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November 30, 2009
November 26, 2009
Astrobiology Science News 26 November 2009
November 25, 2009
Astrobiology Science News 25 November 2009
- Origins of magnetite nanocrystals in Martian meteorite ALH84001, Geochimica et Cosmochimica Acta
- Tidal and Magnetic Interactions between a Hot Jupiter and its Host Star in the Magnetospheric Cavity of a Protoplanetary Disk, astro-ph
- Neutral particle release from Europa's surface, astro-ph
- The Mass of the Candidate Exoplanet Companion to HD136118 from Hubble Space Telescope Astrometry and High-Precision Radial Velocities, astro-ph
November 24, 2009
Astrobiology Science News 24 November 2009
- Variations on Debris Disks II. Icy Planet Formation as a Function of the Bulk Properties and Initial Sizes of Planetesimals, astro-ph
- Enhanced lithium depletion in Sun-like stars with orbiting planets, astro-ph
- Jupiter - friend or foe? III: the Oort cloud comets, astro-ph
- Mapping the Probability of Microlensing Detection of Extra-Solar Planets, astro-ph
November 23, 2009
Astrobiology Science News 23 November 2009
AbSciCon 2010 Call for Abstracts: Integrating Astrobiology Research
The NASA Astrobiology Institute (NAI) is organizing a session at AbSciCon 2010 on "Integrating Astrobiology Research Across and Beyond the Community." The concept for the session reflects one of astrobiology's defining characteristics and a core mission of NAI: bringing together researchers from many disciplines to develop and foster interdisciplinary collaborations in astrobiology research. Participation in this session is invited regardless of affiliation with the NAI. The goal is to develop and foster interdisciplinary collaborations across the astrobiology community, with other science communities not currently engaged in astrobiology research, and with other communities such as philosophy of science, ethics, anthropology, etc.
We invite you to submit an abstract for this session. Abstracts should describe an innovative interdisciplinary collaboration addressing astrobiology research or its societal implications. Presentations on collaborations that are underway, in formation, or contemplated/desired are all welcome. Please note that the abstract deadline is Dec. 3, 2009. For further information about AbSciCon 2010 and abstract submission, please see the following websites:
Meeting date and location: April 26-29, 2010, at the South Shore Harbor Resort and Conference Center in League City, Texas.
Conference website: http://www.lpi.usra.edu/meetings/abscicon2010
Abstract submission information: http://www.lpi.usra.edu/meetings/abscicon2010/abscicon2010.elecinstr.html
ABSTRACT DEADLINE: 5:00 p.m. (CST) Thursday, December 3, 2009
[Source: Carl B. Pilcher, Director NASA Astrobiology Institute]
November 22, 2009
Dr. Linda Billings Recieves Lifetime Achievement Award
Women in Aerospace recently awarded Dr. Linda Billings the Lifetime Achievement Award for more than 25 years of excellence in communicating with the public about the nation's space program. As a journalist, she has covered energy, environment, and labor relations as well as aerospace. As a researcher, she has worked on communication strategy, media analysis, and audience research for NASA's astrobiology, Mars exploration, and planetary protection programs. Her research has focused on the role that journalists play in constructing the cultural authority of scientists, the rhetorical strategies that scientists and journalists employ in communicating about science, and the rhetoric of space exploration.
Currently a research professor at the George Washington University School of Media and Public Affairs in Washington, D.C., she also does communication research for NASA's astrobiology program in the Science Mission Directorate. In addition, she advises NASA's Senior Scientist for Mars Exploration and Planetary Protection Officer on communications. Photographs from the WIA Awards ceremony can be viewed at: http://www.reflectionsorders.com [Source NASA Astrobiology]
Vatican Hosts Study Week on Astrobiology
This past week in Rome as part of the International Year of Astronomy, the Pontifical Academy of Sciences hosted a Study Week on Astrobiology, an interdisciplinary event during which "cloistered astrobiologists confronted each other's fields of research" and dialogued about the connections. The participants included many from the extended astrobiology community, including John Baross, David Charbonneau, Roger Summons, Andy Knoll, Chris Impey, Jonathan Lunine, Jill Tarter, Sara Seager, and Giovanna Tinetti.
