Life Beyond Earth, Part 4: Penelope Boston

Well I'm really happy to be here with everybody this evening and share with you a bit of a potpourri from an alien planet. From an alien planet that is near and dear to our hearts because we live on it. And because we live on it, we think we know about it. But the truth is that there are huge, vast tracks of the surface and particularly the subsurface that are really unknown to us. And so each one of these little planet-lets that go to make up our planet actually harbors life forms and conditions that are radically different from what we experience on the surface. And my way of substituting for getting into my rocket ship and cruising the galaxy looking for cool life forms, which is what I grew up wanting to do, is to have stayed closer to home because I don't have a rocket ship yet, come on NASA. And try to explore templates for the kind of life that we might find on the planets in our own solar system and what kinds of signatures would those leave.

Well, National Geographic has played a big role in my life. And I had my first magazine subscription as a little kid, courtesy of my cousin in 1968. Early on in my attention to caves, they sponsored some of our work, and this is the centerfold from the January 2000 issue. I actually was able to be a centerfold model. And looking as glamorous as I usually look in these kinds of deals, and there I am with Diana Northup and Mike Spilde, two colleagues from the University of New Mexico, and I'm diving for phlegm ball mats totally suited up. If you've read the magazine article this time around you will know that we are still working on that system 15 years later and we are still mystified by the tremendous amount of biological activity in what is to us an extremely toxic environment. This is why we're all duded up, because we are kind of life form, humans, and higher animals find this kind of environment very toxic.

But we are still looking at snottites, these are the famous snottites. And I'm gazing lovingly at them. And taking samples of them, which we will haul back to the lab and then try to poke them with sticks and get them to grow and look at their DNA guts and all that kind of stuff. But this is not where my caving career started. It actually also started by way of a National Geographic special. It was called Mysteries Underground in 1992. And that same year, with several other colleagues, I had published a paper suggesting that the best place to look for life on Mars was not on the surface of Mars, but would be in the subsurface. And I was looking for a way to get into the subsurface of Earth to see what we could find down there. And I was way too poor to actually do drilling. We couldn't get anybody to pay for it, and we saw this National Geographic special, and it said a couple of really important things about the cave. It said it was pristine, that it had been dug into, which meant less contamination. That it had a lot of sulfur, and we already knew that Mars was a very sulfur-rich planet. And the third thing was that one of the geologists from the USGS Geological Survey said that he thought he had seen some kind of little microbial life forms on some of the formations. And so we were sold, and we called him up and we said, “You don't know us but we're from NASA and we'd like to go into your cave.” So we trained for three hours, which if we had known then what we know now, of course this was completely nuts, and then we went on an expedition for five days into this cave.

Now this cave is a huge system. It's 138 miles of mapped passage so far. And exploration is still underway. Of course we were captivated by many of the scenes that you see. This is a beautiful image of what's known as the Chandelier Ballroom. These are big selenite crystals. But really the quarry that I am always after is shown in these orange materials behind where the young man is standing. This brown stuff in the middle, it's not as spectacular, but this is where the real quarry lay. And there are some of my little friends now. These are all microorganism types that are unknown to science. In fact, virtually everything we find in the subsurface is unknown in the databases that we have of surface life forms. The tiny ones there, we call them the tiny guys, isn't that original? These guys are about 100 nanometers across. One of your hairs is about a 100 micrometers across, so this is a thousand times smaller than that. And these are some of the smallest life forms that are clearly growing and alive that have ever been found. The ones with hairy bits sticking off them, we call them smurfs for obvious reasons. And then the others are the death stars. Well these are just a few of the microbial forms that we see in the subsurface. And this is really what got us going, and really caused me to focus my career from a lot of the surface extreme systems that I had been looking at up until that point in my career.

I just wanna dazzle you with cool stuff, okay? So one of the amazing things about caves is just how big the spaces can be underground. Here's a couple of examples. And if you've never been to Carlsbad or Mammoth Cave or any of the beautiful show caves around the world, this is probably what you are looking at. Something like that. But there are many other peculiar and amazing structures. So, see all that white material when you're actually there it sort of sparkles like sugar. There's 18 kilometers of this river underground. This is Snowy River in Fort Stanton Cave, about only an hour and a half away from my campus. But the thing that gets us about this is not just the spectacular mineralogy, but all those dark streaks on the wall. That's where the real action is. And you can almost hear them calling. They're saying, “Hey, hey, stupid, we're up here.” In their tiny little microbial voices. And when we take samples of those, we can find that sure enough they are made by bacteria that make their living off a chemical transformation of minerals that contain the element manganese. This is a pretty exotic way of making your living. They don't eat sandwiches for lunch like we do, they eat rock and minerals. And this is ubiquitous in these kinds of systems.

This is one of my colleagues crawling through some of that beautiful white material. In this material, besides its beauty, it also contains fossilized microorganisms. So we can see that the cave is preserving not only the live guys, that we can go in and look for now, but also the potential for preserving that material into the future to be tested. This is a potpourri of some of our little friends. The upper left hand is spots of goo and little colonies, and all of that is alive. There are probably two or three thousand strains of microbes in there, not a single one of which is very closely related to anything on the surface.

This is in a lava tube cave in Hawaii. The upper right hand side is what under some circumstances would just turn into an ordinary stalagmite dripping water, saturated with mineral, and yet in some circumstances it turns into nests of so-called cave pearls. Why? We think it's biology. We think it's the gooey biofilm that microbes produce that actually causes that to occur. In a mine in northern Minnesota, called the Soudan mine, there are bore holes very narrow that go down to much deeper levels. And when you sample those deeper levels, you still find microorganisms. They are even more exotic in making their living in a totally non-oxygen environment.

