Artist's concept of Voyager
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With scientific instruments on NASA's Voyagers, Galileo, Cassini and more than two dozen other spacecraft, University of Iowa physicist Dr. Don Gurnett has been recording waves that course through the thin, electrically charged gas pervading the near-vacuum of outer space.

Gurnett converted the recorded plasma waves into sounds, much as a receiver turns radio waves into sound waves. "I've got a cardboard box full of cassette tapes of sounds that I've collected over nearly 40 years," he said.

Gurnett's tapes have inspired a 10-movement musical composition called "Sun Rings." The Grammy-nominated Kronos Quartet will premiere "Rings" at the University of Iowa's Hancher Auditorium in Iowa City, Iowa, on Oct. 26.

Composer Terry Riley, selected for the project by Kronos' artistic director, compiled an assortment of melody fragments and ideas from the spacecraft recordings collected near Jupiter, Venus and other planets. "It was a powerful experience to listen to this material and realize it was coming from millions of miles away," Riley said.

Riley listened carefully to some crackling and squealing patterns from the magnetic field the Galileo spacecraft discovered surrounding Jupiter's largest moon, Ganymede. "It sounded to me like a voice saying, 'beebopterismo,' so that's the starting point for one of the movements," he said. "Beebopterismo" comes just before movements named "Planet Elf Sindoori" and "Earth Whistlers," Riley said.

"Sun Rings" directly incorporates some recorded sounds from Gurnett's scientific instruments into the live performance and also uses string instruments to mimic and build upon those elements. Riley added parts for a choir "to further emphasize that this work is largely about humans as they reach out from Earth to gain an awareness of their solar system neighborhood," he said.

The performance will be visual, as well as musical. Willie Williams, who has designed multimedia shows for Rolling Stones concerts and the Super Bowl, created a program of images to accompany "Rings." Some of the imagery comes from the twin Voyager spacecraft flybys of outer planets, including a video clip of Jupiter rotating.

"You don't necessarily need to have a great depth of scientific understanding to appreciate the beauty of these images and the sense of wonderment," Williams said. "This has turned into a much more contemplative piece than what I first thought it was going to be."

The NASA Art Program contacted David Harrington, the Kronos Quartet's artistic director, two years ago with a proposal to create music inspired by Gurnett's research. NASA and University of Iowa's Hancher Auditorium co-commissioned the work. Part of NASA's mission is to inspire future explorers, and the Art Program is one of many ways NASA reaches the public. The Kronos Quartet has scheduled performances of "Sun Rings" in 2003 in Houston, San Francisco, London and California's Orange County.

Gurnett's instruments continue to examine plasma waves at new frontiers of space. On Voyager 1, launched 25 years ago and now farther from Earth than any other human-made object, plasma detecting instruments are returning information about the far reaches of the solar wind. Voyager 1 is expected to eventually record waves at the boundary between the domain of the Sun and true interstellar space. Cassini, with a radio and plasma wave science instrument as part of a diverse suite of instruments, will begin orbiting Saturn in July 2004. Galileo, orbiting Jupiter since 1995, will use a plasma wave subsystem in November to analyze the high-radiation environment closer to the giant planet than the orbiter has ever previously ventured.

Samples of the type of sounds converted from plasma wave instruments are available online at One from Galileo's studies of Ganymede's magnetosphere is at One from Voyager's passage through the bow shock of the solar wind against Jupiter's magnetosphere is at One from Cassini, also of the interaction between the solar wind and Jupiter's magnetosphere, is at

The Jet Propulsion Laboratory, Pasadena, Calif., manages the Voyager, Galileo and Cassini-Huygens missions for NASA's Office of Space Science, Washington, D.C. Cassini-Huygens is a cooperative mission of NASA, the European Space Agency and the Italian Space Agency. JPL is a division of the California Institute of Technology, Pasadena.

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