TY - JOUR
T1 - In situ recording of Mars soundscape
AU - Maurice, S.
AU - Chide, B.
AU - Murdoch, N.
AU - Lorenz, R. D.
AU - Mimoun, D.
AU - Wiens, R. C.
AU - Stott, A.
AU - Jacob, X.
AU - Bertrand, T.
AU - Montmessin, F.
AU - Lanza, N. L.
AU - Alvarez-Llamas, C.
AU - Angel, S. M.
AU - Aung, M.
AU - Balaram, J.
AU - Beyssac, O.
AU - Cousin, A.
AU - Delory, G.
AU - Forni, O.
AU - Fouchet, T.
AU - Gasnault, O.
AU - Grip, H.
AU - Hecht, M.
AU - Hoffman, J.
AU - Laserna, J.
AU - Lasue, J.
AU - Maki, J.
AU - McClean, J.
AU - Meslin, P.-Y.
AU - Le Mouélic, S.
AU - Munguira, A.
AU - Newman, C. E.
AU - Rodríguez Manfredi, J. A.
AU - Moros, J.
AU - Ollila, A.
AU - Pilleri, P.
AU - Schröder, S.
AU - de la Torre Juárez, M.
AU - Tzanetos, T.
AU - Stack, K. M.
AU - Farley, K.
AU - Williford, K.
AU - Frydenvang, J.
AU - Madsen, M.
AU - the SuperCam team
N1 - Publisher Copyright:
© 2022, The Author(s).
PY - 2022
Y1 - 2022
N2 - 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 heat1, (2) the speed of sound varies at the surface with frequency2,3 and (3) high-frequency waves are strongly attenuated with distance in CO2 (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 CO2-dominated atmosphere. We also provide the acoustic attenuation with distance above 2 kHz, allowing us to explain the large contribution of the CO2 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.
AB - 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 heat1, (2) the speed of sound varies at the surface with frequency2,3 and (3) high-frequency waves are strongly attenuated with distance in CO2 (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 CO2-dominated atmosphere. We also provide the acoustic attenuation with distance above 2 kHz, allowing us to explain the large contribution of the CO2 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.
U2 - 10.1038/s41586-022-04679-0
DO - 10.1038/s41586-022-04679-0
M3 - Journal article
C2 - 35364602
AN - SCOPUS:85131106460
VL - 605
SP - 653
EP - 658
JO - Nature
JF - Nature
SN - 0028-0836
IS - 7911
ER -