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  • richardmitnick 12:15 pm on September 16, 2014 Permalink | Reply
    Tags: Astrobiology, , , , , ,   

    From Science Daily: “Martian meteorite yields more evidence of the possibility of life on Mars” 

    ScienceDaily Icon

    Science Daily

    September 15, 2014
    Source: Manchester University
    Katie Brewin/Aeron Haworth
    Media Relations Officer
    The University of Manchester

    A tiny fragment of Martian meteorite 1.3 billion years old is helping to make the case for the possibility of life on Mars, say scientists.

    The finding of a ‘cell-like’ structure, which investigators now know once held water, came about as a result of collaboration between scientists in the UK and Greece. Their findings are published in the latest edition of the journal Astrobiology.

    While investigating the Martian meteorite, known as Nakhla, Dr Elias Chatzitheodoridis of the National Technical University of Athens found an unusual feature embedded deep within the rock. In a bid to understand what it might be, he teamed up with long-time friend and collaborator Professor Ian Lyon at the University of Manchester.

    met
    Nakhla meteorite (BM1913,25): two sides and its inner surfaces after breaking it in 1998

    Professor Lyon, based in Manchester’s School of Earth, Atmospheric and Environmental Sciences explains: “In many ways it resembled a fossilized biological cell from Earth but it was intriguing because it was undoubtedly from Mars. Our research found that it probably wasn’t a cell but that it did once hold water, water that had been heated, probably as a result of an asteroid impact.”

    These findings are significant because they add to increasing evidence that beneath the surface, Mars does provide all the conditions for life to have formed and evolved. It also adds to a body of evidence suggesting that large asteroids hit Mars in the past and produce long-lasting hydrothermal fields that could sustain life on Mars, even in later epochs, if life ever emerged there.

    As part of the research, the feature was imaged in unprecedented detail by Dr Sarah Haigh of The University of Manchester whose work usually involves high resolution imaging for next generation electronic devices ,which are made by stacking together single atomic layers of graphene and other materials with the aim of making faster, lighter and bendable mobile phones and tablets. A similar imaging approach was able to reveal the atomic layers of materials inside the meteorite.

    Together their combined experimental approach has revealed new insights into the geological origins of this fascinating structure.

    Professor Lyon said: “We have been able to show the setting is there to provide life. It’s not too cold, it’s not too harsh. Life as we know it, in the form of bacteria, for example, could be there, although we haven’t found it yet. It’s about piecing together the case for life on Mars — it may have existed and in some form could exist still.”

    Now, the team is using these and other state-of-the-art techniques to investigate new secondary materials in this meteorite and search for possible bio signatures which provide scientific evidence of life, past or present. Professor Lyon concluded: “Before we return samples from Mars, we must examine them further, but in more delicate ways. We must carefully search for further evidence.”

    See the full article here.

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  • richardmitnick 9:43 am on September 16, 2014 Permalink | Reply
    Tags: Astrobiology, , , , , ,   

    From astrobio.net: “NASA Research Helps Unravel Mysteries Of The Venusian Atmosphere” 

    Astrobiology Magazine

    Astrobiology Magazine

    NASA Research Helps Unravel Mysteries Of The Venusian Atmosphere
    Sep 15, 2014
    Source: NASA
    Karen C. Fox NASA’s Goddard Space Flight Center, Greenbelt, Md.

    two
    Earth and Venus – worlds apart. Credits: Earth: NASA; Venus: Magellan Project/NASA/JPL

    Underscoring the vast differences between Earth and its neighbor Venus, new research shows a glimpse of giant holes in the electrically charged layer of the Venusian atmosphere, called the ionosphere. The observations point to a more complicated magnetic environment than previously thought – which in turn helps us better understand this neighboring, rocky planet.

    Planet Venus, with its thick atmosphere made of carbon dioxide, its parched surface, and pressures so high that landers are crushed within a few hours, offers scientists a chance to study a planet very foreign to our own. These mysterious holes provide additional clues to understanding Venus’s atmosphere, how the planet interacts with the constant onslaught of solar wind from the sun, and perhaps even what’s lurking deep in its core.

    “This work all started with a mystery from 1978,” said Glyn Collinson, a space scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, who is first author of a paper on this work in the Journal of Geophysical Research. “When Pioneer Venus Orbiter moved into orbit around Venus, it noticed something very, very weird – a hole in the planet’s ionosphere. It was a region where the density just dropped out, and no one has seen another one of these things for 30 years.”

