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WORK TITLE: Deep Life
WORK NOTES:
PSEUDONYM(S):
BIRTHDATE: 1955
WEBSITE: https://onstott.princeton.edu/
CITY:
STATE: NJ
COUNTRY:
NATIONALITY:
https://www.princeton.edu/geosciences/people/display_person.xml?netid=tullis * https://onstott.princeton.edu/about * https://www.princeton.edu/geosciences/people/data/t/tullis/CV.pdf * https://www.coursera.org/learn/life-on-other-planets/lecture/LQvBc/interview-with-tullis-onstott * http://discovermagazine.com/2012/jul-aug/06-tullis-onstott-2-miles-down-microbes-live-radiation
RESEARCHER NOTES:
PERSONAL
Male.
EDUCATION:California Institute of Technology, B.S., 1976; Princeton University, M.A., 1978; Princeton University, Ph.D., 1980.
ADDRESS
CAREER
Academic and geoscientist. Princeton University, Princeton, NJ, research associate, 1983-85, assistant professor, 1985-91, associate professor, 1991-2001, professor, 2001–. Has served on numerous government commissions and scientific advisory boards.
AWARDS:Presidential Young Investigator Award, 1985-89; Jubilee Medal, Geological Society of South Africa, 1988; Award for Meritorious Research in Subsurface Microbiology, U.S. Department of Energy, 1995; Award for Meritorious Research in NABIR Program, U.S. Department of Energy, 1998; Appreciation Award for Research Excellence, Office of Science, U.S. Department of Energy, 2002; named among the “100 Most Influential People in the World,” Time, 2007.
WRITINGS
Contributor to academic journals, including Geomicrobiology Journal, Applied Geochemistry, Science, Astrobiology, and Geobiology.
SIDELIGHTS
Tullis C. Onstott is an academic and geoscientist. He works largely in the fields of geomicrobiology, geobiology, and astrobiology as a professor at Princeton University, where he has been on staff since 1983. Onstott has participated in workshops and research teams with the National Aeronautics and Space Administration (NASA) and other scientific bodies and is the recipient of numerous awards for his scholarship.
In an interview on the Coursera Web site, Onstott talked with Lisa Kaltenegger about his research on life underground and the impetus behind looking for life so deep below the planet’s surface. He explained that one of the reasons “was that when we first started getting involved in looking for sub-surface life, it was pretty obvious to us that we were seeing evidence that life down there was existing without any interaction at all from the surface photosphere. And if that indeed could occur on the planet Earth, then such circumstances could exist on a planet such as Mars.” Onstott continued, explaining that “in the case of Mars, at one time the surface was habitable. Therefore, the subsurface would have been habitable. Now the surface is really quite inhospitable … to terrestrial life forms. But deep beneath the surface of Mars, communities could still exist. And the reason why we started working in the deep environments in South Africa was to find out in these really old rocks that are buried miles underground, whether or not there [were] still signs of life down there that had been basically living in that environment for millions of years.”
In the same interview, Onstott also discussed energy, which is one of the big questions surrounding the possibility of life so far beneath the planet’s surface. He said: “So the question is … what feeds the microbial communities, and even multicellular organisms that we’ve been finding down there? And what you need is some form of chemical energy. And even [if] in some cases … it’s related to radiation. So what we discovered in South Africa was that the energy source was radiation. Just the decay of radioactive elements, naturally occurring in rocks interacting with water. And what this does is it creates essentially a rechargeable chemical battery for bacteria.”
Onstott published Deep Life: The Hunt for the Hidden Biology of Earth, Mars, and Beyond in 2017. In the account, Onstott examines the subterranean life forms on Earth in areas which until recently were thought to be inhospitable to life. Countering the notion that all living organisms need the sun to survive, Onstott uses this principle to theorize on various forms of existence of extraterrestrial life.
A contributor to Publishers Weekly said that “Onstott’s writing can be jargon heavy, but he so beautifully conveys his excitement that” all levels of readers “will find it a worthwhile read.” In a review in Times Higher Education, Lewis Dartnell noted that “at times, Onstott’s descriptions are as beautifully evocative as those in the best novels.” However, Dartnell countered that “for me, these few sparkling nuggets end up lost in the book’s surrounding bedrock, a densely detailed and dry chronological account of mines visited, meetings attended and other researchers encountered.” Nevertheless, Dartnell conceded that the book “offers great insights for science historians.”
BIOCRIT
PERIODICALS
Discover, July 1, 2012, Valerie Ross, “Tullis Onstott Went Two Miles Down & Found Microbes That Live on Radiation.”
Publishers Weekly, September 5, 2016, review of Deep Life: The Hunt for the Hidden Biology of Earth, Mars, and Beyond, p. 67.
ONLINE
Coursera, https://www.coursera.org/ (June 11, 2017), David Spergel, “Lecture 79—Interview with Tullis Onstott.”
Princeton University Web site, https://www.princeton.edu/ (June 11, 2017), author profile.
