SOUND OF SILENCE
U of T astrophysicists set Cassini’s 20-year space odyssey to music,
There are just weeks left in the extraordinary life of the Cassini spacecraft — and in reverence, astrophysicists at the University of Toronto have painstakingly converted its final mission into music.
After nearly 20 years in space, revealing the Earthlike world of Titan, Saturn’s largest moon, and producing never-before-seen images of Saturn and its whirling, multi-toned features, the Cassini mission will have its curtain call on Sept. 15. It will plunge into the ringed planet’s atmosphere, burning up as a meteor would.
“It’s on a death spiral, really,” Matt Russo, a post-doctoral researcher at the Canadian Institute for Theoretical Astrophysics, said.
Cassini’s last mission began in April and included a final close-up with Titan and 22 dangerous weekly dives between Saturn and its rings.
Converting the inaudible sounds that Saturn and its rings produce into music brings an event that’s occurring billions of kilometres away closer to home, Russo believes.
“It gives you a way to feel science,” he said. “It connects two worlds that people usually think of as separate.”
How does making that connection take place?
“A good way to think of it is to think of Saturn as a musical instrument,” Russo said. “You know how a cello has a lower pitch than a violin? Imagine that, but Saturn-sized!”
It all begins with orbital resonances. If two objects are orbiting Saturn at different speeds, there will inevitably be moments when they arrive at the same spot. A rhythmic gravitational tug emerges, which creates a tightly repeating pattern of waves. This can be converted into musical harmonies.
Of course, with rings more than a million kilometres long, the resonances Saturn emits are far too low to be heard by the human ear.
To hear them, Russo and his colleagues — post-doctoral researcher Dan Tamayo and musician Andrew Santaguida — dialed the notes up 27 octaves. What they were left with was a minute-and-a-half of sound from Cassini’s six-month mission.
The music is dreamy, at first. High notes chime above a reverberating hum. A shaky note crescendos, then there’s a brief pause. The spacecraft’s inevitable death is marked by one final piano chord.
Russo also had a wooden carving created of Saturn’s ring patterns, to create a tactile experience. “You can run your finger along the grooves and follow the bright and dark patches,” he said.
The carving was inspired by a blind woman he corresponded with months ago, who said that converting planetary phenomena into music gave her a way to discover the beauty of the cosmos.
“I realized we take it for granted,” Russo said. “All those beautiful pictures of astronomy . . . They just don’t have access to that visually.”
The Cassini sound project is the beginning of an expanding initiative to make astronomy more accessible to the visually impaired.
Although not strictly Russo’s job at U of T, he feels it’s exactly what science is supposed to be for: “It has to do with finding different ways to see the same data,” he said. “That goes to the other reason why I really like space and astronomy: It’s people’s reactions; you see their eyes widen and their jaws drop.”