Women of MIT: Celebrating Science and Engineering Breakthroughs (Session II)
PRESENTER: Good afternoon. Welcome to the second session this afternoon of celebrating science and engineering breakthroughs. We have yet another all-star cast with two speakers from the School of Engineering and two from the School of Science.
Our first speaker this afternoon is Angela Belcher. She is the W.M. Keck Professor of Energy. She's a full professor in two departments in the School of Engineering, Material Science and Engineering and Biological Engineering. Professor Belcher earned her BA in creative studies at the University of California Santa Barbara in 1991, and her PhD in Chemistry from the University of California Santa Barbara. She was a member of the faculty of the University of Texas Austin from 1999 to 2002. And then she came here to MIT.
Her awards are numerous and extraordinary. I've picked just a couple to tell you about. She won a MacArthur Fellowship award in 2004 and has also received the Presidential early career award in science and engineering and the DuPont Young Investigators award. In 2006 she was named Scientific Americans Research Leader of the Year and was named a member of the Scientific American 50 for her outstanding technological leadership in the use of custom evolved viruses to advance nanotechnology. Her work has been published in many prestigious scientific journals, including Science and Nature, and she has been reported in the popular press including Fortune, Forbes, Discover, The New York Times, the Wall Street Journal. It's with great pleasure I introduce Professor Belcher.
BELCHER: Well, thank you for that introduction, thank you for the invitation to be part of this really extraordinary symposium. Being at MIT I always say it's like being at Disneyland for scientists and engineers where everything is so exciting that's going on around us and that's definitely been true since I've been here. Today I'm going to talk about giving life to materials for energy and the environment. And I put that I'm with my dream team because the group of students, graduate students, and postdocs, and undergraduates I've been working with over the last couple years are just extraordinary. And it really has been a dream come true to work with these students and then also with my collaborators here at MIT.
So I'm going to tell you a little bit about giving a genetic information to nonliving structures. I've been interested in abalone shells for a long time. These are biocomposite materials made out about 90% by mass calcium carbonate 2% by mass protein yet they have a lot of really extraordinary properties. One of the things that's exciting to me is not only about their beautiful structural properties, but when a male and female abalone get together they pass on the genetic information that says, this is how to build an extraordinary structure.
Here's the DNA sequence. The codes for an extraordinary structure that allows an organism to grow in ocean temperatures, in ocean pressures using nontoxic materials and not adding toxic materials back into the environment. So that's been fascinating to me for quite awhile. How can you give genetic information to organisms that haven't had the opportunity to have evolution. And that's the focus of our work. So we basically say how do you go from a beautiful structure like this that's had millions of years of ability to go through evolution to something like this, which is a battery that I'll talk a little bit about today.
So again, looking at the abalone shell, when a male and female abalone get together they pass on the genetic information and make baby abalone. These abalone go along and basically replicate these beautiful structures, these organic, inorganic hybrid materials. Say with diatoms made of silica, made out of glass, there's at least 10,000 different species of diatoms. These are glasseous structures here. And they differ from each other based on their structure. So this structure, this star versus this round structure versus the spaceship kind of structure, are all coded at the genetic level. And these are made under very environmentally friendly conditions.
And so we focus on how do you give genetic information to a solar cell or how do you give a genetic information to a battery. And when we think about future technologies we first start at the beginning of time, this is the beginning of Earth actually. It only took about a billion years to have life on Earth. And they were doing pretty incredible things but it wasn't until about 500 million years ago during this Cambrian geologic time period that there was an explosion of new kinds of organisms making materials. And during this time there's increased calcium and iron and silicon in the ocean and now the organisms had the opportunity to start making hard structures. Before that they were soft bodied kinds of creatures. And so what we thought about is how do you start to get control over organisms to get them to work with anything we'd like them to be able to work with on the periodic table.
Here's a picture of one of my favorite biomaterials. This is my oldest sitting next to one of his favorite biomaterials, the triceratops. And anyone who has young children know their incredibly complex organisms. And so this one won't really do whatever I ask him to do and so you think about how do you start to get control over having an organism grow and construct what you want it to be able to do. And so we focus on simple organisms like bacteria and viruses and yeast. Can we work with these organisms to convince them to work on the parts the periodic table we want to build something useful like, in this case, a battery.
And so there's a lot of really, I always say it's a great time to be a scientist and engineer because there's so many important problems. You just pick one to work on. And some of them are energy and health care in the environment. And these are significant global issues but to a material scientists they're just huge opportunities. Huge opportunities to try to make an impact in these very large issues. And the way that we've focused on it is at the interface between nanoscience and that nanotechnology. And Sangeeta did a really fabulous job of explaining some of the interesting properties of what happens to material when you shrink it down in size. And we look at that interface between nanoscience and biology or biomaterials.
And basically by taking a large structure, by taking a structure that has many, many different atoms or many of the same atom and making it smaller and smaller and smaller and controlling the surface, controlling the edges of these kinds of materials, you can control the physical properties. Their optical properties, electronic properties, their mechanical properties. And we've been interested in doing that to try to change or control materials for solar cells, batteries for energy storage, CO2 sequestration and storage. In medicine for medical imaging and therapeutics and environmental applications like water purification. And the key to us is controlling the materials. Controlling the shape, controlling where those atoms are and how they respond to a particular kind of environment that we need them to respond to.
And so, if you go back and you think about biology, and again you've seen wonderful examples of biological machines, of the enzymes and proteins. We look at biology and we look at the length scale here of things like proteins a beta pleated sheets in DNA and antibodies, and they're already very small, they're already on the nanometer length scale. So if we could actually harness the potential of these biological molecules to do we want them to do, build a material for a battery, build a material for a solar cell, we figure we have an advantage because we're already starting with something nature gave us. It's very precise, very controlled and now we have to harness it to get it to do something we want to be able to do.
And so here's some examples of some natural biomaterials. This is a coccolithophore, it's a unicellular algae here, it's a one micron link scale. This it the abalone shell and if you fracture it and you look at it, it's made of these stacks of calcium carbonate, basically chalk. These are diatoms made out of silica SiO2. And magnetotactic bacteria make small single domain magnetite, Fe304 that's used in navigation. So those are some examples that nature's already provided us with.
And what's the key? Why can organisms make these materials with exquisite structures and in precise geometries all under environmentally friendly conditions? Well a big key to it is proteins. It's the proteins that these organisms have and they secrete in their cells into their extra cellular spaces and they use those to control and grow their particular materials components. And these proteins are made out of just 20 different amino acids that differ from each other based on its functional group. So it's how the organism puts together these 20 different amino acids in a row and how that structure folds up in a particular shape that allows it to be able to control this the structure that has this shell that is actually 3,000 times tougher than it's geological counterpart for example. And so that to us is very fascinating.
Here's some examples of abalone shells and between these inorganic calcium carbonate tablets are these proteins and these proteins are absolutely key to controlling some of these physical properties. And so basically this works by, in nature, in the example of the shell, the organism has these proteins. In the case of abalone that make the shells, these proteins can be very negatively charged. They're rich in the amino acid's aspartic acid.
And I brought with me periodic tables. I have them made for the incoming class. They say, "Welcome to MIT. Now you're in your element." And you turn them over and it's the amino acids with their PKA's and I'd like to pick up one. When President Obama visited last year I gave it to him. I said "I wanted to give this to you in case you're ever in a bind and need to calculate molecular weight." And he looked at it and he said he would look at it periodically. So I pass these around to a lot of elementary school kids that really get a kick out of carrying them.
So the key is, is these amino acids that make up these proteins grab on to calcium out of the environment and put down calcium carbonate, calcium carbonate and can grow these really nice structures. And so what we said, what I thought about when I first started my lab is what if you had a protein that could bind to any kind of inorganic material that you wanted it to be able to bind to but had never had to opportunity to do this through nature. And we developed this kind of interface. I think as Susan had pointed out in her talk, that she had a hard time with the idea of using yeast for her particular system. When I first wrote my very first proposal grant proposal as a professor, my first review came back that she's insane. When I said I was going to try to develop this genetic link between semiconductoral materials and biology. And obviously it worked out okay.
And so, basically going back to the periodic table, nature mostly uses calcium in the form of calcium carbonate, iron, Fe203, Fe304, silicon in the form of silica, but it doesn't really use this part of the periodic table or this part of the periodic table in terms of materials. You saw earlier a really beautiful talk about how biology and enzymes use ions of manganese and iron, but what we want to do is we wanted to get it to build structures like battery electrodes.
And so, what we decided to do was to do a combinatorial approach, basically do a billion of experiments at a time to see if we could fish out a protein that could control or work with something that we'd like it to be able to work with. And so we decided to borrow an idea from the drug discovery industry and use something called phage display.
So a phage is a virus that-- to a material scientist it's an object that's 880 nanometers in this direction and 6 nanometers in this direction and a single strand of DNA. The DNA codes for the proteins that make up its structure. And by going in and making modifications in genes, basically cutting and pasting additional DNA sequences in here, it codes for additional peptide sequences.
And so you can put a billion different random DNA sequences in here and put a billion different random protein sequences right here. Or also in the major code of the virus. And in doing that you can make a library. Now you can have a billion viruses that are genetically identical to each other but they're going to differ from each other in a small amino acid sequence.
And now you take those and you force them to interact with any kind of material you want. A battery electrode, a solar cell, whatever you're interested in and you're looking for that same kind of protein, amino acid recognition for that inorganic material. Now, if you take a billion possibilities, you may have 1,000 of those billion possibilities that have some affinity for those materials. Everything else gets washed away. Now you take those that have some affinity and they can't replicate themselves to infect them into a bacterial host. The bacterial host acts as a factory, makes a million copies for you. And now you have some population of viruses that have some affinity for this material. And you go through this process, kind of our Darwinian process, five times looking for the survival of the fittest, looking for the one out of a billion that can do it what you want it to be able to do. Grow a battery electrode, make that electrode better as a function of time.
And so the idea is to try to do specificity through evolution and man made fabrication to get something we call the evolved hybrid materials which is materials that are at the living, nonliving interface. And so the applications I always say have never been accused of being focused. The applications that we look at in my lab are battery electrode, we look at materials for displays, we look at solar cells. We look at carbon sequestration and storage, photo catalytic splitting of water, materials for fuel cells, fibers where you could take some of these materials, batteries or solar cells, and integrate them into textiles, nanoelectronics and medical applications.
And so you look at this and you say, well this is a lot, why don't you just focus on one of these things. But going back and thinking about it, to us, everything is a material. What we do to make materials. We put materials together in new ways. Then we try to get a genetic link to that material and then work on an application which could be important to society. And so that's basically what our approach is.
