9UNP0186SD_Clark_Johnson_WordPress

- Good evening, everybody. My name's Tom Zinnen. Welcome to Wednesday Nite at the Lab. We do Wednesday Nite at the Lab every Wednesday night, 50 times year, here at the Biotechnology Center. This is where I work. I work for UW-Madison. I also work for UW Extension Cooperative Extension. And on behalf of the Wisconsin Alumni Association, thanks for coming to Wednesday Nite at the Lab. Tonight, we have Clark Johnson, who is a professor in the Geology and Geophysics Department here at UW-Madison. 

He got his undergraduate degree at UC-Davis. And then both his masters and his PhD at Stanford University. And then about 23 years ago, he came here to UW-Madison. Tonight, he's going to talk about astrobiology. What in the heavens is astrobiology? He started by saying, "What in the heck is astrobiology?" But I thought that was a little offensive. 
(laughter)
I didn't want Mr. Dobson calling me. 

Okay, so, please join me in welcoming Clark Johnson to Wednesday Nite at the Lab. 
(applause)
 
- Thank you. That is a different title, as was just mentioned. The original title I picked, "What in the heck is astrobiology?" you'll see kind of dovetails with a couple of slides, so this is kind of a nice juxtaposition to that. What is astrobiology? What I hope to do tonight is give you a feel for what that is. It's a very broad field. 

It's a field that's been around for many decades, actually. It's been called exo-biology, sometimes, or astrobiology is more recent. I'm going to talk a little bit about the perspective from a geologist, the department that I come from. Then I'm going to end talking a little bit about our participation in it. We just started a new five-year $6.5 million initiative with NASA and our department to work on these types of problems, specifically something that we call biosignatures. That is, teasing out signatures for light. So, I wanted to start with a couple of quotes. This goes back to 1964, in a paper in "Science" by George Gaylord Simpson, an evolutionary biologist at Harvard, who was talking about the relative merits of studying life on Eart versus thinking about life elsewhere. He basically came with this quote that's been resonating throughout the community for a while. This "science" astrobiology has yet to demonstrate that its subject matter exists. 

That is, what can we actually measure? And that's a common criticism. Are you guys nuts? What are you talking about, finding life elsewhere. There's no proof that that's a worthwhile endeavor. Where are the textbooks? Where are the subject matters? Now the quote that I actually prefer is this one that's relatively recent. And I wanted to tell you, and hence I picked the title that I did. But then I didn't object to the change in the title, "What the hell is an astrobiologist?" 

And this is a quote from an unknown Secret Service agent who was on then President Clinton's presidential detail at NASA Ames Research Center, which is in the South Bay area of California. Some of you may know that. This coincided in April of 1996 with the first Astrobiology Science Conference run by NASA. This was a conference where people came from all over the world. Clinton frequently flew into Ames Moffett Field Naval Air Station, because it was secure. And Air Force One was parked there. He was visiting his daughter Chelsea at Stanford at the time. And apparently one of the astrobiology participants wandered into an area where he was not supposed to be. And he was detained by the Secret Service. When asked what he was doing, he said well, I'm an astrobiologist. 

And this quote was overheard by the Director of Ames Research Center, just before he went on stage to open the conference and he loved this. So this became the mantra for the conference. "What the hell is an astrobiologist?" But you get the meaning. What is an astrobiologist? So that's what I hope we can address today. Well, we have a person in our department, a microbiologist that studies wetlands here in Alabama. He's an astrobiologist, because he's interested in-- you can't see it too well maybe, but this is iron oxide that's being reduced, changed in its form by iron reducing bacteria. We'll talk about those in a minute, later. But this has clear applications to a place like Mars, believe it or not. 

Obviously, Mars doesn't have all these weeds, and things like that, but there are certain biogeochemical processes that are analogous to that. Geologists are often engaged in astrobiology. These are the world's oldest stromatolites. Stromatolites being the name given for a mound, a fossilized mound of algae. And these are three and a half billion years old. Here's a close-up, looking down on one of them. The next one is a cross section, and the unique feature here is this kind of conical shape like that. And that has not been able to be reproduced anywhere by any biological process. We see that in modern microbial mats. And this is generally accepted to be evidence for the oldest, 3-1/2 billion years old, that's pretty darn old, layered microbial community, mainly based on morphology. 

Extremes of life. Someone who studies let's say, hydrothermal black smokers at the bottom of the ocean is an astrobiologist, to the degree that we think these might be analogous to early Eart environments or maybe a place like Europa, which maybe would support what we call chemosynthetic or chemolithotrophic bacteria. Here's a hot spring, a famous one in Yellowstone, Grand Prism Spring. All of those beautiful colors, some of you have probably been there, are due to microbial processes. And someone who studies this is an astrobiologist. An astronomer looking at extra solar planets, which we're almost up to 300 now, would be an astrobiologist. Someone looking for planets in what we call the habitable zone of a planet. In very rare cases, they can be directly imaged, but if any of you are from that field, you know that we have to look at these in indirect methods. So an astronomer certainly can be an astrobiologist. And at least from NASA's perspective, which has this thing they call the road map. 

There's basically three fundamental questions. How does life begin and evolve? Does life exist elsewhere in the universe? And what is the future of life on Eart and beyond? So pretty big picture questions that could fit into a number of fields, but actually need an aggregate of many fields. Another perspective is this one. This is another quote that I like. Astrobiology comes down to real estate. Is it all ours, or do we have to share it? And believe it or not, that comes from John Rummel, the chief scientist at NASA for astrobiology. 

Okay, so that's the stage. It's pretty large. Here's a plot that would kind of quantify that. The NASA Astrobiology Institute went through a review by the National Research Council last year. And for that they compiled publications. And this is all the publications by field. Primary means, primary author, this one is from astronomy. Okay, astronomy, we think of that. Biology or astrobiology, okay fine, that makes sense. Chemistry. 

Earth Science is the big one. We also have Physics and Planetary Sciences. But geologists are actually the biggest players in astrobiology. And so why is that? We work at the limits that define life in terms of temperature, and things like that. We work at deep sea hydrothermal systems that would support hypothermalfillic microbes. We work in very cold communities, such as the microbial communities living in rock in the Antarctic dry valleys. And here's one of those types of communities, where this is a sandstone. This of course, is the surface, and that's exposed to extreme temperature. And the sandstone has an iron oxide cement to it that's endemic to the rock. 

