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  • richardmitnick 4:43 pm on March 1, 2017 Permalink | Reply
    Tags: 3.77-billion-year-old fossils stake new claim to oldest evidence of life, Astrobiology, , , , , Hydrothermal vents, , ,   

    From Science: “3.77-billion-year-old fossils stake new claim to oldest evidence of life” 

    AAAS
    Science Magazine

    Mar. 1, 2017
    Carolyn Gramling

    1
    These tubelike structures, formed of an iron ore called hematite, may be microfossils of 3.77-billion-year-old life at ancient hydrothermal vents.

    Life on Earth may have originated in the sunless depths of the ocean rather than shallow seas. In a new study, scientists studying 3.77-billion-year-old rocks have found tubelike fossils similar to structures found at hydrothermal vents, which host thriving biological communities. That would make them more than 300 million years older than the most ancient signs of life on Earth—fossilized microbial mats called stromatolites that grew in shallow seas. Other scientists are skeptical about the new claims.

    “The authors offer a convincing set of observations that could signify life,” says Kurt Konhauser, a geomicrobiologist at the University of Alberta in Edmonton, Canada, who was not involved in the study. But “at present, I do not see a way in which we will definitively prove ancient life at 3.8 billion years ago.”

    When life first emerged on Earth has been an enduring and frustrating mystery. The planet is 4.55 billion years old, but thanks to plate tectonics and the constant recycling of Earth’s crust, only a handful of rock outcrops remain that are older than 3 billion years, including 3.7-billion-year-old formations in Greenland’s Isua Greenstone Belt. And these rocks tend to be twisted up and chemically altered by heat and pressure, making it devilishly difficult to detect unequivocal signs of life.

    “It’s a challenge in rocks that have been this messed up,” says Abigail Allwood, a geologist with NASA’s Jet Propulsion Laboratory in Pasadena, California, who was also not involved in the study. “There’s only so much you can do with them.”

    Nevertheless, researchers have searched through these most ancient rocks for structural or chemical relics that may have lingered. Last year, for example, scientists reported identifying odd reddish peaks in 3.7-billion-year-old rocks in Greenland that may be the product of stromatolites, though many doubted that interpretation. The best evidence for these fossilized algal mats comes from 3.4-billion-year-old rocks in Australia, generally thought of as the strongest evidence for early life on Earth.

    But some scientists think ocean life may have begun earlier—and deeper. In the modern ocean, life thrives in and around the vents that form near seafloor spreading ridges or subduction zones—places where Earth’s tectonic plates are pulling apart or grinding together. The vents spew seawater, superheated by magma in the ocean crust and laden with metal minerals such as iron sulfide. As the water cools, the metals settle out, forming towering spires and chimneys. The mysterious ecosystem that inhabits this sunless, harsh environment includes bacteria and giant tube worms that don’t derive energy from photosynthesis. Such hardy communities, scientists have suggested, may not only have thrived on early Earth, but may also be an analog for life on other planets.

    Now, a team led by geochemist Dominic Papineau of University College London and his Ph.D. student Matthew Dodd says it has found clear evidence of such ancient vent life. The clues come from ancient rocks in northern Quebec in Canada that are at least 3.77 billion years old and may be even older than 4 billion years. Dodd examined hair-thin slices of rock from this formation and found intriguing features: tiny tubes composed of an iron oxide called hematite, as well as filaments of hematite that branch out and sometimes terminate into large knobs.

    Filaments and tubes are common features in more recent fossils that are attributed to the activity of iron-oxidizing bacteria at seafloor hydrothermal vents. Papineau was initially skeptical. However, he says, “within a year [Dodd] had found so much compelling evidence that I was convinced.”

    The team also identified carbonate “rosettes,” tiny concentric rings that contain traces of life’s building blocks including carbon, calcium, and phosphorus; and tiny, round granules of graphite, a form of carbon. Such rosettes and granules had been observed previously in rocks of similar age, but whether they are biological in origin is hotly debated. The rosettes can form nonbiologically from a series of chemical reactions, but Papineau says the rosettes in the new study contain a calcium phosphate mineral called apatite, which strongly suggests the presence of microorganisms. The graphite granules may represent part of a complicated chemical chain reaction mediated by the bacteria, he says. Taken together, the structures and their chemistry point to a biological origin near a submarine hydrothermal vent, the team reports online today in Nature. That would make them among the oldest signs of life on Earth—and, depending on the actual age of the rocks, possibly the oldest.

    That doesn’t necessarily mean that life originated in deep waters rather than in shallow seas, Papineau says. “It’s not necessarily mutually exclusive—if we are ready to accept the fact that life diversified very early.” Both the iron-oxidizing bacteria and the photosynthetic cyanobacteria that build stromatolite mats could have evolved from an earlier ancestor, he says.

    But researchers like Konhauser remain skeptical of the paper’s conclusion. For example, he says, the observed hematite tubes and filaments are similar to structures associated with iron-oxidizing bacteria, “but of course that does not mean the [3.77-] billion-year-old structures are cells.” Moreover, he notes, if the tubes were formed by iron-oxidizing bacteria, they would need oxygen, in short supply at this early moment in Earth’s history. It implies that photosynthetic bacteria were already around to produce it. But it’s still unclear how oxygen would get down to the depths of early Earth’s ocean. The cyanobacteria that make stromatolites, on the other hand, make oxygen rather than consume it.

    The new paper makes “a more detailed case than has been presented previously,” Allwood says. Most previous reports of possible signs of life older than about 3.5 billion years have been questioned, she adds—not because life didn’t exist, but because it’s just so difficult to prove the further back in time you go in the rock record. “There’s still quite a bit of room for doubt.”

    See the full article here .

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  • richardmitnick 9:00 pm on February 15, 2017 Permalink | Reply
    Tags: Aromawa Shields, Astrobiology, ,   

    From UCLA: Women in STEM – “Astrobiology’s rising star” Aromawa Shields 

    UCLA bloc

    UCLA

    February 14, 2017
    Nicole Freeling

    1
    Aromawa Shields has used her acting ability to communicate complex science to audiences. Coutesy of TED Talks

    Aomawa Shields studies the climate on distant planets. Her aim: to find those most likely to host alien life. The astrobiologist is a National Science Foundation astronomy and astrophysics postdoctoral fellow working in UCLA’s department of physics and astronomy.

    But she was also an actress with an M.F.A. from UCLA’s School of Theater, Film and Television That’s given her a secret “superpower” that’s helped her make science accessible, a talent that’s attracted nearly 1.5 million views of her engaging TED talk on her search for other life forms in the universe.

    “I’m an African-American female astronomer and a classically trained actress who loves to wear makeup and read fashion magazines. So I am uniquely positioned to appreciate contradictions in nature,” she said in her TED talk, laughing, “and how they can inform our search for the next planet where life exists.”

    In July, Shields starts a new job, as the Clare Boothe Luce Assistant Professor at UC Irvine. A participant in the University of California President’s Postdoctoral Fellowship Program, she is among 24 fellows newly hired by UC campuses this year. The program, which prepares outstanding Ph.D.s for faculty careers, has been lauded as a national model for expanding faculty diversity.

    She talked to Nicole Freeling of the UC Office of the President about her unusual career path, the search for E.T. and her efforts to groom a new generation of star scientists by mentoring middle school girls in an organization she founded, Rising Stargirls.

    What is astrobiology, and how does your work fit in?

    Astrobiology is the study of life in the universe: how it got started on this planet, how it has evolved over time and how widely distributed it might be elsewhere.
    The way I come to the question of “Are we alone?” is to find planets that might have environments suitable for life to develop and sustain itself.

    I use climate models of all different types — most recently, ones that are three-dimensional — to look at the collaboration between surface, atmosphere and incoming starlight and how those interactions affect the climate of a planet.

    Say, there was a habitability pageant for planets. You wouldn’t want to select those that would only be warm enough for surface water under very specific conditions. You’d want planets that could be warm enough for liquid water over a wide range of atmospheres, orbits and surfaces.

    Our goal is to generate a list of planets that are most likely to succeed in the habitability category. That can tell us where to point our telescopes.

    What planets are at the top of your list now?

    A planet was discovered just a few months ago called Proxima Centauri b. That one is particularly exciting because it is orbiting the closest star system to us — just 4.2 light years away.

    It’s in the habitable zone — the region around the star where you might expect the planet to be warm enough to have water on its surface. But as my work has highlighted, just because a planet is in a star’s habitable zone, that doesn’t make it habitable — and just because it’s habitable doesn’t mean it’s inhabited.

