NASA's next Mars rover isn't keeping quiet during its long trek to the Red Planet.
A microphone aboard the Mars 2020 rover Perseverance, which launched on July 30 and will touch down on Feb. 18, 2021, captured the whirring sound made by the car-sized robot's "heat-rejection fluid pump," a newly released NASA audio file reveals.
That microphone was installed to record the sounds of Perseverance's entry, descent and landing (EDL), the "seven minutes of terror" sequence that will end with a rocket-powered sky crane lowering the rover to the Martian surface on cables. The Mars 2020 team turned on the mic on Oct. 19 to determine if it and an associated camera system are functioning properly, capturing the whirring sound in the process.
That sound did not travel through the vacuum of space; sound waves need a medium through which to propagate. In this case, the waves traveled through Perseverance's body, causing mechanical vibrations that the microphone registered.
"With apologies to the person who came up with the slogan for 'Alien,' I guess you could say that in space no one may be able to hear you scream, but they can hear your heat-rejection fluid pump," Dave Gruel, the lead engineer for Mars 2020's EDL camera and microphone subsystem, said in a statement on Wednesday (Nov. 18).
"As great as it is to pick up a little audio on spacecraft operations in flight, the sound file has a more important meaning," Gruel added. "It means that our system is working and ready to try to record some of the sound and fury of a Mars landing."
The heat-rejection fluid pump is part of Perseverance's thermal system, which will keep the rover and its instruments warm on Mars by circulating heat generated by the mission's nuclear battery, NASA officials said in the statement.
Perseverance will explore the floor of the 28-mile-wide (45 kilometers) Jezero Crater, which harbored a lake and a river delta in the ancient past. The rover will characterize the site's geology, hunt for signs of ancient Mars life and cache samples for future return to Earth, among other tasks.
Perseverance will also test technologies for future exploration of the Red Planet. For example, one of the rover's instruments, called MOXIE (short for "Mars Oxygen ISRU Experiment"), will generate oxygen from the thin, carbon dioxide-dominated Martian atmosphere. Such equipment, if scaled up, could help humanity establish a foothold on the Red Planet, NASA officials have said.
Also flying to Mars attached to Perseverance's belly is a tiny helicopter called Ingenuity. If all goes according to plan, the 4-lb. (1.8 kilograms) chopper will make a few short test flights on the Red Planet, becoming the first rotorcraft ever to ply alien skies.
The EDL mic, which was built by Danish company DPA Microphones, isn't Perseverance's only audio equipment. The rover carries a second microphone designed to record sounds made by its rock-zapping SuperCam instrument.
If these microphones work, they'll be the first ever to record true audio on Mars. (NASA's InSight lander captured the "sounds" of the Martian wind shortly after its 2018 touchdown, but that recording processed data gathered by an air pressure sensor and a seismometer.)
But the new microphones aren't the first to fly on a Red Planet mission. NASA's Mars Polar Lander spacecraft, which crashed during its touchdown attempt in December 1999, sported a mic. And NASA's Phoenix lander, which aced its 2008 water-hunting mission, had a microphone built into its descent camera. But the Phoenix team never turned that instrument on, out of concern that its use could complicate the landing process.
Mike Wall is the author of "Out There" (Grand Central Publishing, 2018; illustrated by Karl Tate), a book about the search for alien life. Follow him on Twitter @michaeldwall. Follow us on Twitter @Spacedotcom or Facebook.