But microbial communities have developed a layered stratigraphy in there. They've mobilized the iron. They've actually respired off of the iron. And they live just a little bit below the surface so they don't completely freeze. Okay, another example of extreme life. Here's another example of extremeness in terms of high salinity. This is a bacterial community in Mexico. And it's right here, you can see these guys that are colored, and that is encased in gypsum salt. So we call these hypersaline communities. And again, this is mapping out the extreme limit of life. 

For those of you who work in biology, this is no news to you. We also have the time component. That is unique geology. We work on things that are the oldest rocks known, or minerals. In this case, the absolute oldest terrestrial material that we know of is this little grain called a zircon that has one spot in it that has an age of 4.404 billion years old. It was found out in this low lying area of Australia called the Jack Hills. And that was worked on by professor John Valley in our department. Some of you may know him. This is not a rock that is this age. This is a grain that was derived from some other source terrain and finds itself in a younger sandstone. 

But it's getting pretty darn close back to the initialization age of Earth at 4.5 billion years old, so that's pretty impressive. If you want to go to rocks that you can hold in your hand, they are younger. The oldest one I would call intact sedimentary rocks, that is, those that were laid down at a particular time, not these little grains like the zircons that were from somewhere else. These rocks were laid down at 3.85 billion years old. In southwest Greenland. They're banded. These are well accepted to be the oldest sedimentary rocks. The oldest bacterial fossils, which is disputed, have been proposed to be in this little layer of rock, it's not too exciting unless you look at it in detail. It's a silica rich rock that was deposited 3-1/2 billion years ago in Australia. And we'll talk a little about some of the evidence about how much confidence we have in those interpretations. 

These were interpreted to be photosynthetic cyanobacteria. For astrobiological analogues, Mars is the closest one to Earth. It shares a lot of the bulk physical and chemical properties. It's obviously a little bit smaller, a little bit farther from the sun. But if we look early into its history, there's a lot of evidence that says it might have supported life or had conditions that would be conducive to that. In addition, because of processes like plate tectonics, that you've probably heard about, where plates are moving around and continents are bashing around on the Earth, the very old rock record is very scant. So, going to Mars also gives us a window into a planet that has had a much more quiet tectonic history. And we expect much older rocks to be preserved there. In fact, the evidence is that it's pretty clear looking at things like crater rings. Okay so I wanted to spend a couple of moments talking about the Mars astrobiology missions, because that's what a geologist looks to, the nearest rocky planet that is similar. 

It doesn't mean there aren't other places to go in the solar system like Europa. Those are very important prospects as well. Well, you probably know of a number of these. The Mars Pathfinder which was launched in 1996. It was a small rover. And it was really a test. It was a technical problem of testing the rover concept. It had a couple of very simple spectrometers, some cameras. And it was shut down in September of 1997. After that time, there have been a couple of orbiting missions. 

This one, Mars Odyssey, which did a lot of mineralogy mapping and has continued to do that from orbit, a lot of high resolution imaging. And it also was establishing a critical communications relay with later rover missions. The European Space Agency launched Mars Express Orbiter in 2003. Its mission was quite similar to that of Odyssey. It was paired with the Beagle 2 Lander that you may recall reading about that was lost in this mission. The big stars to date have been the Mars Exploration Rovers, or the MER. Those were launched in 2003. They were two rovers. I know you've heard about these, Spirit and Opportunity. They were placed at opposite points, essentially, in the equatorial band of Mars to maximize the chance of finding something interesting. 

And it was a very simple goal, and that was to find clear evidence for water. Now you probably remember back to textbooks where people talked about these things many decades earlier, about water being inside canyons and things like that. But this was actually to look for mineralogical evidence for things that precipitated from water. Its goal was not to find life, but to find if there were environments that could support life. It had a wonderful array of imaging and mineralogy equipment on there. It was a spectacular success. And some of the key points was that it found iron oxides and sulfate minerals that clearly indicate precipitation from liquid water, and sedimentary rock formations. And they are still operational. And they've driven 20 times farther than they were originally planned, and operated 16 times longer. Just a spectacular success. 

If you look at some of these images, such as this oblique picture of Burns Cliff taken by Opportunity, where you see the layering of the rocks and all of the sedimentary structure. And going up and analyzing those things, you feel like you're just out on a field trip, and you could just touch those. They are just a spectacular success. And that really has driven a lot of our interest in Mars since then. The Mars Reconnaissance Orbiter was launched in 2005. That was to look at more detailed mineralogical studies, again to help plot where future missions would go. It had additional packages like climate instrumentation, radar imaging, and a high speed communications link which was needed to upgrade the communications with Mars. Just recently landed is Mars Phoenix. That was launched late last year and landed about a month ago. It was a reborn mission, if you will, essentially the same equipment from a Mars Polar Lander mission that was lost. 

It landed at the north edge of the polar ice cap. This was a new area to explore. It's a stationary lander. Its goal is to look at soil and ice analyses. And so far in the last 30 days, Phoenix has trenched down to ice and here's a couple of images. This was taken after 20 days on the surface. And here's some ice that's been exhumed. Here's it is after 24. And it's difficult to see, I see in this image, but there are ice crystals here in this detail that are right down in here, where they've completely sublimated or evaporated in this next image taken four days later. So that's very good observational evidence for some type of ice. 

And next would be detailed analysis of the instrumentation on board to really pull out what the ice chemistry is and then look for any organics. The next big one on the plan is Mars Science Lab in 2009. And I'm not going to go through all of this instrumentation package. But it is an amazing array. This is the full blown shooting match. This is an artist's conception of the Mars Exploration Rovers, Spirit and Opportunity, next to Mars Science Lab. And just to illustrate that, here are the tires. There's little Mars Pathfinder. Here's Spirit and Opportunity rovers. And here's Mars Science Lab. 

It is a beast. It is larger than a Volkswagen, in terms of running and requires, of course, a very big rocket and things like that. So that's scheduled to launch. That's clearly launched in 2009. The site selection is going on now, and that should be narrowed down to probably about four sites by the end of the year. Okay, what about off into the future? There are launch opportunities every 25-26 months, so roughly every two years processing a little bit. There's nothing planned by NASA in 2011. European Space Agency will launch a very ambitious project, ExoMars, in 2013. And then in early 2016, 25-26 months later, puts us into the next year, there is a possible target for an astrobiology dedicated mission. 

And that's one that I'll show you an instrument that we hope to fly on. Sample return. When we were at that conference in 1996, where the Secret Service agent made his quote, we were told that Mars sample return would be done by 2009. We're still waiting. Okay? That's tentatively slated at about 2020 or 2022. This would involve probably two rovers, an orbiter, and then a collection in orbit. Basically launch these things like you see in this little thing, package them all up and bring them back. It is a huge project. And the amount of material is very, very small, because of launch issues. 

