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  • richardmitnick 7:32 pm on April 9, 2015 Permalink | Reply
    Tags: Astrobiology, , ,   

    From astrobio.net: “Can we find an ancient Earth-like planet with a dying biosphere?” 

    Astrobiology Magazine

    Astrobiology Magazine

    Apr 9, 2015
    Amanda Doyle

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    The life cycle of a solar-like star shows how our Sun will expand into a red giant. Credit: ESO/M. Kornmesser

    Our Sun will evolve into a red giant star billions of years from now. The increased heat from the expanding Sun will scorch the Earth with dire effects to life. Climate models can be used to predict how this will happen, but, of course, this cannot be tested out on Earth.

    Jack O’Malley-James of the Institute for Pale Blue Dots at Cornell University, along with colleagues, have been calculating the chances of discovering an old-Earth analog approaching the end of its habitable lifetime. This follows his work on Swansong Biospheres in which the potential bio-signatures of a dying world were assessed. The new paper, In Search of Future Earths: Assessing the possibility of finding Earth analogues in the later stages of their habitable lifetimes, has been accepted for publication in the journal Astrobiology and is available in preprint.

    The far future Earth

    Searches are already in place to find Earth’s twin, a planet with a similar mass and radius as the Earth and orbiting at the same distance as the Earth does from the Sun. However, finding an equivalent of Earth’s much older cousin involves a different set of criteria.

    The “habitable zone” is defined as the region where liquid water can exist on the surface of a planet. Habitable zones move outwards as a star ages, so a planet that was in the zone when the star was younger may not necessarily remain there. An old Earth analogue is one that has been in the star’s habitable zone for the entire main sequence lifetime of the star, known as the continuously habitable zone. As the purpose is to study planets in the final stages of habitability, a far future Earth would also have to be approaching the inner edge of the habitable zone.

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    The habitable zone (in blue) extends to greater distances for stars hotter than the Sun. Similarly, the habitable zone will move outwards as our Sun becomes a red giant. The continuously habitable zone is a smaller region where a planet can remain habitable throughout the main sequence lifetime of the star. Credit: Wikimedia

    As up to one-third of main sequence solar-like stars are thought to be in the later stages of their evolution, it is feasible that old Earth analogues could be detected. If any of these planets exist in the solar neighborhood, then they would be excellent candidates for future space telescopes with the capability to characterize a planet’s atmosphere from its spectrum.

    Searching nearby

    There are six solar-like stars within 10 parsecs of the Sun that are old enough to harbor an old Earth analogue.

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    A parsec is the distance from the Sun to an astronomical object that has a parallax angle of one arcsecond (the diagram is not to scale).

    A parsec is the equivalent of 3.26 light years. O’Malley-James calculated the location of the habitable zone for each star over its entire lifetime. He then placed hypothetical planets in each system at a distance where the planet could remain habitable for billions of years. The temperature changes on the planet over the main sequence lifetime of the star can be modeled by comparing the predicted incoming and outgoing radiation.

    The paper concludes that if Earth-like planets existed around these stars, then the one around 61 Vir would be at the right stage of its lifetime to be considered a far future Earth. Such a planet might be home to a declining microbial population, assuming that life evolved there in a similar manner to the Earth. This hypothetical planet would be akin to the stage in future Earth’s lifetime when the temperature has risen too high for complex life to survive, and microbes are the last lifeforms to cling to existence. Other stars could host planets similar to future Earth where only extremophile microbial life remains in a few select niches, however these biosignatures would be much more difficult to detect than the declining microbial biosphere.

    A Galaxy Teeming with Earth-like Planets?

    If an Earth-like planet existed around 61 Vir, it would provide a good opportunity to study the far future Earth. But what are the actual chances of such planets existing?

    O’Malley-James used previous studies by other scientists in order to find out. One study, based on the number of planets found by NASA’s Kepler mission, predicts that 8.6 percent of solar-like stars could harbor an Earth-like planet orbiting in the habitable zone.

    NASA Kepler Telescope
    Kepler

    A solar-like star is one that is of a similar temperature and mass as our own Star. There are 276 stars like our Sun within 100 parsecs, around half of which are older than six billion years. This means that there should be 11 potential targets.

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    61 Vir as seen with a 12.5″ telescope with a field of view of 45.1 arc minutes. Credit: Kevin Heider

    However, another study showed that terrestrial planets are more likely to form less than one astronomical unit (AU), the distance between the Sun and the Earth) from the star. From the six example stars that O’Malley-James studied, the continuously habitable zone is located slightly further from the star than this. Combining these results indicates that there would actually only be one potential old-Earth analogue within the solar neighborhood.

    “It turned out that these planets are probably not that common at all, so in reality any habitable planets in the 61 Vir system will probably not resemble an older version of Earth,” said O’Malley-James. “This study highlights that finding replicas of our own world, in terms of the diversity and complexity of life, is going to be a much harder task than simply finding life.”

    Yet while there may only be one potential old-Earth analogue close enough to be studied in detail, there could still be thousands more in the distant reaches of our Galaxy.

    See the full article here.

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  • richardmitnick 2:46 pm on March 7, 2015 Permalink | Reply
    Tags: , Astrobiology, , Origin of Life   

    From astrobio.net: “NASA Ames Reproduces the Building Blocks of Life in Laboratory” 

    Astrobiology Magazine

    Astrobiology Magazine

    Mar 7, 2015
    No Writer Credit

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    Left to right: Ames scientists Michel Nuevo, Christopher Materese and Scott Sandford reproduce uracil, cytosine, and thymine, three key components of our hereditary material, in the laboratory. Image Credit: NASA/ Dominic Hart

    NASA scientists studying the origin of life have reproduced uracil, cytosine, and thymine, three key components of our hereditary material, in the laboratory. They discovered that an ice sample containing pyrimidine exposed to ultraviolet radiation under space-like conditions produces these essential ingredients of life.

    Pyrimidine is a ring-shaped molecule made up of carbon and nitrogen and is the central structure for uracil, cytosine, and thymine, which are all three part of a genetic code found in ribonucleic (RNA) and deoxyribonucleic acids (DNA). RNA and DNA are central to protein synthesis, but also have many other roles.

    “We have demonstrated for the first time that we can make uracil, cytosine, and thymine, all three components of RNA and DNA, non-biologically in a laboratory under conditions found in space,” said Michel Nuevo, research scientist at NASA’s Ames Research Center, Moffett Field, California. “We are showing that these laboratory processes, which simulate conditions in outer space, can make several fundamental building blocks used by living organisms on Earth.”

    An ice sample is deposited on a cold (approximately –440 degrees Fahrenheit) substrate in a chamber, where it is irradiated with high-energy ultraviolet (UV) photons from a hydrogen lamp. The bombarding photons break chemical bonds in the ices and break down the ice’s molecules into fragments that then recombine to form new compounds, such as uracil, cytosine, and thymine.

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    Pyrimidine is a ring-shaped molecule made up of carbon and nitrogen and is the central structure for uracil, cytosine, and thymine, which are found in RNA and DNA. Image Credit: NASA

    NASA Ames scientists have been simulating the environments found in interstellar space and the outer Solar System for years. During this time, they have studied a class of carbon-rich compounds, called polycyclic aromatic hydrocarbons (PAHs), that have been identified in meteorites, and which are the most common carbon-rich compound observed in the universe. PAHs typically are structures based on several six-carbon rings that resemble fused hexagons, or a piece of chicken wire.

