"NASA's Mars Rovers Still Making Tracks"

ARI SHAPIRO, Host:

Think of the unforgettable moments of joy in your life, maybe when your kid was born or when you got married or when the Red Sox won the World Series - I'm sure that was somebody's unforgettable moment of joy. Well, anyway, for planetary scientists, one of those moments was five years ago today.

Unidentified Man: You can see it. There it is. Finally.

(SOUNDBITE OF CHEERS)

SHAPIRO: That was the sound from the control room at NASA's Jet Propulsion Laboratory in Pasadena when scientists and engineers had confirmation that their Mars rover called Spirit had landed safely on the Martian surface. The rover was designed to have a 90-day mission but today, amazingly, it is still operating on the surface of the Red Planet. NPR's Joe Palca was in Pasadena that memorable day, and he joins me here in the studio. Good morning.

JOE PALCA: Good morning.

SHAPIRO: What was that day like?

PALCA: You know, it's so bad to be an articulate person and to be tongue-tied. But it is indescribable. The - we live - we work in a profession where we get vicarious thrills as other people do interesting things that we talk about, but this was over the top. They were just beside themselves with joy.

SHAPIRO: Even as an outside journalist, you couldn't help but be caught up in the enthusiasm. You can hear it in that tape.

PALCA: Yeah. Well, and some people afterwards said, oh, you know, you sounded like a cheerleader. Well, I couldn't help it. I mean, you know, you're in the room, and these guys are just jumping up and down, and they're on Mars, and then a few minutes later, you see a picture of Mars. Of course, you're excited. It's amazing.

SHAPIRO: And this is not the only rover on Mars, right?

PALCA: No. There - this is the first. And then a few weeks later, a second one called Opportunity, which, again, you know, all these things that had to go right went right, and it landed on the other side of Mars. So it was quite remarkable.

And you know, both missions were supposed to last 90 days, 90 days, and now it's five years later. They've both been taking pictures and studying rocks and looking for signs that there was water in this very dry place that Mars is today.

One thing that's happening, though, is that the rovers are covered in red dust. Mars is a very dusty place, and the dust is now settled on the solar panels, which means the rovers are getting less power from the sun. And that's one of the things that's making them harder to operate.

Now, Steve Squyres has been the principal investigator on the rover since they were conceived, and I talked to him a little while ago. He says the science team is tired, honestly. But he says he and his colleagues try not to lose sight of the remarkable nature of what they're doing.

STEVE SQUYRES: We are conducting humanity's first overland expedition across another planet. And, boy, if you can't get excited to get up and go to work each day if you're doing that, forget it.

PALCA: Squyres says the trick to keeping people motivated is to keep, you know, giving themselves challenges. And so now they're going to try and send Opportunity five miles across the Martian plain to this crater they want to have a closer look at.

SHAPIRO: So, these scientists signed up for a three-month project. They've now been on a five-year project. But they have to know it's going to end eventually, right?

PALCA: Yeah, of course. Of course. But Squyres says he's concerned about how it will end.

SQUYRES: This mission could end because our funding gets cut off. I don't want that to happen. It could end because we screw up and drive a rover off a cliff. I sure don't want that to happen. So you know, I've always felt that the only acceptable ways for the mission to end would be either we just wear them out - that's the one I'm hoping for - we just drive them until they can't do anything anymore, or Mars kills them. Mars reaches out with a dust storm or something and just kills them.

SHAPIRO: He must be incredibly proud of what's he accomplished in the last five years.

PALCA: Yeah. And he's, you know, he's very proud of the rovers, but he's a thoughtful guy, and he has a very sane perspective about when the rovers do die.

SQUYRES: People talk about the plucky little rovers and the determined way(ph). Spirit's not determined. Spirit's not courageous. Spirit doesn't feel pain. Spirit doesn't fear death. Spirit's a robot, OK? All those emotions, they're here on earth. OK? And those are things that we have endowed the vehicle with, but those are human emotions, and they exist among the team that built them and among the people who follow them. And even when the rover dies, we've still got that.

PALCA: But it will be, as Squyres says, it will be a sad day when we have to say goodbye.

SHAPIRO: That's NPR's Joe Palca. Thanks, Joe.

PALCA: You're welcome.

SHAPIRO: To see a slideshow of images shot by the Mars rover, go to npr.org.