NASA has released the audio captured by its Mars rover in which the chopper can be heard humming through the thin Martian air.
NASA's Perseverance rover has for the first time captured the low-pitched sounds from another spacecraft on another planet. The low-pitched sound was recorded during the Ingenuity helicopter's fourth flight on April 30.
NASA has released the audio captured by its Mars rover in which the chopper can be heard humming through the thin Martian air.
NASA's Jet Propulsion Laboratory in California released this first-ever audio on Friday, just before Ingenuity made its fifth test flight, a short one-way trip to a new airfield.
The nearly three-minute-long video begins with the low rumble of wind blowing across the Jezero Crater, where Perseverance landed in February on a mission to search for signs of ancient microbes.
Ingenuity takes off, and its blades can be heard humming softly as they spin at nearly 2,400 rpm on the 872-foot (262-meter) roundtrip.
The mission's engineers weren't sure they would pick up the flight sound at all, given that Perseverance was parked 262 feet (80 meters) away from the takeoff and landing spot.
"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," David Mimoun, a professor said.
How sound travels on Mars
The Martian atmosphere is about one percent the density of our planet Earth, making everything much quieter than on Earth.
Sounds emitted on Mars travel slower than they do on Earth, because of cold temperatures, which average -81 degrees Fahrenheit (-63 degrees Celsius) on the surface.
The speed of sound on the planet is therefore around 540 mph (roughly 240 meters per second), compared to about 760 mph (roughly 340 meters per second) here.
The atmosphere of Mars, made up of 96 percent carbon dioxide, tends to absorb higher-pitched sounds, so only lower-pitched sounds can travel long distances.
(With Agency Inputs)
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 "Perseverance rover image of Ingenuity Mars helicopter")
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