrument. The soundtrack reproduces the amplitude and frequency of the plasma waves as “heard” by Voyager 1. The waves detected by the instrument antennas can be simply amplified and played through a speaker. These frequencies are within the range heard by human ears.

These shrill, wraithlike cries are what helped the Voyager science team determine the density of the interstellar medium, and ultimately deduce that the spacecraft had really, actually, finally left the solar system…

Another artist TEGEL, active in the minimal techno scene used the sounds from LIGO to color one of the tracks called Gravity. LIGO is the world’s largest gravitational wave observatory and a cutting edge physics experiment. Comprised of two enormous laser interferometers located thousands of kilometers apart, LIGO exploits the physical properties of light and of space itself to detect and understand the origins of gravitational waves.

Although LIGO will search for gravitational waves from space, and it is called an “Observatory”, LIGO is not, strictly speaking, intended to be solely an astronomical facility. LIGO is truly a physics experiment on the scale and complexity of some of the world’s giant particle accelerators and nuclear physics laboratories. Though its mission is to detect gravitational waves from some of the most violent and energetic processes in the Universe, the data it will collect will have far-reaching effects on many areas of physics including gravitation, relativity, astrophysics, cosmology, particle physics, and nuclear physics.

HOW IT WORKS

When an object moves — whether it’s a vibrating guitar string or an exploding firecracker — it pushes on the air molecules closest to it. Those displaced molecules bump into their neighbors, and then those displaced molecules bump into their neighbors. The motion travels through the air as a wave. When the wave reaches your ear, you perceive it as sound.

As a sound wave passes through the air, the air pressure in any given spot will oscillate up and down; picture the way water gets deeper and shallower as waves pass by. The time between those oscillations is called the sound’s frequency, and it’s measured in units called Hertz; one Hertz is one oscillation per second. The distance between “peaks” of high pressure is called the sound’s wavelength.

Sound waves can only travel through a medium if the length of the wave is longer than the average distance between the particles. Physicists call this the “mean free path” — the average distance a molecule can travel after colliding with one molecule and before colliding with the next. So a denser medium can carry sounds with shorter wavelengths, and vice versa. Sounds with longer wavelengths, of course, have lower frequencies, which we perceive as lower pitches. In any gas with a mean free path larger than 17 m (the wavelength of sounds with a frequency of 20 Hz), the waves that propagate will be too low-frequency for us to hear them. These sound waves are called infrasound.