    The molecule pyrimidine is found in meteorites, although scientists still do not know its origin. It may be similar to the carbon-rich PAHs, in that it may be produced in the final outbursts of dying, giant red stars, or formed in dense clouds of interstellar gas and dust.

    “Molecules like pyrimidine have nitrogen atoms in their ring structures, which makes them somewhat wimpy. As a less stable molecule, it is more susceptible to destruction by radiation, compared to its counterparts that don’t have nitrogen,” said Scott Sandford, a space science researcher at Ames. “We wanted to test whether pyrimidine can survive in space, and whether it can undergo reactions that turn it into more complicated organic species, such as the nucleobases uracil, cytosine, and thymine.”

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    The ring-shaped molecule pyrimidine is found in cytosine and thymine. Image Credit: NASA

    In theory, the researchers thought that if molecules of pyrimidine could survive long enough to migrate into interstellar dust clouds, they might be able to shield themselves from destructive radiation. Once in the clouds, most molecules freeze onto dust grains (much like moisture in your breath condenses on a cold window during winter).

    These clouds are dense enough to screen out much of the surrounding outside radiation of space, thereby providing some protection to the molecules inside the clouds.

    Scientists tested their hypotheses in the Ames Astrochemistry Laboratory. During their experiment, they exposed the ice sample containing pyrimidine to ultraviolet radiation under space-like conditions, including a very high vacuum, extremely low temperatures (approximately –440 degrees Fahrenheit), and harsh radiation.

    They found that when pyrimidine is frozen in ice mostly consisting of water, but also ammonia, methanol, or methane, it is much less vulnerable to destruction by radiation than it would be if it were in the gas phase in open space. Instead of being destroyed, many of the molecules took on new forms, such as the RNA/DNA components uracil, cytosine, and thymine, which are found in the genetic make-up of all living organisms on Earth.

    “We are trying to address the mechanisms in space that are forming these molecules. Considering what we produced in the laboratory, the chemistry of ice exposed to ultraviolet radiation may be an important linking step between what goes on in space and what fell to Earth early in its development,” said Christopher Materese, another researcher at NASA Ames who has been working on these experiments.

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    An ice sample is held at approximately -440 degrees Fahrenheit in a vacuum chamber, where it is irradiated with high energy UV photons from a hydrogen lamp. The bombarding photons break chemical bonds in the ice samples and result in the formation of new compounds, such as uracil. Image Credit: NASA/Dominic Hart

    “Nobody really understands how life got started on Earth. Our experiments suggest that once the Earth formed, many of the building blocks of life were likely present from the beginning. Since we are simulating universal astrophysical conditions, the same is likely wherever planets are formed,” says Sandford.

    Additional team members who helped perform some of the research are Jason Dworkin, Jamie Elsila, and Stefanie Milam, three NASA scientists at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.

    The research was funded by the NASA Astrobiology Institute (NAI) and the NASA Origins of Solar Systems Program. The NAI is a virtual, distributed organization of competitively-selected teams that integrates and funds astrobiology research and training programs in concert with the national and international science communities.

    See the full article here.

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  • richardmitnick 7:03 pm on February 9, 2015 Permalink | Reply
    Tags: Astrobiology, , ,   

    From astrobio: “Planets Orbiting Red Dwarfs May Stay Wet Enough for Life” 

    Astrobiology Magazine

    Astrobiology Magazine

    Feb 9, 2015
    Charles Q. Choi

    1
    Oceans currents would transport heat to the dark side of tidally-locked exoplanets. Image Credit: Lynette Cook

    Small, cold stars known as red dwarfs are the most common type of star in the Universe, and the sheer number of planets that may exist around them potentially make them valuable places to hunt for signs of extraterrestrial life.

    However, previous research into planets around red dwarfs suggested that while they may be warm enough to host life, they might also completely dry out, with any water they possess locked away permanently as ice. New research published on the topic finds that these planets may stay wet enough for life after all. The scientists detailed their findings online on November 12 in The Astrophysical Journal Letters.

    Red dwarfs, also known as M stars, are roughly one-fifth as massive as the Sun and up to 50 times fainter. These stars comprise up to 70 percent of the stars in the cosmos, and NASA’s Kepler space observatory has discovered that at least half of these stars host rocky planets that are one-half to four times the mass of Earth.

    NASA Kepler Telescope
    Kepler

    Red dwarf planets are potentially key places to search for life as we know it, not just because there are so many of them, but also because of their incredible longevity. Unlike our Sun, which will die in a few billion years, red dwarfs will take trillions of years to burn through their fuel, significantly longer than the age of the Universe, which is less than 14 billion years old. This longevity potentially gives red dwarfs a great deal more time for life to evolve around them.

    Research into whether a distant world might host life as we know it usually focuses on whether or not it has liquid water, since there is life virtually everywhere there is liquid water on Earth, even miles underground. Scientists typically concentrate on habitable zones, the area around a star where it is neither too hot for all its surface water to boil away, nor too cold enough for all its surface water to freeze.

    Recent findings suggest that planets in the habitable zones of red dwarf stars could accumulate significant amounts of water. In fact, each planet could possess about 25 times more water than Earth.

    The habitable zones of red dwarfs are close to these stars because of how dim they are, often closer than the distance Mercury orbits the Sun. This closeness makes them appealing to astrobiologists, since planets near their stars cross in front of them more often, making them easier to detect than planets that orbit farther away.

    However, when a planet orbits very near a star, the star’s gravitational pull can force the world to become “tidally locked” to it. When a planet is tidally locked to its star, it will always show the same side to its star, just as the Moon always shows the same side to Earth. This causes the planet to have one permanent day side and one permanent night side.

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    The extremes of heat and cold that tidally locked planets experience could make them profoundly different from Earth. For example, prior research speculated the dark sides of tidally locked planets would become so cold that any water there would freeze. Sunlight would make water on the sunlit side evaporate, and this water vapor could get carried by air currents to the night sides, eventually leading to sheets of ice miles thick on the night sides and removing all water from the sunlit sides. Life as we know it probably could not develop on the day sides of such planets. Although they would have sunlight for photosynthesis, they would have no water to serve as the primordial soup for life to swim in.

    To see how habitable tidally-locked planets really are, scientists devised a 3D global climate model of planets that simulated interactions between the atmosphere, ocean, sea ice, and land, as well as a 3-D model of ice sheets large enough to cover entire continents. They also simulated a red dwarf with a temperature of about 5,660 degrees Fahrenheit (3,125 degrees Celsius), and investigated whether all the water on these planets would indeed get trapped on their night sides.

    “I’ve been interested in trying to make calculations relevant for M-star planet habitability since being convinced by astronomers that these types of planets will likely be closest (in proximity) to Earth,” said study co-author Dorian Abbot, a geoscientist at the University of Chicago.

    For instance, the nearest known star to the Sun, Proxima Centauri, is a red dwarf, and it remains uncertain whether or not it has a planet. The possibility that red dwarf planets might be relatively near to Earth “means that anything geoscientists can tell astronomers about habitability of these planets will be essential for planning future missions.”

