Video One of the microphones on Perseverance, NASA’s latest and greatest Mars rover, has recorded the sounds of its autonomous helicopter Ingenuity flying on the Red Planet, providing scientists with the first ever audio samples of an aircraft operating on another planet.
You can hear the recording in the video below. Make sure to listen out for a low buzzing sound, which comes from its rotors spinning at 2,537 rpm, as the drone flits in and out of view.
On Friday, David Mimoun – science lead for the SuperCam Mars microphone on Perseverance, and a planetary science professor at the Institut Supérieur de l’Aéronautique et de l’Espace (ISAE-SUPAERO) in France – called the recording “a very good surprise.” The rover is quite far away from Ingenuity, about 80 metres, and the winds billowing through the atmosphere made recording difficult.
“We had carried out tests and simulations that told us the microphone would barely pick up the sounds of the helicopter, as the Mars atmosphere damps the sound propagation strongly. We have been lucky to register the helicopter at such a distance. This recording will be a gold mine for our understanding of the Martian atmosphere,” he added.
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In fact, NASA has massaged the audio sample above to help listeners hear Ingenuity. Sounds below 80Hz and above 90Hz have been turned down in volume so that the 84Hz hum of the tiny computer-controlled craft's rotors can be heard.
A small team at mission control has been experimenting with Ingenuity’s limits for about a month. Over that time, the small autonomous aircraft has performed a series of flights at increasing heights and speeds. The flight data is uploaded to Perseverance and sent back to Earth for the team to study, and the video above is taken from Ingenuity’s fourth flight when it traveled 133 metres south and stayed in the air 117 seconds.
“This is an example of how the different payload instrument suites complement each other, resulting in information synergy," said Soren Madsen, the Perseverance payload development manager at NASA’s Jet Propulsion Laboratory. "In this particular case, the microphone and video let us observe the helicopter as if we are there, and additional information, such as the Doppler shift, confirms details of the flight path.”
The Solar System remains mostly eerily silent to us Earthlings. Although we have a good idea of what other planets look like and what they may be made up of, what they sound like is still a mystery. NASA has kitted out previous Martian spacecraft with microphones; they were installed in its Mars Polar Lander in 1999 and in its Phoenix Lander in 2007, but never had the chance to listen to Mars until now.
The Mars Polar Lander crashed during its landing stage, and NASA had to disable the microphone on its Phoenix Lander because of instrumentation issues. Fortunately, scientists have had much better luck with Perseverance this time round.
Not only has the six-wheeled, 1,025-kilogram trundlebot captured the low-pitch hum of its Ingenuity drone flying in the Martian atmosphere, it has also recorded the sound of wind, lasers zapping rocks, and its own machinery cranking away as it drives around the Jezero crater. ®