"The questions of life's origins and of whether life exists elsewhere in the universe are very suitable and deserve serious consideration," said the Rev. Jose Gabriel Funes, an astronomer and director of the Vatican Observatory, in an Associated Press Interview. Funes, a Jesuit priest, also said that the possibility of alien life raises "many philosophical and theological implications" but added that the gathering was mainly focused on the scientific perspective and how different disciplines can be used to explore the issue. RadioVaticana reports.
Today, NAI Director Carl Pilcher and Vatican Observatory astronomer and Jesuit brother Guy Consolmagno continue the conversation with Anna Maria Tremonti, host of the Canadian Broadcasting Company's radio program The Current. Their discussion ranges from what it would mean to the Church if alien life were found, to whether or not science needs religion. [Source NASA Astrobiology]
Daniel Glavin Wins 2010 Nier Prize
Daniel Glavin has been selected by the international Meteoritical Society as the recipient of the 2010 Nier Prize. The prestigious Nier Prize is awarded to young scientists performing valuable research in fields related to meteoritics and planetary science.
Dr. Glavin was presented with the prize for his work on extraterrestrial organic chemistry. By examining carbonaceous meteorites, Glavin and his team have made important contributions toward understanding why life uses only left-handed versions of amino acids. It turns out that molecules delivered to Earth in meteorites may have played a role in life's eventual bias toward molecules of a specific orientation. The work was recently published in the Proceedings of the National Academy of Sciences. [Source NASA Astrobiology]
November 19, 2009
Astrobiology Science News 19 November 2009
- Constraints on Secondary Eclipse Probabilities of Long-Period Exoplanets from Orbital Elements, astro-ph
- Target selection for the SUNS and DEBRIS surveys for debris discs in the solar neighbourhood, astro-ph
- Transit timing analysis of CoRoT-1b, astro-ph
- A Photometric Transit Search for Planets around Cool Stars from the Italian Alps: Results from a Feasibility Study, astro-ph
November 18, 2009
Astrobiology Science News 18 November 2009
- Epsilon Indi Ba, Bb: a detailed study of the nearest known brown dwarfs, astro-ph
- The CRIRES Search for Planets Around the Lowest-Mass Stars. I. High-Precision Near-Infrared Radial Velocities with an Ammonia Gas Cell, astro-ph
- Atmospheric Circulation of Exoplanets, astro-ph
- Large prebiotic molecules in space: photo-physics of acetic acid and its isomers, astro-ph
- How Common are Extrasolar, Late Heavy Bombardments?, astro-ph
- Do we expect to find the Super-Earths close to the gas giants?, astro-ph
American Society for Gravitational and Space Biology Election Results
ASGSB (American Society for Gravitational and Space Biology) announces new executive director, and elects 2010-2011 president and new members to the board of Directors.
On November 7, 2009, the society elected the following new members to the Board of Directors, Kenneth M. Baldwin, University of California, Irvine; Jeanne L. Becker, NSBRI/Baylor College of Medicine; Cary Mitchell, Purdue University; Joseph S. Tash, University of Kansas Medical Center; and Jack J.W.A. Van Loon VU University Amsterdam, The Netherlands. Dr. Marshall Portfield from Purdue University was selected as the president-elect for 2010-2011.His term begins November 2011. Current ASGSB president, Dr. Terri Lomax from North Carolina State University also announced a new executive director, Ms. Cindy Martin-Brennan. Congratulations to all. [Source: ASGSB]
November 16, 2009
Astrobiology Science News 16 November 2009
- An Efficient Method for Modeling High Magnification Planetary Microlensing Events, astro-ph
- A Spitzer Census of Transitional Protoplanetary Disks with AU-Scale Inner Holes, astro-ph
- Masses and Orbital Constraints for the OGLE-2006-BLG-109Lb,c Jupiter/Saturn Analog Planetary System, astro-ph
- ThReT: A new survey for Extrasolar Planetary transits at Mt. Holomon, Greece, astro-ph
- Exoplanet Characterization and the Search for Life, astro-ph
Avatar: A Stunning New World That NASA Is Ignoring
Editor's note: "Avatar", a film by former NASA Advisory Committee member James Cameron, will debut across the planet on 18 December. Widely hailed as "ground breaking" the film may well push the boundaries of what can be portrayed on the big screen. The film centers around humans mining precious materials on a world in the Alpha Centauri star system - and the inevitable conflict that arises with the local (sentient) inhabitants. The film delves into a wide range of issues that intersect with what NASA's Astrobiology Institute and Exobiology Programs have looked into in one way or another.