    The researchers simulated planets of Earth’s size and gravity that experienced between 63 percent and 77 percent as much sunlight as Earth. They also modeled a super-Earth planet 50 percent wider than Earth with 38 percent stronger gravity, because astronomers have discovered super-Earth worlds around red dwarfs. For instance, Gliese 667Cb, a super-Earth at least 4.5 times the mass of Earth, orbits Gliese 667C, a red dwarf about 22 light years from Earth. They set this super-Earth on an orbit where it received about two-thirds as much as sunlight as Earth.

    The researchers modeled three different arrangements of continents for all these planets. One was a water world with no continents and global oceans of varying depths. Another involved a supercontinent covering the night side and an ocean covering the day side. The last mimicked Earth’s configuration of continents. The planets also had atmospheres similar to Earth’s, but the researchers also tested lower levels of the greenhouse gas, carbon dioxide, which traps heat and helps keep planets warm.

    When it came to super-Earths covered entirely in water, and super-Earths with continental arrangements like Earth’s, the researchers found it was unlikely that all their water would get trapped on their night sides.

    “This is because surface winds transport sea ice to the day side where it is melted easily,” said lead study author Jun Yang at the University of Chicago.

    Moreover, ocean currents transport heat from the day side to the night side on these planets.

    “Ocean heat transport strongly influences the climate and sea ice thickness on our Earth,” Yang said. “We found this may also work on exoplanets.”

    If a super-Earth has very large continents covering most of its night side, the scientists discovered ice sheets of at least 3,300 feet (1,000 meters) thick could grow on its night side. However, the day sides of these super-Earths would dry out completely only if they received less geothermal heat from volcanic activity than Earth, and had 10 percent of the amount of water on Earth’s surface or less. Similar results were seen with Earth-sized planets.

    “The important implication is that it may be easier than previously thought to keep liquid water on the dayside of a tidally locked planet, where photosynthesis is possible,” Abbot said. “There are many issues that will affect the habitability of M-star planets, but our results suggest at least that water-trapping on the night side will only be a problem for relatively dry planets with large continents on their nightside and relatively low geothermal heat flux.”

    Based on present and near-future technology, Yang said it would be very difficult for astronomers to gauge how thick the sea ice or the ice sheets are on the night sides of red dwarf planets and test whether their models are correct. Still, using current and upcoming technology “it may be possible to know whether the day sides are dry or not,” Yang said.

    See the full article here.

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  • richardmitnick 4:39 pm on January 23, 2015 Permalink | Reply
    Tags: Astrobiology, , , U Montana   

    From SPACE.com: “How Did Life Become Complex, and Could It Happen Beyond Earth?” 

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    SPACE.com

    January 20, 2015
    Elizabeth Howell, Astrobiology Magazine

    When astrobiologists contemplate life on nearby planets or moons, they often suggest such life would be simple. Instead of there being some kind of multicellular organism on, say, Jupiter’s moon Europa, scientists instead aim to find something more like a microbe.

    But from such simple life, more complex lifeforms could eventually come to be. That’s what happened here on planet Earth, and that’s what could happen in other locations as well. How did the chemistry evolve to get life to where we are today? What transitions took place?

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    Studying areas such as Titan, a moon of Saturn (foreground) can give researchers ideas about how chemistry eventually created life.
    Credit: NASA/JPL-Caltech/Space Science Institute

    Frank Rosenzweig, an evolutionary geneticist at the University of Montana, is looking into such questions over the next five years with funding from the NASA Astrobiology Institute. His lab studies how life evolves “complex traits,” factors that influence everything from lifespan to biodiversity.

    “Over my career, I’ve been interested in what are the genetic bases of adaptation and how do complex communities evolve from single clones,” Rosenzweig said. “Related to these questions are others such as how do the genetic ‘starting point’ and ecological setting influence the tempo and trajectory of evolutionary change.”

    Shopping for life in the Solar System

    Complex life is only known to exist on Earth, but scientists aren’t ruling out other locations in the Solar System. Our understanding of life’s evolution could be informed by studying the Saturnian moon Titan, whose hydrocarbon chemistry is considered a precursor to a living system. Researchers recently tried to replicate a substance in Titan’s atmosphere called tholins, which are organic aerosols created from solar radiation hitting the methane and nitrogen atmosphere.

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    Tholins, complex organic molecules fundamental to prebiotic chemistry, are apparently forming at a much higher altitude, and in different ways than expected, in Titan’s atmosphere.

    Understanding how tholins and other substances are formed on Titan could give researchers a picture of how early Earth evolved life. Also, studying how Earthly life-forms and their biochemical precursors evolved from simple subunits to successively more complex and interdependent systems could give hints of how life might evolve on other moons or planets.

    On Earth, examples of these transitions include collections of single proteins evolving into protein networks. For example, single-celled bacteria evolve into eukaryotic cells that contain two, or even three genomes. Also, competing microbes come together to form cooperative systems, such as microbial mats in hot springs and microbial biofilms lining the human gut. Each of these transitions results in increased bio-complexity, interdependence and a certain degree of autonomy for a new whole that is more than the sum of its parts.

    Rosenzweig’s research developed out of previous NASA grants over the past six years, and from his being a panelist reviewing team-based proposals for the NASA Astrobiology Institute.

    “There is, and still needs to be a lot of work done on chemical evolution, prebiotic (pre-life) evolution, extreme environments and bio-signatures,”Rosenzweig said. “It struck me that it might be worthwhile trying to convince NASA to add to its research portfolio a set of proposals focused on understanding the genetic basis underlying major evolutionary transitions that have led to higher-order complexity”

    As such, Rosenzweig’s new research will focus on four areas where a complex system has arisen from simpler elements: metabolism, the eukaryotic cell, mutualism (co-operating species) and multicellularity. He will also look into a fifth area — mutations and gene interactions — that critically determines how quickly such complex systems can arise. He believes that lab experiments aimed at replicating key aspects of the evolution of life on Earth can better inform how we search in life-friendly locations on Mars, Europa, Saturn’s moon Titan, or elsewhere.

    Rosenzweig plans to have eight different teams focusing on questions of evolution and changes from simple to more complex life. To integrate his teams’ experimental results into a broader framework he recruited theoreticians in the areas of population genetics and statistical physics.

    Rosenzweig’s previous NASA funding came from the Exobiology and Evolutionary Biology Program. The first project, initiated in 2007, examined how genetic material (or genomes) evolve in yeast species that were cultured under limited resources. A second project, initiated in 2010, is investigating how founder cells in E. coli genotypes, and the environment in which they evolve, influence the diversity and stability of subsequent populations.

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    A species of yeast (Saccharomyces cerevisiae) seen in a scanning electrograph image.
    Credit: NASA

    The first project led to an unexpected finding: stress may increase the frequency with which genome sequences are rearranged. Stress introduces new chromosomal variants into the species; population that could prove beneficial under challenging circumstances. Indeed, previous studies have indicated that new chromosomal variants are stress resistant. In 2013, Rosenzweig’s team, led by University of Montana research professor Eugene Kroll, began studying how yeast cultures respond to starvation.

    This new line of inquiry has already led to one major publication entitled, Starvation-associated genome restructuring can lead to reproductive isolation in yeast, which was published in PLoS One in 2013. Therein, Kroll and Rosenzweig further show that yeast containing stress-adaptive genomic rearrangements become “reproductively isolated” from their ancestors, suggesting that, at least in lower fungi, geographic isolation may not be required to generate new species. A new project through NASA’s Exobiology and Evolutionary Biology Program, awarded Summer 2014, will enable the team to tease out the genetic mechanisms that underlie adaptation and reproductive isolation in starved yeast.