Times Higher Education (London, England), https://www.timeshighereducation.com/ (January 26, 2017), Lewis Dartnell, review of Deep Life.*
Tullis C. Onstott A. PROFESSIONAL PREPARATION California Institute of Technology, Geophysics, B.S., 1976 Princeton University, Geology, M.A., 1978 Princeton University, Geology, Ph.D., 1980 Princeton University/University of Toronto, 40Ar/39Ar geochronology, 1980-1983 B. APPOINTMENTS Full Professor, Princeton University, 2001-present Associate Professor, Princeton University, 1991-2001 Assistant Professor, Princeton University, 1985-1991 Research associate, Princeton University, 1983-1985 Research Assistant at U.S.G.S. Flagstaff, Arizona, 1974-1976 C. PUBLICATIONS C.1 Five related Publications: Dylan Chivian, Eric J. Alm, Eoin L. Brodie, David E. Culley, Paramvir S. Dehal, Todd Z. DeSantis, Thomas M. Gihring, Alla Lapidus, Li-Hung Lin, Stephen R. Lowry, Duane P. Moser, Paul Richardson, Gordon Southam, Greg Wanger, Lisa M. Pratt, Gary L. Andersen, Terry C. Hazen, Fred J. Brockman, Adam P. Arkin, and Tullis C. Onstott. Environmental genomics reveals a single species ecosystem deep within the Earth. Science 322:275-278, 2008. Mac Lean, L.C.W., Pray, T.J., Onstott, T.C. and Southam, G. High-resolution structural and chemical studies of framboidal pyrite formed within a bacterial biofilm. Geobiology, 6:471-480, 2008. Wanger, G., Onstott, T.C. and Southam, G. Stars of the terrestrial deep subsurface: A novel ‘star-shaped’ bacterial morphotype from a South African platinum mine Geobiology 6:325–330, 2008. Sherwood Lollar, B., Voglesonger, K., Lin, L.-H., Lacrampe-Couloume, G., Telling, J., Abrajano, T.A., Onstott, T.C. and Pratt, L.M. Hydrogeologic controls on episodic H2 release from Precambrian fractured rocks - Energy for deep subsurface life on Earth and Mars. Astrobiology Journal 7:971-986, 2007. Mac Lean, L.C.W., Pray, T.J., Onstott, T.C. and Southam, G. Mineralogical, Chemical and Biological Characterization of an Anaerobic Biofilm Collected from a Borehole in a Deep Gold Mine in South Africa. Geomicrobiology Journal 24:491–504, 2007. C.2 Five other publications: M. Elwood Madden, S. Ulrich, T.C. Onstott, and T. Phelps, Salinity-induced hydrate dissociation: a mechanism for recent methane release on Mars. Geophys. Research Letters 34, L11202, doi:10.1029/2006GL029156, 2007. Mailloux, Brian J., Devlin, S.,Fuller, M. E., Onstott, T. C., DeFlaun, M. F., Choi, K-H,Green-Blum, M., Swift, D. J. P., McCarthy, J. and Dong, H., The Limited Role of Aquifer Heterogeneity on Metal Reduction in an Atlantic Coastal Plain Determined by Push-Pull Tests. Appl. Geochem. 22:974-995, 2007. Onstott, T. C., Lin, L.-H., Davidson, M., Mislowack, B., Borcsik, M., Hall, J., Slater, G., Ward, J., Sherwood Lollar, B., Lippmann-Pipke, J., Boice, E., Pratt, L. M., Pfiffner, S. M., Moser, D. P., Gihring, T. M., Kieft, T., Phelps, T. J., van Heerden, E., Litthaur, D., DeFlaun, M., Rothmel, R., Wanger, G. and Southam, G. The origin and age of biogeochemical trends in deep fracture water of the Witwatersrand Basin, South Africa. Geomicrobiology Journal 23:369-414, 2006.
Lin, L.H., Wang, P-L, Rumble, D., Lippmann-Pipke, J., Boice, E., Pratt, L. M., Sherwood Lollar, B., Brodie, Eoin, Hazen, T., Andersen, G., DeSantis, T., Moser, D. P., Kershaw, D. and Onstott, T. C. Long term biosustainability in a high energy, low diversity crustal biome. Science 314:479-482, 2006. Onstott, T. C., McGown, D., Kessler, J., Sherwood Lollar, B., Lehmann, K. K. and Clifford, S. Martian CH4: sources, flux and detection. Astrobiology 6:377-395, 2006. D: OTHER PROFESSIONAL EXPERIENCES U.S. representative to IGCP 108/144 "Correlation of West Africa and Eastern Brazil", 1980-1984. Chairman, GSA Special Symposium on"Radiometric Calibration of thermal histories of rocks" GSA Nat. Mtg., 1985. Chairman of U.S. working group for IGCP 204 "Precambrian Geology of the Amazonas Craton", 1987-1988. Editor, Special Issue of Precamb. Res.,42, 1988. Associate editor for Precambrian Research, 1988-1994. Editor, Special Issue of Precamb. Res., "Precambrian Paleomagnetism, Paleogeography and Paleoclimates, 1994. Co-Chairman of Deep Microbiology Working Group, Subsurface Science Program, U.S. Dept. of Energy, 1994-1996. Co-Chairman of Special Session on Subsurface Microbial Processes, Fall Meeting of American Geophysical Union, 1996. Member of Review Panel for Environmental Management Science Program, U.S. Dept. of Energy, 1996. Program Committee Member for 1997 SPIE Conference for Investigation of Extraterrestrial Microorganisms. Participant of NASA Workshop on Mars Drilling, NASA Ames, Dec. 1996 Participant of NASA Workshop on Mars Sample Return, NASA Ames, June 1997 Member of Athena Proposal Team in charge of Planetary Protection Issues, 06/97 to 04/98 Participant of NASA Workshop on Deep Drilling Mars Mission, Los Alamos,May, 1998. Member of Review Panel for LExEn Program, NSF, May 2000. Organized Workshop on Biogeochemical Processes at Lead, South Dakota as part of Underground Laboratory Conference, Jan. 2000. Participated in three BEESA REU workshops for South African and American minorities from 2001 to 2003. Presenter at NASA Workshop on Deep Drilling Mars Mission, NASA Ames, Feb., 2008. Co-Chairman of Special Session on Underground Laboratories, Fall Meeting of American Geophysical Union, 2008. E: AWARDS AND FELLOWSHIPS Presidential Young Investigator Award, 1985-1989. Jubilee Medal, Geological Society of South Africa, 1988. Award for Meritorious Research in Subsurface Microbiology, U.S. Dept. of Energy,1995. Award for Meritorious Research in NABIR Program, U.S. Dept. of Energy,1998. Appreciation Award for Research Excellence Office of Science, U.S. Dept. of Energy, 2002. TIME100 Most Influential People in the World, 2007. F: SYNERGISTIC ACTIVITIES (up to 5 recent examples) I was a member of S1 DUSEL and coauthor of Deep Science report, 2007, which outlined the scientific impact of an underground lab to the non-scientific community. I participated in a public forum on life in the universe, hosted by the NASA Astrobiology Institute and held in St. Clara in April, 2008. I was the author of the Earth Lab report to NSF, 2004, which provided for the first time a description of the type of science that could be performed within an underground laboratory. I was one of three U.S. teaching Faculty for BEESA REU in South Africa, 2001-2003, which focused on under-represented undergraduates in the U.S.A. and South Africa.
