Two microphones aboard the Perseverance Rover have recorded “alien” sounds on Mars – the sounds of a human-made spacecraft crunching its wheels on the Red Planet’s surface, or its motors whirring, or blasts from its scientific laser instrument. Perseverance’s microphones have also captured the sounds of another spacecraft – the Ingenuity helicopter – taking flight. During the five or so hours recorded so far, you can hear the Martian wind gusting in the background.
“We’ve been able to see Mars from the rovers’ point of view for a quite a long time now,” said Greg Delory, a consultant to the Mars 2020 rover microphone team, “so to have another ‘sense’ on Mars is pretty incredible.”
NASA and JPL have launched an interactive website that gives listeners the chance to hear the recordings from millions of kilometers/miles away on the Red Planet. You can also listen to how sounds from Earth would sound on Mars, and even record your own greeting and hear how you’d sound on Mars.
NASA recommends using headphones while listening to the recordings (such as in the video above), as the sounds from Mars are more subtle and quieter than they are on Earth, due to Mars’ less dense atmosphere.
“If you blow across the top of a Coke bottle, the resultant tone depends the properties of the atmosphere and the size of the bottle,” Delory explained. “If you do that on Mars, the Coke bottle would emit a frequency that is about 2/3 of the value of what you’d get on Earth. There is a general shift in everything sounding lower in frequency.”
Quiet or higher pitched sounds like a person whistling and or a bird chirping would be almost imperceptible on Mars. In fact, scientists and engineers were quite surprised when the microphone picked up the Ingenuity helicopter’s buzzing rotors during its fourth flight, on April 30, from a distance of 262 feet (80 meters).
NASA’s Ingenuity Mars Helicopter acquired this image using its navigation camera, acquired on Oct. 24, 2021 (Sol 241 of the Perseverance rover mission). Credits: NASA/JPL-Caltech
Delory, who is the CEO and co-founder of the space hardware company Heliospace, helped design the first ever Mars microphone. That microphone was part of the ill-fated Mars Polar Lander mission that launched in 1999, but crashed to the surface of Mars. He’s excited to now finally hear the sounds he had hoped to hear decades ago.
“Much of the microphone data sounds like I expected it would,” Delory told Universe Today. “A very quiet background, with the wind as the main contributor, including an occasional dust devil. We had always expected to be able to hear lander or rover generated sounds, and now we have. But I never imagined being able to hear a helicopter. So, in this case, the biggest surprise was not what Mars had to offer, but what we as humans brought there!”
Engineers at JPL say that understanding the nature of sound on Mars could one day help them diagnose problems with a spacecraft on a distant planet, similar to how a car mechanic might listen closely to an engine to figure out what’s wrong with it.
These commercial grade microphones are similar to the ones on board the Perseverance rover. Image courtesy DPA.
The two microphones on Perseverance were created from commercially available, off-the-shelf devices. One of the mics sits on the side of the rover’s chassis. The second mic is on Perseverance’s mast as a complement to the SuperCam laser instrument’s investigations of rocks and the atmosphere.
These photos show the microphones used in two earlier missions. Neither was ever used. On left, the Mars Descent Imager and microphone for the Phoenix lander; right, the device for the failed Mars Polar Lander. Credit: NASA/JPL-Caltech
The microphone Delory helped design for the Mars Polar lander similarly used off-the-shelf parts. He and his team tested their concept in every way imaginable in Mars-like conditions, using wind tunnels, vacuum chambers and thermal chambers. In his own work years ago and then recently consulting for the Perseverance team, he had a pretty good “sense” of what Mars would sound like. Hearing the real sounds now are very gratifying.
“I can indeed imagine being right there,” he said. “I’ve had many moments in desert environments running one test or another, including microphones, and experiencing the eerie silence right before a dust devil passes by, or a lightning strike in the distance. It’s great to see a microphone on Mars finally happen – and to have such a dedicated team behind it.”
Image of the Ingenuity helicopter, taken by the Perseverance rover’s MastCam-Z on June 15, 2021. Credit: NASA/JPL/
Further reading/listening:
Audio from Perseverance
JPL press release
The Planetary Society: Perseverance Microphones Fulfill Planetary Society Campaign to Hear Sounds from Mars
Heliospace