    A distinguishing feature of this research, Rosenzweig notes, is that whereas most studies look at species’ performance in relatively benign environments, the yeast are studied under near-starvation conditions. This kind of severe stress may be a closer analog to what real species face in nature as populations genetically adapt to drastically altered circumstances. Inasmuch as starvation may serve as a cue to any kind of stress, from diminished resources to greatly altered temperature to an invasion by superior competitors, the results of this study should have implications for life on other planets.

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    Studying how life evolved on Earth could lead to a better understanding of habitability conditions in other locations, such as Mars.
    Credit: NASA/JPL

    Indeed, a major theme that runs through all of these investigations is that by studying evolutionary processes in the laboratory using simple unicellular species, we can expect to uncover rules that govern the tempo and trajectory of evolution in any population of self-replicating entities whose structure and function are programmed by information molecules.

    “What I would like fellow astrobiology researchers to be alert to is evidence of differentiation, either at the level of different proteins in a metabolic network, different genotypes in a population of a given species, different genomes in a single cell, or different cells in a multicellular organism. In each case differentiation opens the door not only to competition but also to cooperation between variants, enabling a division of labor.” he said. “We should be mindful that, however they may be encoded, lifeforms are likely to have differentiated on other worlds. Therefore, we should be alert to the signatures left by these more complex forms of life.”

    See the full article here.

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  • richardmitnick 12:59 pm on January 18, 2015 Permalink | Reply
    Tags: , Astrobiology, , Institut d'Astrophysique Spatiale   

    From Institut d’Astrophysique Spatiale: “Detection of sugars in a laboratory simulation of interstellar and pre-cometary organic matter produced from the photo/thermos chemistry of ices” 

    Institut d'Astrophysique Spatiale bloc

    Institut d’Astrophysique Spatiale

    13/01/2015
    No Writer Credit

    Ten aldehydes, including two sugars potentially important for prebiotic chemistry, have for the first time been identified in organic residues issued from photochemistry of interstellar ice analogues, produced in the laboratory by the IAS MICMOC/SUGARS experiment.

    The MICMOC experiment (Matière Interstellaire et Cométaire: Molécules Organiques Complexes) has a variant (Chiral-MICMOC on the SOLEIL synchrotron) which investigates the spatial conformation (left, L, or right D) of the amino acids produced under the photochemical action of ultraviolet circularly polarized light. The aim of this experiment is to propose an astrophysical scenario for the origin of homochirality observed in biological molecules on the Earth. The MICMOC/SUGARS experiment is another variant of the initial set-up. This fully interdisciplinary approach assembles astrophysicists, molecular physicists, and chemists. It mixes an experimental approach including a strong astrophysical background with the simulation of the evolution of interstellar ice analogues in the laboratory and sophisticated analytical chemistry methods for the detection of molecules of prebiotic interest.

    The detection of numerous amino acids in the organic residues produced by the photo/thermo-chemistry of ices has been reported, in part thanks to our collaboration between IAS (Orsay) and INC (Nice). The overall quality of the samples produced by the IAS team « Astrochimie et Origines » has been attested by the use of 13C atoms markers in the original ice samples to avoid any confusion with possible contamination of the samples during manipulation.

    Recently, a change in the analytical procedure has allowed the detection of a new family of molecules: the aldehydes. Among them are the two sugars glycolaldehyde and glyceraldehyde, potentially important for prebiotic chemistry. According to a recent study, these molecules may be considered as possible precursors of ribonucleotides (constituents of RNA), in the same manner that amino acids (which are detected within the same experimental protocol) are key molecules for the early formation of proteins. The detection of these molecules in our samples strengthens the scenario of an exogenous delivery of organic molecules essential for starting prebiotic chemistry at the surface of the early Earth.

    Finally, if glycolaldehyde is indeed detected in the interstellar medium, that is not the case yet for glyceraldehyde, which can be seen now as a potential target for large modern radioastronomy instruments such as ALMA. Glyceraldehyde could also be proposed for detection in primitive carbonaceous meteorites.

    Research paper: P. de Marcellus et al. (2015). Aldehydes and sugars from evolved precometary ice analogues: Importance of ices in astrochemical and prebiotic evolution.
    PNAS. DOI : 10.1073/pnas.1418602112 10.1073/pnas.1418602112

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    Left: UV source for astrochemistry experiments at IAS (picture : P. de Marcellus). Right: the “Pillars of Creation” (in the Eagle nebula) seen by the Hubble Space Telescope (HST, NASA).

    See the full article here.

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    Institut d'Astrophysique Spatiale campus

    The Institut d’Astrophysique Spatiale (IAS) is a laboratory of the National Center of Scientific Research (CNRS) and of the University of Paris-Sud 11. in addition to having the status of Observatory.The IAS comprises 140 scientists, engineers, technicians, administrators and graduate students.

     
  • richardmitnick 10:46 am on January 1, 2015 Permalink | Reply
    Tags: Astrobiology, , , , , ,   

    From SPACE.com: “Planets with Odd, Mercury-Like Orbits Could Host Life” 

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    SPACE.com

    December 31, 2014
    Charles Choi

    Mercury has an oddball orbit — it takes longer for it to rotate on its axis and complete a day than it takes to orbit the sun and complete a year. Now, researchers suggest photosynthesis could take place on an alien planet with a similarly bizarre orbit, potentially helping support complex life.


    Orbit animation

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    During its first Mercury solar day (which is about 176 Earth days long) in orbit, NASA’s MESSENGER spacecraft imaged nearly the entire surface of Mercury to generate a global monochrome map at 250 meters per pixel resolution and a 1 kilometer per pixel resolution color map.
    Credit: NASA/JHU APL/CIW

    NASA Messenger satellite
    NASA/Messenger

    However, the scientists noted that the threat of prolonged periods of darkness and cold on these planets would present significant challenges to alien life, and could even potentially freeze their atmospheres. They detailed their findings in the International Journal of Astrobiology.

    Astronomers have discovered more than 1,700 alien planets in the past two decades, raising the hope that at least some might be home to extraterrestrial life. Scientists mostly focus the search for alien life on exoplanets in the habitable zones of stars. These are regions where worlds would be warm enough to have liquid water on their surfaces, a potential boon to life.

    Although many exoplanets are potentially habitable, they may differ from Earth significantly in one or more ways. For instance, habitable planets around dim red dwarf stars orbit much closer than Earth does to the sun, sometimes even closer than Mercury’s distance.

    Red dwarfs are of interest as possible habitats for life because they are the most common stars in the universe — if life can exist around red dwarfs, then life might be very common across the cosmos. Recent findings from NASA’s Kepler Space Observatory suggest that at least half of all red dwarfs host rocky planets that are one-half to four times the mass of Earth.

    NASA Kepler Telescope
    NASA/Kepler

    Since a planet in the habitable zone of a red dwarf orbits very near its star, it experiences much stronger gravitational tidal forces than Earth does from the sun, which slows the rate at which those worlds spin. The most likely result of this slowdown is that the planet enters what is technically called a 1:1 spin orbit resonance, completing one rotation on its axis every time it completes one orbit around its star.