We'll see if that really happens. Okay, so that's our nearest neighbor, as far as a geologist is concerned. Let's move back to Earth. What I want to now talk about is what our group is doing. And we call ourselves the Wisconsin Astrobiology Research Consortium. Basically, our task is looking for what we call biosignatures. I want to spend a little bit of time talking about biosignatures. What are they? What is the evidence that would convince what should be a very skeptical scientific community, and rightly so, that we've got clear evidence for life processes on another planet or planetary body. Well, on our own Eart, it's no problem. 

We're making lots of biosignatures. And so here we've got an old rusted car. We've left them on the moon, of course, we've left equipment. Remember, that's a human fossil, that's a footprint. Dinosaurs have made lots of those, if you've ever been out to the west or Dinosaur National Monument. Here's some dinosaur tracks. Those are clear biosignatures. What about biosignatures on Mars? Well, we are leaving biosignatures now. There's a whole issue of sterilization and planetary protection, not just for samples we bring back to Earth, but actually so that we don't introduce stuff accidentally on Mars and say, "Oh, look, I found this bacterium, it looks just like something I see on Earth." 

Oh, yeah, well, we brought it there. In any event, we are leaving biosignatures. If we run into something like this and we didn't put it there, we've got a clear biosignature, right? Well, we don't expect something like this. We expect something on a much more primitive level, something on the microbial level. And in fact, the majority of scientists do not believe that life is currently thriving on Mars. We would be looking for an ancient signal of Mars, when Mars had a higher atmosphere abundance and liquid water could exist on the planet more easily than it could today. So the first thing you might think about then are fossil biosignatures. We're not going to find some Martian in a space ship, probably. Let's look at some fossil biosignatures, and let's think about them in the microbial world. 

Now here's a photograph of a modern cyanobacteria. That's probably about 100 microns across. Here is a very well accepted occurrence of fossil cyanobacteria. These have been imaged in three dimensions. They've been analyzed with various spectroscopic methods to show that they contain biologically important elements in the right proportions. And that is in a relatively young rock for a geologist, 800 million years old is young for a geologist. So that's pretty well accepted. But it's not very deep into Earth as history though. Here is the drawings from a paper that came out in Science in 1993 for this proposed 3-1/2 billion-year-old cyanobacteria locality. I showed you a little picture of that out in Australia. 

And these have been highly contentious. These have been reproduced in the lab by abiologic processes. It has now been shown that these rocks were actually hydrothermal vents. They were much higher temperature than probably could support life. It's a tough problem because our record of these very old rocks gets scantly, scantly, scantly small as we go back in time. Here's another place, only a few kilometers from the same locality. Australia is a boon for astrobiology, because it has been tectonically stable for an awfully long period of time. This is a proposed microbial mat. This, the one on the right, is much more accepted than the one on the left. Basically two different things. 

But these are fundamentally morphological characteristics. Now there's another matter of actually preserving organic material. Let's return back to Mars. And we have a very serious problem here. What the plot is on the bottom here, is a plot of the surviving fraction of amino acids under galactic cosmic radiation versus the depth in centimeters. So the bottom of this is four meters deep. This is looking at the survivability. That is one part in a million, ten to the minus six. So with just preserving one part per million of the original organic material in there, you would have to be below one or two meters. So actually, it is no surprise, now that we have a better assessment of these types of things by doing laboratory simulations and having a better idea of galactic cosmic ray flexes, that for example, Viking back in the '70s, found no evidence for organics. 

It might be a better chance of having something preserved up in Phoenix, but it's still a long shot until one can drill. And so for example, sample return is anticipated to have a drill that can go three meters deep into the rock. That just adds to the complexity right there. So we don't expect to find fossilized material, organic material very close to the surface on Mars today. We have a similar, although different reason problem in the Earth. And that is because the Earth is tectonically active. And again, as we go back and back in time, these sedimentary rocks, these low temperature rocks that were deposited in the environments that would support life, are often metamorphosed, that is changed. And many for example, here's just a picture of a three billion-year-old gneiss that's been metamorphosed to 600 degrees. Sorry, folks, the organics are all gone. We have a tough problem looking at fossils, than actually looking at the organic matter after that. 

So what's the approach? The approach that we proposed that is a different way of looking at things is to look at the minerals that are the metabolic by-products, if you will, the waste products, of various microbial metabolisms. And we know from looking at the modern environments, high temperature, low temperature in the laboratory, that there's a limited group of minerals that would include this. We know that these can survive much better the effects of metamorphism or being irradiated with UV radiation. What are they? Jarosite, this was the big winner on the Mars Opportunity and Spirit rovers. Jarosite is an iron sulfate that is very indicative of iron oxidation by bacteria. Hematite, another oxide form, oxidation form, is another biogeneric mineral, if you will. An iron carbonate called Siderite is another one. Magnetite, another iron oxide that has a little bit different chemistry than hematite, is another one. 

And then lastly, old-fashioned pyrite, iron sulfide. The common thing here is iron. So this is something we proposed to do. And this is what our main effort is looking at, the biosignatures that might be preserved in there. Not necessarily the organic matter, because that might be destroyed, but other characteristics of these minerals. The big question is... Yeah? 
- Can you be sure that those substances aren't formed in some other way? 
- Ah, absolutely not! Because if you look at them, how do we know that these minerals formed as a product of biology versus non-biologic processes. 

The answer lies in this funny thing called isotopes. Okay, so we're going to spend a couple of minutes on what this stuff is, on isotopes. So what are isotopes? Well, if you're a fan of the "Simpsons," you've heard of isotopes. Here's Bart Simpson, who was protesting the movement of the baseball team, the Springfield Isotopes to Albuquerque, which actually has an analogy in the real world if you're into baseball. There's a baseball team, the Albuquerque Isotopes. This is Isotope Stadium. That's great. I kind of like their emblem. Don't you like that? 

It looks like a baseball zipping around like it was a little electron or something like that. Okay, well we need a little bit more serious definition. The technical, boring definition is that isotopes are different masses of the same element due to different numbers of neutrons. How does that work? Let's take the simplest one, hydrogen. Hydrogen can exist just as a proton which has a mass of one. We ignore the electron mass. Or, it can have a mass of two, which includes a proton and a neutron, and of course, the mass of two is heavier. That's shown just in this simple little balance. A little bit more complex view of a nucleus might be illustrated like this, where we have our little electron clouds surrounding the nucleus, which includes the positively charged protons. 