I have given numerous lectures in K-12 institutions in the Princeton region including teacher training colloquiums and summer undergraduate workshops at Princeton University. G. COLLABORATORS AND OTHER AFFILIATIONS (i) Collaborators: Alm, Eric J. (M.I.T.) ; Andersen, Gary L. (LBNL); Arkin,Adam Paul (Univ. California, Berkeley); Boice, E. (Exxon Mobil Research and Engineering); Brockman, Fred J. (PNNL); Brodie, Eoin L. (LBNL); Chivian, Dylan (LBNL); Choi, K-H (Old Dominion Univ.); Clifford, S. (LPI); Culley, D.E. (PNNL); DeFlaun, M.F. (Geosyntec Inc.); Dehal, Paramvir S. (LBNL); DeSantis, Todd Z. (LBNL); Devlin, Sarah(Cornell Univ.); Dong, H. (Miami Univ.); Fuller, Mark (Shaw Environmental); Gihring, Thomas M. (Florida State Univ.); Green-Blum, Marie (Old Dominion Univ.); Hazen, T.C. (LBNL); Kershaw, D. (Anglogold Ashanti); Kieft, T. (NMIT); Lacrampe-Couloume, G. (Univ. of Toronto); Lapidus, Alla (JGI); Lehmann, Kevin (Univ. of Virginia); Lippmann-Pipke, J. (Institute of Interdisciplinary Isotope Research); Litthaur, Derek (Free State Univ.); Lowry, Stephen R. (JGI); Mac Lean, L.C.W. (Univ. of Western Ontario); Madden, Megan Elwood, (ORNL); McCarthy, J. (Univ. of Tennessee, Knoxville); Pfiffner, S. (Univ. of Tennessee, Knoxville); Phelps, Tommy Joe (ORNL); Pratt, Lisa M. (Indiana Univ.); Reches, Zeches (Univ. of Oklahoma); Richardson, Paul (JGI); Rothmel, Randi (Shaw Environmental); Rumble, Donald (Carnegie Institute); Sherwood-Lollar, Barbara, (Univ. of Toronto); Slater, G. (McMaster Univ.); Southam, Gordon (Univ. of Western Ontario); Swift, Donald, (Old Dominion Univ.); Telling, John (Univ. of Toronto); Ulrich, Sarah (ORNL); van Heerden, Esta (Free State Univ.); Voglesonger, K. (Univ. of Toronto); Wang, P-L (NTU); Wanger, Greg (Craig Venter Institute) (ii) Graduate and Post-doctoral advisors: Robert H. Hargraves (died 2004), Ph.D. Advisor D. York, (died 2007) Postdoctoral Advisor (iii) Thesis advisor and post-graduate scholar sponsor: Cohen, Harvey (unknown); Davidson, Cameron (University of Alaska, Fairbanks); Davidson, Mark (Geosyntec Inc.); Hall, James (Exxon Mobil Research and Engineering); Janek, Marion (unknown); Kessler, John (Texas A&M University); Lee, James (Queens University); Lemper, Chris (unknown); Lin, Lihung (National Taiwan University); Lo, Ching-Hua (National Taiwan University); Mailloux, Brian (Barnard College); McGown, Dan (Dept of Defense); Mislowack, Bianca (Exxon Mobil Research & Engr.); Moser, Duane (Desert Research Institute); Phillips, David (Australia National University); Thompson, Dan(unknown); Tronick, Shannon. Princeton University); Tseng, H-Y (Exxon Mobil Research & Engr.); Wang, P. (unknown) Total number of graduate students advised is 16. Total number of postdoctoral scholars sponsored is 12.
GEOMICROBIOLOGY
TULLIS ONSTOTT, PROFESSOR OF GEOSCIENCES
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HOME ABOUT ME
ABOUT ME
Tullis OnstottTullis Onstott has been focusing his research for the last 23 years on subsurface microbial life. This research involves exploration of subsurface microbial ecosystems via mines, drilling, and new underground laboratories, and by quantifying their community structure, function, and activity. His group does this by analyzing metagenomes, metatranscriptomes and metaproteomes, performing stable isotope measurements, and combining geochemical measurements with thermodynamic models.
The principal focuses of his research projects are the activity and survival of bacteria and other microorganisms in the deep subsurface (> 0.5 km) of continents, in the shallow permafrost deposits in the polar region and in shallow aquifer sediments. Among the questions his research group address are: 1) How do subsurface microorganisms evolve and what role do subsurface viromes play in evolution? 2) What constrains the diversity and abundance of microorganisms? 3) What role does radiation play as an energy source for life? 4) What types of organic compounds are utilized by subsurface microorganisms and by what processes? 5) How does the methane and nitrogen cycles interact in the subsurface? 6) How will global climate warming impact the methane cycle in the Arctic and in Antarctica. 7) What controls the upper temperature limit of life? 8) How do microbial redox processes control the migration of arsenic in groundwater?
Currently, his group is involved in four field projects, the first situated in the deepest mine in North America and the second sited in the world’s deepest mines in South Africa, the third in the Siberian permafrost deposits and the fourth in shallow groundwater sites in the state of New Jersey. These projects seek to address fundamental scientific questions regarding bacteria/rock/environment interactions while at the same time developing applications of this information that will benefit mankind.
Home»July-August»Discover Interview: Tullis Onstott Went 2 Miles Down & Found Microbes That Live on Radiation
FROM THE JULY-AUGUST 2012 ISSUE
Discover Interview: Tullis Onstott Went 2 Miles Down & Found Microbes That Live on Radiation
Bacteria found in gold mines and frozen caves show the extreme flexibility of life, and hint at where else we might find it in the solar system.
By Valerie Ross|Tuesday, June 26, 2012
RELATED TAGS: UNUSUAL ORGANISMS, EXTRATERRESTRIAL LIFE, OCEAN, MARS, NEW SPECIES, EVOLUTION, ARCTIC & ANTARCTIC, ECOSYSTEMS, EARTH SCIENCE
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Onstott keeps a sealed workspace in his lab at high temperature and free of oxygen—just like home for the bacteria he studies.
Photo: Jess Dittmar
The first time Tullis Onstott ventured underground, he squeezed into an elevator with dozens of South African gold miners and descended a mile into a pit called Mponeng. His goal: Finding the bizarre, hardy microbes that survive in sweltering, inhospitable rock. A geologist by training, Onstott spent his early career studying the Earth’s crust—until he heard a talk in 1993 about colonies of bacteria living thousands of feet below the surface. Ever since, he has made dozens of deep expeditions, sometimes paying his own way, and discovered bacteria living more than two miles beneath the surface in 140-degree-Fahrenheit heat. By investigating microbes in these harsh environments, Onstott is gleaning clues about how life could have begun in Earth’s hot, chaotic early days—and about what it might look like on other worlds. Even his office is underground, in the basement of Princeton University’s geology building, where Onstott met with DISCOVER reporter Valerie Ross.