    This rate of rotation means that one side of that planet will always face toward its star, while the other side will permanently face away, just as the moon always shows the same side to Earth. One recent study suggests that such “tidally locked” planets may develop strange lobster-shaped oceans basking in the warmth of their stars on their daysides, while the nightsides of such worlds are mostly covered in an icy shell.

    However, if a habitable red dwarf planet has a very eccentric orbit — that is, oval-shaped — it could develop what is called a 3:2 spin orbit resonance, meaning that it rotates three times for every two orbits around its star. Mercury has such an unusual orbit, which can lead to strange phenomena. For instance, at certain times on Mercury, an observer could see the sun rise about halfway and then reverse its course and set, all during the course of one mercurial day. Mercury itself is not habitable, since it lacks an atmosphere and experiences temperatures ranging from 212 to 1,292 degrees Fahrenheit (100 to 700 degrees Celsius).

    “If the sun were less intense, Mercury would be within the habitable zone, and therefore life would have to adapt to strange light cycles,” said lead study author Sarah Brown, an astrobiologist at the United Kingdom Center for Astrobiology in Edinburgh, Scotland.

    Light is crucial for photosynthesis, the process by which plants and other photosynthetic organisms use the sun’s rays to create energy-rich molecules such as sugars. Most life on Earth currently depends on photosynthesis or its byproducts in one way or the other, and while primitive life can exist without photosynthesis, it may be necessary for more complex multicellular organisms to emerge because the main source for oxygen on Earth comes from photosynthetic life, and oxygen is thought to be necessary for multicellular life to arise.

    To see what photosynthetic life might exist on a habitable red dwarf planet with an orbit similar to Mercury’s, scientists calculated the amount of light that reached all points on its surface. Their model involved a planet the same mass and diameter as the Earth with a similar atmosphere and amount of water on its surface. The red dwarf star was 30 percent the sun’s mass and 1 percent as luminous, giving it a temperature of about 5,840 degrees Fahrenheit (3,225 degrees Celsius) and a habitable zone extending from 10 to 20 percent of an astronomical unit (AU) from the star. (One AU is the average distance between Earth and the sun.)

    The scientists found that the amount of light the surface of these planets received concentrated on certain bright spots. Surprisingly, the amount of light these planets receive does not just vary over latitude as it does on Earth, where more light reaches equatorial regions than polar regions, but also varies over longitude. Were photosynthetic life to exist on worlds with these types of orbits, “one would expect to find niches that depend on longitude and latitude, rather than just latitude,” said study co-author Alexander Mead, a cosmologist at the Royal Observatory, Edinburgh, in Scotland.

    The research team found these planets could experience nights that last for months. This could pose major problems for photosynthetic life, which depends on light. Still, the scientists noted that many plants can store enough energy to last through 180 days of darkness. Moreover, some photosynthetic microbes spend up to decades dormant in the dark, while others are mixotrophic, which means they can survive on photosynthesis when light is abundant and switch to devouring food when light is absent.

    Another problem these long spans of darkness pose for life is the cold, which could freeze the atmospheres of these planets. Still, the investigators note that heat can flow from the dayside of such a planet to its nightside and prevent this freezing if that planet’s atmosphere is sufficiently dense and can trap infrared light from the planet’s star. This heat flow could lead to very strong winds, but this does not necessarily make the world uninhabitable, they added.

    “Life having to cope with such tidally driven resonances could be common in the universe,” Mead said. “It changes one’s perception of what habitable planets in the universe would be like. There are many possibilities that are very un-Earth-like.”

    However, the researchers noted that the strength of a world’s magnetic field depends in large part on how quickly it spins, which suggests that planets with orbits like Mercury’s might have relatively weak magnetic fields. This could mean these worlds are not as good at deflecting harmful electrically charged particles streaming from their red dwarfs and other stars that can damage organisms and strip off the atmospheres of these planets.

    The investigators suggested that dense atmospheres could help keep such planets habitable in the face of radiation from space. They added that life might be confined to certain spots on the surfaces of those planets that experience relatively safe levels of radiation.

    Are astronomers capable of detecting habitable planets with a 3:2 spin orbit resonance?

    “Measuring the day length of extrasolar planets is enormously difficult, and the first day length measurements for any extrasolar planets were only published this year,” Mead said. “Such a measurement for the planets we discuss would be much more difficult due to the fact that they are small, rocky planets around faint stars. This means that we are probably a long way from measuring the spin rates of such habitable worlds.”

    See the full article here.

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  • richardmitnick 7:58 pm on December 25, 2014 Permalink | Reply
    Tags: Astrobiology, , , , ,   

    From NASA: “NASA Announces Mars 2020 Rover Payload to Explore the Red Planet as Never Before” 

    NASA

    NASA

    July 31, 2014
    Dwayne Brown
    Headquarters, Washington
    202-358-1726
    dwayne.c.brown@nasa.gov

    The next rover NASA will send to Mars in 2020 will carry seven carefully-selected instruments to conduct unprecedented science and exploration technology investigations on the Red Planet.

    NASA announced the selected Mars 2020 rover instruments Thursday at the agency’s headquarters in Washington. Managers made the selections out of 58 proposals received in January from researchers and engineers worldwide. Proposals received were twice the usual number submitted for instrument competitions in the recent past. This is an indicator of the extraordinary interest by the science community in the exploration of the Mars. The selected proposals have a total value of approximately $130 million for development of the instruments.

    nn
    An artist concept image of where seven carefully-selected instruments will be located on NASA’s Mars 2020 rover. The instruments will conduct unprecedented science and exploration technology investigations on the Red Planet as never before.
    Image Credit: NASA

    Planning for NASA’s 2020 Mars rover envisions a basic structure that capitalizes on the design and engineering work done for the NASA rover Curiosity, which landed on Mars in 2012, but with new science instruments selected through competition for accomplishing different science objectives. Mars 2020 is a mission concept that NASA announced in late 2012 to re-use the basic engineering of Mars Science Laboratory to send a different rover to Mars, with new objectives and instruments, launching in 2020. NASA’s Jet Propulsion Laboratory, a division of the California Institute of Technology, Pasadena, manages NASA’s Mars Exploration Program for the NASA Science Mission Directorate, Washington.

    NASA Mars Curiosity Rover
    Curiosity

    m
    NASA/JPL-Caltech

    The new rover will carry more sophisticated, upgraded hardware and new instruments to conduct geological assessments of the rover’s landing site, determine the potential habitability of the environment, and directly search for signs of ancient Martian life.

    “Today we take another important step on our journey to Mars,” said NASA Administrator Charles Bolden. While getting to and landing on Mars is hard, Curiosity was an iconic example of how our robotic scientific explorers are paving the way for humans to pioneer Mars and beyond. Mars exploration will be this generation’s legacy, and the Mars 2020 rover will be another critical step on humans’ journey to the Red Planet.”

    Scientists will use the Mars 2020 rover to identify and select a collection of rock and soil samples that will be stored for potential return to Earth by a future mission. The Mars 2020 mission is responsive to the science objectives recommended by the National Research Council’s 2011 Planetary Science Decadal Survey.

    “The Mars 2020 rover, with these new advanced scientific instruments, including those from our international partners, holds the promise to unlock more mysteries of Mars’ past as revealed in the geological record,” said John Grunsfeld, astronaut and associate administrator of NASA’s Science Mission Directorate in Washington. “This mission will further our search for life in the universe and also offer opportunities to advance new capabilities in exploration technology.”