And then these orange guys are the neutrons. It's changing the number of neutrons that we're going to look at. Could biology discriminate on this? And the answer is yes. And so it's not that for example, siderite, which is iron carbonate is a different chemical composition when it's been produced by biology versus not. It's that the isotope composition, the relative proportions of neutrons of iron are different. So that's where we're headed. How does this work? Well, I'm going to show you a little simple animation. This is based on hundreds of experiments that have been done in the lab, and then going out and field testing them, right? 

Astrobiologists go anywhere. We work any place. And seeing if we get the same results in a natural microbial community. And what we're going to do here is we're going to look at iron reducing bacteria. These are bacteria that pump electrons to a terminal battery, if you will, an electronic receptor, to set up energy pathways that they can respire on internally. And so I'm going to have, let's say, an iron 3 oxide, this just means it has a plus-three charge. And I'm going to pump electrons to that here. Of course, if I pump electrons to the plus-three iron, it's going to get reduced, right? Remember that back in high school chemistry? So that's going to become an iron two. 

So over time, we will make iron two, which is soluble, the iron three is not, and that's becoming this little iron aqueous coming off. And the interesting thing is that the isotopes in this layer that we call iron three, react. It's kind of this reactive layer that's at the site of electron pumping starts to have a different iron isotope composition. And what happens in the end is that there's an exchange going on. If you look carefully, I've shown this for the two most abundant isotopes of iron. There are four of them, iron with a mass of 54, 56, 57 and 58. And 56 and 54 are the most abundant ones. So I've got little 56's here and 54's exchanging. The end product of equilibrium is that the aqueous iron will have a low ratio of 56-54. It's still iron, but just two different amounts of neutrons in them. 

And the iron oxide, this reactive layer will have a high 56-54. So that's the idea behind that. And the really cool thing is that we cannot induce this exchange abiologically. We can, if we really work at it, and go to extreme conditions that aren't found in nature. But this is maybe giving you a hint of what a biosignature would be. Something that's distinctly attachable to microbial respiration. So why would that be? Why would the bacteria induce an isotope exchange that we can then later detect in the rock record that we can't do just by abiologically mixing aqueous iron and these oxides? We think the reason is how they attach. And this has been worked out by a number of other microbial researchers. 

Here is a little image of a iron reducer called Shewenella attached to hematite. And then here is another image that shows what are now known to be these nanowires. Ah, nano comes into it, right? Everything is nano. In this case it really is true. These are electrically conductive pili, or nanowires, that the bacteria attach to the substrate to the iron oxide. And they pump those electrons to there. And we think that because this exists only in a bacterial system and not in a abiologic system, this is the mechanism for inducing the isotope exchange. How do we know that? A gazillion experiments, many years of working this out. 

But this was the premise. And it turned out to be quite well. So we cannot tell the biogeneric siderite, or magnetite, or pyrite, just by looking at it. We need to measure the isotope ratios. That's where the biosignature is hidden in. And I just wanted to give you a little feel for that. Well, what about iron isotopes in the ancient rock record? Let's not worry about what this parameter is. This is just a relative enrichment or depletion of the heavy iron isotope where these would be light. And remember, the iron that was mobilized in that little animation had a low 56-54. 

In other words, it was kind of light. It was impoverished in the iron 56. We see this remarkable thing going from about four billion years old or four thousand million, geologists tend to use those interchangeably, back to about 1-1/2 or two billion years ago. And we think what this means, is that this is recording. We've got some gaps. We've got to look at more areas, but this is giving us a hint, right? This is where we are. That this is the evolution of iron reducing bacteria on Earth. That's really important, because that gives us a constraint on the biogeochemical pathways that might have occurred. Now if you look at that, we're saying, okay, maybe between about 3-1/2 billion and 2-1/2 billion years old, this is when this metabolism became important, at least in the environments in which we sample. 

Again, that's important for a geologist to know, what are the environments. Is this the open ocean? Is this a restricted pool? That's another context that we don't have time to talk about. But you may have noticed that the signal goes away. What's going on there? We know we have iron reducing bacteria today. They're just very restricted in their distribution. And what we think is going on here is that this records a change from about 2-1/2 to two billion years old, where we have something called sulfate reducing bacteria that really kicked on when sulfate content got high in the oceans. They essentially out-competed the iron reducers. 

Again, this is just a very, very brief overview, but I want to give you a feel for where we're headed. Okay. Where do we do these types of analyses? Well, these are a number of our mass spectrometers just down the way in the department. We've got nice big, clean labs that we can process these samples in moderate sized mass spectrometers, truly large, ten ton mass spectrometers. When we include the magnet, and things like that. That's great. That would be what we would use for sample return. A little bit tough to get that on a rover with the weight requirements. But that is our goal. 

So there are some technological advances that we're working on in terms of detector and sample introduction. This is the high risk component. And this is a miniature mass spectrometer. This is the bread board instrument that hope that we will fly. This is being developed with the jet propulsion lab at NASA. It's essentially a miniaturization of one of the instruments that I showed you that would take up a good size of this room. A little bit of ion source. This would be introduced by laser ablation. It turns out that if you do such ablation at about Mars pressures, you get something called thermalization of the ions, that actually enhances transmission by many orders of magnitude. That's kind of luck. 

So it's actually easier to do this analysis on Mars, because we don't have to have all these vacuum pumps attached to it that we would have if we had it right out here in front of us. So that's a little bit of luck. We'll take that. And very small electric field and then a magnetic field. Instead of the traditional way of counting ions, this uses a CCD detector, a newly developed one with an electronics firm in California. And it all fits into this little container right here. There's a laptop for scale, at a Mars simulated pressure. So we have many, several years of getting this off the bread board and to actually running it on a rover. Take it out to a place like Death Valley, go zap a whole bunch of rocks, see if can work. Recognizing that that's a harder problem, because we're at a high pressure. 

And this is ideally suited to low pressure. And then, getting it on the list to make it by 2016, we've got to have this thing pretty much off the bread board in a year or two. Then the 2016 might not fly. We don't know. In any event, that's the target. So what I've given you is a little bit of feel for the range. It's not a comprehensive one. We haven't talked about many different aspects of astrobiology. But I just wanted to end with a little bit of discussion about what we are doing down the way. So our group is a consortium among Madison, the NASA Astrobiology Institute, which is headquartered at NASA Ames in South Bay area of California, Jet Propulsion Lab, the Mass Spectrometer Development, and also the University of Georgia, which had some expertise that we needed to tap into. 

