INTERVIEW WITH THE FOUR
BILLION YEAR OLD MARS ROCK!
by Steve Soter
Q: How does it feel to be four billion years old?
A: Actually it's four and a half billion. I can't complain, really. I've had a pretty exciting life...for a rock. And lately, I've been getting a lot of attention. As a matter of fact, I haven't been left alone since the summer of '96, when your friends announced that I might have traces of life from Mars. Suddenly everybody wanted to know all about me — you'd think I was some kind of rock star. Just between us, I could do without all those nosy scientists examining my history under a microscope. No more privacy, that's for sure!
Q: How do they know you're from Mars? No offense, but to me you look likea pretty ordinary rock.
A: Well, what did you expect? Glowing purple and green stripes? You can't tell where in the solar system a meteorite comes from just by looking at it.
Q: So how did they do it?
A: Well, to begin with, I'm not alone — you have about a dozen Mars rocks on Earth. And all us Mars rocks have some trapped gases inside — carbon dioxide, nitrogen, argon, a few others. The scientists found that the proportions of these gases exactly match the atmosphere of Mars.
Q: How could they know that?
A: Because the Viking spacecraft analyzed the atmosphere when they landed on Mars in 1976. If it's scientific evidence you want, there's your "smoking gun"!
Q: So, how did you get to Earth?
A: Well, one afternoon, about 16 million years ago, I was minding my own business when all of a sudden, an asteroid — or maybe it was a comet (we never knew for sure) — came crashing into Mars. Terrific explosion! It blew billions of tons of rocks and dust into the sky and left a big crater on Mars. Made an awful mess! Most of the stuff fell right back onto Mars, of course, but some of the rocks escaped into space, including me. It was all very upsetting — ruined my whole day.
Q: What happened next?
A: Well, I found myself in orbit around the Sun. And spinning so fast it made me dizzy. Every few thousand years, my new orbit carried me close to Mars, and I thought I might even get home again. But no, it was always a near miss. And each close encounter with Mars changed my orbit more and more, until finally it crossed the orbit of the Earth.
Q: So what was it like in space?
A: Well, the view was nice — I could see the stars for the first time — but I could do without all the cosmic rays. Back on Mars, I never had to worry about that, because I was buried deep under ground. But for 16 million years in space, I was always getting zapped by cosmic rays.
Q: What are they?
A: Cosmic rays? They're tiny fragments of atoms from the Sun and from deep space. They move real fast and pack a lot of energy. I got quite a dose of cosmic radiation. It left chemical traces in my crystals. In fact, that's how the scientists figured out how long I was in space.
Q: So tell us about your arrival on Earth.
A: I arrived in a blazing fireball, with a sonic boom. Quite the dramatic entrance! Like any meteorite, I hit the atmosphere real fast, doing about 12 kilometers per second — 40 times the speed of sound. Well, the friction with the air really put on the brakes. It slowed me right down in about two seconds. The heat was terrific — it melted my crust. And the
shock knocked me out — me, a rock! When I came to and looked around, all I could see was ice. I was alone on a huge sheet of ice — in Antarctica of
all places.
Q: And that's where they found you?
A: Yeah, but not right away. I landed on Earth about 13 thousand years ago, which was long before your ancestors even heard of Antarctica. They were still painting caves in the Old World. Well, it snowed a little every winter, and after a few thousand years I was buried in deep ice. What a bummer, I thought, no one will ever find me now.
Q: So how did they find you?
A: Well, the ice was creeping along real slow. Have you ever ridden inside a glacier? I didn't think so. Let me tell you, it's boring — you only move a few inches a day. And that glacier took its time creeping down toward the
coast. Finally we arrived near the Allan Hills, where the wind sweeps away as much ice as the glacier carries in. That uncovers any meteorites that might be riding along in the glacier and leaves them exposed on the surface. It's easy to see a dark rock on ice. And that's where I was found, by a meteorite hunting party, back in 1984.
Q: What happened then?
A: Would you believe it? They decided I was just an ordinary meteorite — as if I came from some dinky little asteroid. Some welcome! Was that any way to treat a genuine visitor from Mars, and after all I went through to get here?
Q: It seems like an honest mistake. You said yourself it's hard to tell a Mars rock just by looking at it.
A: Well, forget it. Anyway, they put me in a drawer for about ten years. At least it was warm. Finally, they got around to looking at me again, this time more carefully, and — Lo and Behold — they discovered I was from Mars. Also they saw that I was the only Mars rock that had carbonate globules.
Q: What?
A: Little blobs of carbonate — it's like the stuff that builds up in limestone caves. Anyway, some of the scientists said that I must have picked up this stuff in a wet place on Mars.
Q:So?
A: Well, that got their attention because they were interested in life on Mars, and you can't have life without liquid water. The surface of Mars is bone dry today. But way back in my youth — about three billion years ago — we had giant floods of water on Mars. So they decided to look me over real close, to see if I might carry any signs of life.
Q: What did they find?
A: They found tiny grains of magnetic iron, just like certain bacteria make on the Earth. And they found traces of organic gunk like you have in tar or charcoal. And they saw some microscopic rod-shaped things that looked like fossil bacteria.
Q: So they found signs of life on Mars?
A: Maybe yes...and maybe no. Some of the scientists think it all points to ancient life on Mars. But lots of others don't buy it. They claim you can make all those things without life — maybe there's just some strange chemistry on Mars. So there's this big debate. I'm very controversial.
Q: So what's the scoop? Is there any life on Mars?
A: Well, sometimes on a Saturday night...
Q: No, really, it's a serious question. Is there life on Mars?
A: That's for you to find out. If I just told you, it would take away all the fun.
Q: Do you actually know the answer?
A: Of course I know the answer! I wasn't born yesterday. I was there. I know everything that happened on Mars.
Q: Can't you just give us a little hint?
A: No. But I'll leave you with two ideas to chew on. First, IF there was ever life on Mars billions of years ago (and that's a big "if"), then it's a good bet there's still life on Mars today. But not near the surface, which is a frozen desert. If there's any life on Mars today, you'll only find it in liquid water deep under ground, where it's warmer. Tell your friends at NASA.
Q: OK. What's the second idea?
A: Well, you know, Mars rocks have been falling on the Earth ever since the solar system was formed. IF one of those rocks carried the seeds of life from Mars to Earth (and that's an even bigger "if"), then you and all the other life on Earth might be Martians.
Q: You can't be serious!
A: That's for you to find out. Look, I've already told you enough. Besides, I gotta go now. The scientists want me back in the lab. They're trying to pry out my secrets. They actually think they can outsmart an old rock. Well, I'm gonna to keep 'em guessing for a while.
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