ROBERT SIEGEL, Host:
From NPR News, this is ALL THINGS CONSIDERED. I'm Robert Siegel.
MICHELE NORRIS, Host:
And I'm Michele Norris.
Half of a remarkably successful mission to Mars is over. NASA announced it will no longer listen for a signal from Spirit, one of the two six- wheeled rovers that landed on Mars in 2004. Spirit was supposed to run for 90 days. It lasted six years, and it has proven that Mars was once a wetter planet that might, just might have harbored life.
Now that NASA has declared the mission over, NPR's Joe Palca has this remembrance.
JOE PALCA: On landing day 2004, there was a powerful mix of anticipation and anxiety in the rover control room at NASA's Jet Propulsion Laboratory in Pasadena. Everything was looking good. But space missions, especially missions to Mars, have a way of failing at the last minute. Lots can go wrong when you have to go from 10,000 miles per hour to a dead stop in six minutes. But everything worked.
JIM BELL: When we landed, the view was spectacular, and everybody was very excited about the successful engineering achievement.
PALCA: Jim Bell, now at Arizona State University, was in charge of the main cameras on the rover.
BELL: What wasn't so clear was that there was a lot of, sort of scientific disappointment.
PALCA: Disappointment because NASA sent Spirit to Mars to search for signs of water, and the rocks near the landing site were all made in a bone-dry environment. Not far from the landing site were some interesting looking hills.
BELL: We could see them three kilometers off in the distance, and it was just kind of a wistful feeling. It's like, wow, look at that. It looks like just some really cool geology up there. And - but, man, it's three kilometers away. We're never going to get there. There's no way the rover is going to survive to go that far. And of course, none of us ever imagined we'd be sitting on top of that peak in the distance - in the not too distant future.
PALCA: That's because the coffee table-sized rover far exceeded everyone's expectations. Bell says once in the hills, the science started getting exciting. There were signs that volcanic lava mixed with water to form an array of minerals.
BELL: One gets a sort of a mental picture of a Yellowstone-like environment on this part of Mars, you know, three billion years ago or more. And by our reckoning on this planet, that's a habitable environment.
PALCA: At first, it wasn't certain Spirit would even make it through the scheduled 90 days. This report was on ALL THINGS CONSIDERED just three weeks after landing.
(SOUNDBITE OF ARCHIVED BROADCAST)
NORRIS: NASA's Mars rover Spirit is sick, and it may not fully recover.
PALCA: There was a serious problem with the onboard computer. But NASA engineers on Earth, millions of miles away, were able to send commands that restored the computer to perfect health.
Two years later, ALL THINGS CONSIDERED reported on another danger looming for Spirit and its twin rover Opportunity.
(SOUNDBITE OF ARCHIVED BROADCAST)
SIEGEL: Both are showing clear signs of age. And as NPR's Joe Palca reports, the extreme cold of a Martian winter could spell their doom.
PALCA: But both made it through that winter. Over the years, mission managers became very attached to the rovers. Mission manager John Callas shared these thoughts in 2006.
JOHN CALLAS: They see, they move, they interact, they respond to our commands, and they think on their own. And so they are very much like, you know, living creatures, and we've become very fond of them. I know I've become very fond of the rovers.
PALCA: For team members, the rovers became a fixture in their lives. Albert Haldemann was deputy mission scientist in 2006.
ALBERT HALDEMANN: We're used to waking up every day and seeing the latest from the rovers. And they're always there, every day, day in, day out. And if one day that stops being the case, it's going to be very sad.
PALCA: Now, that day has come. In anticipation of a fourth winter on Mars, engineers put Spirit in a kind of deep hibernation mode in March of last year, hoping it would wake up with spring. But it hasn't.
John Grant is a planetary scientist with the Smithsonian Institution and a member of the rover science team.
JOHN GRANT: There was a sense that they've overcome so much in the past that we'd hear from her again. And when that didn't happen, well, maybe this had happened, and they'll keep trying another way. And I guess, a sense of denial, but also a very deep sense of loss that we're not going to hear from Spirit again.
PALCA: Spirit may be gone but there's still one rover left. Opportunity is still chugging along, although scientists know one day it will go silent too.
Joe Palca, NPR News.