    The Mars 2020 rover also will help advance our knowledge of how future human explorers could use natural resources available on the surface of the Red Planet. An ability to live off the Martian land would transform future exploration of the planet. Designers of future human expeditions can use this mission to understand the hazards posed by Martian dust and demonstrate technology to process carbon dioxide from the atmosphere to produce oxygen. These experiments will help engineers learn how to use Martian resources to produce oxygen for human respiration and potentially as an oxidizer for rocket fuel.

    “The 2020 rover will help answer questions about the Martian environment that astronauts will face and test technologies they need before landing on, exploring and returning from the Red Planet,” said William Gerstenmaier, associate administrator for the Human Exploration and Operations Mission Directorate at NASA Headquarters in Washington. “Mars has resources needed to help sustain life, which can reduce the amount of supplies that human missions will need to carry. Better understanding the Martian dust and weather will be valuable data for planning human Mars missions. Testing ways to extract these resources and understand the environment will help make the pioneering of Mars feasible.”

    The selected payload proposals are:

    Mastcam-Z, an advanced camera system with panoramic and stereoscopic imaging capability with the ability to zoom. The instrument also will determine mineralogy of the Martian surface and assist with rover operations. The principal investigator is James Bell, Arizona State University in Tempe.

    SuperCam, an instrument that can provide imaging, chemical composition analysis, and mineralogy. The instrument will also be able to detect the presence of organic compounds in rocks and regolith from a distance. The principal investigator is Roger Wiens, Los Alamos National Laboratory, Los Alamos, New Mexico. This instrument also has a significant contribution from the Centre National d’Etudes Spatiales,Institut de Recherche en Astrophysique et Plane’tologie (CNES/IRAP) France.

    Planetary Instrument for X-ray Lithochemistry (PIXL), an X-ray fluorescence spectrometer that will also contain an imager with high resolution to determine the fine scale elemental composition of Martian surface materials. PIXL will provide capabilities that permit more detailed detection and analysis of chemical elements than ever before. The principal investigator is Abigail Allwood, NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, California.

    Scanning Habitable Environments with Raman & Luminescence for Organics and Chemicals (SHERLOC), a spectrometer that will provide fine-scale imaging and uses an ultraviolet (UV) laser to determine fine-scale mineralogy and detect organic compounds. SHERLOC will be the first UV Raman spectrometer to fly to the surface of Mars and will provide complementary measurements with other instruments in the payload. The principal investigator is Luther Beegle, JPL.

    The Mars Oxygen ISRU Experiment (MOXIE), an exploration technology investigation that will produce oxygen from Martian atmospheric carbon dioxide. The principal investigator is Michael Hecht, Massachusetts Institute of Technology, Cambridge, Massachusetts.

    Mars Environmental Dynamics Analyzer (MEDA), a set of sensors that will provide measurements of temperature, wind speed and direction, pressure, relative humidity and dust size and shape. The principal investigator is Jose’ Antonio Rodriguez-Manfredi, Centro de Astrobiologia, Instituto Nacional de Tecnica Aeroespacial, Spain.

    The Radar Imager for Mars’ Subsurface Experiment (RIMFAX), a ground-penetrating radar that will provide centimeter-scale resolution of the geologic structure of the subsurface. The principal investigator is Svein-Erik Hamran, the Norwegian Defence Research Establishment (FFI), Norway.

    “We are excited that NASA’s Space Technology Program is partnered with Human Exploration and the Mars 2020 Rover Team to demonstrate our abilities to harvest the Mars atmosphere and convert its abundant carbon dioxide to pure oxygen,” said James Reuther, deputy associate administrator for programs for the Space Technology Mission Directorate. “This technology demonstration will pave the way for more affordable human missions to Mars where oxygen is needed for life support and rocket propulsion.”

    Instruments developed from the selected proposals will be placed on a rover similar to Curiosity, which has been exploring Mars since 2012. Using a proven landing system and rover chassis design to deliver these new experiments to Mars will ensure mission costs and risks are minimized as much as possible, while still delivering a highly capable rover.

    Curiosity recently completed a Martian year on the surface — 687 Earth days — having accomplished the mission’s main goal of determining whether Mars once offered environmental conditions favorable for microbial life.

    The Mars 2020 rover is part the agency’s Mars Exploration Program, which includes the Opportunity and Curiosity rovers, the Odyssey and Mars Reconnaissance Orbiter spacecraft currently orbiting the planet, and the MAVEN orbiter, which is set to arrive at the Red Planet in September and will study the Martian upper atmosphere.

    NASA Mars Opportunity Rover
    Opportunity

    NASA Mars Odessy Orbiter
    Odyssey

    NASA Mars Reconnaisence Orbiter
    Mars Reconnaissance Orbiter

    NASA Mars MAVEN
    MAVEN

    In 2016, a Mars lander mission called InSight will launch to take the first look into the deep interior of Mars. The agency also is participating in the European Space Agency’s (ESA’s) 2016 and 2018 ExoMars missions, including providing “Electra” telecommunication radios to ESA’s 2016 orbiter and a critical element of the astrobiology instrument on the 2018 ExoMars rover.

    NASA Insight
    Insight

    ESA Mars 2016 Orbiter
    ESA 2016 Mars Orbiter

    ESA ExoMars 2015
    ESA ExoMars

    NASA’s Mars Exploration Program seeks to characterize and understand Mars as a dynamic system, including its present and past environment, climate cycles, geology and biological potential. In parallel, NASA is developing the human spaceflight capabilities needed for future round-trip missions to Mars.

    NASA’s Jet Propulsion Laboratory will build and manage operations of the Mars 2020 rover for the NASA Science Mission Directorate at the agency’s headquarters in Washington.

    For more information about NASA’s Mars programs, visit:

    http://www.nasa.gov/mars

    See the full article here.

    Please help promote STEM in your local schools.

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    The National Aeronautics and Space Administration (NASA) is the agency of the United States government that is responsible for the nation’s civilian space program and for aeronautics and aerospace research.

    President Dwight D. Eisenhower established the National Aeronautics and Space Administration (NASA) in 1958 with a distinctly civilian (rather than military) orientation encouraging peaceful applications in space science. The National Aeronautics and Space Act was passed on July 29, 1958, disestablishing NASA’s predecessor, the National Advisory Committee for Aeronautics (NACA). The new agency became operational on October 1, 1958.

    Since that time, most U.S. space exploration efforts have been led by NASA, including the Apollo moon-landing missions, the Skylab space station, and later the Space Shuttle. Currently, NASA is supporting the International Space Station and is overseeing the development of the Orion Multi-Purpose Crew Vehicle and Commercial Crew vehicles. The agency is also responsible for the Launch Services Program (LSP) which provides oversight of launch operations and countdown management for unmanned NASA launches. Most recently, NASA announced a new Space Launch System that it said would take the agency’s astronauts farther into space than ever before and lay the cornerstone for future human space exploration efforts by the U.S.

    NASA science is focused on better understanding Earth through the Earth Observing System, advancing heliophysics through the efforts of the Science Mission Directorate’s Heliophysics Research Program, exploring bodies throughout the Solar System with advanced robotic missions such as New Horizons, and researching astrophysics topics, such as the Big Bang, through the Great Observatories [Hubble, Chandra, Spitzer, and associated programs. NASA shares data with various national and international organizations such as from the [JAXA]Greenhouse Gases Observing Satellite.