And so here's our toolkit. This virus, with just a couple of genes, and these genes code for the proteins that make it up. There's one protein over here called P3, which is the major coat protein that is encoded by gene three. There's another protein called gene eight and this is a great gene because this gene codes for protein eight which makes up the coat of the virus here. And there's almost 3,000 identical copies of that protein that make up the coat of the viruses. And DNA is negatively charged, these proteins as they get synthesized basically self-assemble around the DNA structure to make this DNA virus, to make this virus here.
Over here are two more genes that are also encoded by the DNA. And again, to a material scientist, one of the things that's really nice about this is it's always the same length. The function of the length of this virus is a function of its DNA. It's always 880 nanometers in length. You make millions and billions of copies of this, they all become the same length. And if you're going to think about using this as a building block say, a tinker toy or a Lego or something like that, every time you manufacture it, it's going to be the same length. So that's another very desirable feature of this particular virus material.
And if you look at it, it's made out of these alpha helix structures. And we're going to actually do now are stick proteins on the ends of these natural alpha helix structures to get them to do something we want to do. If this was an analogy to the abalone shell we would put sequences on there that say grow an abalone shell. Well, we can't compete with an abalone shell in our case, abalone do a wonderful job of making shells. But we say, now grow a solar cell, now grow a battery. Now grow a material for a fuel cell. That's what we want these virus structures to be able to do.
And so, basically what we do is we go in and we modify their genes, modify their proteins and now we get them to build little inorganic shells of nanoparticles around the structure. And again, because the virus is all the same length, because of the length of the virus is a function of its DNA, then all our nanowires are also the length of the DNA. And it's something that should be very, very reproducible.
And here's some examples. These are transmission electron micrographs. These are 50 nanometer scale bars here. In this case we're growing gold nanowires so this virus has the DNA sequence to be able to take gold ions out of a solution and be able to make gold nanowires. We can do so with a very high conversion efficiency, very good yield of these materials. And very good control over the length and the width of these materials. And so again, you learn how to control it through learning how to control the DNA sequence and the protein sequence.
Now this is something that we're really excited about right now. But this is just a kind of a cartoon, well it's actually kind of a cartoon that we drew, it's also based on crystal structures. But the idea of being able to go from a DNA sequence to control a protein sequence to a functional device.
Towards the end, if I have time, I'll talk about a new material recently, from going from a DNA to a device, to be able to grow a solar cell that increases the efficiency of the solar cell by about 2 1/2 or 3%. Just based on a very small amount of protein. Engineer the virus to be able to grab onto a good conducting material which is a carbon nanotube, engineer the virus to be able to grow an inorganic material, titanium inorganic material around the virus structure, incorporate it into an already existing solar cell and basically be able to increase your electron collection efficiency and increase the efficiency of your solar cell.
We've been working in energy storage for a couple of years now and one of the particular areas we've been working in are lithium ion batteries. It's something that everyone in this room is probably using and is carrying several lithium ion batteries right now. And MIT's an absolutely wonderful place to work in the battery field. And we've been thinking about how do you make biological batteries? How do you basically take a structure, this would be a structure of a lithium ion battery. There's two electrodes, there's a negative electrode, the anode, a cathode over here. And then there's lithium ions that are going back and forth between these structures. And here you can see the lithium ions are stored in this graphite structure on the side of the battery. And they have to be able to cross over and then be able to interact with the electrode on this side of the battery.
And so because we wanted to see if we could build biological batteries. Because biology is so wonderful at packaging things. Think about how DNA is packaged in your cells. We thought about, let's see if biology can help us package inorganic material in a more effective way to make batteries. So we set about to do this.
And so how do you give genetic information to a battery? We wanted to be able to make anodes and cathodes materials, interface them with new kinds of electrolytes. We thought that we could make materials that would be ultra thin and light weight, that would have a higher energy density, and also be flexible, conformable, textile integratable, and synthesize at room temperature. Because just like the abalone chooses to use a manufacturing approach which is environmentally friendly, everything we do in our group we try to do in an environment friendly way. If you're growing bacteria and you're growing viruses or yeast in an environment that's toxic to them they're not going to be that useful to you anyway. And so we try to convince our organisms to work in a way to build these structures in environmentally friendly as possible.
And this work was done in collaboration with a Paula Hammond who is a fantastic collaborator of mine. She's in chemical engineering. And Professor Yet-Ming Chiang is also a fantastic collaborator. So the three of us worked along with our students to make flexible, conformable, room temperature synthesis biological batteries.
The answer for us is usually a virus. And so we were able to select a virus that could grow a material called cobalt oxide which could be a material that is used as a battery electrode. They key for why biology could do it in this case is we're able to make very small nanoparticles with very controlled size. And that was useful for our applications. And then we're going to take advantage of viruses to be able to self-assemble, which I don't have time to talk about today, to self-assemble into a battery electrode and be able to test that. And this is work that was done by a fantastic student of mine, Ki Tae Nam, who's now faculty in Korea.
And then we're going to take advantage of the idea of how biology can tweak things a little more and a little more to try to make them better and better as a function of time. And this is one of things that I like about using biology to make materials because if you can get biology to make a material but the material is not very good, it doesn't have very good characteristics, you have the ability of genetics and you have the ability of evolution to try to make it better and better. And so if we can get any function out of it at first we're happy because we know we have the possibility of trying to manipulate it to make it better.
And so my really brilliant student, Ki Tae, he had the idea to engineer a virus with two genes. One to grow cobalt oxide, the material that's going to be a good ionic conductor. To be able to interact with a lithium. And one that's a good electrical conductor to get the electrons in or out of the system. So it's a two gene system. One virus has two genes to be a good electrical conductor and a good ionic conductor. And he was right.
In this case, this is a transmission electron micrograph here of a single virus, it has two genes. He gives it gold and it grows little gold nanoparticles. And I hope you can see the little gold dense particles here and all the spaces in between. The spaces in between is where it has proteins not to grow gold but it has proteins to grow cobalt oxide. Now he gives it cobalt oxide, or actually cobalt. And then it makes cobalt oxide.
And now over here you have a hybrid material that's cobalt oxide and gold. And now you can go test this as a battery. And so there's different functions you look at or properties you look at in batteries. This is capacity, this is related to how much lithium that it can store. And these are rechargeable batteries. You're going to be able to charge, discharge, charge, discharge these materials.
And so all I want you to look at is this is our first generation battery. One gene here. And this is our second generation battery, two genes. And you can see the improvement in the capacity between these. And so after this point, we started realizing, wow, if we can get one virus to have two genes or one virus to have three genes, what we want it to do- maybe that's a good way to start increasing device performance of these materials.
But then working with our collaborator Paula Hammond, she works a lot on polymer systems. She works on something called layer by layer assembly where you have basically a beaker of positively charged polymers and a bigger negatively charged polymers. And you can take a slide like-- and this is the way I always say it is. My students say it's nothing like it really works. I don't actually even have the code to get into the machine they use but the slide they dip it between positive, negative, positive, negative, positive, negative. And they can build up these little layers that are going to be layers of electrolyte.
And so then we engineered our virus to like her polymer. So we could build up this little polymer, dip it into our virus, our virus now likes her polymer and it lines up on the surface of this polymer. And now you dip it into a third beaker and you now start nucleating or growing a battery electrode material.
And you pull it out like this. This is a transparent electrode material that's self-assembled by a virus. So it kind of looks like Saran wrap. It's flexible. And you can test that as a battery electrode. And these are what the viruses look like, all lined up on that material.
You can do other really fun things like this because it's all solution based process. You could make a stamp. You make thousands of battery electrodes on a stamp and stamp it onto a surface and transport it on it's surface. So these are a bunch of really small micron-size virus battery electrodes that are stamped onto a surface again because it's all made at room temperature at the bench top.
And so we were excited about this and we published this in science and we went to our review for the funding agency and they said, well that's good but you only have half a battery. Where's the other half of the battery? And so it took us a while to get to this point.
So I went back to my students, because I can't actually make anything myself, and I said, where's the other half of the battery? And so they worked really, really hard and it ends up that the positive electrode material is much more difficult to make than the negative electrode material. And part of the reason is the high voltage material. Part of the reason is that you even have to have a better electrical conducting material connected with your ionic conducting material. So I had a fantastic team of students who worked on trying to basically increase electrical conductivity in some of these ionic conducting materials.
And here's part of my dream team here. This is Yun Jung Lee who just took a faculty in Korea as well. And Hyunjung Yi who's getting ready to graduate in a couple months. And here was their idea. Let's engineer a virus to pick up single walled carbon nanotubes. Such a good electrical conducting materials. These materials are very, very small. These materials are like one nanometer in diameter.
And so they engineered these viruses to have a sequence to pick these up and then the engineered the virus to have another sequence that said now grow the rest of the electrode material on top of it. So they were growing iron phosphate material which is a nice material for being environment friendly. And I show this mostly because I always say the best day of my life was the day my kids were born but this is really close next to it because this is the day that we had a genetic sequence, DNA sequence, that was directly related to the quality of the device basically.
So the one particular DNA sequence gave us a high powered battery that was a really fantastic battery. And that's what my group had been working on. That was the whole principle that we were working on is if you have the right DNA sequence, you have the right protein sequence, you can really have state of the art materials and state of the art devices. And so I had to show that because that was a happy day in our lives.
And so then they engineered them to basically pick up single wall carbon nanotubes and they form this percolating network with the good electrical conducting materials interspersed with the rest of the electoral materials. And this is just for fun, this is actually looking at four nanometers link scale. These are single wall carbon nanotubes here on the tip of a virus. This is the tip of virus here and it goes all the way up here would be the rest of the virus. And it's showing the interface between the iron phosphate and the single walled carbon nanotubes. So two different proteins bring these together to bring together these two materials.
And I have four seconds. And basically we're able to make very high rate capability batteries out of these and high powered batteries out of these. This is fun because this is a one gene system, a better one gene system and a two gene system here. We're actually able to get high power battery that were very, very state of the art.
We were able to show these to President Obama when he came to visit. And these batteries, there's actually quite a few of these at different science museums around the country. These high powered batteries that are better, in this case are just lighting up an LED but are made biologically.
We were able to share this actually in other science museums and we had 600 visitors. Paula Hammond and I had 600 visitors and we had 100 kids make battery electrode materials at the science museum. It was very, very fun. They had very good time doing that.
And then we transitioned this to an undergraduate teaching lab. This is 2109. It's a junior level teaching lab where the students are trying to make better and better batteries which is also very, very fun.
This year, we're going to make solar cells in this clas. So the technology-- although I always say the viruses do all the work. The students say, oh, no. That's not true. We find the viruses that do all the work. Once you get them to be able to manufacture these materials in a high quality way then it's not too difficult to transition that technology.
I was going to talk about photocatalytics [INAUDIBLE] in water but that was not very realistic in terms of how much time I had. So I gave you one example of things that we're working on, and I'm over. I thank you.