It's about a dozen on the grant. We have four tasks over five years. We need to understand the survivability of organics in extraterrestrial environments. We need to confirm that we would expect that plot to be as depressing as it would be. That is just some theoretical calculations. Maybe if we're lucky, we might find areas that things could be protected in, and we don't have to drill as deep on a Mars sample return mission. But that has not been quantified in experiments in the lab. Another one is experimental calibration of what I call these isotopic biosignatures, and just briefly mentioned one to do with iron. There are other elements that are selectively fractionated, that is different isotopes are picked by biological processes, versus abiological ones. And that of course, includes carbon, iron, sulfur, calcium and magnesium. 

These are the target elements that we would not have known to go for unless we had the great results from Spirit and Opportunity, the Mars Exploration Rovers. So these feed off of each other, having continual exploration and feedback with what we would do in the lab. We're geologists, we like to go out in the field, so we have a number of field studies. We like to know that we can actually analyze something if Mars sample return is a long way away, or I retire by the time they come back. So we have a series of modern and ancient terrestrial rocks. And we play those off each other. It doesn't mean that you can go to, let's say, a wetland in Alabama and say that's exactly identical to what the Earth was like 3.5 billion years ago. But you can pick specific biochemical pathways to study. It helps ground truth, if you will. Of course, being geologists, we like to run around on old rocks too, even though there are very few. 

The main places, if you want to look at rocks that are three billion years old that are preserved, we're restricted to southwest Greenland, South Africa and western Australia, in just a few localities. Not too many places. And lastly, our high risk kind of component, it's a gamble, whether we can actually shrink this down and get the precision we need. It's a trade off. You can only cheat the laws of physics so much, and that would be our miniature mass spectrometer development. So we have a pretty full plate for about five years. So just briefly, in conclusion, I just wanted to give you a couple of feels for things. Astrobiology asks, how did life evolve here and elsewhere in the universe? It's a pretty fundamental question. The subject matter is there. 

We don't have little green men to analyze yet, but it's modern ancient Earth. Analogues that we think to other planets, and very limited glimpses, either through remote sensing or rover based observations, but those are very limited. That's not like going there. In other parts of the solar system and the galaxy, specifically looking at let's say inhabital planets, planets in the inhabital zone in other solar systems. These are pretty fundamental questions in science. I personally find it the most mind expanding endeavor I've done as a scientist, because you talk with biologists you talk with astronomers, you talk with physicists, and everybody, if you come from those fields, everybody has their different lingo. And the one thing that I learned when starting this, is that if you make a pact with someone and say that I won't laugh at your dumb questions if you don't laugh at my dumb questions, it works great. Because we feel like idiots when we talk to someone who's an expert in his field that I know a little bit about. If you accept that, you get a wonderful experience that drives you out of where sciences tend to go, which is very, very specialized, just really strong specialization. But it's a challenge. 

It's a challenge to have students find career pathways through that. The conclusions are going to be tough. People want to know. You probably heard about the life on Mars meteorite idea that came out in 1996. That was published in Science, and it was a series of observations out of the Johnson Space Center. If you were to poll 100 scientists on the street, 99 or more would say that's bunk. And so, the bar is high. It should be high. And the bar will get higher as we keep going. But what that means is this is a multigenerational aspect. 

So we may not solve this problem by the time I retire. We may not get samples by the time I retire. But again like anything in science, you're laying the ground work. So I personally find it quite interesting. I've got a couple of minutes, I'm just going to add a couple of things. If you might be interested in participating in that. And we are trying to set up a pretty large educational public outreach program. That's being run by our geology museum. And I bet a lot of people have been there, or at least know about it. It has an enormous amount of draw. 

You may not realize that small museum has 40,000 visitors a year, and 14,000 K-12 tours each year. I mean it's phenomenal. That's 14,000 visitors through the tour program. And if you're interested in that, I would encourage you to contact either Rich Slaughter, our Geology Museum director, or Brooke Norstad, our associate director. There's a broader component of outreach that we would love to get volunteers involved in, and that's run out of NASA JPL. There's two of them. One is called the Solar Systems Ambassadors Program. And that is aimed at general public audiences. There's training that people receive by going to workshops at NASA or locally, let's say down in Chicago. And the other one is solar system educators, which is actually aimed more at K-12 teachers to add astrobiology to the curriculum. 

And there's an enormous amount of curriculum material that we can add to that. That may not apply to many people in this audience, but it's a two-pronged component. And if you're interested in that, Kay Ferrari is our contact at NASA on that. These are the Solar System Ambassadors. This is the more general outreach one. And anybody in this room could become a Solar System Ambassador. Notice that there's a couple here in eastern Wisconsin, but none in Madison, and we need that. Then in terms of solar system educators, we have one person, a very well regarded educator at Green Bay. But again, we could certainly use that. That is one thing that NASA is wonderful at, compared to something like the National Science Foundation, that many of you I'm sure are familiar with. 

NASA has a great way of getting the public energized. And that's essential. That goes to science literacy issues, and things like that. And that's all I've got. Thanks! 
(applause)
 Yeah? 
- Are the consortiums doing this kind of work in other countries? 
- There are two countries that are doing this in earnest. The biggest one is Spain. 

So Spain set up a large center of astrobiology a couple of years ago, with a large amount of funding. Funding that we would be quite envious of, from their government. The next one is Australia. Australia, there's a lot of rocks there that are old, you've seen them in Australia. And that went great gang busters up until a few years ago, until their funding got pulled. And now they're kind of looking for a new home. They found it. And that's looking a little more solidified. Then there's talk of starting a Scandinavian-based one. The Canadians are talking about it, but there's not too much more than talk. 

NASA is the heavy hitter still, in terms of this area. 
- What is this radiation that's sterilizing Mars? I haven't heard about that. Tell me about that. 
(inaudible)
 
- Right, so Mars is red because that is all rust from UV photo oxidation. That is an extremely hostile environment to preserve organics. So oxidized forms, I don't want to get too technical, but oxidized forms of substances are stable on Mars under a UV bombardment. Reduced forms, like organic carbon react away very fast. 

Now we are, of course, shielded by that with our atmosphere. 
- You mentioned briefly Europa. Can you talk about potential for discoveries there? 
- So, Europa is of course, very far away from the sun. But there is a lot of evidence that beneath that ice layer, there is liquid water, there's movement dissolution, or melting and then freezing events that seem to be best explained by having some type of liquid water underneath. Why is it there? Because of the tidal forces that Jupiter is imposing. So it is a flexing of the planetoid that's keeping that hot. If that's true, then there might be hydrothermal systems, that is heated water, and we know by going into these deep terrestrial environments at hydrothermal systems, that we can have chemo-lithotrophic metabolisms supported. It has nothing to do with photosynthesis, of course, because these are very deep. 

