Music to alien ears

From Salt Lake City, at a meeting of the Acoustical Society of America

What would a Deep Purple concert sound like on another world? The best rock venue in the solar system, it turns out, might be the surface of Saturn’s moon Titan.

The atmospheres of different celestial bodies have different chemical compositions, densities, viscosities, and temperatures, all of which affect the way sound propagates.

Apart from two Soviet probes that sent crude sound data back from Venus in the early 1980s, the only space mission to have recorded sounds on another world was the European Space Agency’s Huygens probe, which landed on Titan in 2005. Huygens mostly recorded wind noise during its descent.

Space scientists say that acoustical instruments on future missions could measure wind speeds and might answer such questions as whether there’s thunder on Mars.

To help design such experiments, Andi Petculescu of the University of Louisiana at Lafayette and Richard Lueptow of Northwestern University have done the most extensive computer simulations yet of the propagation of sound on three alien bodies—Venus, Mars, and Titan—plus Earth, for comparison.

As expected (SN: 7/8/06, p. 29), Mars’ thin atmosphere would cause sound to fade away after traveling just a few meters. The atmosphere of Venus, almost entirely carbon dioxide, would muffle high-pitched sounds. Titan’s frigid, nitrogen-based atmosphere would offer the best sound transmission across all frequencies.

Petculescu played his simulations of Deep Purple’s guitar riff from “Smoke on the Water” as it would sound on each of the four bodies. Titan is the place to be—if you can stand the –178°C weather, that is.