PRESENTER: Don't go anywhere.
PRESENTER: Thank you, Angie. Questions?
AUDIENCE: I was just taken by your comment, or maybe it was your student's comment, we find the viruses to do the work and maybe you explained this but I'm a mathematician so I might need a little extra explanation. How do you find the viruses to do the work?
BELCHER: That's a good question, I kind of zoomed over that point. Basically we start with a billion possibilities. The way that we used to do it in the old days is we start out with a billion possibilities. We take those billion possibilities and we say, of these, can any of them grow the material that we're interested in growing. And a small population will be able to grow those materials that we're interested in growing.
And so in about a ten microliter sample. Or maybe, I haven't done this myself in a long time. Maybe it's a hundred microliter sample. In a small sample, you can have a billion different viruses. You pipette them out and you force them to interact with the kind of material you want them to be. Is it a semiconductor material? Is it a battery material?
And they're going to be in the solution and they're going to be interacting with that surface. And we're looking for the ones that are the good fits. We're looking for the ones that bind and don't let go. Then we change the conditions under which the semiconductor and the virus are interacting.
So we can basically get rid of anything that didn't stick. And anything that had any affinity for that material at all, we can fish it back out again. We don't know what it's sequence is, at this point we don't care. We say you guys are the winners. You did a good first job.
Now we take it and we say okay, now interact but now we're going to make it harder. We're going to change the pH, we're going to change conditions so now it's even more difficult. Now get rid of all those. And you keep going through that until you find one that's decent. Now we actually, because we've done this for almost 10 years now, we have an idea of what works and what doesn't and now we can do rational design in combination with kind of combinatorial to come up with the best kinds of approaches. Thanks for the question clarification.
AUDIENCE: Hi I've heard you speak a couple of times and you're amazing. I'm wondering the timeline for some of these technologies to become commercially available.
BELCHER: That's a great question. So they have founded two companies and the one company is in transparent conductors for touch screens. And that one doesn't have any biology in it. The ideas were based on biology and that actually has commercial products that can be purchased now.
I have a second company that's in the catalyst in heterogeneous catalysis and that actually is kind of in the earlier stages. Some of the materials I've talked about today are in prototyping with different companies around the world. And none of those are commercially available but they're in about prototyping stage. We're excited about a lot of the technologies. Basically I'll leave it at that.
But we can go from idea to a good working prototype in about a year. Year, year and a half. I'd like to take credit for it but it really is my fantastic students who get in there until it's done. And then it gets harder because you have to think about all kinds of, how to you integrate it in, how do you fit it in with current tooling technologies? How do you scale it? How are you going to put in a rooftop and in every house in America and things like that.
So there are all kinds of things to think about. But we're pretty pleased with the progress right now. I don't want to take away from anymore time.
PRESENTER: Thank you Angie.
So our next speaker is Christina Ortiz. She's a professor of Material Science and Engineering and MIT's Dean for Graduate Education. Professor Ortiz is the leader of MIT's bio nanomechanics laboratory. She received her BS from Rensselaer Polytechnic Institute in 1992 and then both her Master's and PhD from Cornell University. All of her degrees are in the field of material science and engineering.
Professor Ortiz came to MIT and joined the ranks of the faculty in 1999. She focuses her research on the structure and mechanics of biological materials. Her scholarly and leadership achievements at MIT and in her profession have been recognized by her peers and in many awards, including the National Science Foundation Presidential Early Career Award for scientists and engineers and the National Security Science and Engineering Faculty Fellow Award from the Department of Defense. In 2009 Dr. Ortiz received a Dr. Martin Luther King Jr. Leadership Award for recognition of her service reflecting the late civil rights leader's ideals and vision. Her talk today is entitled Biological Structural Materials, Interdisciplinary Convergence of Engineering, Architecture, and Evolutionary Biology. Professor Ortiz.
ORTIZ: Thank you so much I'm happy to be here today. Thank you very much for the invitation it's been a wonderful conference. I'm honored actually to give this talk today. So I'm going to talk about my research today in biological tissues and I'll give you a little bit of my timeline of my research and also where it's going, where it's been and some of our, sort of new areas that we're getting into.
I just wanted to start with, I'll start with the students since they really have done all the work. This is just a listing of some of my current and former students and postdocs that have contributed to the work. And also three of my closest collaborators, Alan Grodzinsky, Mary Boyce, and Subra Suresh who have really inspired me and I've collaborated with them throughout my time at MIT. And so today a lot of the work I'm going to talk about is in conjunction with Professor Mary Boyce who's in our mechanical engineering department and so you'll see a lot of this collaboration between us.
So structural biological materials basically are materials in biology that serve some sort of mechanical function. And this could be load bearing, penetration resistant, lubrication, et cetera. And these materials are highly complex as you also heard from Angie Belcher's talk, that they're generally composite materials with many components and levels of structure that have been sort of designed throughout the evolutionary process for specific mechanical functions. And so, our sort of research has focused on, in the last sort of 15 years, there have been many new methodologies developed where you can probe the structure and properties of materials in general at very, very high resolution. So at unprecedented levels. So down to the single molecule level or the single molecular structure level.
And so with all of these sort of technologies that have become advancing it's been great not only for the field of material science and the discipline of material science, but as I'll show you today, really in the field of also biomaterials and also how this can link to the fields of architecture and evolutionary biology. And hopefully by the end of the talk I'll show you that I think there's great potential for combining a lot of these methodologies from material science with these other fields.
And so generally we work on sort of two classes of materials, musculoskeletal and exoskeleton. Musculoskeletal are those internal to the body and exoskeletons are obviously external to the body. And although they may sound very different, generally they're made out of the same fundamental constituents. Biopolymers, minerals, ceramic minerals, et cetera. And so there's a lot of commonalities between the two of them.
So musculoskeletal includes cartilage, bone, intervertebral discs, et cetera. And then for the exoskeleton work we have sort of three subprograms involved in flexible armor on exoskeletons of animals, transparent armor, and then what we call sort of extreme armor where animals have developed armor that resists very harsh conditions. And this includes things like blasts, underwater volcanoes, high temperatures, high pressures, et cetera.
And on the musculoskeletal side we really are looking at what are the molecular origins of degradation of the tissue with age, disease, and injury. And so our work sort of looking at the structure and properties of these materials really has a medical application in terms of facilitating the development of diagnostics, clinical treatments for disease, and tissue engineering, tissue regeneration. On the exoskeleton side, all of this is really, initially, through funding agencies was, the motivation was really to look at these for inspiration in providing protective systems for defense, military, and other applications. And actually, if you look at it, it is sort of applicable to structural applications in general.
And so I'm just going to briefly touch on the first one. Well first I'll start with this. So basically, our work has really focused-- so as you heard I'm trained as a material scientist and I came to MIT in 1999 after doing a postdoc in Europe. I was on an NSF NATO postdoc fellowship in Holland and at that time many of the new instruments were just starting to be developed and it turned out that this laboratory in Holland actually had a whole array of these new instruments that I could learn and play with. And so I went there for about two years and just learned how to use them, all of them were coming out, it was a really exciting time. And then when I came here I really had an interest in biological materials and because of the complexity and beauty of the structures and the way that they're designed. And so we applied basically-- we developed all these methods.
And the large part of my career here has been really, even though I would consider it interdisciplinary because it involves many different engineering disciplines, material science, you know, mechanical engineering, biological engineering, even electrical engineering because many of these molecules are charged, I would say that it really focused on high resolution structure property relationships which is the classic sort of paradigm for material science and engineering. And as we move forward in the last year or so, or two years, when we look at these systems we realize that the design in them goes way beyond this what we call sort of inherent materiality. And that this inherent materiality works with design principles that exceed and go beyond my discipline.
And this includes things like geometry. As we start to expand into well, how does it work with geometry, and how does it work together to create a functional structure? Now we realize that there are approaches in other fields beyond the engineering field that really can contribute and are essential to understanding and learning.
And conversely, a lot of the interesting things that we've done here can expand these other fields. And this includes, so this is mechanical engineering, material science and engineering. But evolutionary biology I'll talk about their quantitative 2D/3D methods for quantifying shape. And I'll show you also how what we can bring in engineering to the field of evolutionary biology as well as architecture. So we've had two architects in my group. Collaborating with a new architecture professor Neri Oxman on creating new bio inspired designs based on biological structures. And I'll show you a little bit of prototyping that we've done that.
So our work started sort of in the field in collaboration with Alan Grodzinsky who's a professor in three departments, three different departments. And basically we spent a lot of time looking at, so cartilage is this thin tissue at the ends of long bones in your knee joints. And this tiny little strip of tissue can have an enormous impact on the quality of life if it doesn't work properly.
And so my background before I came to MIT was polymer physics, polymer mechanics, polymer synthesis, even, for two years. And so this was a purely polymeric system. It's a charged polymer polyelectrolyte system. It's a fiber composite system. And so we started to think about how to translate some of those ideas from the field of polymer physics to understanding the charged polymer systems. Beautiful polymers, I should say, in the joint which have a direct mechanical function. And so we were able to go through and use a whole array of methodologies to probe down to the single molecule level for the first time. Basically directly visualizing these single molecules in the tissue that are responsible for the function of the tissue and also for the degradation of the tissue when you have an injury or during osteoarthritis and connect these, the molecular structure, basically to sort of the function of the joint in terms of this. So it turns out that the negative charges, the electrostatics, between these molecules give you the stiffness that you need in your joint and the lubrication your joints.
Furthermore, in addition to these high resolution imaging, we were to then go on and actually to measure forces between individual molecules. And how do those forces translate into your stiffness in your joints. Into your modulus, or your stiffness. So we worked both at single molecule level, we've worked at the single cell level, these tiny little areas around cells, what is going on there when you synthesize? When cells are input in scaffolds and synthesize a tissue, what does it really look like?
And then I mean we basically took what was in the fields of classical mechanics of whole tissue. You take out a chunk of whole tissue, you do a mechanical tests on it, and you understand the stiffness at the macro level. So macroscopic means basically you can see the tissue and we basically brought it down to the molecular level. So this is an experiment where we apply a dynamic oscillatory load.
And if you look at the displacement, it's basically one to three nanometers. And so we could basically go down to the molecular level. And this is exactly analogous to decades of experiments that were done at the macroscopic level. And so what we did really was link the molecular level to the macroscopic function and open this sort of area up with the whole suite of new methodologies. And I should say many of these I learned myself when the instruments had just become available in the '90s. And you know the first instruments had come out and learned from scratch just in the lab actually when I was in Holland.
So I'm going to move to exoskeletons. So this is the musculoskeletal. And the rest of my talk's going to be on exoskeleton. So this is our first foray-- well we've worked on other types of animals. We have a lab full of live exotic animals now. Mostly marine aquariums. And this is one of our favorites who unfortunately passed away recently.
