January 12, 2009

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Narrator: Five years of cruisin' on Mars.

I'm Jane Platt with NASA's Jet Propulsion Laboratory in Pasadena, California.
Harsh climate, dust storms, winds, a broken leg--nothing has stopped the twin Mars
Exploration Rovers that are celebrating their fifth anniversary this month. Spirit on
January 3, and Opportunity on January 24. Now these were originally three-month
missions. Joining us is John Callas of JPL, project manager for the rovers.
So John, on those landing days back in 2004, did you or anybody on the team dream that
five years later, both rovers would still be alive and kicking?

Callas: Well I was an optimist so I felt that we would have an extended mission, but I
don't think anyone thought they would extend this long and last for five years.

Narrator: Okay, well here we are and let's just recap a couple of quick factoids. How
many miles have the rovers travelled, how many images have they sent back, etcetera?

Callas: Spirit has traveled about 7-1/2 kilometers, which is about 4-1/2 miles, and
Opportunity has traveled 13-1/2 kilometers, which is a little over 8 miles on the surface
of Mars. And combined they have returned over a quarter million images from the
surface, in addition to many thousands of scientific spectra.

Narrator: And why have the rovers lasted so much longer than originally planned?

Callas: First of all they were very well-built rovers. We designed the rovers for a very
harsh difficult environment, and we also designed the rovers to account for any loss of
performance in the solar arrays. And as it turned out, when we got to Mars, the solar
arrays performed better than expected and the environment wasn't as harsh as we were
anticipating. But also winds have occasionally come along and blown some of the dust
that's accumulating on the solar arrays, so a combination of all those factors allowed us to
survive the winters. We also have to remember that we have some very, very skilled,
capable people operating these rovers, and careful operation of the rovers allowed us to
survive the Martian winters.

Narrator: Where are both rovers now and what are they doing now, and what will they be

Callas: Spirit is located at a place called Home Plate, which is in the inner basin which is
on the other side of the mountains that she crossed. She's now coming out of winter and
planning on moving south about 300 meters, about three football fields, to search for
more evidence for hydrothermal systems, which we think exist in this area.

Opportunity on the other side of the planet has completed her reconnaissance of Victoria
crater, which was this very large crater where we spent a couple of years trying to get to
and then spent about a year exploring. And now we're headed south and to the southeast
towards an even larger crater that's somewhere between 16 to 20 kilometers away, which
is farther than the total distance that Opportunity has driven to date, so there are no
guarantees that we will get there, but scientifically and for exploration reasons this is the
right direction to head.

Narrator: What for you have been some of the highlights for each rover, either in terms
of the science or some maybe scary moment that you overcame?

Callas: Wow, there are so many. In terms of highlights, I think the discovery of high-
purity silica that Spirit made about a year ago, which is evidence of ancient hydrothermal
systems, think of hot springs, if you will, on an ancient Mars. That's significant because
it means that Mars was more Earthlike and that it had the potential for an environment
that could have supported life. Interestingly, Spirit discovered that silica due to its failed
wheel, which is one of the only real serious hardware failures either vehicle has
experienced. And so when we drive, we have to drag that wheel and it cuts a little
furrow, a little trench, if you will. And since we've been driving this way, we've been
unearthing material that's just beneath the surface, stuff that we never would have taken
the time to examine, but since we're getting it for free if you will, we came across this
unexpected discovery of this opaline silica, which is very exciting.

And then for Opportunity it's been finding water, evidence of past water wherever it's
traveled. So the scale of the watery environment that existed in the past was more than
just a puddle or a pond, but we're talking lake-size features at one time.

Narrator: This is probably a good time to bring up, because you mentioned the two
factors--Earthlike and evidence of water--probably a good time to remind people why
we're going to Mars, why the rovers are there, why we have other missions that we've
done and that are coming up.

Callas: Well I think there are two great questions about Mars. One is was there life on
Mars or is there life there today, or can we find evidence of past life? Because the rovers
have told us that Mars was at one time like the Earth, and so provided a potentially
habitable environment. The other great question for Mars is why has it changed, why is it
so different from the Earth today? What happened to Mars? Why did it lose its
atmosphere and its oceans, its surface waters and become a cold, dry, barren planet? So
what changed about Mars and what does that mean for us? So another way to express
those questions: are we alone and what is our future? And exploring Mars helps us to
address those questions.

Narrator: And the more we know about water, which is such an essential ingredient for
life as we know it, the more we know about answering those questions, correct?

Callas: Absolutely.

Narrator: They are however in terms of spacecraft on Mars, they're senior citizens by
now, and they are showing some signs of aging, besides the leg.

Callas: Yes, they've far outlasted their original design life of three months, they are
showing signs of aging. But considering how long they've lasted and how far they've
explored and the environment they're in, they're actually in really good shape. Yes, we
have a wheel that's failed on Spirit, we have the robotic arm on Opportunity that's
becoming somewhat arthritic, but their cameras are in excellent shape, their computers,
their avionics systems, their communications systems, all in really good shape.

Narrator: Do you play through in your mind, because the rovers can't last forever, do you
have scenarios in your mind of what it will be like and how you and the team will feel
when one or both of them does eventually end its life?

Callas: I mean, that will be a difficult day for all of us who have invested so much of our
time and have such a close bond, such a close association with these two intrepid
explorers. But at the same time we also have to remember the tremendous
accomplishments that they have on the surface of Mars and how much they have
informed us about the Red Planet.

Narrator: So what do you think would be the eventual legacy of these rovers? How have
they improved our knowledge of Mars overall, what have they taught us about traveling
on other planets? What will be their legacy?

Callas: Perhaps their biggest legacy will be that they made Mars a familiar place. We
look at these images, and we look at them as if we've been there and that we recognize
features that are familiar to us, even though they are on this alien world hundreds of
millions of miles away. So I think the fact that they've brought Mars to Earth, if you will,
is perhaps their greatest legacy.

Narrator: Okay, well thank you very much, appreciate your time.

Callas: It has been my pleasure.

Narrator: For more information on the rovers, you can go online to www.nasa.gov/rovers
You've been listening to a podcast from NASA's Jet Propulsion Laboratory.

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