    How did you first get interested in this question of “Are we alone?”

    I started looking up at the stars when I was 12, when my seventh grade class watched the movie “Space Camp” about this group of kids who were launched into space.

    Up until that point, I wanted to be a ton of things — a Dallas Cowboys cheerleader, a secretary, an orthopedist. But it wasn’t until seeing this movie that I was, like, that’s it. And, unlike the other aspirations, this one never really went away.

    Your career wasn’t exactly linear, though. You took a decade off from astronomy to earn an M.F.A. from UCLA and work as a professional actress. What led you down that path, and how has it influenced your career as a scientist?

    At first, when I was in college, it seemed that science wasn’t all I thought it was cracked up to be. I was very focused on problem sets and exams, and I forgot the bigger picture: that those are the things you have to get through before you can get to the exciting stuff, which is research.

    Science, as I came to find out, is a very creative endeavor. But at the time I felt like science was over here, and my creative life was over there — and that creative life was just so much more fun.

    It took me a long time to feel connected to what I created as a scientist, rather than detached from it. [But] eventually, I came back to the field. I realized that this was what I was supposed to be doing.

    And it finally occurred to me in grad school that this non-traditional background, which I thought had been an Achilles’ heel, was actually a superpower. It allowed me to communicate the impact of my science the way some other classmates and scientists had trouble doing.

    When you’re not looking for life on other planets, you run Rising Stargirls, a program that uses creative arts to inspire middle school girls to explore the stars. What interested you in mentoring young girls, and why use art as a path to science?

    There was always this feeling that I had to be a certain type of scientist. There were parts of myself that I felt I had to downplay — whether it was by wearing subdued clothes, not wearing makeup, looking very stereotypically masculine, not displaying emotion.

    I don’t believe that anymore.

    I want young girls, especially girls of color and especially middle school-age girls — to understand they can bring all of themselves into their interest in science.

    Art, writing and theater, which are more readily accepted as being personal, can be a gateway to help girls be personally invested in what they’re learning.

    As a woman of color, as well as a returning graduate student, what helped you succeed in a field where you were often something of the odd one out?

    In one word: mentors. The people who answered my questions by sitting down with me for 15 minutes or an hour; who gave me tips, feedback, lessons learned, things they wish they’d known; who helped me negotiate for things I needed to bring my vision to my institution.

    I adopted this attitude of: Whoever has done what I want to do, I’m going to go ask them how they did it. And if they don’t want to share that with me, that’s fine. I’ll go and ask someone else.

    In my experience, pretty much everyone I’ve asked for help has provided it, in whatever way they could spare. And it’s led to a series of successes that have put me in the position I am today.

    The President’s Postdoctoral Fellowship Program is part of that. If I trace back what I know now about how to be a successful researcher, PPFP played a crucial role in my development.

    You write in your blog, Variable Stargirl, about your struggles with imposter syndrome and the feeling of “Is this me, can I do this?” Talk about what imposter syndrome is and how you dealt with it?

    I used to think that I was the only person who suffered from it. I remember a lecturer at a workshop asking if anyone had experienced imposter syndrome, and everyone raised a hand — including professors who were white males. It’s more of a wide-ranging phenomenon in academia than I would have ever anticipated.

    But at least for me, as someone who comes from a community that has historically been marginalized — both as a woman and as an African-American — the propensity to be susceptible to imposter syndrome is especially acute. And, as an older, returning student, I had this feeling that, “Oh my gosh. Everyone who is 20-something has the jump on me. They remember more. They were just in physics courses two months ago, and for me it’s been 11 years.”

    As scientists, evidence is what we value most highly. It’s about following what the data say, not letting preconceived notions dictate your conclusion.

    I’ve had to take an active role in looking at the evidence. I’m a visual person, so actually being able to read the email that said, “You passed your qualifying exam” or looking at the 4.0 that I got in extragalactic astronomy — those things helped me to retrain my mind.

    What that’s done for me is to take those old voices saying, “Everyone else but you is a part of this field,” or “You can’t do it,” and dial the volume way down — so that it’s chatter in the background as opposed to it becoming an obstacle to proceeding with one’s day or one’s academic career.

    Any parting words of advice for aspiring scientists?

    My personal mantra is it’s never too late. The “shoulds” can be debilitating. If possible, I’d say eliminate that word from your vocabulary. It’s about: What do you want now, and who has it? And what can you do to get it too?

    See the full article here .

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    UC LA Campus

    For nearly 100 years, UCLA has been a pioneer, persevering through impossibility, turning the futile into the attainable.

    We doubt the critics, reject the status quo and see opportunity in dissatisfaction. Our campus, faculty and students are driven by optimism. It is not naïve; it is essential. And it has fueled every accomplishment, allowing us to redefine what’s possible, time after time.

    This can-do perspective has brought us 12 Nobel Prizes, 12 Rhodes Scholarships, more NCAA titles than any university and more Olympic medals than most nations. Our faculty and alumni helped create the Internet and pioneered reverse osmosis. And more than 100 companies have been created based on technology developed at UCLA.

     
  • richardmitnick 10:46 am on January 5, 2017 Permalink | Reply
    Tags: Astrobiology, , , , , , The Search for Extraterrestrial Genomes or SETG   

    From Many Worlds: “In Search of Panspermia” 

    NASA NExSS bloc

    NASA NExSS

    Many Worlds

    Many Words icon

    2017-01-05
    Marc Kaufman

    1
    This image is from the NASA Remote Sensing Tutorial. NASA

    When scientists approach the question of how life began on Earth, or elsewhere, their efforts generally involve attempts to understand how non-biological molecules bonded, became increasingly complex, and eventually reached the point where they could replicate or could use sources of energy to make things happen. Ultimately, of course, life needed both.

    Researchers have been working for some time to understand this very long and winding process, and some have sought to make synthetic life out of selected components and energy. Some startling progress has been made in both of these endeavors, but many unexplained mysteries remain at the heart of the processes. And nobody is expecting the origin of life on Earth (or elsewhere) to be fully understood anytime soon.

    To further complicate the picture, the history of early Earth is one of extreme heat caused by meteorite bombardment and, most important, the enormous impact some 4.5 billion years of the Mars-sized planet that became our moon. As a result, many early Earth researchers think the planet was uninhabitable until about 4 billion years ago.

    Yet some argue that signs of Earth life 3.8 billion years ago have been detected in the rock record, and lifeforms were certainly present 3.5 billion years ago. Considering the painfully slow pace of early evolution — the planet, after all, supported only single-cell life for several billion years before multicellular life emerged — some researchers are skeptical about the likelihood of DNA-based life evolving in the relatively short window between when Earth became cool enough to support life and the earliest evidence of actual life.

    1
    A DNA helix animation. Life on Earth is based on DNA, and some researchers have been working on ways to determine whether DNA life also exists on Mars or elsewhere in the solar system. No image credit.

    So what else, from a scientific as opposed to a religious perspective, might have set into motion the process that made life out of non-life?

    A team of prominent scientists at MIT and Harvard are sufficiently convinced in the plausibility of panspermia that they have spent a decade, and a fair amount of NASA and other funding, to design and produce an instrument that can be sent to Mars and potentially detect DNA or more primitive RNA.

    In other words, life not only similar to that on Earth, but actually delivered long ago from Earth. It’s called the The Search for Extraterrestrial Genomes, or SETG.

    Gary Ruvkun is one of those researchers, a pioneering molecular biologist at Massachusetts General Hospital and professor of genetics at Harvard Medical School.

    I heard him speaking recently at a Space Sciences Board workshop on biosignatures, where he described the real (if slim) possibility that DNA or RNA-based life exists now on Mars, and the instrument that the SETG group is developing to detect it should it be there.

    The logic of panspermia — or perhaps “dispermia” if between but two planets — is pretty straight-forward, though with some significant question marks. Both Earth and Mars, it is well known, were pummeled by incoming meteorites in their earlier epochs, and those impacts are known to have sufficient force to send rock from the crash site into orbit.

    Mars meteorites have been found on Earth, and Earth meteorites no doubt have landed on Mars. Ruvkun said that recent work on the capacity of dormant microbes to survive the long, frigid and irradiated trip from planet to planet has been increasingly supportive.

    “Earth is filled with life in every nook and cranny, and that life is wildly diverse,” he told the workshop. “So if you’re looking for life on Mars, surely the first thing to look for is life like we find on Earth. Frankly, it would be kind of stupid not to.”

