Portrait of Alexandre Le Roch ISAE-SUPAERO PhD student

Dr Naomi Murdoch, researcher in space instrumentation and planetary science, and Dr Alexander Stott, post-doctoral researcher, tell us more about the physical characteristics of the Martian atmosphere, in particular about the speed of sound and its attenuation.
These analyses were published in the journal Nature on April 1, 2022 by an international team led by a teacher-researcher from the University Toulouse III - Paul Sabatier and including scientists from CNRS and ISAE-SUPAERO.

Perseverance was parked 80 metres from the small rotorcraft, which rose to five metres and then hovered before flying downrange for 133 metres and returning to its take-off and landing spot. SuperCam’s science microphone, developed by ISAE-SUPAERO, recorded the sound from the helicopter’s whirring rotors during the flight. The sound registered 84 hertz, equivalent to a low E note on the piano or a bass voice type.
“This is a wonderful surprise for the science team!” said Naomi Murdoch, a research scientist with ISAESUPAERO who is studying the data captured by the microphone. “Testing in a Mars atmosphere simulator to design this instrument and our sound propagation theories led us to believe the microphone would find it very difficult to discern sounds from the helicopter. As Mars’ atmosphere is very tenuous, it really attenuates sounds. So we needed a bit of luck to pick up the helicopter from this range. We’re thrilled to have obtained this recording, which is going to be a gold mine for our understanding of the planet’s atmosphere.”
Developed jointly by ISAE-SUPAERO and a consortium of laboratories attached to the French national scientific research centre CNRS and partner laboratories, coordinated by CNES, SuperCam’s microphone is derived from a consumer model adapted to withstand the Martian environment. The microphone is pursuing three science and technology goals of the Mars 2020 mission:
Study the sounds generated by laser impacts on Martian rocks to better understand their surface mechanical properties.
 Seek to gain new insights into surface atmospheric phenomena such as wind turbulence, dust devils and wind interactions with the rover, and now with the helicopter.
 Analyse the sound signature of the rover’s movements, for example when it is using its robot arm, driving on flat or rugged terrain, and operating its pumps.
The microphone was first turned on a few hours after Perseverance’s landing, picking up the first sounds on Mars from atmospheric turbulence. It is used daily in combination with laser-induced breakdown spectroscopy (LIBS) to analyse the chemical make-up of Martian rocks.

She was a PhD student in the Complex Systems Engineering Department (DISC)
The subject of his thesis is “vision-based navigation for autonomous rendez-vous with non-cooperative targets.” She is affiliated with the doctoral school, Aeronautics Astronautics (AA). This thesis is called a CIFRE* PhD and is done in collaboration with Thales Aliena Space
ISAE-SUPAERO welcomes its doctoral students in six ISAE-SUPAERO, ONERA teams and Clément Ader Institute, covering a wide spectrum of scientific disciplines related to aeronautics and space: aerodynamics and propulsion, structures and materials, embedded systems, networks and telecommunications, control and management of systems, human factors, electronics, and signal.
ISAE-SUPAERO offers a rich and diversified program of doctoral training, leading to the PhD, the highest degree awarded by the institute, and recognized internationally.
*Since 1981, The Ministry for Research has financed CIFRES with the double objective of placing doctoral students in the conditions for scientific employment and encouraging research partnerships between the academic and business spheres.