On May 7, 2021, NASA’s Ingenuity Mars Helicopter made its fifth flight, its first to a new landing site.
NASA’s Mars Exploration Rover Perseverance has been the “camera operator” for the Ingenuity Mars Helicopter. camera operator”. On Friday (May 7), NASA said Perseverance captured the sound of the helicopter as it flew over the surface of the Red Planet.
NASA said it was the first time that a spacecraft on another planet had recorded the sound of another spacecraft. The audio is also a gold mine for studying Mars’ atmosphere.
The muffled sound of the paddles turning as the helicopter “Jiji” flew through the thin Martian atmosphere was recorded by the “Trailblazer”.
NASA released new video taken by the Trailblazer on Friday showing the fourth mission of the “Jiji” on the surface of Mars on April 30, and the newly released video is accompanied by audio. “Trailblazer landed on Mars in February this year to look for signs of ancient microbes.
In the 2 minute 44 second video, the sound of wind blowing over Jezero Crater is heard at the beginning, followed by the soft hum of the paddles spinning at 2,400 revolutions per minute during the 262 meter round trip.
The microphone is part of the SuperCam laser instrument on the Trailblazer, but it is not used to record the sound of the Kikki’s flight. Instead, SuperCam uses the laser to vaporize a small sample of rock, which is then analyzed by a spectrometer to infer its chemical composition: the microphone records the sound of the laser’s effects to help calculate factors such as the overall hardness of the rock.
The microphone can also record surrounding noise, such as the sound of the wind on Mars. It was because of background noise, such as wind, that Perseverance picked up the sound of the blades of the helicopter, which were 262 feet (80 meters) apart.
It was no easy task to record the sound of the flight of the “wit”, said a NASA press release, adding that even during the flight, the thin Martian atmosphere greatly muffled the sound of the helicopter’s blades as they spun at 2,537 rpm. All during the initial moments of the flight, the Martian gusts of wind masked the helicopter’s sound. Listen carefully, however, and the hum of the helicopter can still be faintly heard over the sound of those winds.
“It was a very surprising surprise.” said David Mimoun, professor of planetary science at the Institute of Space and Aerospace Research (ISAE-SUPAERO) in Toulouse, France. He is the scientific lead for the SuperCam Mars microphone.
“The tests and simulations we conducted told us that the microphone would barely capture the sound of a helicopter because the Martian atmosphere greatly inhibits sound transmission. We were fortunate to be able to record the helicopter (flight sound) at such a distance. This audio will be a gold mine for our understanding of the Martian atmosphere.”
The Martian atmosphere is only 1 percent as dense as Earth’s, so Mars’ environment is much quieter than Earth’s. In addition, the Martian atmosphere is composed of 96 percent carbon dioxide, which tends to absorb higher-pitched sounds, so only lower-pitched sounds can travel farther.
NASA needs to do some post-processing to get audible sound details. The audio captured by the microphones was mono, and the JPL team isolated a specific frequency of the helicopter blade sound, “84 Hz,” by reducing the sound below 80 Hz or above 90 Hz. NASA said, “Some frequencies were cut out to accentuate the helicopter’s buzz as it is loudest when it passes through the camera’s field of view.”
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