The first time you went underground to look for life, in 1996, you had no idea what to expect. What was that trip like?
The miners took me into the stopes, the tunnels where they mine gold, to sample the rocks. We were looking at an organic rock layer just millimeters thick that had lots of carbon, because we
figured somewhere with a lot of carbon was a good place to look for life. The stopes are a meter high and they tilt downward at a steep angle, so you go down them almost like a slide, passing from one tunnel to the next. I basically slipped into a rabbit hole and got this big chunk of rock. I put it in an autoclave bag [normally used for sterilizing equipment], stuffed it in my knapsack, and then I went down the stope further until I came out the bottom into another, deeper tunnel.
What did you do with the sample you collected?
We measured the rock’s radioactivity. The Geiger counter showed it was hot as a pistol, so we sealed it up in a steel canister and filled the canister with argon gas, which pushed out all the oxygen. Organisms that live deep down are not normally exposed to oxygen, and in fact it could be toxic to them. So we sealed the rock away until we could get it back into the lab. I checked this radioactive rock inside a steel thing as baggage on a plane. This was 1996. Airport security was not like it is today.
When you analyzed the sample back at your lab, did you find any life?
We found one bacterium species similar to one previously identified from a hot spring in New Mexico. But the surprise was that this particular species could do something the other hot spring organisms could not: reduce [i.e., transfer electrons to] iron, which is present in minerals that are abundant in the mine’s rocks, and uranium, part of soluble compounds found in water in the mine. That helped us understand how they got their energy.
Then you found still more perplexing discoveries in other South
African mines—for instance, microbes similar to those previously seen only at the bottom of the ocean.
That’s right. We went back to South Africa in 1998, this time to Driefontein Mine, located about 40 miles southwest of Johannesburg, and took water samples, which are easier to work with than rock and less likely to be contaminated. We started finding the same organisms that people were reporting from deep-sea hydrothermal vents [where hot, mineral-laden fluid flows through volcanic rock into the ocean from deep within the Earth]. We don’t know how the same organisms got to be in both places, because South African crust has not seen ocean water in two-and-a-half billion years. It’s very much a mystery. We published the data, and the National Science Foundation gave us more money to go back again in 2000.
What happened on your third deep excursion in South Africa?
The next time, we purchased a house in one of the villages near the gold mines and set up a semipermanent lab there. Over two years, a rotating team from my lab and six other institutions collected most of the samples that we’re still working on today. One thing we did was expand on our first find and look at more radioactive samples. We began developing an idea that radiation in the rock provides energy for microorganisms. Wherever we had radiation, we tended to see hydrogen gas forming. It made me realize that radiation should produce hydrogen by breaking water bonds. Hydrogen is the key component the bacteria need to make ATP, the molecule they use for energy.
One bacterium we found is entirely self-
sufficient, a one-species ecosystem. Such things aren’t supposed to exist.”
That’s amazing, since we usually think of radioactivity as deadly—but these organisms were actually living on radiation?
Well, not just radiation, but radiation, water, and rock were all that was needed to support life at depth. You don’t need light, food, or anything else from the surface. Plus, it’s a renewable energy source. It turns water into hydrogen and hydrogen peroxide, which helps make the metals that the organisms consume. It is like recharging an electric battery. The radiation keeps on recharging the battery for the bacteria that then do their thing. Those bacteria could then sustain other deep organisms. That finding was really important to NASA because you can imagine any body in the solar system that has liquid water beneath the surface—like Jupiter’s moon Europa, probably—will have energy for organisms as well.
Can we observe these organisms at work in the lab?
The rule of thumb is that when you get back to the lab, you can grow less than 0.1 percent of what actually exists down there. We tried all sorts of ways to grow them, gave them all sorts of nutrients we thought they might want, and we failed miserably.
Since you couldn’t grow the bacteria that you found deep down, how did you learn just how they functioned?
We looked at their DNA instead, which we filtered out of the water, to determine where these things fit in with other sorts of microbial life.
Organisms so far underground, reliant on so few resources, must live a pretty limited existence, right?
Since the population of cells down there is small, most people thought they would just barely be able to eke out a living, that they were organisms with very few capabilities. But it turns out that was totally wrong. We did a full analysis of Candidatus Desulforudis audaxviator, an organism we found again and again in different mines in South Africa at the greatest depths—never above 2 kilometers (1.2 miles)—that made up 99.9 percent of the DNA in some of our samples. This thing had everything. It could take nitrogen directly from its environment, something we did not expect subsurface organisms to do because it takes so much energy. But the real surprise was that it had genes for flagella, tails bacteria use to propel themselves, which basically means it could be swimming around in the environment. It had genes for gas vesicles, which means it can adjust its buoyancy in the environment. And it had genes for chemoreception, which tells us it’s sensing something. The genome is saying it’s a very adaptable organism, and it has the capability of moving around. The idea that organisms down there might be moving around and interacting with the environment—that was really surprising. The only tip-off from the genome that this is a subsurface organism is that it has no protection against oxygen. As soon as it hits air, it’s dead.
And does that microbe interact with other species down deep?
Candidatus Desulforudis audaxviator is entirely self-sufficient. It has its energy source, radiation. It contains everything it needs to exist, and it requires nothing from another organism. The fact that we’ve found it almost by itself tells us that it’s a one-species ecosystem. Such things aren’t supposed to exist. We thought all organisms depended on others, but this one doesn’t. We’ve found a whole new way to live.
In addition to bacteria you also discovered more complex, multicellular organisms living 1.5 kilometers down—almost a mile underground. What are they, and how did you find them?
In 2006 I was contacted by Gaetan Borgonie, a Belgian scientist who had found microscopic roundworms, or nematodes, in caves in Central America. After he contacted me, I remembered seeing worms in biofilm, a goop made up of bacteria, in a mine in South Africa, too. So we went down together into the mines in South Africa to collect samples of biofilms. It turned out that the biofilms in the mines were just loaded with them. This nematode has about 1,000 cells, so it’s not exactly a big guy, but still—I never would have expected to find it so deep.
