Introduction to virtual field trip

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Introduction to the virtual field trip project


This is a transcript of a QuickTime movie (48.8 MB) recorded at the Macquarie ICT Innovations Centre in 2006 when Carol Oliver, from the Australian Centre for Astrobiology, introduced the virtual field trip project and demonstrated the tools for high school students.

Transcript:

This project is really based on that question, Are we alone in the universe? But we aren’t actually going to look at aliens today. What I’m trying to put into context for you is that it actually concerns an area here in Australia, in fact in Western Australia, in the Pilbara of Western Australia. In this particular part of Western Australia is one of the oldest places on Earth today. All of you will know from plate tectonics that what happens is our Earth gets munched up and scrunched up and subducted you get more continental parts and all the rest of it. So the land changes and changes form and comes together and splits apart so a lot of changes happen over time. This area in Western Australia hasn’t done that, in fact it’s been there almost since the beginning of the formation of our planet. It’s more than three and a half billion years old. Now if you can’t get your head around a billion, I was told think about talking to Bill Gates about the difference between millions and billions. But the other way of thinking about it, and I think it’s a really neat way, as I was shown by a researcher, is actually thinking about the span of time using your own body. Now if you stretch out your arm like this and imagine the beginning of our planet, the formation of our planet, is four and a half billion years old, Okay? It’s actually about 4.6 billion. It’s there. What we’re going to talk about, the context of this project today, is right here on your shoulder, three and a half billion years, Okay? At that time our planet was very, very different, perhaps a water world with no icy poles, the water was very hot with probably only a few volcanic island chains sticking up around the world and that’s all. That’s what it was. The days, we know, were much shorter, about fifteen hours. Our sun was weaker but there was a lot of heat coming up from the earth, the planet coming together and radioactivity, absolutely almost no oxygen in our atmosphere at that point. It’s a very alien planet. So we’re looking at three and a half billion years old and this is where this area of Western Australia, it’s still as it was three and a half billion years old. It’s just weathered over time. Nothing has been laid on top or if it has, it has all gone. So wherever you walk there, it’s that kind of age. Now thinking about your arm stretched out like this, you take your, looking at your fingernails and you’re going to sort of file that off, all right. As you file that off you file off the entire history of human civilisation. Another way of thing about it, I’ve often seen about it, is using a clock. An hour represents the entire history of our planet. Well then you’re looking at us in part of the last minute of that hour. So we’re very, virtual newcomers. Complex life has not been on this planet more than six hundred million years, not billion, six hundred million years, so only a fraction of that time. All the rest of that time our planet has been ruled by microbes, stuff that you can’t see. And in fact, even today, the microbes that are beneath our feet, around us and above us equal more in biomass than all of humanity, so they’re very prevalent. They’re very interesting because we’ve discovered a lot about microbes and still we’ve got a lot to learn but we only know perhaps one percent of what there is to know about microbes. But they have shown us that life can exist in very extreme circumstances. So we live in this narrow sort of envelope where it’s sort of like, you know, between zero and well maybe forty degrees. That would be, you know, at zero we could still get our jackets on and at forty degrees it starts to get really hot and fifty degrees then it’s very seriously a problem for us as human beings. Microbes can live way, way beyond fifty degrees, 120C, more than that in some circumstances. We’re still looking at that. They can live in frozen environments. They can very comfortably live there. They can live kilometres down in the rock, without any sunlight, with only minerals and a little bit of water to live on. They can live in hot springs, they can live in very acid environments, very alkaline environments and they can live even in the presence of radioactivity. In fact, on the Mars missions, when they tried to scrub the spacecraft clean, free of all microbes so we don’t go and contaminate other planets, it turns out, not only is it impossible, but we create life that can actually, it adapts to this very super clean environment. So they pick it up, they desiccate it, they punch it all around and they put it in a culture and it still springs back to life. So life is very, very resistant and far from the fragility we think about that it has. So this gives us hope that there may be life on other worlds. But first of all we’ve got to look at life on our planet and how it began and we don’t know the answers to that. The thing I’m going to show you today, if I suggest to you it’s a fact, it’s only the truth as we actually know it right now. It’s on the cutting edge of the research.