    The instrument being developed by the group, which is led by Ruvkun and Maria Zuber, MIT vice president for research and head of the Department of Earth, Atmospheric and Planetary Sciences. It would potentially be part of a lander or rover science package and would search DNA or RNA, using techniques based on the exploding knowledge of earthly genomics.

    The job is made easier, Ruvkun said, by the fact that the basic structure of DNA is the same throughout biology. What’s more, he said, there about 400 specific genes sequences “that make up the core of biology — they’re found in everything from extremeophiles and bacteria to worms and humans.”

    Those ubiquitous gene sequences, he said, were present more than 3 billion years ago in seemingly primitive lifeforms that were, in fact, not primitive at all. Rather, they had perfected some genetic pathways that were so good that they still used by most everything alive today.

    And how was it that these sophisticated life processes emerged not all that long (in astronomical or geological terms) after Earth cooled enough to be habitable? “Either life developed here super-fast or it came full-on as DNA life from afar,” Ruvkun said. It’s pretty clear which option he supports.

    Ruvkun said that the rest of the SETG team sees that kind of inter-planetary transfer — to Mars and from Mars — as entirely plausible, and that he takes panspermia a step forward. He thinks it’s possible, though certainly not likely nor remotely provable today, that life has been around in the cosmos for as long as 10 billion years, jumping from one solar system and planet to another. Not likely, but at idea worth entertaining.

    Maria Zuber of MIT, who was the PI for the recent NASA GRAIL mission to the moon, has been part of the SETG team since near its inception, and MIT research scientist Christopher Carr is the project manager. Zuber said it was a rather low-profile effort at the start, but over the years has attracted many students and has won NASA funding three times including the currently running Maturation of Instruments for Solar System Exploration (MatISSE) grant.

    “I have made my career out of doing simple experiments. if want to look for life beyond earth helps to know what you’re looking for.

    “We happen to know what life on Earth is like– DNA based or possibly RNA-based as Gary is looking for as well. The point is that we know what to look for. There are so many possibilities of what life beyond Earth could be like that we might as well test the hypothesis that it, also, is DNA based. It’s a low probability result, but potentially very high value.”

    DNA sequencing instruments like the one her team is developing are taken to the field regularly by thousands of researchers, including some working with with SETG. The technology has advanced so quickly that they can pick up a sample in a marsh or desert or any extreme locale and on the spot determine what DNA is present. That’s quite a change from the pain-staking sequencing done painstakingly by graduate students not that long ago.

    Panspermia, Zuber acknowledged, is a rather improbable idea. But when nature is concerned, she said “I’m reticent to say anything is impossible. After all, the universe is made up of the same elements as those on Earth, and so there’s a basic commonality.”

    Zuber said the instrument was not ready to compete for a spot on the 2020 mission to Mars, but she expects to have a sufficiently developed one ready to compete for a spot on the next Mars mission. Or perhaps on missions to Europa or the plumes of Enceladus.

    he possibility of life skipping from planet to planet clearly fascinates both scientists and the public. You may recall the excitement in the mid 1990s over the Martian meteorite ALH84001, which NASA researchers concluded contained remnants of Martian life. (That claim has since been largely refuted.)

    Of the roughly 61,000 meteorites found on Earth, only 134 were deemed to be Martian as of two years ago. But how many have sunk into oceans or lakes, or been lost in the omnipresence of life on Earth? Not surprisingly, the two spots that have yielded the most meteorites from Mars are Antarctica and the deserts of north Africa.

    And when thinking of panspermia, it’s worthwhile to consider the enormous amount of money and time put into keeping Earthly microbes from inadvertently hitching a ride to Mars or other planets and moons as part of a NASA mission.

    The NASA office of planetary protection has the goal of ensuring, as much as possible, that other celestial bodies don’t get contaminated with our biology. Inherent in that concern is the conclusion that our microbes could survive in deep space, could survive the scalding entry to another planet, and could possibly survive on the planet’s surface today. In other words, that panspermia (or dispermia) is in some circumstances possible.

    Testing whether a spacecraft has brought Earth life to Mars is actually another role that the SETG instrument could play. If a sample tested on Mars comes back with a DNA signature result exactly like one on Earth–rather one that might have come initially from Earth and then evolved over billions of years– then scientists will know that particular bit of biology was indeed a stowaway from Earth.

    Rather like how a very hardy microbe inside a meteorite might have possibly traveled long ago.

    See the full article here .

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    About Many Worlds

    There are many worlds out there waiting to fire your imagination.

    Marc Kaufman is an experienced journalist, having spent three decades at The Washington Post and The Philadelphia Inquirer, and is the author of two books on searching for life and planetary habitability. While the “Many Worlds” column is supported by the Lunar Planetary Institute/USRA and informed by NASA’s NExSS initiative, any opinions expressed are the author’s alone.

    This site is for everyone interested in the burgeoning field of exoplanet detection and research, from the general public to scientists in the field. It will present columns, news stories and in-depth features, as well as the work of guest writers.

    About NExSS

    The Nexus for Exoplanet System Science (NExSS) is a NASA research coordination network dedicated to the study of planetary habitability. The goals of NExSS are to investigate the diversity of exoplanets and to learn how their history, geology, and climate interact to create the conditions for life. NExSS investigators also strive to put planets into an architectural context — as solar systems built over the eons through dynamical processes and sculpted by stars. Based on our understanding of our own solar system and habitable planet Earth, researchers in the network aim to identify where habitable niches are most likely to occur, which planets are most likely to be habitable. Leveraging current NASA investments in research and missions, NExSS will accelerate the discovery and characterization of other potentially life-bearing worlds in the galaxy, using a systems science approach.
    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 8:18 pm on December 20, 2016 Permalink | Reply
    Tags: 2015 Axial Seamount eruption, Astrobiology, , Plumes of water,   

    From SA: “Plumes Spotted on Europa Suggest Easy Access to Water” 

    Scientific American

    Scientific American

    12.13.16
    Lee Billings

    1
    Credit: COURTESY OF NASA, ESA AND KURT RETHERFORD Southwest Research Institute

    An ocean within Jupiter’s icy moon Europa may be intermittently venting plumes of water vapor into outer space, according to a new study in the Astrophysical Journal. The finding suggests the ocean, thought to lie underneath perhaps 100 kilometers of ice, may be more amenable to life—and more accessible to curious astrobiologists—than previously thought. “If there are plumes emerging from Europa, it is significant because it means we may be able to explore that ocean for organic chemistry or even signs of life without having to drill through unknown miles of ice,” says study lead William Sparks, an astronomer at the Space Telescope Science Institute. The plumes would also suggest a potent source of heat lurking within Europa that could sustain living things.

    With the help of the Hubble Space Telescope’s imaging spectrograph, Sparks and his team observed Europa 10 times between late 2013 and early 2015 as it crossed the face of Jupiter. Watching in ultraviolet light, in which Europa’s icy surface appears dark, they looked for silhouettes of any plumes contrasted against Jupiter’s bright, smooth cloudscapes. Intensive image processing unveiled what looked like three instances of ultraviolet shadows soaring over the southern edge of Europa’s dark bulk. If the shadows were produced by plumes and not glitches in Hubble’s instruments, they would collectively contain an estimated few million kilograms of water and reach about 200 kilometers above Europa’s surface.

    Sparks acknowledges that his team’s results remain frustratingly hazy. “These observations are at the limit of what Hubble can do,” he says. “We do not claim to have proven the existence of plumes but rather to have contributed evidence that such activity may be present.” Previous evidence of similar plumes was reported in 2014 in Science, but after follow-up observations, those water vapor spouts seemed to have stopped—or were not there in the first place. In that regard, “this [new observation] is exactly as likely as the last detections” to be real, says Britney Schmidt, who is a planetary scientist at the Georgia Institute of Technology and was not involved with the research.

    Such caution is justified—the presence (or absence) of Europa’s plumes could profoundly alter the future of interplanetary exploration, redirecting billions of dollars in funding toward new exploratory missions. NASA and the European Space Agency already aim to lead missions to the tantalizing Jovian moon in the 2020s.

    Science paper:
    Seismic constraints on caldera dynamics from the 2015 Axial Seamount eruption, Science

    See the full article here .

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    Scientific American, the oldest continuously published magazine in the U.S., has been bringing its readers unique insights about developments in science and technology for more than 160 years.

     
  • richardmitnick 1:20 pm on December 10, 2016 Permalink | Reply
    Tags: , , Astrobiology, L2 Puppis, Will Earth still exist 5 billion years from now?   