This is Polypterus senegalus. It's an armored fish, one of the few fish that still maintains a robust exoskeleton from 500 million years ago. You can see he's quite flexible from Africa, from Senegal. And full exoskeleton suit. You can't see it really but the exoskeleton is underneath the scales. The scales are mineralized. Basically they're 95% ceramic in the outer layers. So it has a full exoskeleton suit.
And yet it's incredibly fast, incredibly flexible. It's amazing, the path that my career has taken at MIT because there's been so many serendipitous twists and turns that I could have never imagined the point I am now to where I actually started when I first arrived here. And this fish actually arrived, basically one of my students had gone to a museum in France and brought back a sample that he had been talking to curators in the museum. And we started looking at it and it was just amazing and has led to all kinds of different research for us.
So as I said before, we first started out looking at the inherent material structure of this. And the things that emerged from studying the structure of this guy were pretty amazing. It had the armor basically was designed to resist penetration. It has a multi-layered structure that has the exact layer thicknesses and sequences in order to resist penetration. Has interfaces that were reinforced. It has its crystallography axis in the right directions.
And we had the methodology. So if you think about it, you know this fish is pretty small and then you want to test one tiny little scale. And because the methods were never available to test animals like this before, now with the advent of all these techniques to test tiny, tiny little things, we could go in and actually measure the properties of each one of these and do a simulation. Put this into simulations to predict how this guy resist penetration.
Now, when we looked at this you can see there's a whole other length scale of design that works with this penetration resistance of the scales. And this is sort of where we've been looking at lately. And I'll go on with it. So when we started studying this structure and we published a series of papers on why this layer's anisotropic, what do these gradients do, what if we change the sequence of two material layers and then everything doesn't work anymore? How does it stop the penetration from going into the tissue? All kinds of interesting things came out.
So if you look, this was one of the papers we published. One of the most interesting things that we found was that when you do a penetration from the top of the scale, even though the scale's around 95% ceramic and typically an armor also works this way. When you have a ceramic material, basically cracks propagate outward radially. When we do a test on this guy here, and we predicted this with modeling as well, the cracks propagate in a direct circle around the site.
And the reason for this is because the multi-layered structure actually changes the way the cracks propagate. And it basically localizes the fracture instead of going all the way out radially, it's localized at one site and then the fish can get away and repair itself. So it doesn't damage the structural integrity of the entire scale. And so basically the fish regenerates it's armor. And this is a really interesting result.
So we've gone on now to look at the shape and morphometrics of these guys. And this is my student Steffan Reichert, who is one of the architects who was in my group and got his thesis. Is now back in Germany as an architect. And he basically wrote a thesis on bio inspired designs based on Polypterus.
And you can see that when we look at these designs, we base this off of three dimensional x-ray microcomputed tomography images where you get the full 3D structure. And he was able to create these designs using computational design and then 3D print it using a multi material 3D prototype and printer and amazingly there's all kinds of interesting designs that come out of this.
First of all, you can see that even though this guy is completely armored, it maintains the flexibility of the back rubber sort of plate. Secondly, no matter how you flex it you still get the same sort of almost the same thickness uniformity of coverage all around the entire thing. And there are so many more interesting things like the joint mechanism to get the right ranges of motion. So we actually have designed all kinds of bio inspired prototypes at the macro scale based on these different armors.
And surprisingly, even if you look at different armored fish of which there are not that many, well there is a number of species, even the joints, the plate shapes, all the difference. There's a diversity of armor even with an armored fish. And yet there are still some uniform, what I would say, universal design principles that emerge that we've basically started to identify.
So let's get to the last section on evolutionary biology. So a couple years ago me and my students were invited to go to the society of integrative and comparative biology and give a talk which just happened to be in Boston. And we went over there and at that point we just published the work Polypterus and were involved heavily on Polypterus.
And we ran across a few talks on another armored fish call the three spined stickleback. And it turned out that this armored fish was one of the most popular models for evolutionary biology. And so it was really a perfect match because we had all this experience at looking at armored fish at these high resolutions. And so basically this fish has diversified very rapidly throughout the lakes all through Alaska. So this fish really is used as one of the most common models.
So let's just look at this map for evolutionary biology. And so basically most of the work with stickleback and others has focused on the genotype-phenotype relationship in terms of natural selection. When a phenotype emerges it then leads to function, performance, and fitness. And so it's because of genotype, genome wide mapping most of the work is functioned here. But there's a huge gap in understanding in terms of the detailed structure of the phenotype when the phenotype is a material and how that leads to a quantitative measure of function and performance. And so I would posit that that material, that engineering can fill this sort of enormous gap greatly and contribute greatly to the total understanding of this evolutionary process.
So our question that we're trying to answer with this guy is why do certain divergent phenotypes translate into superior function and performance leading to greater survival and more opportunities to produce offspring. And so here, if you look at this analogy, the phenotype basically equals a material. A structural tissue plus some geometry. So here's material science, here's architecture, and the performance and function is mechanical. And so it's just a great match. So our work on stickleback, we've got collected our collaborator, Matt Wund, who is an evolutionary biologist, has collected stickleback from all over Alaska and they change their armor depending on where, all throughout very rapidly. And there's been known that there's genetic origins as well as environmental origin. So marine stickleback have a full plate of armor and then the others reduce their armor as they translate into the lakes throughout Africa. I'm sorry, Alaska.
So this is the size of stickleback. And again no one has really been able to look at the structure and properties at such great detail because none of the methods were really available, right. So an armor is a mechanical function, right? It is designed to provide penetration resistance. But how do you take this tiny little fish and a tinier little piece of armor and test it for penetration resistance. And that's sort of where our expertise comes in. So this is really the sort of, the common way of assessing morphology in these systems. So they count plates, they score things as like one, two, three, four. And basically, look what we do. We basically use material science to think of composition, nanostructure, porosity, crystallography, and local mechanical properties and even more three dimensional full structure. So this is an x-ray computed tomography image of the entire fish.
So when we started looking at this fish, we discovered something which was well known at the time that has taken us in a whole 'nother direction and has dominated our lives recently. This structure at the bottom here called the pelvic assembly. And this is what it looks like. It's basically this wonderful mechanical structure that is a suture joint with two joints that move out.
So when the fish is in its rest state, it has the-- this is the rest state that's shown here-- it has two spines that are next to the plate. And then I'll show you a video that when it's in the offensive state it swings these guys out, like this, and it increases its body size by three times. And they are also sharp. So it's a predatory thing when predators come.
So we've started to study the mechanics of this joint and all kinds of design principles emerged. So basically we can look at the frequency, the amplitude of the suture, the mechanics of the entire structure, and one of the latest sort of results that we found is like these are both termed full morph. They're both have all the components of what's considered a full morph structure from the marine and the freshwater but when you look at the details, you can see not only are they completely structurally different, but they're completely mechanically different. And so it's just opening up sort of a whole new area of diversity within populations that they thought were very similar before.
So we can quantify all these things. This is work with Mary Boyce and Dr. Yaning Li, who's a postdoc in our group, now actually has come up with a model for this suture joint that can produce, we basically input the parameters that we get from the experiments directly into the model, both analytical and finite element, and can get out functional parameters of stiffness, strength, of mechanical function, and you can see the dramatic differences between the two different populations. Something that has never been really known before.
And it turns out that this stiffness here, right, exhibits right at the joint because that's where-- so everything is designed. That whole spatial distribution of frequency and amplitude is all designed so that the mechanical function works, right? So this maximum in stiffness right at the joint site, is because when the fish opens up the joint, the predators will come, they apply a bending moment on it and that's where you need the most stiffness, right there.
And so the designs that, even more surprising, is that the geometry of the joint has been optimized to completely eliminate stress concentrations. So you get a uniform stress distribution through the whole suture joint, everything participates in load bearing, you get a weight advantage, you don't get any stress concentrations for fracture, for fatigue, for cyclic loading. All these sort of new principles have emerged from this.
So this is the rest to offensive sort of transition, which also, again, has never been seen before and 3D. And basically what we're looking at is this is the bottom of the fish. The fish would fit in here and the spines go out. And so this is x-ray data, 3D data. And so when you look through it there's a whole mechanism behind this conformational transition in the armor. So what you have here is basically a dynamically active armor that's changing its mechanical properties based on the state of predatory attack. And not only that, it changes its design principles in the active versus the passive state. So the overall structure is mechanically optimized and also this mechanism as well. So there's lots of interesting things here for the design of armor joints.
So I'm going to show you a video after this. I think it's going to go on. It's going to do a fly by. This is three dimensional. This is the joint. So this is 3D x-ray microcomputed tomography data. And this is the front of the joint, the suture. And then these are the two swing out joints of the spines. And so you can see how the amplitude and frequency of the joint change.
So this is the entire armored fish. You can see the spines are out here and has all the armor all around it. And of course there's lots of design principles in the armor plates themselves. This is a freshwater stickleback that has lost a lot of its armor but it still has its spines. The fish would be right here.
It's going to zoom in and I'm going to show you sort of the intricacies of the design as it opens up and closes. You're going to see, this is actual data. So this isn't an animation, this is data. And you're going to see the conformational transition going from the rest to the offensive position.
And so what you've seen there is not only do the spines go out but the entire structure changes its conformation and changes its mechanical properties. There it goes again. You can see it locks as it goes out. So the fish actively controls this whole process as it goes through. I'll show it again. This is from this side, from the backside. So you see how this whole thing changes its conformational properties. And that again, none of this has ever been seen before.
And we'll go around. It's going to open it up so you can see that actually not only is the frequency and the amplitude modulated, but there's angles inside which are also modulated to provide the right mechanics. And all of those go into the model that we've developed with Mary Boyce. So now you're going to see the flyby as you go in.
So all this, all these angles here have been optimized plus the height at the joint. And you can see the other side of the joint. And then they're going to do one more from the top. This video was put together by Sergio Araya who's another architect in my group as well. And you can see the conformational transition in the top and again that's the top of it. And so the more we study even one species, he put that on there, the more we study one species like the more design principles, you could literally spend your whole life really studying a single species because there's just an almost an infinite amount that you can learn in the beauty of these systems.
So thank you very much. I'm happy to take any questions.
PRESENTER: Thank you Christine. Questions?
AUDIENCE: Has your research on cartilage had any implications for medical or health care benefits?
ORTIZ: Yeah I mean I think definitely we've been working on understanding sort of engineered tissues and also the process of degradation during disease and injury and so some of the things that we've seen is how the individual molecules change as basically as you get older, or you have disease. And so I think this opens up sort of a whole new area in terms of targeting clinical treatments based on molecules. Rather than based on sort of a macroscopic continuum level area. And the other area that we've looked is, as I said, engineering tissues and what do those look like at the molecular level.