Unparalleled simulations of an extrasolar planet with a whole new ecology - but it would seem that NASA is not really interested in this film.
NASA has made a variety of attempts to collaborate with Hollywood in the past to promote movies that have some resonance with what NASA does (or what people think it does). Recent examples include "Buzz Lightyear" and "Planet 51". Some of these collaborative efforts have resulted in substantial public interaction - often with people who would not normally stop to ponder what it is that NASA does or how it might relate to them. On the other hand, NASA has also engaged in a campaign to refute the utter stupidity contained in the recently released film "2012".
Given that NASA is not afraid to weigh in on both positive and negative (stupid) films, is NASA going to take advantage of this film's debut to engage the public on issues relevant to Astrobiology and life in the universe? So far, I am told that the answer is "no".
If NASA can spend taxpayers dollars to shoot down stupid movies and fly action figures and DVDs in space to promote a film, then you'd think that they'd also consider something focusing more on hard science. With regard to "Avatar", were NASA so inclined to do so, one outreach effort might include materials distributed in (online and in person) in coordination with the film that focus upon how topics of interest to both Astrobiologists - and the general public - are addressed in this movie.
- What alternate biochemistries/atmospheric compositions would be compatible with "life as we know it"?
- On a world with lighter gravity than Earth what modes of movement would be more probable?
- what is the state of the art in terms of understanding alternate genetic systems? Would they be similar to those utilized by terrestrial biota? Different? How?
- what are the ethics of altering an alien biosphere - including forward and back-contamination
- what is the habitability potential for terrestrial-class planets in orbit about a gas giant - in a trinary star system?
- what is the state of the art vis-a-vis human-machine interactions, augmented reality, exoskeletons, virtual reality, etc.?
- re bipedal mammals the only body form one would expect for extraterrestrial sentient beings?
So far NASA has told me that no outreach activities in connection with this film are being considered. If that ends up being what happens, then I think that NASA will have wasted a sterling opportunity to engage the public in a meaningful way - using a film that hundreds of millions of people will see - one that blends awe and wonderment of tomorrow with the things that are being done - by NASA - today.
November 12, 2009
Astrobiology Science News 12 November 2009
November 10, 2009
Astrobiology Teachers Academy
NAI's New York Center for Astrobiology held its first Teachers Academy at RPI on July 13-16, 2009. Nine high school science teachers from four local school districts collaborated with six NAI scientists to learn about topics in astrobiology. The participants represent disciplines across the sciences: biology, chemistry, earth science, forensic science, and physics. The goal of the Academy was to develop a learning module infused with astrobiology and aligned with New York State standards and NASA Astrobiology Science Goals. The teachers used science lectures, existing astrobiology curriculum materials, and consistent interaction with the scientists to develop their learning modules, which ranged in topic from the physiochemical limits to sustainable life, to colors of photosynthetic organisms on exoplanets, to nucleosynthesis of biologically-relevant elements. The teachers are implementing their modules in their classrooms this school year, and the Academy will be featured at the annual regional meeting of the Science Teachers Association of New York State in March, 2010. [Source: NAI Newsletter]
Teachers from Around the World Examine Life in Extreme Environments
This summer, sixteen teachers from around the world convened with NAI's team at Montana State University for a week-long class called "Examining Life in Extreme Environments: Insights into Early Earth and Beyond." Students in the course gained an understanding of the relation of extreme environments to early Earth, learned about the latest research conducted in these areas, and worked on how to teach and discuss these topics within their own classrooms.
Part of the class included a field trip to Yellowstone National Park in which the teachers sampled and characterized extreme environments. Joe Deluca, who teaches in the Netherlands, was amazed by Yellowstone and was most surprised by "how drastically and quickly the changes in microbe gradients were in the thermal features." Paula Wang, a teacher from Sidwell Friends School in Washington, D.C. called the class "fun, convenient, and practical."