The deepest organisms you have found so far are from 3.8 kilometers
(2.4 miles) underground—the farthest that it’s been possible to explore until now. How much deeper might life go?
At Mponeng mine, a company is now drilling a tunnel to explore for gold five-and-a-half kilometers down. Gold prices are so high that for them, it’s economically feasible. For us, we think, “Yay!” The deeper, the hotter, the better. Down that far, it’ll be 90 degrees centigrade, about 195°F. That’s almost boiling. It’s a significant increase in depth, and we’re excited to see what the next several years will turn up.
What will going that deep into the planet tell us about life and evolution up here on the surface?
We’re trying to see what the base of the biosphere, of all life on Earth, looks like. If DNA organisms exist down that far and at such high temperatures, we want to find them, and if they don’t, we want to understand why. And if there are no DNA organisms, are there other types of organisms that might occur there in very small concentrations? There may exist a shadow biology—very, very primitive organisms that may have come into existence very early on our planet but were completely replaced by DNA organisms everywhere else.
So far you’ve talked only about hot environments, but what about the other extreme? Many of the places elsewhere in the solar system where we’re looking for life, like Mars, are intensely cold. Have you explored any analogous low-temperature environments on Earth?
Mars has this very thick cryosphere, or permanently frozen rock layer, on its surface. So we went to a gold mine deep beneath the permafrost in the high Arctic, in the Nunavut territory in Canada. The mine has a helical tunnel that goes a kilometer and a half down. All this warm air comes up from below, and as soon as it hits the permafrost layer, where the ground is permanently frozen, all the moisture in the air crystallizes and you get huge snowflakes, a couple of feet wide. You get ice stalactites and ice stalagmites all over. It looks like Superman’s sanctuary. It’s easy to imagine there might be something like this on Mars as well. I had an epiphany within these ice caves: This is the kind of environment you’d want to explore if you ever went to Mars; send your rover inside the caves and have a look around. There’s moisture there. There’s plenty of room for life in these environments. Unfortunately, we never really had a chance to explore and look for life in those caves before that mine shut down.
Could we pick out signs of microbial life on Mars even before we go digging around in caves there?
On parts of Mars, there’s methane gas that may be seasonal. It seems to appear and then go away. That means something unusual is happening: There has to be something that makes the methane and something that consumes it. The question is, are life-forms making and consuming the methane? If life is generating and consuming that methane, its chemical signature will change because of those biological processes. So as a project with NASA, we’re developing an instrument that we hope will fly to Mars and measure the composition of the methane gas. If we find that it is going through a seasonal cycle and its composition is changing, that’s a very good indication that there’s something alive on Mars. But whatever that something is, it’s going to be something quite different from anything we’ve seen on Earth because the surface conditions on Mars are pretty inhospitable to life as we know it.
You’ve looked at other extremely cold environments to learn more about life here on Earth, too. What was that like?
We’ve gone up to Axel Heiberg Island, a Canadian island high in the Arctic Ocean, to do some work there at the McGill Arctic Research Station, a.k.a. Mars. It’s one of the largest uninhabited islands in the world, and very beautiful. It has enormous mountain glaciers, almost like a little Swiss Alps, so it’s a nice change from the mines. We went up there to study microbes living in the permafrost that have been frozen for millennia.
The Arctic regions where those microbes live are warming rapidly. What impact might that have on the Earth?
There’s a concern that those microorganisms will all of a sudden kick on and start chewing up organic matter, making carbon dioxide and methane. That could cause a runaway greenhouse effect in the later part of the century. Our mission is to try and understand whether that will happen. We collected 40 ice cores from the island. We’re gradually thawing them to study which microorganisms are doing what, and which gases are being released and how quickly. Then we’re comparing this to field measurements that we can make in the Arctic, to see if the environment seems to be doing the same things as the permafrost in the lab. A lot of groups are doing similar studies across the Arctic. We don’t know the answer yet, but what we all find should further our understanding of what to expect over the next 100 years.
Has studying these various kinds of extreme, deep-dwelling microbes changed your thinking about what’s necessary for life?
The more I learn, the more it seems that the requirements for life are pretty minimal. The niches that life can occupy never cease to amaze me. A place may look terrible to us, but to something else, that’s their Eden.
OTHER SUBTERRANEAN HABITATS
While Onstott searches for microbes in gold mines and permafrost, other researchers are seeking out life in other deep locations. Their results are filling the picture of Earth’s buried ecosystem.v. r.
1 Around Hydrothermal Vents The scalding hot, sulfur-laden waters of hydrothermal vents, where ocean water heated by magma reemerges through cracks in the seafloor, are teeming with microscopic life. These bacteria support complex ecosystems in dark, otherwise sparsely populated ocean depths. Oxford zoologist Alex Rogers and his team explored the life around a 720°F vent off the East Scotia Ridge near Antarctica (shown here). In January they reported a host of unusual animals living near the vent, including a seven-armed sea star, a “ghostly white” octopus, and a new species of yeti crab, its underside covered in hairs.
2 Under the Ocean Floor Several teams are currently hunting for life beneath the seabed. Earlier this year, geomicrobiologist Katrina Edwards of the University of Southern California and her colleagues drilled into the crust of the Atlantic Ocean and installed small subsurface observatories to monitor microbial life. In 2010 scientists from Oregon State and other institutions drilled into the gabbroic layer—the deepest layer of the oceanic crust, close to the hot, mineral-rich mantle—to find a host of bacterial species capable of gobbling up hydrocarbons from an unknown source.
3 In the Deepest Caves The world’s deepest known cave, Krubera-Voronja in the Republic of Georgia, extends down a mile and a quarter. Biologist Ana Sofia Reboleira of the University of Aveiro in Portugal, who has been exploring caves since she was a teenager, recently searched Krubera-Voronja for the rare, small organisms that populate it—a cold business, since temperatures in the pitch-black depths hover just above freezing. This year, she and her team reported four new species of eyeless, wingless insects at various depths, ranging from 60 meters to almost 2,000 meters (more than a mile), near the cave’s bottom.