     
  • richardmitnick 10:10 am on December 25, 2014 Permalink | Reply
    Tags: Astrobiology, , , , , ,   

    From astrobio.net: “AstroWomen: Mini Interview with Caroline Freissinet” 

    Astrobiology Magazine

    Astrobiology Magazine

    Dec 25, 2014
    This story comes from Astrobiology Magazine’s AstroWomen blog at: http://www.astrobio.net/astrowomen/. Check out AstroWomen for more important work from women scientists in fields related to the space exploration and planetary science.

    c
    Caroline Freissinet, NASA postdoctoral fellow at the Goddard Spaceflight Center in Greenbelt, MD. Credit: NASA Mars Program

    Caroline Freissinet has been making headlines for her work with the Sample Analysis at Mars (SAM) team on NASA’s Mars Science Laboratory mission. The team recently made an announcement at the 2014 Fall Meeting of the American Geophysical Union concerning the Curiosity rover’s detection of organic molecules on the surface of Mars.

    NASA Mars Sample Curiosity Module
    NASA Mars Sample ANalysis at Mars (SAM) Module

    NASA Mars Curiosity Rover
    Curiosity

    Caroline Freissinet is a postdoctoral researcher in NASA’s Solar System Exploration Division, and works with NASA’s Curiosity rover on Mars. Freissinet is part of the team of scientists who recently used Curiosity’s Sample Analysis at Mars (SAM) instrument to make the first definitive detection of organics on the Mars surface.

    Freissinet is the lead author of a paper concerning Curiosity’s discovery of organics on the surface of Mars that has been submitted to the Journal of Geophysical Research-Planets.

    This mini-interview comes from the SAM Science Team website at NASA’s Goddard Space Flight Center:

    What is your role in the SAM project?

    I’m a chemist, involved in the GC-MS part of SAM, and more specifically in the derivatization experiment, which enables SAM to detect and identify heavy organic molecules such as carboxylic and amino acids in Mars solid samples.

    What about SAM do you find most interesting? Most challenging?

    Most interesting is to see all the different persons, coming from such diverse backgrounds, all working on this same and one project which is SAM. This passionate work of all these people for a unique cause is incredible. Most challenging is to make something work as a whole on Mars when it’s so complex to make each part of it work independently in the lab! Also, every little detail had to be thought carefully because there is nothing possible to add or remove once there, or noone to fix it. You can’t forget anything. It’s far beyond the level of when you are in the field trip and have to work with what you brought only, which is already so much challenging.

    Have you worked on other missions or flight instruments? If so which ones?

    I’ve worked during my PhD on research and technology program applied to the Mars Organic Molecules Analyzer (MOMA) experiment onboard the NASA-ESA joint ExoMars mission.

    What kind/level of education do you have?

    PhD in analytical chemistry which I defended at Ecole Centrale Paris in 2010. My background is in molecular biology, biochemistry and evolutionary biology.

    What are your favorite things to do outside of work?

    Outside of work, I love to be outside of the world, shooting the most remote and inspiring landscapes with my Nikon after endless hikes, vertical rockclimbing, mountain treks and/or backcountry skiing. I travel the world to find such stunning places and adrenaline to get there. I can still bring non-contaminated samples from such remote locations!

    See the full article here.

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  • richardmitnick 3:53 pm on December 22, 2014 Permalink | Reply
    Tags: Astrobiology,   

    From astrobio.net: “Barren Deserts Can Host Complex Ecosystems in Their Soils” 

    Astrobiology Magazine

    Astrobiology Magazine

    Dec 22, 2014
    Adam Hadhazy

    Biological soil crusts” don’t look like much. In fact, people often trample right over these dark, or green-tinted, sometimes raised patches in the desert soil. But these scruffy stretches can house delicate ecosystems as varied and complexly interwoven as that of a lush, tropical rainforest.

    Life forms including bacteria, algae, fungi and lichens, as well as plants such as mosses and liverworts, can band together to create biological soil crusts in dry, nutrient-starved environments. Scientists are just beginning to document the diversity of species that call biological soil crusts home.

    “These are incredibly diverse microbial communities with hundreds of different organisms,” said Jason Raymond, assistant professor in the School of Earth and Space Exploration at Arizona State University. “If you were counting animals in the Amazon, you wouldn’t come close to the diversity of these biological soil crusts.”

    Raymond is the senior author of three new papers in the scientific journal Genome Association, which shed light on the microbes that commonly set up shop in biological soil crusts in Utah’s Moab Desert. The papers present a genome of three different bacteria. These genomes contain genes known to enable certain biological forms and functions. Identifying these genes therefore speaks to the interplay of these bacteria as they eke out a living in their shared, severe environment.

    Figuring out how life thrives in biological soil crusts, in conditions that would fell most other life on the planet, will help in gauging the habitability of other worlds.

    “Biological soil crusts are an outstanding example of nature coping with a really challenging set of environmental conditions,” said Raymond. “We’re pushing as close as we can to extreme environments on other planets.”

    Starved in the desert

    Although the Moab Desert is hot and dry, the biggest challenge for life in its biological soil crusts, as in other such places, is obtaining nutrients — food, essentially. The new studies reveal the array of adaptive tools the microbes possess for ensnaring scarce, vital nutrients and preventing them from leaching away into the environment.

    c
    A picture of Canyonlands National Park near the city of Moab, Utah. Credit: NOAA/NGDC, John Lockridge, Longmont, Colorado

    On a basic level, humans, like all other life, do not need hot dogs to eat or ice tea to drink to survive. When it comes to food and beverage, it boils down to chemical elements. The most basic set of chemical elements life typically needs is summed up by the acronym CHNOPS, made up of the letter signifiers of the elements carbon, hydrogen, nitrogen, oxygen, phosphorus and sulfur. (Complex life, like humans, need a whole bunch of other elements as well, such as selenium and iodine.)

    In the Moab Desert, carbon and nitrogen are two particularly dear elements. In more hospitable habitats, like a grassland in a temperate climate, carbon — organic matter — is readily available from fallen leaves, dead plants and animals, and so on. Nitrogen is “fixed,” or nabbed from the atmosphere by numerous microbes and taken up by plants for subsequent dissemination in the environment. In the Moab, in contrast, not enough plants or animals can survive to keep these two elements widely available for use by other organisms.

    “If you’ve been there or seen pictures, you know how barren that landscape is,” said Raymond. “In terms of fundamental nutrient availability of carbon and nitrogen, these things are tough to get your hands on when you’re in a biological soil crust.”

    Living on the edge

    To get a bead on understanding how the Moab Desert’s microbial critters make do, Raymond and his Arizona State University colleagues obtained samples of biological soil crusts found there. Three microbes grew readily in a growth medium in the lab. The medium, however, was not exactly a smorgasbord. To get by on the available nutrients, the microbes still had to be resourceful and obtain nutrients from the air, such as carbon via carbon dioxide gas, or use one of a small handful of compounds the team supplied in the media.

    b
    A Bacillus species with evident flagella, the whiplike tails many microbes use to move around. Credit: CDC/Dr. William A. Clark/Wikipedia

    “It was a very minimal media,” said Raymond. “If something’s growing on there, you know it’s able to fix carbon and nitrogen out of the atmosphere, or using one of the specifically chosen carbon and nitrogen compounds we add to the media. Either way, these organisms are very efficient recyclers of organic material.”