So here is a whole picture, I’m sorry it’s sort of a grainy kind of a picture but it’s from the Hubble space telescope and it shows galaxies way, way away from us, billions of light years away from us, almost back to the beginning of time in the universe. We think that the universe is something like 13.7 billion years old. Our planet has only been around for 4.6 billion so we’re sort of like new kids on the block, if you like. So what’s happened here could have happened maybe three or four times over, going one after the other and if you think of a temporal overlap, then many, many times. Each one of these galaxies contains something like a hundred billion suns. Our star (Sun) is a sun (star). It’s a very average star, a yellow dwarf star and it has a life of ten billion years and we’re right in the middle of it. We’re just in the right spot. So in all of this, I’ll just bring you back to something that looks like our galaxy, and we’re sort of like out on an arm of the galaxy, somewhere like that, looking, and actually in Australia we actually look into the galactic centre. And in that little bit of our galaxy, all around us we’ll find this kind of star-forming region where new suns are being born and new planetary systems. And here is another closer up, this is the Eagle’s Nest nebula and stars being thrown out here, ready to form new solar systems. You get a mass, it starts to swirl through gravity and as it does so it comes out to look like an egg shape and planets form. How many planets have we got in this solar system, can anybody tell me?

Eight now.

Good, excellent, you watch the news. Okay. And there are planets being born right now. And in the last hundred years we’ve actually had the technology to say, hey, are we alone? In all of this cosmos, can we possibly be alone? We are one of one hundred billion suns in our galaxy and our galaxy is one of one hundred billion other galaxies spread over this vast space and time, 13.7 billion years. To remind you, light travels at 300,000 kilometres per second. If you travelled at that speed, it would take you four and a half years just to get to the next nearest star. Our galaxy alone is a hundred light years across, a hundred thousand light years across, so if you were to travel one to the other side at 300,000 kilometres per second, that’s how long it would take you, a hundred thousand years. And we’ve even left our planet, gone to the Moon. We have done a lot of stuff in orbit around our own planet and we’re even planning expeditions to Mars.

Mars is an interesting planet. It’s much smaller than the Earth. It doesn’t seem to have had any plate tectonics to any degree. It’s got a mostly carbon dioxide atmosphere. It has very low pressure. So if you stood on the surface of Mars today it would be a toss up, without a space suit, it would be a toss up as to whether you would die from your blood boiling instantly or suffocating. So it’s not a place to go for a vacation. Even the equator, where it sometimes gets to a nice twenty degrees C, it’s still not a place to go. So there is no liquid water on the surface. The fact that your blood would boil indicates that. This low pressure causes it to go from ice to gas without going through the liquid phase. That says it sublimates from one to the other. But it wasn’t always like that.

Today Mars looks pretty much like that but perhaps three and a half billion years ago or maybe even four billion years ago it looked more like that. It wouldn’t have had grass. That green doesn’t represent grass, that’s too complex. But microbes can describe this colour so it might be that microbial slime, if you like, like cyanobacteria, covered the surface of Mars. And the sky would have indeed been blue because although today’s, let me go back, today you see this is a very sort of salmony colour, that’s because of the dust that’s suspended in the atmosphere. Okay. And that’s on the surface of Mars today. There are two Rovers there at present, Opportunity and Spirit. Spirit is at the Gusev crater, Opportunity at the Meridiani Planum and they’re looking for the geological circumstances for life. There’s only ever been one probe to Mars to look for the biology and that was Viking in 1976. There were two landers and it was very controversial because those landers seemed to have found life in the soil but then they decided that actually there was a problem with the experiments. We’ve been very anthropocentric and there was some strange chemistry going on and it didn’t indicate life at all. So we still don’t know the answer to the question. But what’s been very, very exciting about the things that Opportunity and Spirit have found is yes, the geological circumstances for past liquid water on Mars where the pressure would be higher is very evident, lots and lots of it.