MAPPING DEEP LIFE WITH DNA
Onstott calls his trips into the gold mines “underground safaris,” but finding new species in the depths of the Earth is a far cry from spotting them on the savannah. The only species Onstott has observed in action are nematode worms; he could see them squirming under a microscope, and took detailed electron microscopy images of their hundredth-of-an-inch-long bodies. He also found cells of D. audaxviator, a bacterium that made up 99.9% of the organisms he recovered from one of the filters used to extract water from rock fractures deep in the mines. Onstott imaged what he could of those cells with a transmission electron microscope. But he has never been able to see any bacteria moving around, or grow them in the lab. Instead, the vast majority of what he studies is DNA traces. D. audaxviator provided enough genetic material to yield that species’ whole genome, allowing Onstott to ascertain that the organism belonged to a self-sustaining ecosystem and could sense its environment. In other cases he has found bits of free-floating genetic material from other species—just enough, he says, to show that each one exists deep in the mines and is largely specific to the fracture in which it was found. “As you move from one fracture to the next,” Onstott notes, “the microbial species change.”
Lecture 79 - Interview with Tullis Onstott
In this lesson
Interview with Tullis Onstott
Interview with Lisa Kaltenegger
Imagining Other Earths
Princeton University
David Spergel
Princeton University
About this course
Are we alone? This course introduces core concepts in astronomy, biology, and planetary science that enable the student to speculate scientifically about this profound question and invent their own solar systems.
Lecture transcript
Hi. Welcome today we have the pleasure of talking with T.C. Onstott from the geology department here at Princeton and he studies a really fascinating part of the planet. He goes deep underground to find life. That's right. Worst place you'd want to go to find life . So Why do you start deep underground to find life? Well for two reasons. One was that when we first started getting involved in looking for sub-surface life, if was pretty obvious to us that we were seeing evidence that life down there was existing without any interaction at all from the surface photosphere. And if that indeed could occur on the planet Earth, then such circumstances could exist on a planet such as Mars. In the case of Mars, at one time the surface was habitable. Therefore, the subsurface would have been habitable. Now the surface is, really quite inhospitable. To a certain extent, to terrestrial life forms. But deep beneath the surface of Mars, communities could still exist. And the reason why we started working in the deep environments in South Africa was to find out in these really old rocks that are buried miles underground, whether or not there was still signs of life down there that had been basically living in that environment for millions of years. So one of the things I learned in school which is not true. A lot of those >> There's a lot of those things. That's right, that the sun is the source of life, right. All life depends on solar energy. That you know, that is certainly true if surface plants, they get their energy from the sun we eat the plants. That's right. Yeah, when you go down in these mines, the energy source isn't the sun. That's right. And so the question is what feeds, what feeds the microbial communities, and even multicellular organisms that we've been finding down there? And what you need is some form of chemical energy. And even in some case even if it's related to radiation. So what we discovered in South Africa was that the energy source was radiation. Just the decay of radioactive elements, naturally occurring in rocks interacting with water. And what this does is it creates essentially a rechargeable chemical battery for bacteria. It splits the water into hydrogen and oxygen, which are two very, very potent electron donors, electron acceptors when they come back together again, they provide a lot of energy that can be utilized by microorganisms. And they use it up, but natural radioactive decay regenerates it again. So, you need to have this sort of continual source in order to sustain life over the long haul, alright? And the other sources of energy kind of like this are the minerals themselves, because most rocks that form under high temperatures on the Earth, or Mars for example, contain transition metals like iron, manganese, that are in their reduced form and sulfur in a sulfide form. So they release potent electron donors. And so they can also do two things. They can, they can split the water and makes some hydrogen. But they can also combine with CO2 and actually form organic matter in C2 as well. And we discover that in South Africa as well. We discovered that in, in our deep environments, there was hydrocarbons being formed down there, that had nothing at all to do with you know, the oil deposits that you'd normally find, closer to the surface that you know could result to the death and maturation of organic matter, that had been formed by a photo-sphere. So this is truly what we call abiotic. Organic matter. You might even call it, you know, pre-biotic or abiogena. So when you talk about being deep down, how deep do you go and how do you get there? So, that's okay. So, you go down about three and a half to four kilometers, okay? And to get down, you have to take all your gear with you , your sampling gear, right? So you put on your backpack, and you get into the cages, same cages that are used by the miners. And these are often, these are gold mines? These are gold mines. Right. Because that's one of the things that motivates people to dig down there. Gold mines are the deepest mines of the planet. You know, definitely. There are platinum mines that also go down to pretty deep in. So, easy gold mines, they're in 3 billion year old rocks, too. And these rocks are very organic except for these compounds that I was talking about. So you cram into the cage with about 30 other miners. and the size of it, you know, a closet. And it drops. It literally drops. And it'll drop 1.8 kilometers. It doesn't go any deeper than that with the first hull because of the strength of the cables, it'll give out, you know? So once you're done at one point eight, you'd get off. You go to the next cage, and you drop again. And then after you get out of that, you go off and you drop a third time to get you down to your depth. So, you're down there. So, you've gone much further down. Yeah. In this elevator, than anyone who's ever that's ever gone up. This is exactly right. It's a really a weird feeling when you're walking around at a depth where, if you were drilling to that depth, from the surface, you'd have a 10 story high, you know, oil rig drilling down to this, and we're walking around at the depth where people are, you know, pumping oil out of the ground, and this is kind of what it looks like, you know? It's hot, it's obviously dark, and there's this very, very acrid smell in the air, almost like a burnt rock. And that's because of all the dynamiting that's going on, but also because of some of the weird gases that are coming out of these fractures that we sampled as well. And the water that comes out, you know it's like 70 degrees centigrade, it's so hot that it's scolding, so you have to wear gloves on your hands in order to collect the water samples in the first place. So how common do you think underground life is on Earth, in your sampling a few places? Well it's, so we do this estimate of the biomass, right? And we estimate that the living organic matter that's present beneath the surface of the planet is on the order of let say one tenth the amount of the entire surface biomass. Which, the surface biomass is primarily composed of the terrestrial plants matter. Mm-hm. That's really the bulk of the organic matter on our planet. And, and we're one tenth of that, which is pretty substantial. So one tenth of biomass is humans? >> There's a lot of us. That's right. And some of us are pretty massive. That's right. And you know, is there enough room down there? Well, actually it turns out there is enough room for that biomass. And what's really limiting is, you know, the energy. Mm-hm. That's available. And you might say, okay, well, what about the organic carbon and nitrogen, stuff like that. These organisms fix this stuff themselves. They'll take in, you know, such organic carbon, nitrogen gas and make amino acids out of it down there because there's enough energy they can actually do that. So where do they get the nitrogen gas? Is it in the rock? Then, that's So that's a good question. So, some of that nitrogen gas, okay, is in the fracture water itself. And has to represent either a source that's coming from the atmosphere or coming from, you know, essentially degassing nitrogen from the mantle. Mm-hm. Or from recycled ocean sediments that went under the crust. At some point, then gets cooked up or releases ammonia that comes up and then forms nitrogen gas