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In situ recording of Mars soundscape

2022; Nature Portfolio; Volume: 605; Issue: 7911 Linguagem: Inglês

10.1038/s41586-022-04679-0

1476-4687

S. Maurice, Baptiste Chide, Naomi Murdoch, R. D. Lorenz, D. Mimoun, R. C. Wiens, Alexander Stott, Xavier Jacob, Tanguy Bertrand, Franck Montmessin, N. Lanza, César Álvarez-Llamas, S. Michael Angel, M. Aung, J. Balaram, Olivier Beyssac, A. Cousin, G. T. Delory, O. Forni, Thierry Fouchet, O. Gasnault, Håvard Fjær Grip, M. H. Hecht, J. A. Hoffman, J. J. Laserna, J. Lasue, J. N. Maki, J. B. McClean, P. Y. Meslin, Stéphane Le Mouëlic, Asier Munguira, Claire Newman, J. A. Rodríguez‐Manfredi, Javier Moros, A. Ollila, P. Pilleri, Susanne Schröder, Manuel de la Torre Juárez, Theodore Tzanetos, K. M. Stack, K. A. Farley, Kenneth H. Williford, R. C. Wiens, T. E. Acosta-Maeda, R. B. Anderson, D. M. Applin, Gorka Arana, M. Bassas-Portús, R. Beal, Pierre Beck, Karim Benzerara, Sylvain Bernard, P. Bernardi, Tanja Bosak, Bruno Bousquet, A. J. Brown, Alexandre Cadu, Philippe Caïs, Kepa Castro, Elise Clavé, S. M. Clegg, E. A. Cloutis, Stephanie Connell, A. Debus, E. Dehouck, D. Delapp, Christophe Donny, A. Dorresoundiram, Gilles Dromart, Bruno Dubois, C. Fabre, A. Fau, Woodward W. Fischer, Raymond Francis, J. Frydenvang, T. S. J. Gabriel, Erin Gibbons, I. Gontijo, J. R. Johnson, Hemani Kalucha, Evan M. Kelly, Elise Wright Knutsen, Gaétan Lacombe, Stéphane Le Mouëlic, Carey Legett, Richard Léveillé, É. Lewin, G. López-Reyes, Eric Lorigny, Juan Manuel Madariaga, M. B. Madsen, S.N. Madsen, Lucia Mandon, N. Mangold, Mati Mann, J. A. Manrique, Jesús Martínez‐Frías, L. E. Mayhew, T. H. McConnochie, S. M. McLennan, Noureddine Melikechi, F. Meunier, Gilles Montagnac, Valérie Mousset, T. Nelson, Raymond Newell, Yann Parot, C. Pilorget, P. Pinet, G. Pont, F. Poulet, Cathy Quantin‐Nataf, Benjamin Quertier, W. Rapin, A. Reyes‐Newell, S. Robinson, L. Rochas, Clément Royer, F. Rull, V. Sautter, Shiv K. Sharma, V. Shridar, Anthony Sournac, Michael J. Toplis, I. Torre-Fdez, Nathalie Turenne, S. Udry, Marco Veneranda, Dawn Venhaus, David Vogt, Peter A. Willis,

Space Science and Extraterrestrial Life

Abstract Before the Perseverance rover landing, the acoustic environment of Mars was unknown. Models predicted that: (1) atmospheric turbulence changes at centimetre scales or smaller at the point where molecular viscosity converts kinetic energy into heat 1 , (2) the speed of sound varies at the surface with frequency 2,3 and (3) high-frequency waves are strongly attenuated with distance in CO 2 (refs. 2–4 ). However, theoretical models were uncertain because of a lack of experimental data at low pressure and the difficulty to characterize turbulence or attenuation in a closed environment. Here, using Perseverance microphone recordings, we present the first characterization of the acoustic environment on Mars and pressure fluctuations in the audible range and beyond, from 20 Hz to 50 kHz. We find that atmospheric sounds extend measurements of pressure variations down to 1,000 times smaller scales than ever observed before, showing a dissipative regime extending over five orders of magnitude in energy. Using point sources of sound (Ingenuity rotorcraft, laser-induced sparks), we highlight two distinct values for the speed of sound that are about 10 m s −1 apart below and above 240 Hz, a unique characteristic of low-pressure CO 2 -dominated atmosphere. We also provide the acoustic attenuation with distance above 2 kHz, allowing us to explain the large contribution of the CO 2 vibrational relaxation in the audible range. These results establish a ground truth for the modelling of acoustic processes, which is critical for studies in atmospheres such as those of Mars and Venus.