The class was offered by MSU as part of the Master of Science in Science Education Program (MSSE) and is only one of the many MSSE courses that involve field work in Yellowstone and the surrounding areas. The course provided graduate credit in chemistry and/or biology for professional development purposes. This interdisciplinary course featured NAI scientists John Peters, PI of the NAI MSU team, and John Priscu, professor of Land Resources and Environmental Sciences and member of the NAI Icy Worlds team. More information about MSU's Astrobiology Biogeocatalysis Research Center can be found at abrc.montana.edu and the MSSE program can be found at montana.edu/msse. [Source: NAI Newsletter]
Two Post-doc Positions in Astrobiology Available at JPL, Caltech
The California Institute of Technology (Caltech) Postdoctoral Scholars Program at the Jet Propulsion Laboratory (JPL) invites applicants to apply for two postdoctoral research positions at JPL in the Planetary Science Section of the Science Division. Each opportunity is supported by a NASA grant to two separate, small, collaborative teams. The successful candidates, while having their own projects, will be expected to work with team members in other institutions.
Topic 1, Mineral biosignatures.
This topic forms part of the work supported by the NASA Astrobiology Institute through its Wisconsin Astrobiology Research Consortium team (U. Wisconsin, JPL and U. Georgia).
The aim of the research is to develop new biosignatures and paleoenvironmental proxies, with a focus on sulfate evaporate minerals. The planned work has two main strands. It will involve comparing the isotopic compositions of minerals formed by microbial oxidation of sulfides and the abiotic equivalents and also to make laboratory simulations of evaporation sequences and to use the isotopic data to constrain amount of water involved and the paleo-atmospheric-humidity. The biosignatures and paleoenvironmental indicators will be tested by application to the Rio Tinto system, Spain.
Topic 2, The Earth's deepest hydrothermal vents.
This research is funded by the NASA program, Astrobiology Science and Technology for Exploring Planets (ASTEP). The work is a collaboration between Woods Hole Oceanographic Institution (WHOI), JPL, the Marine Biological Laboratory (MBL) and Duke University Marine Laboratory (DUML).
We will be using WHOI's new Hybrid-ROV, Nereus, to investigate hydrothermal systems (past and present) along Earth's deepest mid-ocean ridge: the ~110km long ultra-slow spreading Mid-Cayman Spreading Center. Sampling is scheduled for Oct-Nov 2009. The results of the work will be used to plan astrobiological exploration of any planetary body that can host hydrothermal circulation (for example, Jupiter's moon, Europa). The research will involve characterization of minerals and their geochemical and stable isotope compositions to contribute to understanding the present and past energy budgets of the system. The post-doc also will be involved in the application of the integrated results to planning future NASA planetary exploration missions.
The selected candidates will both be guided by the JPL advisor, Dr. Max Coleman, to ensure that the research work will result in publications in the peer-reviewed literature.
Candidates should have a Ph.D. in geochemistry, astrobiology, biogeochemistry, geology, chemistry, environmental science (or other sciences) with a strong background in stable isotope analysis. The appointment is contingent upon evidence of completion of a Ph.D.
For more information: http://postdocs.jpl.nasa.gov/researchapplicants/jobpostings/index.cfm?FuseAction=ShowJobPosting&JobPostingID=179 [Source: NAI Newsletter]
NASA Earth and Space Science Fellowship (NESSF) Program
NASA announces a call for graduate fellowship proposals to the NASA Earth and Space Science Fellowship (NESSF) program for the 2010-2011 academic year. This call for fellowship proposals solicits applications from accredited U.S. universities on behalf of individuals pursuing Master of Science (M.Sc.) or Doctoral (Ph.D.) degrees in Earth and space sciences, or related disciplines. The purpose of NESSF is to ensure continued training of a highly qualified workforce in disciplines needed to achieve NASA's scientific goals. Awards resulting from the competitive selection will be made in the form of training grants to the respective universities.
The deadline for NEW applications is February 1, 2010, and the deadline for RENEWAL applications is March 15, 2010.
