RACHEL MARTIN, HOST:
Space watchers, mark your calendars. NASA's Perseverance rover is scheduled to land on Mars one week from today. The scientific instruments on these rovers tend to mimic human senses, like vision and touch. As NPR's Joe Palca reports, this mission will add one more sense.
JOE PALCA, BYLINE: That sense is hearing. Baptiste Chide is at the French Institute of Astrophysics and Planetology. He's one of the scientists on the Perseverance mission. He says the rover is carrying two microphones.
BAPTISTE CHIDE: Those two microphones will be the first microphone - we call audible sounds from the surface of Mars.
PALCA: Mars has a very thin atmosphere, mostly made of carbon dioxide and it's cold, all three factors that affect the way sound travels. Chide says the most noticeable difference is that sound just doesn't travel very well.
CHIDE: So for instance, our conversation would sound like whispers.
PALCA: Chide says one of the microphones is on an instrument called SuperCam. That mic can be used to study wind speed and direction at the landing site. It can also be used to study rocks. Nina Lanza is a geologist at Los Alamos National Laboratory. SuperCam has a laser that shoots at rocks, revealing their chemical composition.
NINA LANZA: You can actually hear the change in the zapping sound as we penetrate through thin layers of material. That was really interesting to me because I'm really interested in rock coatings because that's a great place for microbes to live.
PALCA: Or, in the case of Mars, microbes to once have lived. That's one of the goals of the Perseverance mission, to search for signs there might once have been life on Mars. Now, the microphone on SuperCam is for serious science. You could say the other microphone on the rover is there for fun. David Gruel is an engineer at NASA's Jet Propulsion Laboratory. He says, they thought it would be nice to have some cameras and a microphone to record the events as Perseverance came in for a landing. But there wasn't money in the budget to build such a system from scratch. So he found cameras and a mic you could buy on the Internet.
DAVID GRUEL: When we first brought this to our review, the review board is like, wait a minute. You want to put a off-the-shelf camera onto a flagship mission? Is that - really? Is that - can we do that?
PALCA: He managed to convince the reviewers that, yeah, you can. And the mic sounds good. Listen to this.
GRUEL: My name is David Gruel. I am an employee with the Jet Propulsion Laboratory.
PALCA: That's good audio. And he's not joking about buying it off the Internet. It comes from a company called DPA.
GRUEL: You can go to their website. And you can buy the exact same thing that we're flying.
PALCA: Gruel and I spoke over a video call so he could show me the mic. It's a small canister about the size of your thumb.
GRUEL: The only thing that we added is you take this grill off, which is used to help with wind noise and stuff. And the vendor put a fine mesh on the inside of it just to keep dust out of the diaphragm.
PALCA: Gruel says the plan is to turn on the microphone as the rover plows through the Martian atmosphere. He thinks it should be able to hear the roar of the rocket engines on the descent stage that will lower the rover to the surface.
GRUEL: And then, we hope to hear the wheels, the crunch of the wheels hitting the surface of Mars, followed by the pyrotechnic devices going off that separate the rover in descent stage. And then, the descent stage disappears and gets quieter and quieter. And you're left listening to the ambient noises of Mars for the first time in our history. That's awesome. It's going to be so exciting if it works.
PALCA: It might not. Mars can foil the best laid plans. But Gruel has high hopes.
GRUEL: We want it to work. It's got to work.
PALCA: Joe Palca, NPR News.
(SOUNDBITE OF SOLAR HEAVY'S "THE FALL") Transcript provided by NPR, Copyright NPR.
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