    From astrobio.net: “Will Earth still exist 5 billion years from now?” 

    Astrobiology Magazine

    Astrobiology Magazine

    Dec 9, 2016
    No writer credit found

    1
    Composite view of L2 Puppis in visible light | © P. Kervella et al. (CNRS/U. de Chile/Observatoire de Paris/LESIA/ESO/ALMA)

    What will happen to Earth when, in a few billion years’ time, the Sun is a hundred times bigger than it is today? Using the most powerful radio telescope in the world, an international team of astronomers has set out to look for answers in the star L2 Puppis.

    3
    L2 Puppis http://www.surastronomico.com/variable-10-l2-puppis.html

    Five billion years ago, this star was very similar to the Sun as it is today.

    “Five billion years from now, the Sun will have grown into a red giant star, more than a hundred times larger than its current size,” says Professor Leen Decin from the KU Leuven Institute of Astronomy. “It will also experience an intense mass loss through a very strong stellar wind. The end product of its evolution, 7 billion years from now, will be a tiny white dwarf star. This will be about the size of the Earth, but much heavier: one tea spoon of white dwarf material weighs about 5 tons.”

    This metamorphosis will have a dramatic impact on the planets of our Solar System. Mercury and Venus, for instance, will be engulfed in the giant star and destroyed.

    “But the fate of the Earth is still uncertain,” continues Decin. “We already know that our Sun will be bigger and brighter, so that it will probably destroy any form of life on our planet. But will the Earth’s rocky core survive the red giant phase and continue orbiting the white dwarf?”

    2
    ALMA is the world’s largest observatory at millimetre wavelengths. It is installed on the high-altitude plateau of Chajnantor in the Atacama desert (Chile). It consists of 66 individual radio antennas used jointly to synthesize a giant virtual telescope of 16 km in diameter. Credit: ALMA (ESO/NAOJ/NRAO)

    To answer this question, an international team of astronomers observed the evolved star L2 Puppis. This star is 208 light years away from Earth – which, in astronomy terms, means nearby. The researchers used the ALMA radio telescope, which consists of 66 individual radio antennas that together form a giant virtual telescope with a 16-kilometre diameter.

    “We discovered that L2 Puppis is about 10 billion years old,” says Ward Homan from the KU Leuven Institute of Astronomy. “Five billion years ago, the star was an almost perfect twin of our Sun as it is today, with the same mass. One third of this mass was lost during the evolution of the star. The same will happen with our Sun in the very distant future.”

    300 million kilometres from L2 Puppis – or twice the distance between the Sun and the Earth – the researchers detected an object orbiting the giant star. In all likelihood, this is a planet that offers a unique preview of our Earth five billion years from now.

    A deeper understanding of the interactions between L2 Puppis and its planet will yield valuable information on the final evolution of the Sun and its impact on the planets in our Solar System. Whether the Earth will eventually survive the Sun or be destroyed is still uncertain. L2 Puppis may be the key to answering this question.

    See the full article here .

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  • richardmitnick 2:41 pm on December 9, 2016 Permalink | Reply
    Tags: Astrobiology, , , Could these Earth fossils give clues to life in outer space?,   

    From Astronomy: “Could these Earth fossils give clues to life in outer space?” 

    Astronomy magazine

    astronomy.com

    December 08, 2016
    Stephanie Margaret Bucklin

    1
    One of the largest concentrations of Riftia pachyptila observed, with anemones and mussels colonizing in close proximity.
    WikiMedia Commons

    It’s no secret that life on other planets may look very different than life on Earth. But could extremophiles—those organisms that live in the most extreme environments on earth, including hydrothermal vents and inside Earth’s crust—provide some clues about the life that we might expect to find in space?

    The answer may be yes: such organisms, some scientists say, may help us understand the rich variety of life that we could expect to find elsewhere in space.

    “Research that expands our knowledge of the environmental limits of life is indispensable as a strategic element of astrobiological exploration,” said Jack Farmer, Professor of Geobiology at Arizona State University and a participating scientist on the Mars Exploration Rover mission.

    One such research study published in Geology provides some intriguing clues as to just what this bacteria could look like. A team of scientists from the University of Cincinnati discovered fossils in two separate locations that appear to be somewhere between 2.5 and 3.5 billion years old, from the Archean Eon. The fossils, found in the Northern Cape Province of South Africa, are the oldest sulfur-oxidizing bacteria (bacteria that are able to derive energy by oxidizing hydrogen sulfide into sulfur) that have thus been found, and likely lived in a deep-water environment containing little to no oxygen.

    The bacteria likely lived at a time when the atmosphere on Earth had oxygen levels of less than 1 percent—and less than one-thousandth of one percent of what they are today, according to a press release on the study. While the bacteria are much larger than most modern bacteria, they are similar to some single-celled organisms that live in sulfur-rich parts of the deep ocean today.

    “These are some of the largest fossil cells ever found in the Archean Eon,” Andrew Czaja, assistant professor at the University of Cincinnati in the Department of Geology and the first author of the paper, told Astronomy. “Only a couple of other examples of deep marine fossil microorganisms have been reported from any time in the geologic record.”

    The study, Czaja added, could help expand the types of environments in which we can find evidence of past life. Czaja said research into extremophiles in general gives scientists confidence that life can exist anywhere where the appropriate building blocks, including a liquid medium (such as water) and a source of energy, exist.

    “Every time we find evidence of life in a new type of environment on Earth, we increase our confidence in finding life on another planet,” Czaja told Astronomy.

    Another use of extremophile research? Helping scientists figure out where, exactly, to search for life on other planets: Czaja noted that studies like his own could help scientists select a landing site for future space missions.

    Farmer agrees: when seeking life on other planets, he told Astronomy, we tend to “follow habitability,” meaning that we seek zones where the basic requirements for life are met, which is informed by our prior knowledge of what the environmental limits of life are.

    “When paleontologists go to South Africa and explore for an Archean fossil record, they are essentially going to another planet—the early Earth,” Farmer said. What we learn there then informs our strategies on how we look for life on other planets, especially fossil records on other planets.

    One such mission? NASA’s next Mars rover, which NASA will send to space in 2020 in order to search for the biosignatures of life, Farmer said. According to a press release on the mission, the rover will investigate a specific region of Mars that may, at one point in the ancient past, have had favorable conditions for microbial life.

    Still, not all scientists are confident that such extremophiles may provide clues about life on other planets. Malcolm Walter, professor of astrobiology at the University of New South Wales in Sydney and the director of the Australian Center for Astrobiology, told Astronomy that information about extremophiles on Earth does not change his own views about the life we might expect to find on other planets.

    “It gets very speculative,” Walter said. “We know so little about environments of planets beyond our solar system.” Since, Walter continued, we only have one sample of life—life on Earth—it’s difficult to predict what types of organisms we might encounter in space.

    Interestingly, though, Walter noted that in our own solar system, some rocks can get blasted off from one planet and land on another, potentially even carrying microbial life with them.

    Thus, it’s possible that the life we find in space may be very similar to our own, if it shares a single source. Additional research and exploration may shed more light on these possibilities.

    See the full article here .

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  • richardmitnick 11:32 am on October 7, 2016 Permalink | Reply
    Tags: Alternative Earths project, Astrobiology, , , , NASA Astrobiology Institute (NAI)   

    From Many Worlds: “One Planet, But Many Different Earths” 

    NASA NExSS bloc

    NASA NExSS

    Many Worlds

    Many Words icon

    2016-10-07
    Marc Kaufman

    1
    Artist conception of early Earth. (NASA/JPL-Caltech)

    We all know that life has not been found so far on any planet beyond Earth — at least not yet. This lack of discovery of extraterrestrial life has long been used as a knock on the field of astrobiology and has sometimes been put forward as a measure of Earth’s uniqueness.

    But the more recent explosion in exoplanet discoveries and the next-stage efforts to characterize their atmospheres and determine their habitability has led to rethinking about how to understand the lessons of life of Earth.

    Because when seen from the perspective of scientists working to understand what might constitute an exoplanet that can sustain life, Earth is a frequent model but hardly a stationary or singular one. Rather, our 4.5 billion year history — and especially the almost four billion years when life is believed to have been present — tells many different stories.

    For example, our atmosphere is now oxygen-rich, but for billions of years had very little of that compound most associated with complex life. And yet life existed.

    The same with temperature. Earth went through snowball or slushball periods when most of the planet’s surface was frozen over. Hardly a good candidate for life, and yet the planet remained habitable and inhabited.

