UMAIR IRFAN: Remember last week, when Ira and science reporter Kendra Pierre-Louis were talking about the news that the Mars Rover, Perseverance, had collected its first rock samples? Kendra was pretty excited. But Ira was more measured.

IRA FLATOW: “People shouldn’t get too excited too quickly. Because we have no mission yet to go pick up those samples.”

KENDRA PIERRE-LOUIS: Fair.

[LAUGHTER]

IRA FLATOW: “I mean, we talk about them. And they’re planning for it. But there’s no spaceship out there in space going to pick them up tomorrow and bring them back, I guess, is the point I’m making.”

UMAIR IRFAN: Turns out Ira wasn’t the only one asking questions about this.

LUCILLE: “How do samples get back to Earth from Mars?”

UMAIR IRFAN: That’s seven-year-old listener, Lucille. Who was one of the young people we recently invited to ask their most pressing questions about the Mars 2020 mission and the Perseverance rover. The answers came from Dr. Katie Stack Morgan of NASA’s Jet Propulsion Laboratory.

DR. KATIE STACK MORGAN: Yes, thanks, Lucille. That is a great question. And something that NASA is working on right now. So Perseverance’s job is to collect rock and soil samples and store them in little tubes and leave them on the surface of Mars. Or potentially pass them off to the next rover that we call a “fetch” rover. Just like your dog would fetch something, this rover would fetch the samples that Perseverance collects.

Then, the next leg of that mission would involve taking those samples and blasting them off the surface of Mars. But then, that rocket that would blast off the surface of Mars, has to rendezvous and meet up with another orbiter that would be circling Mars.

And so we transfer the samples from the surface of Mars to an orbiter. That would then fly through space, back to Earth, and then go through the Earth atmosphere and land those samples back on the surface of Earth.

So the way that we would get samples from Mars to Earth is through a series of different missions. So it’s not all Perseverance’s job, but a series of missions– rovers to orbiters– to get those samples back. So it’s a pretty complex series of maneuvers we have to pull off.

But each one NASA’s done before. We just have to string them all together and hope the timing is just right. And gets those samples back to Earth.

UMAIR IRFAN: But these kids had other questions, too. Like Gia, age nine, who wondered how the rover stays clean on the dusty Mars surface?

GIA: “So how does Perseverance dust itself off, if it can?”

DR. KATIE STACK MORGAN: That is a great question. And the answer is, Perseverance does not dust itself off. Best experience we have is with Curiosity.

When the rovers first land on Mars, they’re looking pretty sparkly clean. But over the years– and Curiosity has been on the surface of Mars now for over 9 years– things get pretty dusty. And so when we take images of the deck of the rover, we can see how dusty it gets over time.

But that’s OK. Because Curiosity and also Perseverance, actually, don’t use solar power. So previous smaller rovers, like Spirit and Opportunity, had solar panels. And so those solar panels got dusty and would need to be cleaned off intermittently.

But with Curiosity and Perseverance, they have a nuclear power source. So even when it’s really, really dusty and when the rovers get really dusty, it doesn’t so much matter. Because they can still generate the power that they need to operate.

But I will mention a really neat thing that Perseverance has. It has a tool to do dust clearing– not of the rover itself, but of dust that we have on the ground. So when Perseverance drills or creates a little– has a tool that can abrade the surface of the rock, remove the surface of the rock. It creates a bunch of fine dust.

And so then we have basically a little gas puffer that goes “poof” and can actually blow that dust away. And we call it the “Gas Dust Removal Tool.” And it can actually blow dust off the surface of Mars. And it makes it a little clean area on the surface.

And so we won’t use that tool, necessarily, on the rover itself. But we do have a way to clear dust. It’s just on the ground, instead.

UMAIR IRFAN: That’s Dr. Katie Stack Morgan from NASA’s Jet Propulsion Laboratory answering kids’ questions about the Mars mission. To see more questions and answers from our live Zoom event, go, to sciencefriday.com/marsquestions.

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