Timothy G. Leighton from the University of Southampton in the U.K. designed a software program that produces extraterrestrial environmental sounds and predicts how human voices might change in distant worlds. He will demonstrate his work at the upcoming 184th Meeting of the Acoustical Society of America, running May 8-12 at the Chicago Marriott Downtown Magnificent Mile Hotel. His presentation will take place Thursday, May 11, at 12:00 p.m. Eastern U.S. in the Chicago room.

The presentation is part of a special session that brings together the acoustics and planetary science communities. Acoustical studies became essential during the Huygens lander's descent into Titan's atmosphere in 2005 and in the more recent Mars InSight and Mars 2020 missions. These successful missions carried customized active and passive acoustic sensors operating over a wide spectrum, from very low frequencies (infrasound, below the human hearing threshold) to ultrasound (above human hearing).

"For decades, we have sent cameras to other planets in our solar system and learned a great deal from them. However, we never really heard what another planet sounded like until the very recent Mars Perseverance mission," said Leighton.

Scientists can harness sound on other worlds to learn about properties that might otherwise require a lot of expensive equipment, like the chemical composition of rocks, how atmospheric temperature changes, or the roughness of the ground.

Extraterrestrial sounds could also be used in the search for life. At first glance, Jupiter's moon Europa may seem a hostile environment, but below its shell of ice lies a potentially life-sustaining ocean.

"The idea of sending a probe on a seven-year trip through space, then drilling or melting to the seabed, poses mind-boggling challenges in terms of finance and technology. The ocean on Europa is 100 times deeper than Earth's Arctic Ocean, and the ice cap is roughly 1,000 times thicker," said Leighton. "However, instead of sending a physical probe, we could let sound waves travel to the seabed and back and do our exploring for us."

Planets' unique atmospheres impact sound speed and absorption. For example, the thin, carbon dioxide-rich Martian atmosphere absorbs more sound than Earth's, so distant noises appear fainter. Anticipating how sound travels is important for designing and calibrating equipment like microphones and speakers.

Hearing the sound from other planets is beneficial not just for scientific purposes, but also for entertainment. Science-fiction films contain vivid imagery to mimic the look of other worlds but often lack the immersive quality of how those worlds would sound.

Leighton's software will showcase predictions of the sounds of other worlds at planetariums and museums. In the case of Mars, it will include actual sounds thanks to the U.S./European Perseverance team and China's Zhurong mission.

The special session, chaired by Leighton and Andi Petculescu, is the third forum on acoustics in planetary science organized at a meeting of the Acoustical Society of America.

"The success of the first two ASA special sessions on this subject has led to quite a few collaborations between the two communities, a trend that we hope will carry on," said Petculescu.

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American Institute of Physics
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