    And in its early days, Earth had a very weak magnetic field and was receiving only 70 to 80 percent as much energy from the sun as it does today. Yet it supported life.

    “It’s often said that there’s an N of one in terms of life detected in the universe,” that there is but one example, said Timothy Lyons, a biogeochemist and distinguished professor at University of California, Riverside.

    “But when you look at the conditions on Earth over billion of years, it’s pretty clear that the planet had very different kinds of atmospheres and oceans, very different climate regimes, very different luminosity coming from the sun. Yet we know there was life under all those very different conditions.

    “It’s one planet, but it’s silly to think of it as one planetary regime. Each of our past chapters is a potential exoplanet.”

    2
    A particularly extreme phase of our planet’s history is called the “Snowball Earth” period. During these episodes, the Earth’s surface was entirely or largely covered by ice for millions of years, stretching from the poles to the tropics. One such freezing happened over 700 to 800 million years ago in the Pre-Cambrian, around the time that animals appeared. Others are now thought to have occurred much further back in time. They varied in duration and extent but during a full-on snowball event, life could only survive in ice-free refuges, or where sunlight managed to penetrate through the ice to allow photosynthesis. No image credit.

    Lyons is the principal investigator for one of the newer science teams selected to join the NASA Astrobiology Institute (NAI), an interdisciplinary group hat calls itself “Alternative Earths.”

    Consisting of 23 scientists from 14 institutions, its self-described mission is to address and answer these questions: How has Earth remained persistently inhabited through most of its highly changeable history? How has the presence of very different kinds of lifeforms been manifested in the atmosphere, and simultaneously been captured in what would become the rock record? And how might this approach to early Earth help in the search for life beyond Earth?

    “The idea that early Earth can help us understand other planets and moons, especially in our solar system, is certainly not new,” Lyons said. “Scientists have studied possible Mars analogues and extreme life for years. But we’re taking it to the next level with exoplanets, and pushing hard on the many ways that conditions on early Earth can help us study exoplanet atmospheres and habitability.”

    The importance of this work was apparent at a recent workshop on biosignatures held by NASA’s initiative, the Nexus for Exoplanet System Science (NExSS.) As Earth scientists, Lyons and his group are expert at finding proxy records in ancient rocks that hold information important to exoplanet scientists (among others) want to know.

    Those proxy fingerprints occur as elemental, molecular, and isotopic properties preserved in rocks that correspond to ancient characteristics in the ocean or atmosphere that can no longer be observed directly.

    “We can’t measure the pH in ancient oceans, and we can’t measure the composition of ancient atmospheres,” Lyons said. “So what we have to do is go to the chemistry of ocean and land deposits formed at the same time and look for the chemical fingerprints locked away and preserved.”

    At the exoplanet biosignatures workshop, Lyons was struck by how eager exoplanet modelers were to learn about the proxy chemicals they could profitably put in their models for clues about how distant planet atmospheres might form and behave. It’s clear that no single element or compound will be a silver bullet for understanding whether there’s life on an exoplanet, but a variety of proxy results together can begin to tell an important story.

    2
    The element chromium and its isotopes have become important proxies for the measurement of oxygen levels in the atmosphere of early Earth and have led to some revised theories about when those concentrations jumped. Understanding the potential makeup of early Earth’s atmosphere and oceans is a pathway to understanding exoplanets. No image credit.

    “We told them about the range of things they should be modeling and, wow, they were interested. I was thinking at the time that ‘you guys really need us — and vice versa.’”

    Some of the researchers most intrigued by potentially new geochemical proxies from the University of Washington’s Virtual Planetary Laboratory, They’ve been a pioneer in modeling how different atmospheric, geological, stellar and other factors characterize particular kinds of planets and solar systems and their possibilities for life.

    In keeping with the growing connection between exoplanet and Earth science, Lyons just brought one of the VPL top modellers, Edward Schwieterman, to UC Riverside for a postdoc as part of the Alternative Earths project.

    Among his initial projects will take the new data being generated by the Alternative Earths team about the atmosphere and oceans of early Earth, and model what would happen on a planet with that kind of atmosphere if it was orbiting a very different type of star from our own.

    “It’s a direct use of early Earth research on exoplanet studies, and is exactly the kind of work we plan to do be doing,” Lyons said. “Eddie is the perfect bridge between the lessons learned from early Earth and their implications for exoplanets.”

    3
    Banded iron formations at Karijini National Park, Western Australia. The layers of reddish iron point to an early ocean poor in oxygen and rich in dissolved iron. These formations date most commonly from the periods just before and right after the Great Oxidation Event, which spanned from about 2.4 to 2.0 billion years ago. Their distributions over times and their chemical properties are key proxies for the tempo and fabric of the earliest permanent oxygenation of Earth’s atmosphere. No image credit.

    Lyons, along with colleagues Christopher Reinhard of Georgia Tech and Noah Planavsky of Yale and other members of their Alternative Earths team, are especially focused on an effort to understand Earth’s atmosphere—as tracked in the rock record—over the eons and especially the levels of oxygen present.

    The concentration of oxygen in the atmosphere is now about about 21 percent and, by some estimates, reached as high as 35 percent within the past 500 million years.

    In comparison, early Earth had but trace amounts of oxygen for two billion years before what is called the Great Oxidation Event—when marine O2-producing photosynthesis outpaced reactions that consumed O2 and allowed for the beginnings of its permanent accumulation in the atmosphere. Estimated to have occurred 2.4 billion years ago, it began (or was part of) an oxidizing process that led to ever more complex life forms over the following one to two billion years.

    There is a spirited scientific debate underway now about whether that “Great Oxidation Event” triggered permanently high levels of oxygen in the atmosphere and the oceans, or whether it began an up and down process through which the presence of oxygen was quite unstable and still well below current levels until relatively recent times.

    Lyons and Reinhard are of the “boring billion” school, arguing that oxygen levels did not head continuously upwards after the Oxidation Event, but rather stayed relatively stable and still very low for most of a billion and half years after the Great Oxidation Event and continued to challenge O2-requiring life—for almost a third of Earth history.

    This would be primarily an Earth science issue if not for the fact that oxygen — on its own and in conjunction with other compounds — is among the most prominent and promising biosignatures that exoplanet scientists are looking for.

    In fact, not that long ago, it was widely accepted that a discovery of oxygen and/or ozone in the atmosphere of a planet pretty much proved, or at least strongly suggested, the presence of some sort of biology on the planet below. That view has been modified of late by the identification of ways that free oxygen can be formed abiotically (without the presence of photosynthesis and life), potentially producing false positives for potential life.

    While the field is a long way from an active search for direct, in situ fingerprints of life on exoplanets light years away, oxygen and its relationship with other atmospheric gases remains a lodestar in thinking about what biosignatures to search for. The technology is already in place for characterizing the compositions of very distant atmospheres.

    And this is where, for Lyons, Reinhard and others, things get both interesting and complicated.

    For more than a billion years before the Great Oxidation Event Earth demonstrably supported life. It consisted mostly of anaerobic microbes that did just fine without oxygen, but in many cases needed and produced of methane, an organic compound with one carbon atom and four hydrogen.

    So if an exoplanet scientist from a distant world were to search for life on Earth during that period via the detection of oxygen only, they would entirely miss the presence of an already long history of life. Searching for the large-scale presence of methane might have been more productive, though that is a source of rigorous debate as well.

    4
    An image of a rock with fossilized stromatolites, tiny layered structures from 3.7 billion years ago that are remnants from a community of microbes. Found in a part of Greenland new exposed by melting glaciers, Australian scientists reported in the journal Nature that the stromatolites lived on an ancient seafloor at a time when Earth’s skies were orange and its oceans green. They describe the stromatolites as perhaps the oldest fossil found so far on Earth, although chemical suggestions of life may extend further back in time . (Allen Nutman/University of Wollongong)

    Because both oxygen and methane can be formed without life, a current gold standard for detecting future biosignatures on exoplanets is the presence of the two together. Because of the way the two interact, they would remain in an atmosphere together only if both were being replenished on a substantial, on-going scale. And as far as is now understood, the only way to do that is through biology.

    Yet as described by Reinhard, the most current research suggest that oxygen and methane were probably were in the Earth’s atmosphere together at levels that would be detectable from afar. There was a lot of methane in the very early Earth atmosphere, and there has been a lot of oxygen for the past 600 million years or so, but as one grew in concentration the other declined — and during the “boring billion” both were likely low.

