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JULY 9, 1997TRANSCRIPT |
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More images from the Sojourner Rover studying the surface of Mars have given scientists clues to the makeup of the many rocks found on the Red Planet. Their latest observations show that Martian rocks may not be too different from our own.
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Sojourner finds signs of ancient floods on the surface of Mars.
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December 4, 1996:
The Pathfinder Mars probe takes off.
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JIM LEHRER: Reading the rocks on Mars, Jeffrey Kaye of KCET-Los Angeles has an update.
JEFFREY KAYE: Scientists today released more pictures of the ancient Martian flood basin where Pathfinder landed July 4th.
Geologists have described its features as earth-like. Earlier today in a flood basin adjacent to the Jet Propulsion Laboratory in Pasadena, JPL geologist Robert Anderson, a member of the Pathfinder science team, compared the geology of the two planets.
ROBERT ANDERSON, Pathfinder Geologist: If a geologist looks at a rock, he can turn around and find the environment where the rock formed. For example, these very, very large crystal says that this rock cooled very, very low in the surface, okay, and it was eventually brought up to the surface and then carried on. So this means that it had a really deep burial. Whereas, this rock meant that it was at one time very similar to this rock but then was re-subjected to heat. Okay? So you can turn around--by just looking at these types of rocks you can figure its history out.
The other things you can figure out is that once it comes to the surface, they're always very angular, which tells us the amount of transportation we have. For example, this rock is broken up. It's very sharp edges means that it has not traveled very far; whereas, you look at this rock right up here.
You can see that it looks--you can see that it's very, very rounded, which means that the rock was in a stream bed and traveled for a long period of time, and it had a chance to wear down the edges as it rolled down to the water.
JEFFREY KAYE: So what does this tell you about the geology and the geological history of this area?
ROBERT ANDERSON: Well, this tells us that most of these rocks were not formed in this area. In fact, we know this here on Earth, but we know that they came from the mountains up there and were transported down.
This is very similar to what we're looking at in Ares Vallis on Mars. We picked that area because we know that the material have been carried from the highlands down and then dropped here. And that gives us an idea of what the geology and what the history--so if a geologist now was to go up into the mountains, you'd be looking for these types of rocks and find out where they came from.
JEFFREY KAYE: Anderson says the Martian landscape shows evidence of rushing water eons ago.
ROBERT ANDERSON: The other thing that we found since we've landed on the surface of Mars recently with Pathfinder is that we see what's called scallop marks, we believe. And these are areas where the water just rushed through and had turbulent flow, and it cut these little reels down--these reels have been filled in with other material now. But this shows us an idea that it is carved by water.
JEFFREY KAYE: So looking at the pictures and studying the data so far from Mars, what can you say generally about the history of that area?
ROBERT ANDERSON: Well, right now, we're beginning to find out some very interesting things. For example, in the news recently we saw "Barnacle Bill." Well, "Barnacle Bill," we're now realizing that it may be a rock which is called an andesite, which means that it was from the mountains; it was an igneous rock that formed, but it meant that--
JEFFREY KAYE: Igneous rock--
ROBERT ANDERSON: Igneous rock means fire rock. It means rock formed from volcanoes, but what--the key clue about an andesite is that it means that the material inside is very high silica. Silica is quartz. It's common on the Earth as sand, beach sands and stuff. And what it means is that the material has been reworked so that the silica concentration has gotten higher and higher and higher, because silica is one of the hardest minerals we have.
Okay. So as this rock was cooling, it means you have multiple episodes of volcanic activity on this one little rock. And so it's telling us that the crust right now, we believe, is becoming very active, or not becoming very active but has been active in the past. It's not like the Moon, that just formed and then hardened up and had some minor episodes. We're looking at something that is still dynamic.
Whether it's dynamic at the present day is what we're working on now, but it was dynamic up until the recent past because the rocks have been recycled with the amount of silica that's in the rocks.
JEFFREY KAYE: Similar to Earth?
ROBERT ANDERSON: Right now, yes. Andesite is a very common rock. In California, Hawaii, we find all kinds of andesite.
ROBERT ANDERSON: The sharp ones are probably the result of impact crater. We know we're near a small impact crater, so it's probably the result of these material being thrown out and onto our landing site. It is the rounded ones that they were dropped there by the water that came through.
JEFFREY KAYE: If you were standing on Mars, where the landers is right now, what would seem strange and what would seem familiar?
ROBERT ANDERSON: That's a good question. What would seem familiar would be the way I look at it looks very similar to some of the areas that we see down in the dry valleys of Antarctica. Okay. Now if you took these rocks right here and got rid of the vegetation, got rid of the water, got rid of us, and made the temperature about 5 degrees Fahrenheit, and it wouldn't be too undifferent I think right now.
Like I said, we've only explored a very small, little fragment so far, but one of the things that makes it so exciting about the Pathfinder landing site versus what we see in the Viking land sites is that we have mountains. See, in the Viking landing sites they were just--the horizon was flat.
JEFFREY KAYE: Right.
ROBERT ANDERSON: I mean, now we have all kinds of mountains.
JEFFREY KAYE: You have mountains and you have canyons.
ROBERT ANDERSON: And we have what we believe are channels. We have scour marks. We have all kinds of rocks. I mean, it's a geological paradise.
JEFFREY KAYE: The colors that we've been seeing in the pictures, reddish rocks, but lots of blues and grays, is that true color?
ROBERT ANDERSON: Yes, that is, and that's what's really exciting us, because those are rocks that are not covered with dust. Why they're not covered from dust we don't have the answer to that yet, but they are fresh rocks. And when we send our little sniffer, Sojourner rover, up to it, we would really like to see the fresh rocks, because if we have a rock that's covered with dust and we put the instrument on top, we get the dust signature in there. So what we're doing, like "Barnacle Bill," there had a side of it which got its name Barnacle, where it had no dust, and so that's where we went up and put our little instrument on.
JEFFREY KAYE: Anderson says that so far Pathfinder's geological survey has yielded few surprises.
ROBERT ANDERSON: We haven't seen anything we haven't studied on Earth, so there's no--we think, so far, like in the deserts of the Southwest, we see a lot of these features which are very indicative of the Ares Vallis landing sites. So far we haven't seen anything that scares us yet.
JEFFREY KAYE: So you feel at home?
ROBERT ANDERSON: Oh, yes.
JEFFREY KAYE: Bob Anderson, thanks very much.
ROBERT ANDERSON: Thank you.
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