and then works its way up into the crust. So, there's that sort of deep nitrogen cycle that's taking place there. So, one of the many fascinating implications of this is you can, the fact that life can persist and survive, and thrive in this environment. Mm-hm. Means you can imagine life, subsurface Mars, life on extra-solar planets. Right the one of the things we've talked about in the class is the notion of a habitable zone, that you need to be a certain distance from the sun, and at a certain temperature. That's right. But you could imagine taking the life forms you find, and putting them, you know? If by hand you transported them, and planted them if you like else where in the solar system. Mm-hm. There's a pretty wide range of environment where they might be able to survive. Yeah, is there a reason why any of the organisms that we find in a subsurface would not do very, very well in the subsurface of Mars. In fact, we performed experiments where we've taken organizations and subjected them to Martian environmental conditions. And even when you bury them with just a few centimeters of soil they actually do, they are able to survive under those circumstances for quite a while which was surprising. And when you go further out in the solar system, as you will undoubtedly do in this course, you also discover that there are other icy satellite. Mm-hm. That also have, because of tidal forces generating internal heat liquid environments, as well, which could also provide as you say, a sort of planetary habitable zones that exist at depth. The big question however, for us, in the end, is whether or not life could actually originate beneath the surface of a planet. Or does the essential steps that. Mm-hm. Eventually lead to the type of life we know requires interaction with with some type of solar energy in one wavelength or another. And that is the question that was driving our interest to go to South Africa as well. Because in that environment, we know that these rocks have been cooked up to very high temperatures and then cooled down. And now we're going in there. We're seeing there's forms of life in there but what we'd really like to see would be to find in the subsurface, a pocket of water that's been isolated from the surface for tens of millions of years. The subsurface version of Darwin's little ponds essentially. Mm-hm. And to see whether or not there are, other than these out caves, any other prebiotic ingredients that have formed through these interactions with sulphur, metals under different temperatures, with high hydrogen concentrations present. So underground you'll find not just single cell, but multicellular life forms? Yes, indeed and viruses as well. Do you think they have an independent origin from the multicellular life forms on the surface or is it the same, you know, was there one transition from single cell to multicell or did it happen, Both. At different times and different places? Oh, okay so those are two different questions. So, I think most of the things that we see in the subsurface came from the surface at one point in time. And we don't know exactly when that they and how long they've been down there. This is always the question that we get. But and there's obviously very complex relationships between the multicellular organisms. It's kind of like the multicellular organisms are feeding upon the singular cellular organisms. They obviously found a niche, God knows how they got down there to find it. And they're adapted to that environment as well. They can handle the hot temperatures, the low oxygen levels, and they sexually reproduce. So the question then becomes is whether or not you can form, there's times when you can form either through, let's say endosymbiotic events. Mm-hm. occurring, and we've seen this occur, in the evolutionary time scale. For at least two different cases, right? And those events, once they've occurred, they must have occurred more than once, right? It's just, sort a matter of what's they left behind that you can actually see. And I can see that in the subsurface you could get these kind of events occurring, as well. So, I could see, I imagine that evolutionary processes in the subsurface now are more complex than we had originally believed they were, say 10 years ago. And as for the transition of singular to multicellular organisms you're already, you're like way ahead of me David I I don't know I have to think about that one a little bit . That would be intriguing. because you do get obviously these very close associations, syntrophic relationships- Mm-hm. Between prokaryotes. And that's definitely taking place at the subservice. And it's just a question of whether or not these clusters of cells either become more coassembled into an entity that acts like a multi-cellular organism. Right. and, and that transition is not a big step to make you know? So it would be intriguing to see whether or not you can imagine that scenario taking place which would be great. Because maybe that's exactly what has happened on Mars if life does exist beneath the surface. What do you think are the prospects of finding life like this on Mars? Both prospects. How likely do you think it is and then- >> . How, how will you go find it? Sorry. Likelihood, I say yes. Very likely it exists there. It's one of the best places to stay on the surface of Mars. But the likelihood of actually detecting it, given current circumstances, it would require a man mission, for sure. I should say a human mission to Mars, one that would be dedicated to drilling quite deep. Because you can't, to get beneath the cryosphere, that ice saturated zone of Mars, unless we find some type of hot spot there. Right. We would have to drill several kilometers down, through icy rock. And I can tell you from personal experience that is not an easy thing to do. Ask the Russians about Lee Far Star and they'll tell you. So it would require a human mission. We had hope that the detection of methane in the atmosphere more. Right. And you'll learn more about that for sure. In this course. We actually started out by, the beginning of the class, by talking about methane. Oh excellent. Excellent. The first, and then came back to it a little bit in the discussion of Mars. Yep, that's great. That, if you find these discrete sources of methane on the planet. It could provide you with a place to go look and search for life, if they are there. And that's the best hope we have in terms of let's say robotic missions. So you're certainly capable of doing something like that. But we don't have robotic capabilities for drilling through three kilometers of icy rock. It's an ambitious thing also for the the first human settlements. Yeah that's true. There'd be good reason for them to do that. Right. I think that's probably doable. They all have a lot of time on their hands, they need something to do. Drilling down a couple of kilometers, getting nice fresh water. That would be okay. Yeah. Gas, methane gas maybe. I mean one notion for human exploration of Mars is we send people and eventually get them back,- Yes. But they would have a long time there. Yeah, that's right. And there would be established settlements, and send supplies and Yes. This would be among the things that they would be doing. Exactly. And it's a perfect plot for a science fiction movie, too. I can see it right now. So are you involved in the Mars 2020 discussions? So I was. I was on the 2020 science definition team and that was an interesting experience, that's for sure. I know there are, the intent of this mission, is to act as the first step for returning a sample from the Martian surface. Uh-huh So this rover is going to be designed with a very small drill let's hope. To go out to a site and drill a variety of samples. Hopefully samples that may also contain some kind of signature suggestive. Some ancient life form, cache those samples, and then several years later hopefully a second robotic mission would land close by. Send out a little fetch rover that would go over and pick up the cache wherever it was lying. Mm-hm. Bring it back and put it into little tiny rocket, you know, miniature rocket that we shall lift it up into orbit around Mars. And then, you know, be in orbit around Mars. Right. It will then rendezvous in dark with the yet another space craft as designed to receive. That cash sample. In a little, tiny enclosed sphere. And, that space craft will then return to Earth. And, this rather elaborate scenario will require three missions. It'll be quite expensive. And it's also designed in such a way that if the samples had any type of biological biota. I should say martian biota that are potentially alive, they would be entirely encapsulated. There wouldn't be any soft of carry over transfer from this surface of Mars to the planet Earth. Mm-hm. And as long as that little sphere arrives intact and is not breached, then we should be able to examine the samples. Well, thanks for having me. It was a pleasure. 356 00:18:55,700 --> 00:18:55,790
Tullis C. Onstott
Department/Program(s):
Geosciences
Position: Active Faculty
Title: Professor of Geosciences.