    “So we have a complicated situation here where using the best exoplanet biosignatures we have now, intelligent beings looking at Earth over the past 4.5 billion years would not find a convincing signature of life for most, or maybe all, of that time if they relied only on co-occurrence of oxygen and methane,” Reinhard said. Yet there has been life for at least 3.7 billion years, and those beings studying Earth would have come up with a very false negative.

    Lyons insists this is should not be a source of pessimism in the search for life on exoplanets, instead it is a “call to arms for new and more creative possibilities rather than the lowest hanging fruit.” It’s a challenge “to help us sharpen our thinking in a search that was never going to be easy.”

    And the best test bed available for coming up with different answers, he said, may very well be the many different Earths that have come and gone on our planet.

    See the full article here .

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    About Many Worlds

    There are many worlds out there waiting to fire your imagination.

    Marc Kaufman is an experienced journalist, having spent three decades at The Washington Post and The Philadelphia Inquirer, and is the author of two books on searching for life and planetary habitability. While the “Many Worlds” column is supported by the Lunar Planetary Institute/USRA and informed by NASA’s NExSS initiative, any opinions expressed are the author’s alone.

    This site is for everyone interested in the burgeoning field of exoplanet detection and research, from the general public to scientists in the field. It will present columns, news stories and in-depth features, as well as the work of guest writers.

    About NExSS

    The Nexus for Exoplanet System Science (NExSS) is a NASA research coordination network dedicated to the study of planetary habitability. The goals of NExSS are to investigate the diversity of exoplanets and to learn how their history, geology, and climate interact to create the conditions for life. NExSS investigators also strive to put planets into an architectural context — as solar systems built over the eons through dynamical processes and sculpted by stars. Based on our understanding of our own solar system and habitable planet Earth, researchers in the network aim to identify where habitable niches are most likely to occur, which planets are most likely to be habitable. Leveraging current NASA investments in research and missions, NExSS will accelerate the discovery and characterization of other potentially life-bearing worlds in the galaxy, using a systems science approach.
    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 3:32 pm on September 2, 2016 Permalink | Reply
    Tags: , , Astrobiology, , , Phosphorous, , Schreibersite   

    From astrobio.net via SETI: “Did meteorites bring life’s phosphorus to Earth?” 

    Astrobiology Magazine

    Astrobiology Magazine

    Aug 30, 2016
    Keith Cooper

    1
    An artist’s impression of meteors crashing into water on the young Earth. Did they bring phosphorous with them? Image credit: David A Aguilar (CfA)

    Meteorites that crashed onto Earth billions of years ago may have provided the phosphorous essential to the biological systems of terrestrial life. The meteorites are believed to have contained a phosphorus-bearing mineral called schreibersite, and scientists have recently developed a synthetic version that reacts chemically with organic molecules, showing its potential as a nutrient for life.

    Phosphorus is one of life’s most vital components, but often goes unheralded. It helps form the backbone of the long chains of nucleotides that create RNA and DNA; it is part of the phospholipids in cell membranes; and is a building block of the coenzyme used as an energy carrier in cells, adenosine triphosphate (ATP).

    Yet the majority of phosphorus on Earth is found in the form of inert phosphates that are insoluble in water and are generally unable to react with organic molecules. This appears at odds with phosphorus’ ubiquity in biochemistry, so how did phosphorus end up being critical to life?

    In 2004, Matthew Pasek, an astrobiologist and geochemist from the University of South Florida, developed the idea that schreibersite [(Fe, Ni)3P], which is found in a range of meteorites from chondrites to stony–iron pallasites, could be the original source of life’s phosphorus. Because the phosphorus within schreibersite is a phosphide, which is a compound containing a phosphorus ion bonded to a metal, it behaves in a more reactive fashion than the phosphate typically found on Earth.

    Finding naturally-formed schreibersite to use in laboratory experiments can be time consuming when harvesting from newly-fallen meteorites and expensive when buying from private collectors. Instead, it has become easier to produce schreibersite synthetically for use in the laboratory.

    Natural schreibersite is an alloy of iron, phosphorous and nickel, but the common form of synthetic schreibersite that has typically been used in experiments is made of just iron and phosphorus, and is easily obtainable as a natural byproduct of iron manufacturing. Previous experiments have indicated it reacts with organics to form chemical bonds with oxygen, the first step towards integrating phosphorous into biological systems.

    However, since natural schreibersite also incorporates nickel, some scientific criticism has pointed out that the nickel could potentially alter the chemistry of the mineral, rendering it non-reactive despite the presence phosphides. If this were the case it would mean that the experiments with the iron–phosphorous synthetic schreibersite would not represent the behavior of the mineral in nature.

    Since the natural version incorporates nickel, there has always been the worry that the synthetic version is not representative of how schreibersite actually reacts and that the nickel might somehow hamper those chemical reactions.

    “There was always this criticism that if we did include nickel it might not react as much,” says Pasek.

    Pasek and his colleagues have addressed this criticism by developing a synthetic form of schreibersite that includes nickel.

    2
    This 15cm wide fragment of the Seymchan meteorite found in Russia in 1967 is an iron-nickel pallasite. The long filament of dark grey material in the center is schreibersite. Image credit: University of South Florida.

    Nickel-flavored schreibersite

    In a recent paper published in the journal Physical Chemistry Chemical Physics, Pasek and lead author and geochemist Nikita La Cruz of the University of Michigan show how a form of synthetic schreibersite that includes nickel reacts when exposed to water. As the water evaporates, it creates phosphorus–oxygen (P–O) bonds on the surface of the schreibersite, making the phosphorus bioavailable to life. The findings seem to remove any doubts as to whether meteoritic schreibersite could stimulate organic reactions.

    “Biological systems have a phosphorus atom surrounded by four oxygen atoms, so the first step is to put one oxygen atom and one phosphorous atom together in a single P–O bond,” Pasek explains.

    Terry Kee, a geochemist at the University of Leeds and president of the Astrobiology Society of Britain, has conducted his own extensive work with schreibersite and, along with Pasek, is one of the original champions of the idea that it could be the source of life’s phosphorus.

    “The bottom line of what [La Cruz and Pasek] have done is that it appears that this form of nickel-flavored synthetic schreibersite reacts pretty much the same as the previous synthetic form of schreibersite,” he says.

    This puts to rest any criticism that previous experiments lacked nickel.

    3
    A bubbling hydrothermal pool in the Mývatn area of Iceland. Could such pools have pro-moted P–O bonds on the surfaces of schreibersite meteorites that had fallen into the pools? Image credit: Keith Cooper

    Shallow pools and volcanic vents

    Pasek describes how meteors would have fallen into shallow pools of water on ancient Earth. The pools would then have undergone cycles of evaporation and rehydration, a crucial process for chemical reactions to take place. As the surface of the schreibersite dries, it allows molecules to join into longer chains. Then, when the water returns, these chains become mobile, bumping into other chains. When the pool dries out again, the chains bond and build ever larger structures.

    “The reactions need to lose water in some way in order to build the molecules that make up life,” says Pasek. “If you have a long enough system with enough complex organics then, hypothetically, you could build longer and longer polymers to make bigger pieces of RNA. The idea is that at some point you might have enough RNA to begin to catalyze other reactions, starting a chain reaction that builds up to some sort of primitive biochemistry, but there’s still a lot of steps we don’t understand.”

    Demonstrating that nickel-flavored schreibersite, of the sort contained in meteorites, can produce phosphorus-based chemistry is exciting. However, Kee says further evidence is needed to show that the raw materials of life on Earth came from space.

    “I wouldn’t necessarily say that the meteoric origin of phosphorus is the strongest idea,” he says. “Although it’s certainly one of the more pre-biotically plausible routes.”

    Despite having co-developed much of the theory behind schreibersite with Pasek, Kee points out that hydrothermal vents could rival the meteoritic model. Deep sea volcanic vents are already known to produce iron-nickel alloys such as awaruite and Kee says that the search is now on for the existence of awaruite’s phosphide equivalent in the vents: schreibersite.

    “If it could be shown that schreibersite can be produced in the conditions found in vents — and I think those conditions are highly conducive to forming schreibersite — then you’ve got the potential for a lot of interesting phosphorylation chemistry to take place,” says Kee.

    Pasek agrees that hydrothermal vents could prove a good environment to promote phosphorus chemistry with the heat driving off the water to allow the P–O bonds to form. “Essentially it’s this driving off of water that you’ve got to look for,” he adds.

    Pasek and Kee both agree that it is possible that both mechanisms — the meteorites in the shallow pools and the deep sea hydrothermal vents — could have been at work during the same time period and provided phosphorus for life on the young Earth.