AUDIENCE: I have a question entirely from ecology. Which is, my memory is that a stickleback fish was a major ecological issue for some place in California maybe? And I'm wondering if that is, if I'm remembering correctly, and if those sticklebacks are related to your guys?
ORTIZ: Yeah, no, all of our-- I mean I don't know about California, but all of ours are from the Alaskan area and our collaborator basically collects them from the ocean and from all the lakes in those areas. But I haven't heard anything about that in California.
AUDIENCE: Well the point in my mind is that one could argue, that saving this little tiny fish will let the army have flexible armor.
ORTIZ: Well I think that I think a lot of the design principles that come out of this are good for all types of protective devices and that includes cars. All kinds. I mean anything that's a protective device. And so I think it's beneficial in terms of it's also advancing the field of mechanical engineering as well so.
PRESENTER: Thank you, Christine.
So at this point in the program we'll move from exoskeletals to exoplanets. Our next speaker is Sara Seager. She is the Ellen Swallow Richards Professor of Planetary Science and Professor of Physics at MIT. Before joining MIT in 2007, she spent four years on the senior research staff at the Carnegie Institution of Washington. And before that, three years at the Institute for Advanced Study in Princeton, New Jersey. She earned her PhD at Harvard University in 1999. And her Bachelor's Degrees in math and physics at the University of Toronto.
Professor Seager is the 2007 recipient of the American Astronomical Society's Helen B. Warner prize and was named in Discover magazine's 2008 Best 20 Under 40 and also named fifth in Popular Science magazine's 2006 annual Brilliant 10. Professor Seager.
SEAGER: Good afternoon everyone, it's a pleasure to be here. How many of you recognize this planet? This is an interactive part of the lecture. No one's brave enough to put their hand up and actually look again if you thought it was Earth. It's actually an artist's conception of an exoplanet. And I love to start out with this planet because the question is, how much detail will we be able to see and how much do we really need? Unlike most of the other talks, we will never see a planet like this outside of our solar system. At least not at anytime that we can conceive of. The planet will instead look like a pale blue dot. Like one of those dots in the background but even that will be extremely difficult.
Okay. I'm going to start with a brief history of the field because it is a new field. And history also captures the future. Well first, just to make sure everyone's on the same page, here is a real photograph of a galaxy, a collection of stars bound together by gravity.
We think that our own Milky Way Galaxy also looks like this. And our galaxy has hundreds of billions of stars. And astronomers believe that there are upwards of hundreds of billions of galaxies.
So the question that we like to ask is, what is the chance there's another planet, like Earth, out somewhere in the universe. It seems like it must be a sure thing. But a harder question for us is how hard or easy it is for us to find one of those planets. And what I've done is I've put a little dot very approximately where we think our sun would be if this were the Milky Way. And the question is, with respect to our sun, how far from our sun do you think we could find an Earth? Just like Earth,a planet with what we think has oceans and maybe continents and signs of life in the atmosphere. If anyone wants to take a guess just let me know. It's a much harder question. The first one everyone agreed on so I didn't ask for an answer.
It would actually be within that red circle. So if we want to find a planet just like Earth, one that, in the next decades, we can actually look at the atmosphere and look for signs of life and determine robustly whether the planet has sure signs of liquid water on the surface, an ingredient that all life as we know it needs. That's where we'll be. So my talk, I'm going to tell you a bit about my work on exoplanets. And first I'm going to start with that background.
Here's a figure of known planets in 1995. On this graph you see mass and Earth's masses versus semi-major axis. That's the planet-star separation in units of Earth semi-major axis. And what you'll first see is this a log-log plot. So it covers a wide range of plant masses and distances from the star.
So in 1995 here are the planets we knew. There's Venus and Earth that are about one Earth mass and one semi-major, one astronomical unit from the sun. You have Mercury, Venus, Earth, Mars, Uranus, Neptune, Jupiter, Saturn. Actually let me go in order. Okay, Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune. And here we have two interesting objects. In 1995 it was actually really the start of the whole field when the first planet around a sun-like star was discovered. And look here where it is.
It was really this one. This one we're little unsure of. It's kind of might be too massive to be a planet. But this planet, it's actually much closer to its star than Mercury is to our sun. Almost 10 times closer. And this is a real shock to the field because many people wanted to believe the paradigm where big planets are far from the star and smaller plants are much closer to the star. And no one though any planet could have such a short year, only four days. And actually the field has continued to unfold that way.
Now the next year, 1996, is actually when I started working on exoplanets. And people were so uncertain that these were real planets. They were changing the paradigm and people were really unhappy about this.
But nonetheless I started to work on it and you wouldn't believe how many people told me, don't work on this. Tons of people thought it would never happen. And actually what I was working on was exoplanet atmospheres. How to study their atmospheres and find out the chemical composition and temperatures. And so even among the people, even five years later who believed they were planets, most people believed by then that they were robust signatures. Thought we would never have any chance of looking at the atmosphere. But nonetheless, I, at the time, actually was not committed to a career in science and I was always a risk taker.
And actually at this time when I was making that decision I was working on theory. It was a computer code describing how the radiation from the star interacted with the atmosphere and I knew you could always have the thesis that was theoretical.
Okay, so in year 2000 we start to have more and more planets. And then I'm going into five year intervals, by 2005 look how many planets there are. Even by 2005 alone. This is about the time that I visited MIT for the first time. I had actually never been here before 2005. Came to look around, I think at that time MIT was thinking about working on exoplanets. But still, a lot of people around the country and it's actually still somewhat true today, weren't sure if we would have enough detail to really make this a really kind of hard, substantial science.
Now you can see there's a lot of different planet techniques. I'm not going to explain what they are, just look for the symbols, they're different coming into play. There's a dark area of the diagram that's very, very hard for technology to reach, including that near Earth's. But things were changing rapidly. And by 2010, look there's lots of planets, lots of different techniques. The ones with red circles are planets whose atmospheres have been measured. And so the work that I did 10, 15 years ago and still continue to do actually plays a major role here.
And just so you see what's even happened this year alone, just to sort of make it complete, here's 2011 already. You see people are pushing down in mass, down to the lower parts. But I love this diagram. It's one of my favorite figures in all science because it really shows you know for exoplanets anything is possible. Any kind of planet mass, semi-major axis, it turns out orbit and it's possibly true the atmospheres. Anything you can think of is possible and is out there. Really it's just a matter of having the right technology to find what you're looking for.
So to summarize this part of the talk, there are hundreds of exoplanets are known. But we don't want to just do stamp collection. That's often a criticism against some fields in astronomy and astrophysics. We want to determine what the planet interiors and atmospheres are made of and if any have signs of life in their atmospheres.
So the most natural way to think of doing this is actually what we call direct imaging. And I'm going to describe the hardest problem first and that is how to find an Earth and look at its atmosphere. And actually, I was consulting for National Geographic a few years ago, this field is just completely crazy in the news. You've probably read about it. If you look at the science page of any newspaper or magazine, it's almost every month there's some big story.
Anyway at the time a few years ago, National Geographic was doing an article and it was my job to help with the illustrations and the photographs to make sure that they were legitimate. So they wanted to capture the analogy of how hard it is find an Earth. It's like trying to see a fire, and by the way, finding an Earth, taking an image like a photograph with a fancy telescope in space, is not as hard-- Earths are not that faint. They're not fainter than the faintest galaxies ever observed by the Hubble Space Telescope. The problem is they're right next to an extremely bright star, the sun, a star like the sun.
And to find an Earth next to a sun-like star is like looking for a firefly next to a searchlight. In the glare of that searchlight when the whole firefly and searchlight are 2,400 miles away. That's like from here to Los Angeles.
So now they want to take the real picture. And it turns out if you can't do the engineering problem to find this you actually can't take the picture. It's the contrast that's the problem because the Earth is 10 billion times fainter than the sun.
So they actually rented the searchlights. That's what this picture is. And the first thing I complained about was see the cluster of four in the background? We don't see stars like all stuck together like that. And they came back, they ended up having to fudge it clearly.
But the part about this actually that was the most fascinating to me was these National Geographic photographers and researchers are really, they're among the most hard thinking people alive, basically. And they actually came back with the firefly in front of the star. And they'd taken a picture somehow. I don't know if it was a fake or real firefly, but in front of the sun they said, look, we can do this.
And it turns out that's another planet-finding technique that is the most popular currently which I'm going to talk about next. And they just showed sort of in a layman photography way that they could do that. That problem is not one part in 10 billion, it's only one part in 10,0000. And for any scientist here think about what measurement of one part in 10,000 means. It's actually still really hard. But that's what they actually figured out and that's what I'm going to talk about next.
So what we have for a transiting planet is a planet that goes in front of the star as seen from Earth. And there's an illustration up there. Look really hard and you can see the Earth-sized planet against the sun-sized star. Now for stars and planets we'll never get a picture like that. We'll never so-called spatially resolve the star. But what you can see in the little animation at the bottom, or the figure, is you can see a green line which is showing you brightness is a function of time.
And so the star is almost in constant brightness, not changing much. And then when the planet goes in front of the star you see a tiny drop in brightness. Even though you can't see the star itself, you just see a point of light. It changes in brightness by a tiny, tiny amount. And that one part in 10,000 about is what Earth would do in from the sun.
I'm showing you a picture of the NASA's Kepler Space Telescope Launch. I'm part of the Kepler Science Team. And Kepler is looking at 150,000 sun-like stars looking for planets like Earth. Kepler wants to be able to tell the world how common are other Earths. Does every single star have an Earth-sized planet in an Earth-like orbit or is it fewer or more? And it's really exciting to be part of the Kepler team. If you've read anything in the news about exoplanets lately it's probably been related to Kepler.
But I actually came here to tell you a few things that I'm working on. And one of them is kind of related to Kepler in a more complicated way. And I'm going to try to explain that now because it has to do with something that I started working on when I came to MIT and that I'm still working on now. And I brought a demonstration model. It's a space satellite that we're building and hoping to launch at the end of 2012 here at MIT in collaboration with Draper Labs. Here's an engineering demonstration model. It's not a flight quality model. And this was built by students in the class but I'll tell you that in a minute.
So what we're trying to do is Kepler is trying to answer the frequency. How common are other Earths? And in that sense Kepler has to look at a lot of stars but to see a lot of stars at one time they're all very faint. To faint for us to do followup measurements with. It's hard to find the mass on individual objects. Nonetheless Kepler will make its pioneering goal in a few years from now.
We're trying to do the opposite problem and to look at the very bright stars in the sky. The closest sun-like stars, they're spread all around the sky. And you can't just have one telescope. Imagine trying to have one telescope trying to look at all these bright lights. It's not possible so we're hoping to launch what we call a fleet or a constellation of these. Some will have to be bigger. And each of them will target it one star at a time looking for an Earth-sized planet. Ideally in an Earth-like orbit but initially we'll just look for planets closer to the star which for a variety of reasons are easier to find.