So that's the idea. That's the idea. Much harder to do a mission to Europa. Mars is hard enough. More missions have been lost on Mars than ever reached there. The Russians did a ton of them that were all lost. 
- Samples will be brought back to Earth, right? 
- That's the plan. 
- Will all the analysis for the isotopes, and so on, be done here on Earth? 
- Well let's say that the mission launches, the soonest launch date that is conceivable now is 2020. 

There would be a follow-up mission in 2022. They would all be collected and brought back several years later, probably, to arrive. We're talking 2026. I won't have retired by then, but if it's pushed back from that, who knows. Now in the meantime, it's very unlikely that we're going to have our mass spectrometer that we have now. We would, of course, there would be something newer and more important. So we would have different instruments. Deciding who gets the instruments, or who gets to analyze these things. The maximum amount to be returned is on the order of 50 grams to maybe 100 grams. That's not even a pound. 

And so there is going to be a very careful worldwide set of protocols for labs to propose to do this and that. It should be open. It shouldn't be only for NASA people. So we would love to do it, is the quick answer to your question. It's a long way away before we know whether that will actually happen. 
- Do you think instrumentation will progress to the point where you could do those analyses in situ? 
- That's the goal. It's a little bit of a quandary when you think about it. Let's say, let's take our instrument for example. If we want to fly on 2016, that means all the instrument package would have to be approved for engineering two years earlier at the latest, and then we back that out to where there would be competitions for multiple instruments, because probably ten times more instruments would be proposed than could be flown. 

If you back all that out, that means you have to close the door on your own technology development probably eight years prior to flight, which means you know you're going to be flying obsolete stuff. But there's no way around it. It's very different than how we tend to think of-- It's not a project you put your PhD student on. 
(laughs)
 It would take ten years. You would approach it by having just this be one of multiple things. So yes, we are feverishly trying to work out some technological hurdles, but we only have a couple of years to do it, otherwise we've lost the opportunity. 
- Is there, when you look at biologists working on DNA, they can do stuff in months. You're talking about close to decades. Just from a personal level, is there a frustration that things just take a long time and there's no way around it? 

- Yeah. That's a good question. The way that one personally survives is to have multiple things going on that you can get done. So if we were told for example, I doubt if anyone would want to sign on to this project where they were just developing this thing, they're working furiously in the lab, and then maybe you'd find something in ten years, but you weren't allowed to go out and play around with real rocks and go look at new environments. I don't think many people would sign up for that. There's a interesting thing if you talk to the career NASA scientists. I have other lives, other projects and things like that here. The NASA scientists have it harder, I think, because they're locked into that. They're civil servants. And they are working on a particular thing. 

And if you ask them, many of their ten year programs are all of a sudden just cut. So a good example of this was the morale problem that happened a couple years ago in NASA, when President Bush announced a reorientation to go back to the moon, which drove a lot of scientists nuts, because there was no new money. It was a complete internal reorientation. All of these planetary missions are actually unmanned missions and are quite cheap compared to manned missions by many orders of magnitude. And they just had to completely swing and put away things that were a decade. Faculty members are a little bit more insulated, because they're lives are a little bit more diverse. But you feel badly for some people that have their careers just turned on a political dime, basically. 
- You mentioned issues with sterilization and cross contamination with interplanetary missions. Have all of the missions that have gone up, have cares been taken, or is there a possibility that tainting already exists? 
- A lot of care has been taken to sterilize the rovers, but not hit them with things that are so hard that you would damage instruments. 

And that's a tough one. Are people 100% sure that no microbes have been introduced with Mars, I bet something has. Most people. From the general public's perspective, they are much more concerned, although scientists are not as concerned as the public, about the return. The Andromeda Strain problem, if you saw that movie a couple of decades ago. Yes, having a pathogen come back from Mars. That is another part of the sample return issue. But it's a problem that has not been solved yet, because let's think about this for a minute. So we have for example, the sulfate minerals called Jarosite, that are very fragile, if anybody's ever played with Epsom salts, or something, that's a magnesium sulfate. So sulfates are very susceptible to breaking down, if you just suddenly change the temperature of the pressure. 

Let's say you take that sample. You put in a little sample return canister, it experiences two years of time in space at absolute zero and at a higher vacuum. A lot of people have concern, and that's not even with the sterilization issues that would be done on top of it, that the samples, the integrity of them will not be what they were on Mars. So the counter for that is sample return, the advantage there, is we can put any instrument, it can be the size of Camp Randall Stadium, and we can analyze it, no problem. But maybe the samples will be all compromised. And so that's why the desire to do in situ measurement is high. The disadvantage, of course, is that you're limited in what you can send up. Just to give you a feel, that little miniature mass spectrometer. The maximum current that could be was 1.5 watts for the whole thing. That's what we were limited to. 

That was the technical spec we had to limit. So that's a very dim night light. 
- You mentioned that the isotopic functions that are unique to biological-- fractionations can be re-created in some quirky lab conditions. Would you mind? Do you know offhand? 
- Oh, yeah, we've been working for many years on that. 
- Would you repeat the question? 
- The question was, you mentioned that these isotope fractionations could be produced in the lab, by an abiologic process, but I said it was very difficult to do. What do I mean by that? It's not an on/off switch. 

None of these things are, right? Yes, what we can do in pure systems, and pure systems for the details. If we have pure aqueous Fe-2, iron 2, that's plus 2, interacting with a pure iron oxide, we can induce some of that fractionation without biology. What we find is that if we put it in a medium, in a solution that reflects complex chemistry that we think actually occurs in these solutions, if we take, let's say, the data where we think the ancient oceans were, which had a lot more silica for example, and calcium magnesium in them. Or what we think might have been the fluids that precipitated the minerals on Mars, then that exchange is shut off. And the little bit of data that we've done shows that the biology can still overcome it, but we haven't explored the full range of how far you can push it and have biology still do it. But, you'd love to have the on/off switch, right? It's binary. Life, no life. None of these are going to be like that. 

Nope, sorry, haven't discovered it yet. 
- I don't know whether we know why the bacteria concentrate the iron 54, but is it possible that Mars bacteria don't do that or they concentrate it the other way, or is there some reason for this concentration that seems inseparable? 
- Right, that is-- More broadly, your question is we're basing all of our search for life on what we know on Earth. That's kind of an expansion of your question, and that's a real fundamental question. The cheap answer is, that's all we've got to study. It's not very satisfying. It gives you a knot in your stomach. I am more comfortable extrapolating that to an Earth like planet like Mars, where I understand its bulk chemistry, I have a little feel for its temperature, history, although it's not directly analogous, of course. So that you would hope that the metabolisms that we are exploring and the processes, the experimental setups that we do here, and then find in nature on Earth have some relevance to Mars, but it's a nagging question. It is a nagging question. 