Area(s):
Geomicrobiology
Field: Astrobiology and Geobiology
Office: B79 Guyot Hall
Phone: 609-258-7678
Email: tullis@princeton.edu
Homepage: https://onstott.princeton.edu/
Deep Life: The Hunt for the Hidden Biology of Earth, Mars, and Beyond
Publishers Weekly. 263.36 (Sept. 5, 2016): p67.
Copyright: COPYRIGHT 2016 PWxyz, LLC
http://www.publishersweekly.com/
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Full Text:
Deep Life: The Hunt for the Hidden Biology of Earth, Mars, and Beyond
Tullis C. Onstott. Princeton Univ., $35 (496p) ISBN 978-0-691-09644-5
[ILLUSTRATION OMITTED]
"We must always be prepared to be surprised," writes Princeton geoscientist Onstott as he ventures into the world of "subterranauts," creatures that inhabit underground regions that were previously thought inhospitable to life. He exhaustively details some of the expeditions that are leading scientists to overturn the dogma that all life needs the sun. Chemolithoautotrophs, for example, do not; they create energy by splitting minerals. Such extremophiles offer clues to what extraterrestrial life might be like, so Onstott travels beneath Earth's hottest spots (Africa) and coldest spots (the Arctic) to learn more about them. He colorfully describes these almost primordial worlds: mines where one can find "mushrooms the size of hubcaps," an Arctic tunnel in which hangs "one ice chandelier after another," and caves that feature biofilms wafting across underground lakes in "massive rafts" or hanging off walls like a living Jackson Pollock painting. A colleague's discovery of a microscopic worm a mile below earth was "like finding Moby Dick swimming around in Lake Ontario"--a discovery with "enormous implications." Onstott himself found bacteria living on "radioactive water." Onstott's writing can be jargon heavy, but he so beautifully conveys his excitement that laypeople and scientists alike will find it a worthwhile read. Photos. (Nov.)
Deep Life: The Hunt for the Hidden Biology of Earth, Mars, and Beyond, by Tullis C. Onstott
A subterranaut burrows beneath ice and sand in search of hidden depths, writes Lewis Dartnell
January 26, 2017
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By Lewis Dartnell
Twitter: @lewis_dartnell
Texaco workers at Thorn Hill Farm
In 1864, the pioneering science fiction writer Jules Verne imagined in Journey to the Centre of the Earth a fantastic array of life deep underground, from forests of giant mushrooms to plesiosaurs splashing in subterranean seas. In recent decades, science has been catching up, providing the dawning realisation that the ground beneath our feet does indeed harbour a whole host of previously unimagined life. The crust of planet Earth is alive with hardy microorganisms, thriving in its dark, hot depths. And Tullis Onstott has been at the forefront of the exploration of its subterranean mysteries. If you had to compare him to an iconic figure, I don’t think that you’d go far wrong seeing him as a microbiologist Indiana Jones, clambering through dimly lit mining tunnels far below the surface, sampling tubes in hand. In Deep Life, he takes us with him on his adventures: 3.2 kilometres (2 miles) underground in South African gold mines, in an ancient seabed deep beneath the desert landscape of the American Southwest and below the frozen wastelands of the Arctic tundra. The stunning realisation he shares is that this deep, dark biosphere probably holds more living matter in it than all of the sunlit surface and oceanic ecosystems of the Earth.
Deep Life covers 25 years of Onstott’s illustrious career as a “subterranaut”, starting in 1986 and the very beginnings of the department of the environment’s subsurface science programme that coupled microbiologists with industrial mining operations, to 2009 and the discovery of “the worm from Hell” found living without oxygen a kilometre underground. Along the way, he addresses some of the deepest questions – if you’ll excuse the pun – in modern biology: just how far down could life survive? Might cells be living off radiation released by the surrounding rock? Could life itself have originated in the deep subsurface? And what does the incredible subterranean extent of terrestrial life tell us about the possibility of organisms on other planets and moons?
At times, Onstott’s descriptions are as beautifully evocative as those in the best novels. While exploring a tunnel half a kilometre underground, used to mine the potash laid down about a quarter of a billion years ago as an ancient sea evaporated, he recounts: “The salt was remarkably clear. We took the lights off our hard hats, placed them against the tunnel wall, and peered inside the salt bed to see the light reflecting off the three-dimensional relict textures of a Permian seafloor. I peered into the salt beds as I scanned my headlamp around as if I was scuba diving across the Permian seabed. Could it be that within this congealed seawater, halophiles [extremely salt-tolerant organisms] still breathed? Was ours the first light that their pigments had detected since they were buried alive 250 million years ago?”
But for me, these few sparkling nuggets end up lost in the book’s surrounding bedrock, a densely detailed and dry chronological account of mines visited, meetings attended and other researchers encountered. Many of the best popular science books are written by researchers in the forefront of the field and deliver an alluring narrative of the trials and tribulations of modern science and the thrill of discovery. But this requires a particular knack for storytelling and focusing on the interesting details for a lay audience and, for me, Deep Life doesn’t quite deliver on this potential. It offers great insights for science historians or students in the discipline, but not the heady adventure tale it could be for general readers.
Lewis Dartnell is professor of science communication, University of Westminster, and author of The Knowledge: How to Rebuild our World from Scratch (2014).