So that's sort of the overview. This thing here it's actually called Triple CubeSat Form Factor for any engineers here. And this is the standard kind of size and mass. And it means that some commercially available parts are available. And it's supposed to simplify things and make launch opportunities more frequent and cheaper. And I'm just sort of thinking in the back of my mind, a lot of thoughts are going through my mind but one of them is 50 years from now I actually plan to still be alive and it will be great to see what happens at the 200 symposium. And if this new paradigm that we're part of will really happen.
And what we're trying to do, I'm going to come back to this afterwards, is we want to launch, like I said, a constellation. And you can see in the background is an artist's conception of what it would look like. We would launch probably dozens of these into low Earth orbit. We're not the only ones want to do this kind of thing. And it's kind of a new paradigm for space missions. Space Science missions. Like, Kepler, for example, was over 25 years from conception to launch. Its very high risk and complicated and really expensive. In this plan we have a science case but we have a limited goal for the first one. And so we have a graduated population of this constellation. That's our overall goal.
But at this point in my talk I want to just tell you a bit about the class that's been working on this project and about some students and a bit about my time at MIT. So what I want to say first before I get to this was I came to my team of scientists that's what we heard as scientists.
One thing I love about MIT is that people are so open to new ideas and trying new things that the rest of world thinks are really crazy and impossible. So when I came to MIT-- I've had this idea for a while, but I decided to try to take advantage of being at MIT and integrate with the engineers.
So I had known Professor David Miller from other exoplanet engineering science work and I said, Dave I really want to do this. And he said okay, that's not bad, good idea, here's a couple students. So I worked with those students and the students went on to do something else and then we started with a new group of students who are doing a fantastic job. And I said, Dave I've heard about this Space Systems Engineering Class, I want to do this as part of the class. And he said, okay, we can do that. In the next cycle we managed to make that happen.
Now the thing is, the thing we have to do with this little tiny nanosatellite is the smaller it is, the easier it is to be disturbed in space. And to make a very precise measurement where you want to see a signal of one part in 10,000, this has to be pointed extremely precisely. In fact, so that the stars are on the same fraction of a pixel at all times. And that we have to do something that's basically almost 100 times better than was conventionally expected. So even with that I say, here's what we want to do. And people say, you know, we can do this. And so we've had a kind of long journey, we work also with Draper Labs and we're going to make this happen.
Now when I came to MIT, when I was an undergraduate in the early 1990s I was at the University of Toronto. There had never been a female physics professor ever in the history of the University. And after a couple of years one appeared and then left about eight months later.
And so one of the most important things for me about, one of the really great things about being at MIT was there's not just one other female physics professor, but there's lots and lots and lots of extremely successful senior female scientists and engineers. And before I came here I actually only knew one really successful female scientist. And I don't mean to look at the PhD's who are just sort of doing general things. I'm looking for the really off the chart people. And there's a whole bunch of them here and that has been really powerful for me.
But another really important experience for me has actually been working with the next generation of what I expect to be women leaders in science and engineering. And here's a picture that was in the Wall Street Journal a few weeks ago about the project. And you can see two undergraduates, they're actually working on this. And the photographer, Dominick Reuter, he's actually our photographer today, you'll see him walking around. He wasn't allowed to take any picture that was like faked in anyway. So they're actually assembling this demonstration model in that picture and I just want to briefly tell you a couple things about a couple of the students in the class.
First of all, what we did that was new for the class was bring in science. It's got physics students and course 12 students and Earth and planetary students as well. And prior to that the students, it's a design and build class. This time it's a three-semester class so they design-- they don't often like fully build the satellite, it's component testing. But we brought the science students in so there would be a science team.
And one of the things that happened was after the class the feedback was, it took us a month, this is from the science students, it took us a month to learn how to talk to the engineers. You know you should have taught us. Well that was the point of the class. And the engineers on their own-- this little telescope it's supposed to go into low Earth orbit. So it has orbit day and orbit night. In orbit day it will recharge it's batteries from solar power, in orbit night it will do science observations.
And the engineering students would say, well, we can't observe every orbit night because we won't have enough power. We need to soak in shoot. Just do a few orbits so we can build up power. And the science students would say, no, that's ridiculously. We would never waste a single photon. And so we had this great back and forth in the class where they have a real science payload and their working toward a goal. And this project will be too mature for the next kind of round of the class but we'll do a new project then.
So on of the students, Mary Knapp, in that picture, she actually came to myself and Professor Miller and she said, you know I want to go to Japan. I want to enter a contest for nano satellite constellation contest. It's in Japan. Would this be okay?
And actually we said, you know, you really should focus on your grades. Going to Japan would be really distracting. And she was very adamant. She really wanted to go to Japan.
So she and another student, Ian Sugel, they submitted to this contest and they became in the top 10, so they got a free trip to Japan. And actually in the morning of the earthquake, the earthquake happened at 4:00 AM local time. Their plane left at 9:00 AM and went to Japan. And Mary went to Japan and presented to like an international panel with people from all around the world. It's not an undergraduate contest. So there are representatives from aerospace companies and other places also wanting to do fleets for different things. And she actually came second, only behind a Japanese group.
So I'm really proud of Mary. She did a great job despite the earthquake and everything. Represented the team of ExoplanetSat and MIT extremely well.
The second story about another student in the class is Becky Jensen-Clem, she's a physics student who went in this class, it's very unlike most physics classes. It's actually not a physics class. We do a lot of problem solving but it's a different kind of problem solving and she really shone in this class is as a leader.
And we set her and another student Jill McCarter to JPL. JPL provides us with some funding for the class. And they went to JPL, they got a tour and they're representing the class trying to show our good work. And I got a couple of emails from my colleagues, this has happened last week. And they said, you know, we were blown away by your students. They actually answered every question at an extremely high technical detail. I actually think, based on the emails I got, they actually did better than most PhD scientists who show up to give talks in this field. They nailed all the questions.
And JPL was pleased because they want to see that their money's being spent well. And they said you know your students they're the best ambassadors for you, the team, the class, and for MIT. So that was my little interlude just telling you why I'm really thrilled to be to MIT, to be a part of the whole women role model boat on either end of it, and that's been a real pleasure for me.
Okay, so there's ExoplanetSat. Let's skip that. So finding Earths suitable for followup observations is technologically challenging. We want Earths around very, very bright stars so we have enough photons to do follow up mass and other types of measurements. Transiting Earths make the problem a little easier.
But Earths are really hard. We don't know how common they are. We know they're really tiny, we know the sun is really massive and bright and big compared to Earth. And so this is sort of our dream, we're working really hard towards this. But I wanted to tell you about something that's happening in the shorter term because you might hear about this any day in the news. And actually that's something a little different.
We call this the M star opportunity. What it really means is, how could we find another Earth sooner? We can actually expand our definition of Earth. So if we take Earth to be something bigger, around a different kind of star actually it's a much easier problem. It always reminds me of the person who dropped their keys and looks under the search light because that's the only place to look right now.
But basically on Earth, the background is on Earth, all life requires liquid water. And if we want to find a planet with liquid water we think about the surface temperature of the planet. So we say where can we find a planet that has a surface temperature suitable for liquid water. This is a schematic showing you this planet Earth and the sun. There are a lot of stars that are really small stars. And their energy output is very, very low, their luminosity output is small.
And so, planets are heated externally from the star, largely so. For terrestrial planets. And so a planet really close to the star actually would be the right surface temperature for liquid water. With a lot of caveats that I won't get into. And so this idea is to look for these planets close to the star. And, in fact, those planets they're much easier to find in basically every single way. The signal is stronger, for the mass, for the size. And even for atmospheres. And so that's why a lot of people are searching for these right now.
I was going to go into like a technical description of all my computer models and through application how they integrate, but instead of doing that, I thought I would take you on a virtual trip to one of these planets. This is an artist's conception of one.
And on this planet, first of all, you can see the sun. Your star, the sun would be extremely big in the sky. What's more is that these planets are so close to the star, they're what we call tidally locked. Just like the moon, they show the same face to the star at all time. What this means for us, if we were able to visit this planet, would be that the star, the sun, would be in the same place in the sky at all times.
So you could decide where you would spend your time there. On the day side where it's always day. If you are an astronomer or astrophysicist you would go to the night side where it's always dark. And it's really kind of interesting to think of all the different things. We really do actually. We try to think what their atmospheres would be like, what they could be made of. If the planets would retain their atmospheres because of atmospheric escape. There's a lot of details to get into.
Now when you try to think about life on some these planets it actually might not be that great after all. Such a great place to visit. These low mass stars they actually, they have a lot of flairs. And so you probably wouldn't be able to use your iPhone or play your video games or anything that involved wireless because the flairs are so bad. The UV is so strong, you think about damage from UV and you know mutations. Surface life could have a really, really, really tough time on this planet.
There's a lot of other reasons. People who work on planet formation think the delivery of volatiles, that means water itself, to these planets would be very difficult in the time scale the planet takes to form. But nonetheless, I say that you know observers will never be daunted by theory and expectations. And remember I said before in exoplanets, anything is possible. I'm sure those planets are out there and I'm sure they will be found any time.
So I did, instead of telling you about my computer code, I did want to just give you a very brief kind of generic overview without talking about code. But here's what we do really. We have this thing we call it region of transfer. It's actually how light moves through the atmosphere. And this actually applies to Earth's atmosphere. Part of my teaching involves students who work on Earth's atmosphere itself. And basically that's what we call rate of transfer.
You never hear about this. Even in physics, you hear about f equals ma, e equals mc squared. I wish we had a cute little catchy acronym for this. Instead We just call it rate of transfer.
We actually worry about atomic molecular lines. And these come from quantum mechanical calculations. We take millions and millions of lines, the same ones that cause global warming. Those are good ones for us for exoplanets because it means they have a strong molecular signature and some of them we can observe in atmospheres of a specific subset of exoplanets, hot Jupiters that are available to our technology today.
Now but actually all this is really tied to the composition. We don't expect the composition to be exactly like Earth or like Jupiter even. But we try to figure that out with computer codes. And I put a series of them here. Really photo chemistry and chemical equilibrium. And actually for some exoplanets we don't even really know what their composition is, we'll have to observe them and see. But we're using our tools of modeling to try to extract information from data we do have. We also have to worry about other things like clouds on other planets. And on really hot planets these aren't icy clouds like water ice. These are high temperature condensates. We call them like iron, silicate, other things actually. So we have a lot of interesting cross disciplinary work in exoplanets.
We also worry about atmospheric circulation, which is one of the most difficult applied physics topics involving fluid mechanics and other things. And that actually also plays a role in exoplanets. And then there's the cartoon with the Hubble Space Telescope here or other space telescopes above the blurring effects of Earth's atmosphere that enable us to really get real data.
