“A ghostly hum has been echoing across the plains of Mars’ Jezero Crater,” reports Business Insider.
Perseverance’s microphone was turned on during the flight, and despite Ingenuity being over 260 feet away, it was able to capture both sight and sound of the historic event.
While the majority of sound is Martian wind rustling against the microphone, NASA enhanced the sound to make the rotor sounds more audible. They are most apparent when Ingenuity returns to its takeoff spot and the rotor hum dies down when the blades come to a halt.
“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,” said NASA’s science lead for the Perseverance rover’s microphone.
“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.”