TOPICS > Science

Mars Rover Begins Exploration of Key Crater

September 29, 2006 at 6:45 PM EDT

JEFFREY BROWN: When two solar-powered rovers began their
exploration of Mars in early 2004, scientists hoped the vehicles would operate
for 90 days. Now, some 900 days later, “Opportunity”
and “Spirit” are still at it, offering an exciting window on the
planet’s present and past.

While “Spirit” monitors the Martian climate south
of the equator, its twin, “Opportunity,” has reached the edge of a
200-foot-deep, half-mile-wide crater named Victoria. And scientists are calling this
the most spectacular moment yet in the mission.

Among those very excited scientists is Steve Squyres, the
mission’s principal investigator and a professor of astronomy at Cornell University.

Welcome back to our program.

STEVE SQUYRES, Mars Rover Project: Hi, glad to be here.

JEFFREY BROWN: Why is looking at this particular crater,
Victoria, so important?

STEVE SQUYRES: Well, the rocks at this place are layered,
like a stack of pancakes. And for two years, we’ve been driving around on top
of that stack without being able to see inside it. What this big hole in the
ground does for us is let us see what’s down in that stack of layers and what
those rocks have to tell us about the past history of Mars.

JEFFREY BROWN: So you’ve got some early pictures here. Tell
us about them. Tell us what you’re seeing.

STEVE SQUYRES: Well, what these images do initially is just
simply reveal the scope of this crater. We’re going to later be taking much
higher-resolution pictures in color. This is our first glimpse. We literally
just got here a couple days ago.

But what they show is cliffs 50 to 100 feet high, a very
deep, bowl-shaped crater, a sand dune field down in the bottom. What gets us
excited, as scientists — I mean, aside from just the sheer spectacle of this
view — is these cliffs show an enormous deep sequence of layered rocks.

And what that means is, if we can get to those rocks and get
to them up close and measure their composition, we can learn a lot about what
conditions were like when the rocks formed.

Getting inside Mars

JEFFREY BROWN: Now, is something that you might learn aboutconnected to whether Mars, in fact, could have supported life?

STEVE SQUYRES: Yes, exactly, exactly. We found in some ofthe rocks we've looked at already, which correspond to the ones up towards thetop of the stack, some of the youngest rocks, that conditions would have beensuitable for life. There was water at the surface; there was water below thesurface.

What we don't know is what came before that. What was thestory that's told by the deeper rocks, the older rocks further down in thecrater? And that's what we hope to find out here.

JEFFREY BROWN: Now, you're talking about getting up close. Sowhat's next? Are you going to send "Opportunity"down into the crater?

STEVE SQUYRES: That's the big question. If it is safe to doso, if we can safely send the vehicle in, you bet. We definitely will.

It's very steep here. It's steep; it's dangerous. There arecliffs. We've really got to watch our step. These are precious vehicles.

So the first thing to do is just survey. I mean, imagine youwere an explorer here yourself. You'd never been here. You'd walk up to thething, and you'd look around, and you'd see what looks safe, what looksdangerous. What's the best way to go at this thing?

We just arrived here two days ago. We're still figuring thatout. I hope that we will be able to go in, I really do.

A bit of engineering, a bit of luck

JEFFREY BROWN: Is "Opportunity,"in fact -- how much is it on its own, and how much of it is what you guys tellit to do? I was reading about it. It's sort of fascinating, as it comes up tothe precipice and has to decide whether to take the next step, in this case.

STEVE SQUYRES: Yes, it's sort of a collaborative effortalmost, between the engineers on the ground and the rover on the surface ofMars. We tell it what we would like it to do in broad strokes, but there aresome things where we leave it up to the rover to make its own decisions,particularly when it comes to safety.

If the rover suddenly feel that it's tilting too much, it'llstop what it's doing. If it suddenly feels that its wheel is dropping down,say, if it came across an unexpected hole, it will stop what's is doing. Therover is actually a lot smarter now than it was just a couple weeks ago, too,because we just put some brand-new software on board the thing that gives it awhole bunch of new, autonomous capabilities. So they're pretty smart machines.

JEFFREY BROWN: These rovers are now like the little enginesthat could?


JEFFREY BROWN: When we talked to a couple -- we talked withyou a couple of years ago. And you were expecting any moment they could stop. Howdo you explain what's happened? Why have they continued on?

STEVE SQUYRES: Well, it's been a couple of reasons. Part ofit is just testimony to the hard work that was done by all of the engineers atthe jet propulsion laboratory and elsewhere who built these things. They builtsome darn good hardware.

But on top of that, we've been lucky. We've been lucky withthe weather. We thought the thing that was going to kill these rovers was goingto be dust, Martian dust, settling out on the solar arrays. And what we didn'tcount on was the wind.

We've had several lucky gusts of wind that have just cleanedthe dust off the solar panels, given us more electrical power and a new leaseon life. And that's happened several times with both rovers. So it's been acombination of hard work and luck.

The past and future on Mars

JEFFREY BROWN: Well, it's well over more than two years now.What do we know about Mars that we didn't know before?

STEVE SQUYRES: What we know is that Mars -- while Mars todayis a cold, and dry, and desolate place, Mars in the past was quite different. Therewas water beneath the surface. It occasionally would rise to the surface andflow across the surface. It would evaporate away and leave salts behind.

It was a very, very different world from what it is today,and one that was significantly more suitable for life.

JEFFREY BROWN: And I know we've asked you this before, buthow long can this go on?

STEVE SQUYRES: I have no idea. You know, we expect -- wedesigned these things to last for three months. We tested many of thecomponents to four times that, like 12 months, just to be on the safe side andmake sure that these things would really last.

It's been almost three years now on the surface of Mars. Andright now, we have no basis for guessing how long they're going to last. Theycould last for another year or they could die tomorrow. So we just try to drivethem everyday as if it's our last, because we never know when it's going toend.

JEFFREY BROWN: Well, that is what you said, I think, twoyears ago. So we'll see when we get to talk to you again.


JEFFREY BROWN: Steve Squyres, thanks a lot.

STEVE SQUYRES: Yes, same story. Nice to be here. Thanks.