Okay, so what we really want to do is find signs of life. And this whole computer network is actually really relevant to that because on our own Earth, the signs of life are what we have in our atmosphere. Oxygen, created by plants and other photosynthetic bacteria. It would be 10 orders of magnitude less oxygen on our planet without life. And so we're looking for gases that actually don't belong in a planet atmosphere but it's not that simple. Because the destruction, gas can be made by life but it's destroyed by chemistry, UV radiation and other chemical reactions.
And so we have to have this big network to try to understand which of the many gases on Earth actually could be viable biosignatures on exoplanets that have very, very different environments. And that's actually what much of my present work is focused on.
And I actually put this little alien up here to say we're actually not going to know if there are intelligent, alien-like creatures out there or if it's bacteria. All we will know is that there's some kind of chemistry in the atmosphere that's unusual by many, many orders of magnitude. And we will try to interpret that as a sign of life on another planet.
Okay, I'm going to summarize. Hundreds of exoplanets are known. Finding Earths suitable for followup observations is technologically challenging. I mentioned the way that we're trying to do it here at MIT, with this engineering demonstration model. I explained how students, we have actually undergrads, graduate students, and collaborators at Draper and other places working on this.
Super Earths orbiting small stars are a nearer term possibility. And instead of telling you about all of my technical computer codes, I gave you kind of this overview summary of how we're trying to put this all together. And out of Earth's numerous biosignature gases, we're trying to determine which are relevant under the diversity of exoplanetary environments.
And I wanted to just finish with one more kind of overview slide. MIT's really big on surface and being practical for the world. And exoplanets, we're not going to do anything practical. People often want to know why are we doing this, why should we support exoplanets. And I know even though I don't have to justify to you, I still want to. And so we divide it into two.
One is a reason all of us here can say. We have a problem with innovation in the country. Exoplanets is a huge topic of interest to, you wouldn't believe how much time I spend talking to journalists. How many emails I get just for all types of people, children, high school students, college people, just random people out there.
People love exoplanets. And we don't want everybody to work on exoplanets, we just want to inspire the nation. We're trying to do technologically innovative things as well. But actually the real reason that I and others work on this is we really want to change the world. We want to be able to take our children, grandchildren, nieces, and nephews to a dark site and to point to a sun-like star and tell them, that star has a planet like Earth. And in that way we really hope to change the way that everybody sees our place in the universe. Thank you.
PRESENTER: Thank you Sara. Questions?
AUDIENCE: I have a quick question.
SEAGER: Sure go ahead.
AUDIENCE: By the way, I'm really happy to hear ExoSat is doing well.
SEAGER: Okay, great that's one of our students from the first semester.
AUDIENCE: I was wondering more specifically about the state of the [INAUDIBLE]. Is that anywhere [INAUDIBLE]?
SEAGER: Okay. State of the project?
SEAGER: First of all, I'll give you the big picture was-- so we applied to-- NASA has this CubeSat launch initiative. And they want to start launching a lot of these things. So they had like 30 people apply, 20 got a slot, we were ranked number five. And what that did was it forced us to sort of reevaluate and try to move forward quickly. That's typically what happens. So where we are we at now? Well, we have demonstrated in the lab that we can reach the pointing necessary to reach our photometric precision goal.
So her second question is whether the avionics can actually support that, whether it's sort of doable in the time we need using the sort of real avionics that would have to happen. So we're right there right now. And now we're trying to evaluate among two or three different options and in terms of simplification.
For example, you might remember we had the one CCD in the six CMOS, but one question is with all the interfaces, whether it's really possible to do that. So do we want to go to one science CCD and one guidestar CCD. So we're sort of in the process of evaluating that. And we'll see what's going on. But meanwhile, in the class they've been doing a great job with the structure and with other aspects. So that's sort of the overview but I'd be more than happy to give you another more technical update offline. One more?
AUDIENCE: I just wanted to ask what the definition is of a Super Earth.
SEAGER: Good question. The questions is what is the definition of Super Earth. And the answer is we really don't have a very specific definition. Loosely, people want to call it something between one and 10 Earth masses. Other people would say it has to be something that is a planet that is primarily rocky. That doesn't have a significant gas envelope around it.
PRESENTER: Thank you again.
So our last speaker of the day is Maria Zuber. She is the EA Griswold Professor of Geophysics and head of the Department of Earth, Atmospheric, and Planetary Sciences here at MIT. She has the distinction of being the first woman to lead a science department at MIT.
Professor Zuber received her BA in Astrophysics from the University of Pennsylvania and her masters and doctoral degrees in Geophysics from Brown University. She has served on the faculty of Johns Hopkins University and as a research scientist at the NASA Goddard Space Flight Center in Maryland.
She was inducted into the National Academy of Sciences in 2004 and in the same year was awarded the NASA distinguished public service medal. In 2008, she received an honorary doctor of science degree from Brown University and has been named as one of the 50 most important women in science by Discover magazine.
She is currently the principal investigator for the Gravity, Recovery, and Interior Laboratory mission being managed by NASA's Jet Propulsion Laboratory. It's a mission that will map the gravity field of the moon to higher resolution than Earth's gravity field. Professor Zuber has been involved in more than half a dozen NASA planetary missions aimed at mapping the moon, Mars, Mercury, and several asteroids. She is one of two first women to be named scientific leader on her own NASA Robotic Space mission. And was named one of America's best leaders in 2008 by US News and World Report. Maria Zuber.
ZUBER: Thanks. Thanks very much. I just want to say what an honor it is to be involved in this historic conference here. And really what a great privilege and gift it is to be here at MIT and part of this community. I thought for the purpose of this that I would talk about, since we're looking at the future and this anniversary year for MIT, that I would talk about the most absolutely out their thing that I was working on, which is looking for life on Mars. But then I follow Sara Seager and I feel like I'm playing in the backyard. And that's great because it keeps me at the top of my game. And so this talk actually is going to be somewhat transitional between Sara's talk and some of the Life Science talks that you've heard earlier.
So okay so just to pose the question here. This is, as part of Mars Exploration, this is some of the questions that we really want to deal with. Did life ever develop on Mars? And if life ever initiated, did it persist to the present. Okay. And the way that we address this is really through parallel lines of inquiry. The first is to study the environment at Mars and study the conditions under which that were available for life to develop or not. And then to take the additional step of actually trying to detect whether or not that life exists or existed. And my talk today will start with this and then move on to this. And then this part of my talk actually is my contribution to the discussion at MIT of the convergence of life sciences and engineering.
Okay, so thinking about habitability, here are some of the questions that we try to address. So first of all, what were the environmental conditions on early Mars and what was the relationship of the environment to the development or not of life? So actually I should say either life developed at one point on Mars or it didn't.
Okay, and technically speaking, these are equally interesting answers to the questions because either we're special or we're not. At least in the solar system neighborhood. And we really want to try to understand, as an Earth scientist, which I am, just what role the environment might have played in this.
And then we're interested in the additional question how and why did Mars' climate change from the earliest epoch. And if life ever developed early on, could that life have survived to the present in light of what I will show you to be dramatic evidence for climate change. And it will be clear as we go along that really studying the history of water is a key consideration here. Okay, so we need to think about time scales, okay.
And here is a very idealized stratigraphic record for Earth and then over here for Mars. And let me put some events on this calendar. So here we are. This is the present day right here.
And then we go back, so I expand this area right up in here. And then we go back to about 4.5 billion years when we are formed and Earth and Mars formed at about the same time. So the dinosaurs went extinct at this first line up here, 65 million years ago. The oldest ocean basin preserved on the Earth is about 200 million years, back in the mesozoic. So that's actually relatively recent in Earth's history. So 60% of the surface of the Earth has it been around less than 200 million years. So there isn't a lot for us to work with here.
Angela Belcher mentioned the Cambrian explosion 570 million years ago when life really took off and radiated. The first eukaryotes formed between one and two billion years ago. And there's some suggestion or some arguments that the first prokaryotes were formed as far back as more than three billion years ago. And basically what's preserved on Earth at this point in time are some rocks and even some mineral grains as you go little bit farther back. But the conditions, we don't actually preserve lot of the Earth's surface back at this time when we think life developed. And we don't know how many times life developed before it really stuck.
Okay, so then if we do we go to Mars. Here the Amazonian Era is recent Mars history and it goes back nearly three billion years, okay. And most of the surface of Mars actually is back here from about 3.8 billion years and older and it's a period of time that's called the Noachian which is named after a type location on Mars called Noachis, after Noah for the flood. And the reason I'm going to show you some images here of Noachian Mars-- and I will show you images at many different spatial scales, orders of magnitude, different spatial scales so you can get a sense that we really have this very well characterized.
So the key thing about the Noachian is there is abundant evidence of liquid water on the surface of Mars. So you see streamlined islands indicative of water flowing. We see a valley networks and outflow channels here which I will talk more about. Here are more shots of, I could show you, we could stand up here for hours and I could just show you pictures of the surface of Mars which evidence for past water. And again, I'd like to emphasize to you here that these are all Noachian features and I want to underscore the fact, because we're going to come back to it, that all valley networks on Mars, these tributary river-like structures are Noachian in age. So none are younger than about 3.8 billion years ago.
Here's some pictures of mud cracks taken from orbit so you can see the size of these things, they're absolutely huge. And then, let's see, if you can run the movie now. This is a simulation of a feature that I'm going to show you in the next slide. This is a simulation of water flowing over sand and creating ripples and preserving features called cross beds here. And over here are cross beds that are preserved in rocks on Earth. And here are the same features taken from the microscopic imager on one of the Mars Exploration rovers. So vast evidence for liquid water on early Mars.
Okay, so there was, the first question that we wanted to ask is how long did liquid water persist on the surface. Because if the only thing that happened is that you had all volcanic intrusion that melted some ice, you put water on the surface and that water froze over rather quickly, then the development of life as we know it associated with water, only had a much shorter period of time to develop. Whereas if Mars was warm enough that liquid water could have persisted on the surface then theoretically it's a longer period of time for life to develop.
Now there were some thoughts that liquid water on Mars did not persist on the surface for a long period of time. And this is an area of Mars called Tharsis, which is a large volcanic province. And this region in here which is blown up is called Kasei Valles. And this is evidence for catastrophic flooding. Okay, the flood. Okay, Noachian in age.
And so there was some sense that maybe liquid water didn't stay on the surface for a long period of time. But we knew we wanted to look at this province in some detail because of the fact that this is, it's composed of minerals or rocks called basalts which you can see in some section here in some images taken from orbit. And the salts have the same composition as the Earth's ocean floor, the same composition as volcanoes in Hawaii. And they have to have a lot of volatiles associated with them. And so if you look at the lavas on the top of the most recent of these volcanoes the lavas are as young as about 100 million years. And so people thought that this volcanic province on Mars was forming throughout the 4 billion years of Mars' history.
