NASA's Spirit rover has faced several challenges over the past five years but it's always been 'the little rover that could.'
"What do we see?"
"We see it!"
(Scott Maxwell) This experience with Spirit is something that I've really kind of integrated into my whole identity.
You know, this has become part of what I do. And it looked, at the very beginning of the mission, like this was going to be something that I got to do for a very brief time, for three months.
And that was terrific, and it was unique, and it was special, and I was really looking forward to it -- and I never in my wildest imagination believed that it was going to go one for five years!
(Ashley Stroupe) Spirit has really had to have a lot of "spirit" to keep going.
It's been the little rover that could, in a way.
It's had to work very hard for all of its discoveries.
(Scott Maxwell) Shortly after Spirit landed, we had a problem -- we lost contact with the rover for a couple of days.
And this was a particularly scary time, because not only had we lost contact with one of the rovers and we didn't know why -- we had another rover coming in for a landing hard on her heels.
And we didn't know if whatever had happened to the first rover was going to happen to the second one.
It turned out that we were able to regain control of Spirit.
She had filled up her own memory system -- the equivalent of her hard disk -- and she couldn't boot up.
And she started booting up and said, "Oh look, my hard disk is full. I can't boot up. Let me try rebooting."
And so she was basically just sitting there on Mars, punching her own reboot button, until we finally came along and figured out what was going on and were able to get her to stop.
One of Spirit's very dramatic challenges was when she was racing the clock for her first -- trying to get to her first winter haven, to try to get to a hill where she could point her solar panels directly toward the sun and survive for the winter.
And she was already a little bit behind schedule, and she was racing across these plains toward the hill, and as she was on her way, her right front wheel -- which had been giving us some trouble -- finally stopped working.
And so now, instead of having a six-wheeled rover, we had a rover with five wheels and an anchor.
(Ashley Stroupe) We've ended up having to drive backwards, because it's a lot easier to pull an anchor than to push one.
But naturally, since it's built to have very good traction it basically is digging into the ground and digging this trench behind us.
And as we did this trench, we're able to see things that are normally invisible -- things that are under the surface.
One thing that we seem to be finding almost anywhere we're digging this trench are these widespread deposits of various kinds of salts and minerals.
They look this brilliant white or yellow in the color images.
And that's because they're either sulfur or silica or salts of various kinds.
And the really important thing about these minerals -- and salts in particular -- is that the only way they form is with water.
So the fact that we're finding these salts is real evidence that there was hot water over a very widespread area where Spirit is exploring right now -- not just little isolated pockets.
Mars really could have been a place that supported life.
And without these rovers driving over these vast distances, far beyond their expectations, we would never have known that.
(Scott Maxwell) Even on Mars, life can give you lemons -- but you make lemonade out of that.
In Spirit's case, she turned dragging that right front wheel into a great scientific discovery.
Winter is a harsher time for Spirit. She was up on the top of "Home Plate," and we were scooting across the top of "Home Plate" as fast as we could toward the north face so we could tilt her solar panels as directly as possible toward the Sun.
And as we were doing that, she went over a little rise and down into a pit, which we now call "Tartaros."
In this case, not only was she figuratively on the edge -- she was also literally on the edge, because the only way to escape from that pit was to drive right up along the edge of "Home Plate" -- with absolutely no margin for error whatsoever -- and kind of drive up and around this feature and then off to where she was trying to get to and where she could be safe for the winter.
Certainly the biggest thing that stands out in Spirit's whole mission is her view from the top of "Husband Hill."
This little rover that wasn't ever really designed to climb over anything bigger than her own wheels had now climbed a hill the height of the Statue of Liberty, and was standing there at the top of that hill...
(Ashely Stroupe) ...and took this beautiful 360-degree panorama, and just saw the most beautiful, striking, hilly landscape with this spectacular orange sky and the beautiful, rust-colored ground.
And it just sort of put the whole project in perspective for me.
This is what we were there for -- to explore and go out and see new places that have never been seen by human eyes.
Mars is a pretty harsh place. We've had dust storms before; we've had really low power situations in winter; we've had other small glitches that have caused us some tense moments, but Spirit seems to always find a way of turning some kind of adversity into something positive.
It was only be outlasting her design specifications, and never giving up, and absolutely never letting Mars get her down that she ended up finding what she had gone to Mars for.
NASA, Jet Propulsion Laboratory, California Institute of Technology