    NASA Pioneer Venus Orbiter
    NASA/Pioneer Venus Orbiter

    Until now.


    New research shows giant holes in Venus’ atmosphere – which serve as extra clues for understanding this planet so different from our own. Image Credit: NASA’s Goddard Space Flight Center/G. Duberstein

    Collinson set out to search for signatures of these holes in data from the European Space Agency’s Venus Express. Venus Express, launched in 2006, is currently in a 24-hour orbit around the poles of Venus. This orbit places it in much higher altitudes than that of the Pioneer Venus Orbiter, so Collinson wasn’t sure whether he’d spot any markers of these mysterious holes. But even at those heights the same holes were spotted, thus showing that the holes extended much further into the atmosphere than had been previously known.

    ve
    ESA/Venus Express

    The observations also suggested the holes are more common than realized. Pioneer Venus Orbiter only saw the holes at a time of great solar activity, known as solar maximum. The Venus Express data, however, shows the holes can form during solar minimum as well.

    Interpreting what is happening in Venus’s ionosphere requires understanding how Venus interacts with its environment in space. This environment is dominated by a stream of electrons and protons – a charged, heated gas called plasma — which zoom out from the sun. As this solar wind travels it carries along embedded magnetic fields, which can affect charged particles and other magnetic fields they encounter along the way. Earth is largely protected from this radiation by its own strong magnetic field, but Venus has no such protection.

    What Venus does have, however, is an ionosphere, a layer of the atmosphere filled with charged particles. The Venusian ionosphere is bombarded on the sun-side of the planet by the solar wind. Consequently, the ionosphere, like air flowing past a golf ball in flight, is shaped to be a thin boundary in front of the planet and to extend into a long comet-like tail behind. As the solar wind plows into the ionosphere, it piles up like a big plasma traffic jam, creating a thin magnetosphere around Venus – a much smaller magnetic environment than the one around Earth.

    ve
    Venus Express aerobraking. Credit: ESA

    Venus Express is equipped to measure this slight magnetic field. As it flew through the ionospheric holes it recorded a jump in the field strength, while also spotting very cold particles flowing in and out of the holes, though at a much lower density than generally seen in the ionosphere.

    The Venus Express observations suggest that instead of two holes behind Venus, there are in fact two long, fat cylinders of lower density material stretching from the planet’s surface to way out in space. Collinson said that some magnetic structure probably causes the charged particles to be squeezed out of these areas, like toothpaste squeezed out of a tube.

    The next question is what magnetic structure can create this effect? Imagine Venus standing in the middle of the constant solar wind like a lighthouse erected in the water just off shore. Magnetic field lines from the sun move toward Venus like waves of water approaching the lighthouse. The far sides of these lines then wrap around the planet leading to two long straight magnetic field lines trailing out directly behind Venus. These lines could create the magnetic forces to squeeze the plasma out of the holes.

    But such a scenario would place the bottom of these tubes on the sides of the planet, not as if they were coming straight up out of the surface. What could cause magnetic fields to go directly in and out of the planet? Without additional data, it’s hard to know for sure, but Collinson’s team devised two possible models that can match these observations.

    In one scenario, the magnetic fields do not stop at the edge of the ionosphere to wrap around the outside of the planet, but instead continue further.

    “We think some of these field lines can sink right through the ionosphere, cutting through it like cheese wire,” said Collinson. “The ionosphere can conduct electricity, which makes it basically transparent to the field lines. The lines go right through down to the planet’s surface and some ways into the planet.”

    ct
    Venus cloud tops. Credit: ESA/MPS/DLR/IDA

    In this scenario, the magnetic field travels unhindered directly into the upper layers of Venus. Eventually, the magnetic field hits Venus’ rocky mantle – assuming, of course, that the inside of Venus is like the inside of Earth. A reasonable assumption given that the two planets are the same mass, size and density, but by no means a proven fact.

    A similar phenomenon does happen on the moon, said Collinson. The moon is mostly made up of mantle and has little to no atmosphere. The magnetic field lines from the sun go through the moon’s mantle and then hit what is thought to be an iron core.