This is a salty, briny iron mush that they're living in. And you can see little bubbles of their activity coming up from below. In that same mine, on a March afternoon in 1962, the miners were told that the mine closed, and they threw down all their stuff and left in disgust. 50 years later, what we find are these structures that you can see, this tower of dark material, actually growing on one of those miner's jackets that had been discarded on that day. And this is entirely composed of iron and manganese-utilizing microorganisms and the minerals that they excrete. If you go to southeast Alaska and are lucky enough to be able to find one of the caves that exist there in the Tongass National Forest, and you take a sample of some of the material there and you bring it back to the laboratory and look at it with a scanning electron microscope, you will see this beautiful forest of crystals. All of those filamentous things that you see weaving through them are microbes, and the microbes are facilitating the creation of these beautiful structures.

Here, these pool, out of which these fluffy foof balls, or poof balls we call them. This is the Poof Ball Sea. And this is a system that is always right around or below freezing. So you can see that the temperature range within which we can operate is really great. This system is in Ukraine. This is one of the largest gypsum caves, in the rock type gypsum, in the world. It's between 90 and 100 kilometers of passage, so it's a very big system. And it's covered by these screaming red towers that look sort of like stalagmites. And the color is indeed as brilliant, as you can see from the knife that's in the picture. And when we look at those with an electron microscope, we see this is not just mineral, that it is composed of these tulip-shaped microorganisms all glued together with iron compounds. We don't know who those are.

Even something like granite, and this shows a granite cave in northern Spain with colleagues from Spain and Portugal and Brazil. Just looks like an ordinary granite surface. But actually the granite itself is sort of a yellow color, and that gray color that you're seeing is really composed of these little guys. So fluffy strings of bacteria are making their living on the inside of this granite cave. And they are producing beautiful little silica-containing speleothems, or decorations as they're called. Tiny little stalactites and stalagmites. And they are doing that because by their very life processes they're helping to dissolve that granite. So individually they're very tiny, but in the aggregate they're incredibly powerful. Even in ice, which is particularly important when we come to think about icy bodies in our own solar system and the potential presence of life in those systems.

This is Aaron Curtis, one of our graduate students at New Mexico Tech, who's doing his dissertation work on the ice caves around the volcano Mount Erebus in Antarctica. And not only are these magnificent caves with beautiful decorations in them just like you would find in a limestone cave perhaps, but there are also life forms in those ices. Here's one that looks like a twisted candy cane. So there is nowhere that is bug free. No matter what you hear on TV about how you should live a germ-free life, you should not believe that.

I wanted to give you a glimpse of a mystery that we are pursuing and have been pursuing for about 15 years. And you can see some of the macroscopic evidences of it in this beautiful little cave decoration here. This is a copper mineral called chrysocolla, and it is a beautiful blue color. And when we first saw these we were entranced and thought, “Gee, they seem to be gooey,” and they were gooey. And we took samples of them and lo and behold they had many microorganisms in them. Since this initial effort, we found them in many different caves around the world. And they often contain structures that look like this. These look like empty mesh stockings, right? But we don't know what they are. We don't know what kind of life form they are. They all have the same pattern, although there are variations. And now we've found them in probably about 50 or 60 different caves around the world in all different kinds of chemistries, all different kinds of temperatures. All different circumstances. Some are shallow, some are deep. We don't know who these are. They're not fungi, they're not amoebas, they're not bacteria. We don't know. So 15 years of pursuing what I think of as the wild boojum right here on this planet, even with all of the science that we have at our disposal, and we still have aliens right here underneath our feet.

I want to end with this spectacular image by a wonderful cave photographer, Carsten Peter. This is the Naica system in Chihuahua in Mexico. National Geographic has done a wonderful article on that in 2008. There have been two National Geographic television specials that we've been privileged to participate in. And yes, those crystals are that big. And the reason that we're in these little orange suits is not to keep us warm as you might think, but to actually keep us cool enough to work in there. So are essentially in suits packed in ice in order to keep us from dying from the heat in there. The heat ranges from about 105 degrees to perhaps well over 140 degrees Fahrenheit. And this is just not survivable for humans. And yet this entire system has microbes everywhere. It has them in the walls, on that orange material. And particularly interesting to us, it has them in little tiny fluid pockets within the giant crystals. And because the crystal growth rate has been measured and also age dated, we know that the samples that we were able to take in some of those crystals are at a time depth of between about 10 and perhaps about 50,000 years. So we have been able to go into the crystals and use these little pockets of time capsules. And not only were we able to find DNA and organic remains of microorganisms, but we were able to actually bring a lot of them into culture alive. So we're very excited about this because this shows that microorganisms can tolerate significant periods of time, geologically significant periods of time, in a state of relative inactivity, and yet still remain viable, still remain life-containing, and still able to be brought back to life so to speak once they get released from these materials.

So our own mini solar system underneath our feet is acting as practice really as we try to do what my colleagues have suggested. And that is take our knowledge, take our science, take our melding of the discipline of science with the magic of exploration and the beauties of what we see and what we experience and combine those together in order to advance our knowledge of the universe. So we are right on the cusp of this kind of exploration. And the work that I and my colleagues do will hopefully help to give us models for how organisms can make their living in this amazing array of planets that we have in our solar system and this amazing array of planets that we apparently have in our galaxy and our universe. Thank you.