This is the Pilbara today so without all the greenery and stuff you can see it’s very, very similar. This is a sort of a chert, which is a sedimentary rock, in which you find something called stromatolites. Now this stromatolite is actually a very special stromatolite. It’s actually been into space. Our only Australian astronaut, Andy Thomas, was on the Return to Flight mission on Discovery last year and he asked us if there was something that he (we) would like us (him) to fly into space. He always likes to take a little piece of Australia so we asked him to take a stromatolite that was three and a half billion years old. We think that this describes life flourishing at that time. It’s just a, quite a heavy sedimentary rock and you can see these layers, see the layers in there? These, we think, were made by microbial mats, mats of microbes that existed at that time, flourishing in a shallow marine environment and if you look at the top you see these very strange conical shapes. And if you go out onto the beach and try that, you will find that it’s very, very hard to make those shapes, with or without water. You can see those layers, just like layers in a tree trunk like that. Now this comes from part of a system, what we think is an ancient microbial reef that is actually the subject of a professional journal paper by one of the students at the Australian Centre for Astrobiology. So that’s been in space. I’ll actually leave it out so you can go and all have look at it a bit later. It’s travelled six million miles, so that’s ten million kilometres, been up to the international space station, so it’s been on quite a journey, it can tell its own story and been brought back to us. Actually on the last part of its journey Andy Thomas popped it into a box for us so while we were testing for the mid term project and I opened the box here in front of the students, it might have even been this high school, I don’t know, and out popped the stromatolite with the space ticket and everything else like that, which was a lot of fun. Then that last part of the journey, been up there on the space shuttle, came back via Fedex. I’m sure they’d be delighted to know that’s how Fedex was used.

Okay, Mars on Earth. This is actually the Pilbara where that stromatolite was collected. It was actually collected on this side here, on North Shaw. This is the Shaw River. It’s dry most of the year, as you can see here. These two little white dots are actually cars. They’re vehicles that we, four-wheel (drive) vehicles that we use out there because there are no roads to go on. And this is the Trendall locality. It looks quite verdant and green but it’s actually covered by spinifex, which is very spiny and sticks into you. Sometimes this all gets blown away by fire and you just see rock. Last time I was out there it wasn’t at all green, it was all rocky and so, let me show you another picture here, this is how it might have looked three and a half billion years ago. So these volcanoes would have been surrounded by water, this would have been a water environment and this picture from the Smithsonian indicates stromatolites, these humpy things, so it’s not conical like that one but these are humpy kind of cabbage things growing in this very hot water, no oxygen in the atmosphere. It looks very balmy there but it wouldn’t have been, again, a very nice place to go for a holiday. In the modern day environment you can find these cabbagey stromatolites and you can see where the artist has taken that imagery from. But you can actually find these also in the ancient rocks and this is a cabbage type one. You can see the similarity. You can see the scale as well. They’re very slow growing. They grow perhaps a millimetre a year, built by these mats of microbes that munch up carbon dioxide and put oxygen into the atmosphere. So they’re our first photosynthesisers, not plants, microbes. And there is the stromatolite there that I’ve shown you there is another type of one. There’s my watch. See the little Mickey Mouse ears here in the rock. This is a lateral type. And what scientists say is no geology can create this kind of stuff. It can’t be created by chemical and physical processes. The only other explanation is that it is indeed these microbial mats that we see in the modern day environment. And these are the microbes that made these stromatolites probably from around three billion years ago, not in the Pilbara but at three and a half billion there would have been sulphur munching types of bacteria. But they would have been very similar, with these filamentous hairs that are sticky and what happens is the water goes over them, the sediments stick to these hairs, a layer is formed by the sediment, then the next colony of microbes comes up over that and creates yet another mat and then so on and so forth. So you get that kind of ring structure.

And here is Opportunity or Spirit. That’s an artist’s impression and the kind of instruments that are on board. It’s quite a complex thing. To give you an idea of size, think of a supermarket trolley. It’s a little bit bigger than that. And there is what is made by the RAT instrument. It grinds into the rock to get a nice, fresh surface, an unweathered surface. And all over both locations, Gusev and Meridiani, you see this nice layered structure in the bedrock, suggesting layering from deposition of sediments, and also these little, what they call blueberries, all over the surface. They’re actually haematite and can only mostly form like that in the presence of water. You see whole fields of these blueberries in both locations.

Water ice exists on Mars. Some of what you see here is actually carbon dioxide ice, dry ice, but some of it is also water ice, so it can exist on the surface in that condition. And this one is all water ice. We know that from the signature from it. We also know that the planet contains an awful lot of water under the surface because we’ve detected that via spacecraft.

So the circumstances for life are there. Life needs water. Wherever you look on this planet there is life except in very dry places like the Atacama Desert where you get something like half a millimetre of rain per decade. There you don’t find anything. The soil is virtually sterile, well it is sterile. Everywhere else, even in Antarctica, you find life hanging on to whatever circumstances there are.

Contents


Introduction

Context

Early Life

Evidence

Acknowledgements

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