And so what we decided to do is to try to figure out when that province may have formed. So there's actually a picture of a Martian gravity field and this is that Tharsis province that I talked about. And here red corresponds to high gravity and blue corresponds to low gravity. And essentially what this pattern corresponds to here is if you consider that Mars is a beach ball, okay, and you insert your fist into the beach ball and load it, what happens is you get an indentation or a moat around the load. Okay, and we can calculate that except we can't treat Mars as a beach ball which uses thin shell theory, we have to use the full thick shell theory to do that. But we can look at that we can calculate what the deflections look like.
The other thing that we have to take into account is that Mars at the south pole is six kilometers higher than it is at the north pole. So everything on Mars flows north. So this is a cross section through the prime meridian of Mars starting at the south pole and going north at zero longitude. Which I believe is the zero longitude line.
So what we did is we took the deflections that are associated with this south to north slope and we took the deflections that are associated with the entire load of the Tharsis province which we can determine, which we have determined using gravity from Mars orbiters and also altimetry from Mars orbiters and so we can calculate that load and then we add together those two deflections and then we go to our friends the valley networks and, son of a gun, the azimuths of the valley networks, they basically match up to deflections that you see.
And I told you that all these valley networks, none of them are younger than the Noachian. And so what this indicated to us is that the bulk of the Tharsis province was emplaced on Mars before the end of the Noachian. And that there may have been some additional small lava flows out onto the surface after that but the bulk of this volcanic intrusion happened very, very early in Martians history.
And so why is this important? Okay, well, this turns out to be important because we can calculate the amount of lava here and if these lavas are like Hawaiian volcanoes. We have here 10,000 Mauna Loas' worth of volcanism. And this corresponds to 300 million cubic kilometers of magma which was emplaced during a relatively short period of time in planetary history. And we have CO2 and water in these lavas similar to like we do in Hawaii that would give you a bar and a half of a CO2 atmosphere where Mars' atmosphere today is six millibars and it would give you 120 meters global equivalent layer of water on the Martian surface. So that's where the water came from and that's where the thick atmosphere came from. So this was all work that we've done at MIT.
So then the question is can we warm up the atmosphere to be above the melting point of water early in Mars' history because Mars is 1 1/2 times farther from the sun than the Earth does. So can Mars ever heat up enough.
So here we go to the thesis work of Sarah Johnson. And Sarah is currently a White House Fellow working on climate change policy for the Obama administration. But she did global warming on Mars for her PhD thesis. And these are temperature increases due to sulfur dioxide for a 50 millibar atmosphere and a 500 millibar atmosphere. So this is a third density of the atmosphere as we could get from degassing Tharsis.
Actually what we did is the constraints in this is we took the composition of the salt that was measured at the surface of Mars at the Gusev site for the Mars Exploration rovers, figured out what the source region was, figured out what the solubility of sulfur was, and then degassed that amount of sulfur into the atmosphere. And so it turns out you get a minimum of 25 degrees greenhouse warming due to SO2 above that you would get from CO2 and water vapor is an even more intense greenhouse gas than the sulfur dioxide. So you can get an additional 25 to 45 degrees of warming. So the fact of the matter is that there's no problem warming up Mars high enough so that the surface temperature is above that for liquid water. And you would get hundreds of pulses of this occurring throughout the Noachian as Tharsis was forming.
Okay, so there's another part of the early Mars environment picture that we want to talk about and that's surface chemistry. So this is again, a microscopic image of a rock called Guadalupe and this was taken at the opportunity site which is approximately 0 latitude, 0 longitude on Mars.
And here these are concretions formed of hematite. You may have heard them referred to as blueberries. These are millimeter sized Fe203 nodules that we now know precipitated out of water.
But what I wanted to point out are these holes in the rock right here. These are called vugs. And this is actually, these are very common on Earth in certain kind of desert areas. These are minerals that have eroded away because these are magnesium sulfates and they're extremely friable. And so it let us know that there were magnesium salts on Mars. So that we had not only standing water but salty standing water.
And then, really the kicker in the story-- and I'm leaving a whole lot out-- but the detection of a mineral jarosite here from the Mars Exploration rovers, which is potassium sodium iron sulfate. This type of rock only forms in a pH of less than 2. So what it tells you is that this early standing water on Mars was not only salty, it was like an acid mine pool in a way. And so this is what we're dealing with.
So this is the opportunity site in meridiani planum. And you can still see these are ripple marks now due to wind and not flowing water. But we now know that this was a very water rich but actually highly acidic area on the early Martian surface.
Okay, so how does that compare to what we have now. So we can now fast forward 3.9 billion years to present day Mars where we have a 95% CO2 atmosphere. And we always talk about Mars as having an atmosphere like Earth but the atmospheric pressure on average is equivalent to 100,000 feet on Earth. So it's the equivalent if you were flying in a spy plane how much atmosphere you would have associated with it. The surface pressure varies by about 30% over the course of the year.
Water vapor fascinatingly is-- there's very little in the atmosphere. So 10 precipitable microns, which means if you took all the water in the atmosphere and you scrunched it down to the surface it would be a layer 10 microns thick and there's been claims, independent claims of the detection at methane. But the signal to noise ratio on those detections is one. So it's a very weak signal if it exists the average surface temperature is -53 C and pure water, liquid water is not stable on the surface.
So where did all this water go? Okay, well, here's another recent discovery. It's still there. This is a map centered on the north pole of Mars of the neutron flux where blue means no neutrons. And what happens is when cosmic rays hit the surface of planets they are they knock off neutrons and if there's water there water moderates neutrons. So it picks up the neutrons and makes heavy water and it also gives out gamma rays which we can measure.
And actually, we've been able to show that the amount of water in the top meter of the Martian surface is far greater than you can store in mineral grains, so it's there as water ice and it gets to be as much as 70% by volume when you get up to high latitudes. So the ocean on Mars is still there. It's beneath the surface. As you go beneath the surface it gets warmer so that ice goes to water as you go to great depths. So it's reasonable to think that if life had ever developed on Mars that it would have retreated underground as the atmospheric conditions have changed. And so that's something that we can test.
Okay, so here's just a little cartoon saying okay, if there is life on Mars they say it probably won't look anything at all like us. And that's fine, but the fact of the matter is that when we study Mars, we have an incredible emotional bias to look for life like Earth life. Okay.
And, in fact, the Viking biology experiments, which were sent in the '70s, were designed to detect metabolism that were involved, organic compounds. However, there was a gas traumatic graph mass spectrometer which showed that there were no organic compounds on the Martian surface.
And in fact there were three different experiments, and they were control experiments. They were control samples sent that had no life in them. And two of the three experiments got positive results for both the sample of Mars and the control, which we knew had no life in them. And then one gave a positive result on the sample only but an ambiguous interpretation. And so it turns out what happened is that you had UV production of strong oxidants on the surface from absorbed of water in the soil and it produced hydrogen peroxide. And basically these results can be explained purely by non-biological processes.
And so when you think about life detection, the strategies that are general but have been implemented, have been looking for morphological structures, like fossils possibly. Which are extremely subjective. And then looking at chemical or isotopic signatures of enzymatic processes. But these approaches aren't particularly sensitive and of course they have abiotic pathways as you saw for the Viking experiments.
And so my colleagues and I have been developing instrumentation to look for life that is rooted and similar to life on Earth because at least that's a well posed problem and we know what to look for and we can use an information rich technique to classify the most divergent structures. And why would we look for this? And to make a long story short because of impacts on planetary surfaces there certainly has been exchange of material between Earth and Mars and so this life, on whichever of the two planets that it developed on could potentially have been exchanged between the two.
And so we've been really investigating the common ancestry hypothesis where life on Earth and present or past life on Mars has a single geneses which is really rooted deeply on the tree of life. And so the question is if we look for samples on Mars where would they occur on the tree of life and actually I should say that we're doing a lot of bench biology in extreme environments and are actually making good progress in just trying to understand early life forms and life in extreme environments and how that fits into the tree of life.
And so the approach that we've taken is to look using ribosomal RNA and we're looking at the 16 S gene. And the ribosomal RNAs their primary structure and catalytic components of ribosome that translates RNA into proteins. And this is extremely well conserved in life over the past 3 to 4 billion years making it a great detector. So we've been developing primers on this. And we basically are using the techniques that you use in the lab for DNA detection and amplification which is polymerase chain risk reactions, or PCR techniques which is basically a thermal cycling technique which detects and amplifies genetic material.
So we've actually built one of these machines. Here's a picture of our prototype and we've taken it out in the field to extreme places and we've made these measurements. And we're now in the process of modifying this so that it could work on Mars. And we've actually gotten together with the business community, we're actually working with a company called Ion Torrent which instead of the usual way of doing PCRs we're getting rid of the need to do fluorescence of molecules and getting rid of complex optics and essentially this machine is the world's tiniest pH sensor and we're using this kind of approach. And so I'm going to stop right here because this is a work in progress but here's just a list of all my collaborators which includes biologists, planetary scientists, people from the entrepreneurial community, as well as some fantastic postdocs, research scientists, graduate students, and undergraduates. And the learning curve on this project is actually vertical because the people from so many different backgrounds are here. But whenever we get together everybody learns a lot because we're from entirely different backgrounds. And it's really it's just so fantastic to be at a place like MIT where when you say you want do something like look for life on Mars, people want to come and help you as opposed to telling you that you're out of your mind.
AUDIENCE: You pointed out that intriguing location of ice but it's under the surface?
ZUBER: It's in the-- so we call it the layer of neutron production. We're able to detect from orbit. We can only detect the top meter, okay. You don't know how deep it goes. But there's actually sounding radar, which I didn't have time to talk about, which shows that it goes down a farther way. Many say hundreds of meters. But our thought is that this ocean has gone deep into the crust. And if you think about planetary surfaces they've been impacted so they're very rubbly and it's actually a great reservoir for water beneath the surface.
AUDIENCE: Do you have any hypotheses slash wild imaginative guesses as to how this formed?
AUDIENCE: How that reservoir formed.
ZUBER: Okay, so I think the water was degassed into the atmosphere and then as Mars started to, as the climate started changing on Mars, the water started seeping beneath the surface and so it's still there. A lot of people have thought about how the ocean on Mars was lost to space. It was not lost to space. It's still there.
AUDIENCE: Hi. You mentioned the belief that how it changes the high from the south to the north pole of Mars. Is there an explanation for that? That the south pole is thicker than this north pole?
ZUBER: We think the crust is thicker in the southern hemisphere than the northern hemisphere.
AUDIENCE: Is there an explanation for that?
ZUBER: Is there an explanation for that, yeah there was probably a giant impact in the northern hemisphere that blew away part of the crust and caused it to subside.