And so what you try to do is you try to explore a range, let's say, of different microbial parts on the tree of life. And so far, things point in the same direction. But that is not a guarantee that something weird would happen on Mars that we couldn't figure out. Yep, I agree. 
- What are some of the pre-existing or co-existing elements involving life from many year years ago to now? 
- Okay the question was, what are...? 
- Some of the co-existing conditions, like water, etc. 
- Oh, okay, right. So here we come back to this issue of how we search for life. The question is, what are the pre-existing conditions that we are framing our search for, basically, I think is what you're asking. 

Water is at the top of the list. We believe that we need a solvent, some medium, to do chemistry with. We believe that you need some type of cellular containment to isolate that chemistry, so we can set up chemical gradients, energy gradients, essentially, to support metabolism. Those are fundamental. So far, until we can occupy other worlds for long periods of time and study them, we are grounded in using what we know on Earth as the framework. And they are water, because of the chemistry, some type of membrane, some type of organic material. The organic material is actually becoming quite interesting, because there was a paper that came out just last week in a journal called "Earth and Planetary Science Letters," it came out of our group, as well as the Goddard, and another group at NASA, that shows that enormous amounts of organics-- surprisingly high amounts of organics in meteorites. And so a lot of these basic raw materials could have been delivered to a planet. It doesn't mean they're still there on the surface of Mars, because it could have been removed, right, by all that UV. But the building blocks are probably already in existence. 

The Earth, we have a relatively young solar system. Yeah? 
- The heavenly bodies farther than Mars, where we can't physically go, and not to mention breathe. Are there any spectroscopic or any other means? 
- Oh, that's a great question. Yeah, thank you. The question is, it's so far to go to Mars, are there other methods of, I think you're saying remote sensing, remotely sensing a biosignature. Of course, for that we start thinking about astronomical types of observations. And there is one group at NASA out of the University of Washington that's pursuing that. They're called the Virtual Planet Lab. 

It's largely a computational supercomputer lab, where they make planets by having a certain amount of chemistry, certain size, certain amount of raw materials, and they let it run. Huge computing power. And they make virtual worlds. And so they had a paper out in Nature about a year ago, where if you change the light distance of a particular sun, and you have different wave lengths of absorption of photo synthetic pigments, all the trees could be pink. Something like that. That's cool to think about. But this is being pursued. Can I make that distinctive few pixels, if you will, that an astronomer can observe. Can I predict what other ranges that would be unique to life. So that is being pursued on a theoretical basis by a group out of the University of Washington. 

Yeah? 
- Is there any value in looking for DNA or components of DNA remnants in any of this? 
- Well, that's certainly the goal of both Phoenix, which is there now, to see if there are high mass organic compounds, that's not DNA, but organic compounds. That's also the goal of Mars Science Lab that will go in 2009. But everybody is pretty pessimistic that it's preserved at the shallow levels, at which they would be scraped because of this ultraviolet radiation. That's why the attention is on can one drill a couple of meters at depth, as your best chance of finding it. 
- Are the isotopic segmentation studies been done on the meteorites from Antarctica? 
- The question is, have the isotope studies been done on the meteorites from Antarctica. And you might be thinking specifically about the ones that were proposed to come from Mars with life in them? Right. 

Yes, some of the work has been done on that, and that has been quite controversial. There's one group that thinks that the minerals that were proposed to be biogenic, which were magnetite and the iron carbonate siderite, formed at extremely high temperatures, probably something to do with impact volatilization, because when you think about getting a meteorite from Mars to land on an ice sheet in Antarctica, it had to have been blasted out by an impact on Mars, right? Otherwise, you wouldn't get it out into space, so it's had a tough life. And then there's another group that said, no, these are low temperatures. And there's no resolution to that, which is kind of a sad state. And there's only one that has that age, that's of the early part of Mars. Most Martian meteorites, there's about a dozen of them now, are very young actually. They're young volcanic rocks. So those, that's not high on anyone's list of looking at evidence of life, because it's so young. It's after Mars lost its atmosphere, after it got very cold. 

There's only one sample, the highly debated one, that's 4.5 billion years old that would be the early part. 
- What was Mars' atmosphere? 
- Well, it was probably not as dense as ours, even at its maximum. But it should have had water and CO2. It was a water and CO2 atmosphere, probably. Yeah? 
- Is there a possibility of biological signatures in the atmosphere of Mars? 
- Oh, yes. So the question is, is there evidence in the atmosphere of Mars for biology? Several months ago, there was a discovery of methane from one of the orbiting orbiters. 

That got everybody really excited, because methane, that's a really highly biosignature kind of element. Then there's a counter argument that came, well, you know, with the sensitivity of the spectrometers that were used and the peak matching of the peaks, it's not methane. That remains unresolved. There's a group that believes there's methane in Mars' atmosphere today, which would be phenomenal. That means there's active biology perhaps. And others say that it was an insensitivity of having unique spectra. But that is something that is continually being looked at in terms of more the climate of what that is. And Mars Science Lab will have atmospheric samplers to test that. 
- Well, can't those kinds of things, like presence of methane be remotely sensed? 
- No. 

Not at the very low levels that, if it does exist on Mars. The question was, can the methane be remotely sensed from Earth? That's a very tough one to do from Earth at the low levels that are thought might exist, but there's a big group that thinks it doesn't. 
- I wasn't clear on what you said about how you keep from introducing pathogens from Mars into Earth, like sterilization. 
- The question was, what are the specifics about how you would sterilize samples to be returned from Mars, so that they won't, when they come back to Earth, they won't bring bacteria. Heat is pretty much out, because all of these minerals that we're looking at are formed at low temperatures. They are stable today at low temperatures on the surface of Mars. The surface of Mars varies between minus 20 and minus 80 Celsius. So heat is out. Ultraviolet sterilization is the favored one, but of course, that has some limitations that you will not penetrate the whole sample. 

If you have what we call an endolithic community, a microbial community that's deep inside a sandstone, ultraviolet sterilization may not be an issue. So then you'd go look at more harsh radiation things. Then you run into issues of bringing those radioactive sources, those high energy sources, to Mars. So the problem has not been solved. So you are correct to think that you're not clear about why it is. These are all the issues that are weighing-- If you were only interested in sterilizing the samples, blast them and be done with it. But then the mineralogists and other people would say, well the minerals would all be gone. So you just wasted your time bringing it. So it's finding that balance. But it has not been solved yet. 