    In the second scenario, the magnetic fields from the solar system do drape themselves around the ionosphere, but they collide with a pile up of plasma already at the back of the planet. As the two sets of charged material jostle for place, it causes the required magnetic squeeze in the perfect spot.

    Either way, areas of increased magnetism would stream out on either side of the tail, pointing directly in and out of the sides of the planet. Those areas of increased magnetic force could be what squeezes out the plasma and creates these long ionospheric holes.

    Scientists will continue to explore just what causes these holes. Confirming one theory or the other will, in turn, help us understand this planet, so similar and yet so different from our own.

    See the full article here.

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  • richardmitnick 8:40 am on September 16, 2014 Permalink | Reply
    Tags: Astrobiology, ,   

    From astrobio.net: “Microscopic Diamonds Suggest Cosmic Impact Responsible for Major Period of Climate Change” 

    Astrobiology Magazine

    Astrobiology Magazine

    Sep 16, 2014
    From University of Chicago
    Emily Murphy / University of Chicago Press / emurphy@press.uchicago.edu

    A new study published in The Journal of Geology provides support for the theory that a cosmic impact event over North America some 13,000 years ago caused a major period of climate change known as the Younger Dryas stadial, or “Big Freeze.”

    freeze
    Credit: iStockphoto/Trevor Hunt

    Around 12,800 years ago, a sudden, catastrophic event plunged much of the Earth into a period of cold climatic conditions and drought. This drastic climate change—the Younger Dryas—coincided with the extinction of Pleistocene megafauna, such as the saber-tooth cats and the mastodon, and resulted in major declines in prehistoric human populations, including the termination of the Clovis culture.

    With limited evidence, several rival theories have been proposed about the event that sparked this period, such as a collapse of the North American ice sheets, a major volcanic eruption, or a solar flare.

    However, in a study published in The Journal of Geology, an international group of scientists analyzing existing and new evidence have determined a cosmic impact event, such as a comet or meteorite, to be the only plausible hypothesis to explain all the unusual occurrences at the onset of the Younger Dryas period.

    Researchers from 21 universities in 6 countries believe the key to the mystery of the Big Freeze lies in nanodiamonds scattered across Europe, North America, and portions of South America, in a 50-million-square-kilometer area known as the Younger Dryas Boundary (YDB) field.

    Microscopic nanodiamonds, melt-glass, carbon spherules, and other high-temperature materials are found in abundance throughout the YDB field, in a thin layer located only meters from the Earth’s surface. Because these materials formed at temperatures in excess of 2200 degrees Celsius, the fact they are present together so near to the surface suggests they were likely created by a major extraterrestrial impact event.

    In addition to providing support for the cosmic impact event hypothesis, the study also offers evidence to reject alternate hypotheses for the formation of the YDB nanodiamonds, such as by wildfires, volcanism, or meteoric flux.

    The team’s findings serve to settle the debate about the presence of nanodiamonds in the YDB field and challenge existing paradigms across multiple disciplines, including impact dynamics, archaeology, paleontology, limnology, and palynology.

    See the full article here.

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  • richardmitnick 10:45 am on September 15, 2014 Permalink | Reply
    Tags: Astrobiology, , , , , ,   

    From Astrobiology: “Planets with Oddball Orbits Like Mercury Could Host Life” 

    Astrobiology Magazine

    Astrobiology Magazine

    Sep 15, 2014
    Charles Q. Choi

    mercury
    On Mercury a solar day is about 176 Earth days long. During its first Mercury solar day in orbit the 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

    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.

    However, the scientists noted that the threat of prolonged periods of darkness and cold on these planets would present significant challenges to 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.

    spin
    The 3:2 spin orbit resonance of Mercury and the Sun. Credit: Wikicommons

    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 multi-cellular organisms to emerge because the main source for oxygen on Earth comes from photosynthetic life, and oxygen is thought to be necessary for multi-cellular 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.)

    spin
    The 1:1 spin orbit resonance of Earth and the Moon. Credit: Wikicommons

    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 do not just vary over latitude as they do on Earth, where more light reaches equatorial regions than polar regions, but also varied 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.”

    big
    It is difficult to form Mercury in solar system simulations, suggesting that some of our assumptions about the small planet’s formation might be wrong, a new study suggests. NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

    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.”

    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.”