    Meanwhile David Deamer, a biologist from the University of California, Santa Cruz, has gone one step further by merging the two models, describing schreibersite reacting in hydrothermal fields of bubbling shallow pools in volcanic locations similar to those found today in locations such as Iceland or Yellowstone.

    Certainly, La Cruz and Pasek’s results indicate that schreibersite becomes more reactive the warmer the environment in which it exists.

    “Although we see the reaction occurring at room temperature, if you increase the temperature to 60 or 80 degree Celsius, you get increased reactivity,” says Pasek. “So, hypothetically, if you have a warmer Earth you should get more reactivity.”

    One twist to the tale is the possibility that phosphorus could have bonded with oxygen in space, beginning the construction of life’s molecules before ever reaching Earth. Schreibersite-rich grains coated in ice and then heated by shocks in planet-forming disks of gas and dust could potentially have provided conditions suitable for simple biochemistry. While Pasek agrees in principle, he says he has “a hard time seeing bigger things like RNA or DNA forming in space without fluid to promote them.”

    See the full article here .

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  • richardmitnick 11:32 am on April 26, 2016 Permalink | Reply
    Tags: Astrobiology, , , , ,   

    From Many Worlds: “Breaking Down Exoplanet Stovepipes” 

    NASA NExSS bloc

    NASA NExSS

    Many Worlds

    Many Words icon

    2016-04-25
    Marc Kaufman

    1
    The search for life beyond our solar system requires unprecedented cooperation across scientific disciplines. NASA’s NExSS collaboration includes those who study Earth as a life-bearing planet (lower right), those researching the diversity of solar system planets (left), and those on the new frontier, discovering worlds orbiting other stars in the galaxy (upper right). (NASA)

    That fields of science can benefit greatly from cross-fertilization with other disciplines is hardly a new idea. We have, after all, long-standing formal disciplines such as biogeochemistry — a mash-up of many fields that has the potential to tell us more about the natural environment than any single approach. Astrobiology in another field that inherently needs expertise and inputs from a myriad of disciplines, and the NASA Astrobiology Institute was founded (in 1998) to make sure that happened.

    Until fairly recently, the world of exoplanet study was not especially interdisciplinary. Astronomers and astrophysicists searched for distant planets and when they succeeded came away with some measures of planetary masses, their orbits, and sometimes their densities. It was only in recent years, with the advent of a serious search for exoplanets with the potential to support life, that it became apparent that chemists (astrochemists, that is), planetary and stellar scientists, cloud specialists, geoscientists and more were needed at the table.

    Universities were the first to create more wide-ranging exoplanet centers and studies, and by now there are a number of active sites here and abroad. NASA formally weighed in one year ago with the creation of the Nexus for Exoplanet System Science (NExSS) — an initiative which brought together 17 university and research center teams with the goal of supercharging exoplanet studies, or at least to see if a formal, national network could produce otherwise unlikely collaborations and science.

    That network is virtual, unpaid, and comes with no promises to the scientists. Still, NASA leaders point to it as an important experiment, and some interesting collabortions, proposals and workshops have come out of it.

    “A year is a very short time to judge an effort like this,” said Douglas Hudgins, program scientist for NASA’s Exoplanet Exploration Program, and one of the NASA people who helped NExSS come into being.

    “Our attitude was to pull together a group of people, do our best to give them tool to work well together, let them have some time to get to know each other, and see what happens. One year down the road, though, I think NExSS is developing and good ideas are coming out of it.”

    2
    Illustration of what a sunset might look like on a moon orbiting Kepler 47c and its two suns. (Softpedia)

    One collaboration resulted in a “White Paper” on how laboratory work today can prepare researchers to better understand future exoplanet measurements coming from new generation missions. Led by NExSS member Jonathan Fortney of the University of Clalfornia, Santa Cruz, it was the result of discussions at the first NExSS meeting in Washington, and was expanded by others from the broader community.

    Another NExSS collaboration between Steven Desch of Arizona State University and Jason Wright of Penn State led to a proposal to NASA to study a planet being pulled apart by the gravitational force a white dwarf star. The interior of the disintegrating planet could potentially be analyzed as its parts scatter.

    Leaders of NExSS say that other collaborations and proposals are in the works but are not ready for public discussion yet.

    In addition, NExSS — along with the NASA Astrobiology Institute (NAI) and the National Science Foundation (NSF) — sponsored an unusual workshop this winter at Arizona State University focused on a novel way to looking at whether an exoplanet might support life. Astrophysicists and geoscientists spent three days discussing and debating how the field might gather and use information about the formation, evolution and insides of exoplanets to determine whether they might be habitable.

    One participant was Shawn Domogal-Goldman, a research space scientist at the Goddard Space Flight Center and a leader of the NExSS group. He’s an expert in ancient earth as well the astrophysics of exoplanets, and his view is that the Earth provides 4.5 billion years of physical, chemical, climatic and biological dynamics that need to be mined for useful insights about exoplanets.

    When the workshop was over he said: “For me, and I think for others, we’ll look back at this meeting years from now and say to ourselves, ‘We were there at the beginning of something big.”

    NExSS has two more workshops coming up, one on “Biosignatures” July 27 t0 29 in Seattle and another on stellar-exoplanet interactions in November. Reflecting the broad reach of NExSS, the biosignatures program has additional sponsors include the NASA Astrobiology Institute (NAI), NASA’s Exoplanet Exploration Program (ExEP), and international partners, including the European Astrobiology Network Association (EANA) and Japan’s Earth-Life Science Institute (ELSI).

    3
    By looking for signs of life, scientists focus on the potential presence of oxygen, ozone, water, carbon dioxide, methane and nitrous oxide, which could indicate plant or bacterial life. The figure above shows how complex Earth’s spectra is compared to Mars or Venus. This is a reflection of the intricate balance and control of elements needed to support life. The upcoming NExSS workshop will focus on what we know, and need to know, about what future missions and observations should be looking for in terms of exoplanet biosignatures. (ESA)

    The initial idea for NExSS came from Mary Voytek, senior scientist for astrobiology in NASA’s Planetary Sciences Division. Interdisciplinary collaboration and solutions are baked into the DNA of astrobiology, so it is not surprising that an interdisciplinary approach to exoplanets would come from that direction. In addition, as the study of exoplanets increasingly becomes a search for possible life or biosignatures on those planets, it falls very much into the realm of astrobiology.

    Hudgins said that while this dynamic is well understood at NASA headquarters, the structure of the agency does not necessarily reflect the convergence. Exoplanet studies are funded through the Division of Astrophysics while astrobiology is in the Planetary Sciences Division.

    NExSS is a beginning effort to bring the overlapping fields closer together within the agency, and more may be on the way. Said Hudgins: “We could very well see some evolution in how NASA approaches the problem, with more bridges between astrobiology and exoplanets.”

    NExSS is led by Natalie Batalha of NASA’s Ames Research Center in Moffett Field, California; Dawn Gelino with NExScI, the NASA Exoplanet Science Institute at the California Institute of Technology in Pasadena; and Anthony Del Genio of NASA’s Goddard Institute for Space Studies in New York City.

    All three see NExSS as an experiment and work in progress, with some promising accomplishments already. And some clear challenges.

    Del Genio, for instance, described the complex dynamics involved in having a team like his own — climate modelers who have spent years understanding the workings of our planet — determine how their expertise can be useful in better understanding exoplanets.

    These are some of his thoughts:

    “This sounds great, but in practice it is very difficult to do for a number of reasons. First, all the disciplines speak different languages. Jargon from one field has to be learned by people in another field, and unlike when I travel to Europe with a Berlitz phrase book, there is no Earth-to-Astrophysics translation guide to consult.

    “Second, we don’t appreciate what the important questions are in each others’ fields, what the limitations of each field are, etc. We have been trying to address these roadblocks in the first year by having roughly monthly webinars where different people present research that their team is doing. But there are 17 teams, so this takes a while to do, and we are only part way through having all the teams present.

    “Third, NExSS is a combination of teams that proposed to different NASA programs for funding, and we are a combination of big and small teams. We are also a combination of teams in areas whose science is more mature, and teams in areas whose science is not yet very mature (and maybe if you asked all of us you’d get 10 different opinions on whose science is mature and whose isn’t).

    What’s more, he wrote, he sees an inevitable imbalance between the astrophysics teams — which have been thinking about exoplanets for a long time — and teams from other disciplines that have mature models and theories for their own work but are now applying those tools to think about exoplanets for the first time.