The NESSF call for proposals and submission instructions are located at the NESSF 09 solicitation index page at http://nspires.nasaprs.com/ - click on "Solicitations" then click on "Open Solicitations" then select the "NESSF 10" announcement. Also refer to "Proposal Submission Instructions" listed under "Other Documents" on the NESSF 10 solicitation index page.
All proposals must be submitted in electronic format only through the NASA NSPIRES system. The advisor has an active role in the submission of the fellowship proposal. To use the NSPIRES system, the advisor, the student, and the university must all register. Extended instructions on how to submit an electronic proposal package are posted on the NESSF 10 solicitation index page listed above. You can register in NSPIRES at http://nspires.nasaprs.com/.
For further information contact Russell Deyoung, Program Administrator for NESSF Earth Science Research, Telephone: (757) 864-1472, E-mail: larc-nessf-Earth@lists.nasa.gov or Dolores Holland, Program Administrator for NESSF Heliophysics Research, Planetary Science Research, and Astrophysics Research, Telephone: (202) 358-0734, E-mail: hq-nessf-Space@nasa.gov. [Source: NAI Newsletter]
Ribosomes as Ancient Molecular Fossils
Members of NAI's team at Georgia Tech have a new paper in Molecular Biology and Evolution describing an analysis of ribosomal structure and sequence. Their approach chronicles the ribosome's evolution, effectively interpreting the ribosome as a fossil. Using the highest resolution structures available, of two species that represent disparate regions of the evolutionary tree, they have sectioned the large subunit of each ribosome into concentric shells, like an onion, using the site of peptidyl transfer as the origin. Their results suggest that the structure and interactions of both RNA and protein can be described as changing, in an observable manner, over evolutionary time. [Source: NAI Newsletter]
Astrobiology Graduate Conference (AbGradCon) 2010
Taellberg, Sweden - June 14-18, 2010: In 2010, AbGradCon, the foremost astrobiology meeting for early-career researchers, will be held in Europe for the first time in its history. Graduate students and early-career postdocs from all over the world will come together to present their research in a comfortable environment, to learn of the latest developments in astrobiology, to network and to forge new collaborations. The meeting will comprise oral and poster presentations, half-day workshops and a one-day field trip to geologically instructive sites in the astrobiologically interesting Siljan impact crater. Attendees are encouraged from the very wide range of subjects pertinent to astrobiology. Financial assistance will be available to invited attendees. Further information is available at the conference website: http://www.abgradcon2010.org [Source: NAI Newsletter]
November 9, 2009
'Ultra-Primitive' Particles Found in Comet Dust
Dust samples collected by high-flying aircraft in the upper atmosphere have yielded an unexpectedly rich trove of relicts from the ancient cosmos, report scientists from NAI's Carnegie Institution of Washington team in Earth and Planetary Science Letters. The stratospheric dust includes minute grains that likely formed inside stars that lived and died long before the birth of our sun, as well as material from molecular clouds in interstellar space. This "ultra-primitive" material likely wafted into the atmosphere after the Earth passed through the trail of an Earth-crossing comet in 2003, giving scientists a rare opportunity to study cometary dust in the laboratory.
t high altitudes, most dust in the atmosphere comes from space, rather than the Earth's surface. Thousands of tons of interplanetary dust particles (IDPs) enter the atmosphere each year. "We've known that many IDPs come from comets, but we've never been able to definitively tie a single IDP to a particular comet," says study coauthor Larry Nittler, of Carnegie's Department of Terrestrial Magnetism. "The only known cometary samples we've studied in the laboratory are those that were returned from comet 81P/Wild 2 by the Stardust mission." NASA's Stardust mission collected samples of comet dust, returning to Earth in 2006.
Comets are thought to be repositories of primitive, unaltered matter left over from the formation of the solar system. Material held for eons in cometary ice has largely escaped the heating and chemical processing that has affected other bodies, such as the planets. However, the Wild 2 dust returned by the Stardust mission included more altered material than expected, indicating that not all cometary material is highly primitive.
The IDPs used in the current study were collected by NASA aircraft in April 2003, after the Earth passed through the dust trail of comet Grigg-Skjellerup. The research team, which included Carnegie scientists Nittler, Henner Busemann (now at the University of Manchester, U.K.), Ann Nguyen, George Cody, and seven other colleagues, analyzed a sub-sample of the dust to determine the chemical, isotopic and microstructural composition of its grains.