- Are there volcanic activities in any of the new planets outside of our solar system? 
- Yes. Oh, I'm sorry. The question is, are there other planetary bodies in our solar system that are volcanically active outside of Mars, which, the youngest volcanic activity that we know from Mars meteorites is about 100 million years old, which is young to a geologist. Mars is 4.5 billion years old. Then the other big winner would be one that has large sulfur volcano eruptions, a moon of Jupiter. 
- Are there new ones outside of our solar system? 
- Outside of our solar system, we do not have the resolution to know about volcanic activity on other planetary bodies around solar systems. All that we know is that they exist by the perturbations of the stars around which they go, because they can't be imaged directly, except for maybe one or two cases. 
- Are there any groups that are seriously studying about how to colonize Mars or some of the others? 

- So the question was, are there any groups thinking about colonizing Mars? 
- Or some of those other planets around, where there's some water. 
- I read, a couple of years ago, well several years ago, I read an article about if you wanted to terraform Mars, what is the most, what is the best plant species to introduce. Anybody here remember that article? Anybody want to guess what it was? Dandelions! 
(laughter)
 So you export your weeds from your lawn, and those are just supposed to thrive if you get anywhere near habitable conditions. There are people that talk about it, but it's kind of a fringe. 
- On "Coast to Coast"? 

(laughs)
 I listened to that earlier this week. They think there might be life on the other side of the moon. They're over there kind of hiding out. 
- Sure, yeah. 
- You talked about, for example, in western Australia. Are they in an area that is easy enough for people to see or visit? 
- The question is, the rocks that I showed you in western Australia, how easy are they to get to. And the answer is, extremely difficult, which is great. 
(laughter)

 And the reason for that is for example, these stromatolites that are 3.5 million years old, they are a treasure for humanity. The Australians have debated about whether to put a big fence around them. And they decided not to. They kind of know who goes in and out of this. This is very remote country. They are very careful to preserve them. If they existed in downtown Manhattan, they'd be gone, right? And so, it is an interesting accident that some of the oldest rocks that we are desperate to study, that are treasures for the planet, are extremely remote. The same applies for Greenland. Less so for South Africa. 

South Africa, these important localities are very easily accessed. There is a sad story that I'll just mention of why this is a concern. There's another very old group of rocks up in central Canada. It's called the Acasta Gneiss. And that was, at one time, the oldest rocks you could touch at 4.1 billion years old. It was an outcrop that was about the size of this podium, or this area here. And it was discovered by a geologist at MIT. And he kept the location secret, secret, secret. He wouldn't tell anybody where it was. Word leaked out, and a bunch of geologists from another country came and dynamited the whole outcrop. 

Those things happen, even though it's a pretty remote place. 
- Why did they do that? 
- To collect it. Dynamite's very efficient at collecting rocks. Those things happen. We try to rely on everybody recognizing that these are incredibly precious things. The Australians are trying to watch that. But in a subtle manner, without drawing attention to where it is. 
- Do they know who did it? 
- Yeah, we know who did it. 

- Are they prosecuted? 
- No, they're shunned. 
(laughter)
 Not appreciated. 
- I'm confused about these old rocks. If rocks aren't old, where do they come from? Why aren't all rocks old? 
- That's a good question. Why aren't all rocks old? On Earth, they become young when they are essentially melted. 

So a geologist kind of defines the age of a rock when it has been either so thoroughly re-crystallized, metamorphosed and squeezed. We're talking about temperatures of 600-1,000 degrees Celsius, at pressures that are 10K deep in the Earth. Or, completely melted would be the extreme of that. And it launches itself out as a volcano. Then it's a new rock. So we get those situations in a planet that is what we call tectonically active. That is, it has plates that move around on the surface of the Earth, like a surface like Earth. And that's fundamentally driven by loss of heat from the interior of the Earth. So things rise when they heat, they make plate tectonics, they dive back in. So the plate tectonic cycle makes rocks young. 

- If we dug down below this building and reached bedrock, that rock that's down there would be how old? 
- We would think that in Wisconsin, which has not been a part of the plate tectonic cycle. It hasn't had a plate boundary since about 1 billion years ago, and most of this part of the world would be older than that, about 1.8 billion years old. We would anticipate that if you drilled all the way through, you would find rocks of similar age. 
- So they were reformed a billion years ago? 
- Right, right. That's a great question though, that's what makes the age of a rock. The remarkable thing about the Australian and some of these other localities, is that these are sedimentary rocks that are still flat lined. They haven't even been tilted on end. They are not metamorphosed. 

They've been weathered deeply. Australia has had a deep weathering profile, but they're still preserved. 
- So if I took an old rock and melted it, and then it re-crystallized, you say it was a new rock. 
- Correct. 
- How would you know? 
- Yes, that's a good question. How do I tease out this cycle? There are a few little hints of things that survive. And one of them I mentioned is this mineral called zircon. It is a small mineral that is extremely retentive of the isotopic clocks, the decaying clocks, like uranium decay, even at very high pressures and temperatures. 

What we commonly find is the vestiges of these old rocks exist as maybe the core of a zircon that we analyze with a very small ion beam. And the rim, the younger zircon is new. But they're very, very small little hints. You have to look at materials that we know from laboratory experiments are very resistant to being completely reset. There are a few. 
- So how old is the stone or rock that's used in building construction be? 
- Oh, it could be any age. The question was, how old would a rock be from a building stone? I can tell you that for example, that the main granite of the State Capital is a granite of about 300 million years old from New England. But you could go up and get the Wisconsin state granite, which actually is very crumbly, it's not a very good building stone, but you see countertops made out of it. 

That's about 1.8 billion years old. It varies all over the place. 
- You mentioned that in Wisconsin, the oldest rocks are about a billion years old. I thought the Baraboo rock, Precambrian bedrock was around 3 billion. 
- So the question is, is 1 billion years old the oldest rock in Wisconsin? No, it's the youngest of the new rock. So, 1 billion years old is when magmatic or volcanic activity stopped in Wisconsin. It's been quiet since then. We haven't been at a plate boundary since then. There are rocks older than that. 

- You mentioned the Geology Museum. My daughter, 3 1/2, went there today for the first time. It is a really great destination on campus. It's great to hear about all the work you're going to be doing in astrobiology there. So, if you've never been to the Geology Museum, I encourage you to go. Otherwise, thank you very much for coming tonight. I hope to see you next Wednesday. 
(applause)