    But he sees these issues as challenges rather than show-stoppers, and expects to see important — and unpredictable — progress during the three-year life of the initiative.

    Natalie Batalie said that she became involved with NExSS because “I wanted to help expedite the search for life on exoplanets.”

    “Reaching this goal requires interdisciplinary thinking that’s been difficult to achieve given the divisional boundaries within NASA’s science mission directorate. NExSS is an experiment to see if cooperation between the divisions can lead to cross-fertilization of ideas and a deeper understanding of planetary habitability.”

    She said that in the last year, scientists working on planetary habitability both inside and outside of NExSS — and funded by different science divisions within NASA — have had numerous NExSS-sponsored opportunities to interact, learn from each other and begin collaborations.

    The Fortney et al “White Paper” on experimental data gaps, for example, was conceived during one of these gatherings, as was the need for a biosignatures analysis group to support NASA’s Science & Technology Definition Teams studying the possible flagship missions of the future.

    In full disclosure, Many Worlds is funded by NExSS but represents only the views of the writer.

    See the full article here .

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    About Many Worlds

    There are many worlds out there waiting to fire your imagination.

    Marc Kaufman is an experienced journalist, having spent three decades at The Washington Post and The Philadelphia Inquirer, and is the author of two books on searching for life and planetary habitability. While the “Many Worlds” column is supported by the Lunar Planetary Institute/USRA and informed by NASA’s NExSS initiative, any opinions expressed are the author’s alone.

    This site is for everyone interested in the burgeoning field of exoplanet detection and research, from the general public to scientists in the field. It will present columns, news stories and in-depth features, as well as the work of guest writers.

    About NExSS

    The Nexus for Exoplanet System Science (NExSS) is a NASA research coordination network dedicated to the study of planetary habitability. The goals of NExSS are to investigate the diversity of exoplanets and to learn how their history, geology, and climate interact to create the conditions for life. NExSS investigators also strive to put planets into an architectural context — as solar systems built over the eons through dynamical processes and sculpted by stars. Based on our understanding of our own solar system and habitable planet Earth, researchers in the network aim to identify where habitable niches are most likely to occur, which planets are most likely to be habitable. Leveraging current NASA investments in research and missions, NExSS will accelerate the discovery and characterization of other potentially life-bearing worlds in the galaxy, using a systems science approach.
    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 2:56 pm on March 29, 2016 Permalink | Reply
    Tags: Astrobiology, , , Life's Building Blocks Form In Replicated Deep Sea Vents, ,   

    From SPACE.com: “Life’s Building Blocks Form In Replicated Deep Sea Vents” 

    space-dot-com logo

    SPACE.com

    March 28, 2016
    Charles Q. Choi

    1
    Alkaline hydrothermal vents may have played a role in the origin of life.
    Credit: NOAA

    Chimney-like mineral structures on the seafloor could have helped create the RNA molecules that gave rise to life on Earth and hold promise to the emergence of life on distant planets.

    Scientists think Earth was born roughly 4.54 billion years ago. Life on Earth may be nearly that old with recent findings suggesting that life might have emerged only about 440 million years after the planet formed.

    However, it remains a mystery how life might have first arisen. The main building blocks of life now are DNA, which can store genetic data, and proteins, which include enzymes that can direct chemical reactions. However, DNA requires proteins in order to form, and proteins need DNA to form, raising the chicken-and-egg question of how protein and DNA could have formed without each other.

    To resolve this conundrum, scientists have suggested that life may have first primarily depended on compounds known as RNA. These molecules can store genetic data like DNA, serve as enzymes like proteins, and help create both DNA and proteins. Later DNA and proteins replaced this “RNA world” because they are more efficient at their respective functions, although RNA still exists and serves vital roles in biology.

    However, it remains uncertain how RNA might have arisen from simpler precursors in the primordial soup that existed on Earth before life originated. Like DNA, RNA is complex and made of helix-shaped chains of smaller molecules known as nucleotides.

    One way that RNA might have first formed is with the help of minerals, such as metal hydrides. These minerals can serve as catalysts, helping create small organic compounds from inorganic building blocks. Such minerals are found at alkaline hydrothermal vents on the seafloor.

    Alkaline hydrothermal vents are also home to large chimney-like structures rich in iron and sulfur. Prior studies suggested that ancient counterparts of these chimneys might have isolated and concentrated organic molecules together, spurring the origin of life on Earth.

    To see how well these chimneys support the formation of strings of RNA, researchers synthesized chimneys by slowly injecting solutions containing iron, sulfur and silicon into glass jars. Depending on the concentrations of the different chemicals used to grow these structures, the chimneys were either mounds with single hollow centers or, more often, spires and “chemical gardens” with multiple hollow tubes.

    2
    Chimney-like mineral structures created in the lab created from solutions containing iron, sulfur and silicon under a) low concentrations and b) high concentrations. Structures in a) represent mound (left) and spindle (right) formations, while those in b) represent chemical garden formations.
    Credit: Bradley Burcar et al., Astrobiology.

    “Being able to perform our experiments in chimney structures that looked like something one might encounter in the darker regions of Tolkien’s Middle Earth gave these studies a geologic context that sparked the imagination,” said study co-author Linda McGown, an analytical chemist and astrobiologist at Rensselaer Polytechnic Institute in Troy, N.Y.

    The chimneys were grown in liquids and gases resembling the oceans and atmosphere of early Earth. The liquids were acidic and enriched with iron, while the gases were rich in nitrogen and had no oxygen. The scientists then poked syringes up the chimneys to pump alkaline solutions containing a variety of chemicals into the model oceans. This simulated ancient vent fluid seeping into primordial seas.

    Sometimes the researchers added montmorillonite clay to their glass jars. Clays are produced by interactions between water and rock, and would likely have been common on the early Earth, McGown said.

    The kind of nucleotides making up RNA are known as ribonucleotides, since they are made with the sugar ribose. The scientists found that unmodified ribonuclotides could form strings of two nucleotides. In addition, ribonucleotides “activated” with a compound known as imidazole — a molecule created during chemical reactions that synthesize nucleotides — could form RNA strings or polymers up to four ribonucleotides long.

    “In order to observe significant RNA polymerization on the time scale of laboratory experiments, it is generally necessary to activate the nucleotides,” McGown said. “Imidazole is commonly used for nucleotide activation in these types of experiments.”

    The scientists found that not only was the chemical composition of the chimneys important when it came to forming RNA, but the physical structure of the chimneys was key too. When the researchers mixed iron, sulfur and silicon solutions into their simulated oceans, instead of slowly injecting them into the seawater to form chimneys, the resulting blend could not trigger RNA formation.

    “The chimneys, and not just their constituents, are responsible for the polymerization,” McGown said.

    These experiments for the first time demonstrate that RNAs can form in alkaline hydrothermal chimneys, albeit synthetic ones.

    “Our goal from the start of our RNA polymerization research has been to place the RNA polymerization experiments as closely as possible in the context of the most likely early Earth environments,” McGown said. “Most previous RNA polymerization research has focused on surface environments, and the exploration of deep-ocean hydrothermal vents could yield exciting new possibilities for the emergence of an RNA world.”

    One concern about these findings is that the experiments were performed at room temperature. Hydrothermal vents are much hotter, and such temperatures could destroy RNA. [Video: The Search For Another Earth]

    “Keep in mind, however, that hydrothermal vents are dynamic systems with gradients of chemical and physical conditions, including temperature,” McGown said.

    In principle, cooler sections of hydrothermal vents might have nurtured RNA and its precursor molecules, she said.

    In the future, McGown and her colleagues will perform experiments investigating what effects variables such as pressure, temperature and mineralogy might have on the formation of RNA molecules, focusing primarily on conditions mimicking deep-ocean environments on an early Earth and those that may also have existed on Mars and elsewhere, McGown said.

    The scientists detailed their findings in the July 22 issue of the journal Astrobiology.

    Science team:

    Bradley T. Burcar,1,2 Laura M. Barge,3,4 Dustin Trail,1,5,* E. Bruce Watson,1,5 Michael J. Russell,3,4 and Linda B. McGown1,2
    1 New York Center for Astrobiology, Rensselaer Polytechnic Institute, Troy, New York.
    2 Department of Chemistry and Chemical Biology, Rensselaer Polytechnic Institute, Troy, New York.
    3 NASA Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California.
    4 NASA Astrobiology Institute, Icy Worlds.
    5 Department of Earth and Environmental Sciences, Rensselaer Polytechnic Institute School of Science, Troy, New York.

    See the full article here .

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