"What we found is that they are very different from typical IDPs" says Nittler. "They are more primitive, with higher abundances of material whose origin predates the formation of the solar system." The distinctiveness of the particles, plus the timing of their collection after the Earth's passing through the comet trail, point to their source being the Grigg-Skjellerup comet.
"This is exciting because it allows us to compare on a microscopic scale in the laboratory dust particles from different comets," says Nittler. "We can use them as tracers for different processes that occurred in the solar system four-and-a-half billion years ago."
The biggest surprise for the researchers was the abundance of so-called presolar grains in the dust sample. Presolar grains are tiny dust particles that formed in previous generations of stars and in supernova explosions before the formation of the solar system. Afterwards, they were trapped in our solar system as it was forming and are found today in meteorites and in IDPs. Presolar grains are identified by having extremely unusual isotopic compositions compared to anything else in the solar system. But presolar grains are generally extremely rare, with abundances of just a few parts per million in even the most primitive meteorites, and a few hundred parts per million in IDPs. "In the IDPs associated with comet Grigg-Skjellerup they are up to the percent level," says Nittler. "This is tens of times higher abundances than we see in other primitive materials."
Also surprising is the comparison with the samples from Wild 2 collected by the Stardust mission. "Our samples seem to be much more primitive, much less processed, than the samples from Wild 2," says Nittler, "which might indicate that there is a huge diversity in the degree of processing of materials in different comets." [Source: NAI Newsletter]
Oxygen Production in Earth's Early Oceans Predates the Great Oxidation Event
It is widely accepted that around 2.4 billion years ago, the Earth's atmosphere underwent a dramatic change when oxygen levels rose sharply. Called the "Great Oxidation Event" (GOE), the oxygen spike marks an important milestone in Earth's history, the transformation from an oxygen-poor atmosphere to an oxygen-rich one paving the way for complex life to develop on the planet.
Two questions that remain unresolved in studies of the early Earth are when oxygen production via photosynthesis got started and when it began to alter the chemistry of Earth's ocean and atmosphere.
A research team that includes members of NAI's Arizona State University team corroborates recent evidence that oxygen production began in Earth's oceans at least 100 million years before the GOE, and goes a step further in demonstrating that even very low concentrations of oxygen can have profound effects on ocean chemistry. Their study is published in the current issue of Science.
To arrive at their results, the researchers analyzed 2.5 billion-year-old black shales from Western Australia, samples provided through the NAI's Astrobiology Drilling Program. Essentially representing fossilized pieces of the ancient seafloor, the fine layers within the rocks allowed the researchers to page through ocean chemistry's evolving history.
Specifically, the shales revealed that episodes of hydrogen sulfide accumulation in the oxygen-free deep ocean occurred nearly 100 million years before the GOE and up to 700 million years earlier than such conditions were predicted by past models for the early ocean. Scientists have long believed that the early ocean, for more than half of Earth's 4.6 billion-year history, was characterized instead by high amounts of dissolved iron under conditions of essentially no oxygen.
Said Timothy Lyons of UC Riverside who led the study, "This is important because oxygen-poor and sulfidic conditions almost certainly impacted the availability of nutrients essential to life, such as nitrogen and trace metals. The evolution of the ocean and atmosphere were in a cause-and-effect balance with the evolution of life." [Source: NAI Newsletter]
University of Washington Astrobiology Seminar: Kevin Hand, "Joule Heating of the South Polar Terrain on Enceladus"
Date/Time: Tuesday November 10, 2009 2:30PM Pacific
Speaker: Kevin Hand (Jet Propulsion Laboratory)
Abstract: The plumes and observed heat flux in the South Polar Terrain of Enceladus remain a considerable mystery. We report that Joule heating in Enceladus - resulting from the interaction of Enceladus with Saturn's magnetic field - may account for several, to a few tens of megawatts of power across the observed "tiger stripe" fractures. Electric currents passing through subsurface channels of low salinity and just a few kilometres in depth could supply a source of power to the South Polar Terrain, providing a small but previously unaccounted for contribution to the observed heat flux and plume activity. For more information and participation instructions: http://astrobiology.nasa.gov/nai/seminars/detail/164 [Source: NAI Newsletter]
UH Team Member Tobias Owen Receives 2009 Gerard P. Kuiper Prize in Planetary Sciences
The NAI extends its congratulations to University of Hawaii team member Tobias Owen for receiving the 2009 Gerard P. Kuiper Prize. The Gerard P. Kuiper Prize was established by the Division for Planetary Sciences (DPS) to recognize and honor outstanding contributors to planetary science. It is to be awarded to scientists whose achievements have most advanced our understanding of the planetary system. For more information: http://dps.aas.org/prizes/kuiper [Source: NAI Newsletter]
NAI Director's Seminar: Andrew Pohorille, "Is Water Necessary for Life?"