    After growing the cultures, the scientists sequenced the genes of the organisms present. Three different species in the Microvirga, Bacillus and Massilia genera stood out. The three species are alike in some ways. For instance, all have genes for making structures such as flagella —whiplike tails — to allow them to get closer to areas with favorable nutrient availability. Once there, all three microbes have genes for producing “biofilms,” a tactic of binding together to remain in place.

    Significant differences in their genetic toolkits exist as well. Each bacterium tries to occupy a niche in the biological soil crust community, in partnership or perhaps even at the occasional expense of its neighbors. The Bacillus strain, for instance, has genes for pumping out what are known as siderophores. These molecules bind readily to iron, for instance, another chemical element that many organisms need to survive.

    The Microvirga bacterial strain identified by Raymond and colleagues has genes for sucking up siderophores from the environment, but not for making them. It seems that the Microvirga benefits from the Bacillus going to the trouble of sending out siderophores.

    “The interesting thing is that the Bacillus sends out these little shuttles to hopefully get ahold of iron and bring it back, but there is no guarantee,” said Raymond.

    The Microvirga, in this instance, might well be freeloaders.

    Letting nothing go to waste

    In other ways, the three species coexist peacefully, particularly when there’s no speakable limit to the resource. All three benefit from the general ability to obtain nutrients from the air, which is certainly a “more the merrier” type of situation in a biological soil crust.

    h
    A moss species, called hairless twisted moss, growing as part of a biological soil crust in Utah. The member species of biological soil crusts each play important roles in maintaining the health of the overall community. Credit: NPS/Neal Herbert

    “There is an incredible efficiency in recycling organic matter so that it doesn’t go back into the environment,” noted Raymond.

    On an individual basis, the bacteria can complement each other. The Massilia, for example, fills a niche by apparently being able to survive in oxygen-free, “anaerobic” conditions. That ability suggests it contributes to the overall community’s wellbeing by still retaining nutrients in the shared environment in internal or underground locations sealed off from the outside air.

    “Each microbe has a specialty and they are complementary,” said Raymond.

    Characterizing all three microbes, Raymond said: “They’re sort of the trash compactors of this community. They’ll literally grab ahold of any nutrient-rich sources in the environment and try to metabolize it. That’s a testament to how limited this environment is.”

    The new studies suggest the high degree to which species living in biological soil crusts rely on their neighbors to play respective parts in nutrient fixation, processing, dead member decomposition, and more.

    “Nearly every organism in this community is dependent on some other organism’s waste product or byproduct,” said Raymond.

    Delicate, yet steadfast

    Interdependence at such a high level does leave biological soil crusts vulnerable. Human activity in particular, such as four-wheeling in remote desert environs caked by biological soil crusts, can devastate whole mini-ecosystems, which might take centuries to recover.

    “Any perturbation has the potential to have catastrophic consequences,” said Raymond.

    On the other hand, the ties that bind in biological soil crusts do point, more positively, to how organisms can cooperate to turn a wasteland into an oasis. Environments that scientists would expect to be sterile often astonish us with the lengths to which their denizens go to survive. And as in the case of biological soil crusts, surprising complexity can arise in some of the harshest places.

    e
    An artist’s impression of sunset on an austere exoplanetary landscape, in this case of the super-Earth Gliese 667 Cc. The exoplanet resides in a triple star system and the three suns are visible in the sky. Credit: ESO/L. Calçada

    The same paradigm probably holds true for other worlds with conditions that look abjectly dismal for life.

    “One of the things that constantly surprises me is, wherever people seem to go on the planet, there’s life,” said Raymond. “Anywhere we go on Earth, life has figured out a way to penetrate that niche and take advantage of some aspect of that environment.”

    Accordingly, Raymond thinks that because defining habitability is proving so slippery, astrobiologists might want to take the opposite approach in setting out the parameters of clear inhabitability.

    “We’re trying to find examples of the most extreme environments we can on Earth,” said Raymond. “We’re trying to get into places where biology runs headlong into the inorganic part of the Earth, where any nutrient you want to pick up you’ve got to get from a rock or the atmosphere.”

    Essentially, if life can make it there, in these places on Earth, it might just make it anywhere.

    See the full article here.

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  • richardmitnick 6:43 am on December 21, 2014 Permalink | Reply
    Tags: Astrobiology, ,   

    From astrobio.net: “Asteroid that wiped out dinosaurs may have nearly knocked off mammals, too” 

    Astrobiology Magazine

    Astrobiology Magazine

    Dec 20, 2014
    Source: Pensoft Publishers

    The extinction of the dinosaurs 66 million years ago is thought to have paved the way for mammals to dominate, but a new study shows that many mammals died off alongside the dinosaurs.

    Metatherian mammals–the extinct relatives of living marsupials (“mammals with pouches”, such as opossums) thrived in the shadow of the dinosaurs during the Cretaceous period. The new study, by an international team of experts on mammal evolution and mass extinctions, shows that these once-abundant mammals nearly followed the dinosaurs into oblivion.

    mm
    Part of skeleton of Lycopsis longirostris, a fossil marsupial
    Lycopsis is an extinct genus of South American metatherian, that lived during the Miocene.

    When a 10-km-wide asteroid struck what is now Mexico at the end of the Cretaceous and unleashed a global cataclysm of environmental destruction, some two-thirds of all metatherians living in North America perished. This includes more than 90% of species living in the northern Great Plains of the USA, the best area in the world for preserving latest Cretaceous mammal fossils.

    d
    This diagram is showing how severely metatherian mammals were affected when an asteroid hit Earth at the end of the Cretaceous, 66 million years ago. In North America, the number of metatherian species dropped from twenty species within the last million years of the Cretaceous Period, to just three species in the first million years of the Paleogene Period. Credit: Dr Thomas Williamson

    In the aftermath of the mass extinction, metatherians would never recover their previous diversity, which is why marsupial mammals are rare today and largely restricted to unusual environments in Australia and South America.

    Taking advantage of the metatherian demise were the placental mammals: species that give live birth to well-developed young. They are ubiquitous across the globe today and include everything from mice to men.

    Dr. Thomas Williamson of the New Mexico Museum of Natural History and Science, lead author on the study, said: “This is a new twist on a classic story. It wasn’t only that dinosaurs died out, providing an opportunity for mammals to reign, but that many types of mammals, such as most metatherians, died out too – this allowed advanced placental mammals to rise to dominance.”

    Dr. Steve Brusatte of the University of Edinburgh‘s School of GeoSciences, an author on the report, said: “The classic tale is that dinosaurs died out and mammals, which had been waiting in the wings for over 100 million years, then finally had their chance. But our study shows that many mammals came perilously close to extinction. If a few lucky species didn’t make it through, then mammals may have gone the way of the dinosaurs and we wouldn’t be here.”

    Dr. Gregory Wilson of the University of Washington also took part in the study.

    The new study is published in the open access journal ZooKeys. It reviews the Cretaceous evolutionary history of metatherians and provides the most up-to-date family tree for these mammals based on the latest fossil records, which allowed researchers to study extinction patterns in unprecedented detail.

    See the full article here.

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