Date/Time: Monday, November 30, 2009 11:00AM Pacific Speaker: Andrew Pohorille (NASA Ames Research Center)
Abstract: "Follow the water" is the canonical strategy in searching for life in the universe. Conventionally, discussion of this topic is focused on the ability of a solvent to support organic chemistry sufficiently rich to seed life. Although this is a necessary condition for the emergence of life it is far from being sufficient. Perhaps more importantly, solvent must promote self-organization of organic matter into functional structures capable of responding to environmental changes. In biology, they are mostly based on non-covalent interactions (interactions that do not involve making or breaking chemical bonds), strength of which must be properly tuned. If non-covalent interactions were too weak, the system would exhibit undesired, uncontrolled response to natural fluctuations of physical and chemical parameters. If they were too strong kinetics of biological processes would be slow and energetics costly.
Non-covalent interactions are very strongly mediated by the solvent. In particular, potential solvents for life must be characterized by a high dielectric constant to ensure solubility of polar species and sufficient flexibility of biological structures stabilized by electrostatic interactions. Among these solvents, water exhibits a remarkable trait that it also promotes solvophobic (hydrophobic) interactions between non-polar species, typically manifested by a tendency of these species to aggregate and minimize their contacts with the aqueous solvent. Hydrophobic interactions are responsible, at least in part, for many self-organization phenomena in biological systems, such as the formation of cellular boundary structures or protein folding. Strengths of electrostatic and hydrophobic interactions are similar and can be balanced over a wide range of temperatures, which considerably increases the repertoire of interactions that can be used to modulate biological functions.
Some properties of water, e.g. its chemical activity against polymerization reactions, are considered as unfavorable to life. In actuality, this might be a favorable trait because life requires a balance between constructive and destructive processes. For example, molecules synthesized in response to specific conditions must be degraded once these conditions change. Otherwise regulation of biological processes would be virtually impossible.
Water might not be the only liquid with favorable properties for supporting life. One example is formamide, which might be present elsewhere in the universe in sufficient quantities to warrant interest as a potential alternative to water for the origin of life. However, further studies on physical, chemical and biological properties of non-aqueous solutions are needed to draw firmer conclusions on this subject.
For more information and participation instructions: http://astrobiology.nasa.gov/nai/seminars/detail/161 [Source: NAI Newsletter]
Astrobiology Science News 9 November 2009
- Government-sponsored SETI -- In The 1920's, OnOrbit
- When E.T. phones the pope, Washington Post
- Discovery of the Coldest Imaged Companion of a Sun-Like Star, astro-ph
- The Stability and Dynamics of Planets in Tight Binary Systems, astro-ph
November 8, 2009
Astrobiology Science News 8 November 2009
November 6, 2009
Astrobiology Science News 6 November 2009
November 3, 2009
Astrobiology Science News 3 November 2009
November 2, 2009
Astrobiology Science News 2 November 2009
- The Cyborg Astrobiologist
- The solar, exoplanet and cosmological lithium problems, astro-ph
- Explorations into the Viability of Coupled Radius-Orbit Evolutionary Models for Inflated Planets, astro-ph
- The Cyborg Astrobiologist: Testing a Novelty-Detection Algorithm on Two Mobile Exploration Systems at Rivas Vaciamadrid in Spain and at the Mars Desert Research Station in Utah, astro-ph
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