    It is difficult to form Mercury in solar system simulations, suggesting that some of our assumptions about the small planet’s formation might be wrong, a new study suggests. NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

    It is difficult to form Mercury in solar system simulations, suggesting that some of our assumptions about the small planet’s formation might be wrong, a new study suggests. NASA/Johns Hopkins University

    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 8:35 pm on September 14, 2014 Permalink | Reply
    Tags: Astrobiology, , , , , ,   

    From Astrobiology: “NASA Research Gives Guideline for Future Alien Life Search” 

    Astrobiology Magazine

    Astrobiology Magazine

    Sep 13, 2014
    At NASA
    William Steigerwald
    NASA’s Goddard Space Flight Center, Greenbelt, Maryland

    Gabriela Frias
    Universidad Nacional Autonoma de Mexico, Mexico City

    Astronomers searching the atmospheres of alien worlds for gases that might be produced by life can’t rely on the detection of just one type, such as oxygen, ozone, or methane, because in some cases these gases can be produced non-biologically, according to extensive simulations by researchers in the NASA Astrobiology Institute’s Virtual Planetary Laboratory.

    two
    Left: Ozone molecules in a planet’s atmosphere could indicate biological activity, but ozone, carbon dioxide and carbon monoxide — without methane, is likely a false positive. Right: Ozone, oxygen, carbon dioxide and methane — without carbon monoxide, indicate a possible true positive. Image Credit: NASA

    The researchers carefully simulated the atmospheric chemistry of alien worlds devoid of life thousands of times over a period of more than four years, varying the atmospheric compositions and star types.

    “When we ran these calculations, we found that in some cases, there was a significant amount of ozone that built up in the atmosphere, despite there not being any oxygen flowing into the atmosphere,” said Shawn Domagal-Goldman of NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “This has important implications for our future plans to look for life beyond Earth.”

    Methane is a carbon atom bound to four hydrogen atoms. On Earth, much of it is produced biologically (flatulent cows are a classic example), but it can also be made inorganically; for example, volcanoes at the bottom of the ocean can release the gas after it is produced by reactions of rocks with seawater.

    Ozone and oxygen were previously thought to be stronger biosignatures on their own. Ozone is three atoms of oxygen bound together. On Earth, it is produced when molecular oxygen (two oxygen atoms) and atomic oxygen (a single oxygen atom) combine, after the atomic oxygen is created by other reactions powered by sunlight or lightning. Life is the dominant source of the molecular oxygen on our planet, as the gas is produced by photosynthesis in plants and microscopic, single-cell organisms. Because life dominates the production of oxygen, and oxygen is needed for ozone, both gases were thought to be relatively strong biosignatures.

    But this study demonstrated that both molecular oxygen and ozone can be made without life when ultraviolet light breaks apart carbon dioxide (a carbon atom bound to two oxygen atoms). Their research suggests this non-biological process could create enough ozone for it to be detectable across space, so the detection of ozone by itself would not be a definitive sign of life.

    “However, our research strengthens the argument that methane and oxygen together, or methane and ozone together, are still strong signatures of life,” said Domagal-Goldman. “We tried really, really hard to make false-positive signals for life, and we did find some, but only for oxygen, ozone, or methane by themselves.”

    orb
    Credit: NASA Ames/SETI Institute/JPL-Caltech

    Domagal-Goldman and Antígona Segura from the Universidad Nacional Autónoma de México in Mexico City are lead authors of a paper about this research, along with astronomer Victoria Meadows, geologist Mark Claire, and Tyler Robison, an expert on what Earth would look like as an extrasolar planet. The paper appeared in the Astrophysical Journal Sept. 10, and is available online.

    Methane and oxygen molecules together are a reliable sign of biological activity because methane doesn’t last long in an atmosphere containing oxygen-bearing molecules. “It’s like college students and pizza,” says Domagal-Goldman. “If you see pizza in a room, and there are also college students in that room, chances are the pizza was freshly delivered, because the students will quickly eat the pizza. The same goes for methane and oxygen. If both are seen together in an atmosphere, the methane was freshly delivered because the oxygen will be part of a network of reactions that will consume the methane. You know the methane is being replenished. The best way to replenish methane in the presence of oxygen is with life. The opposite is true, as well. In order to keep the oxygen around in an atmosphere that has a lot of methane, you have to replenish the oxygen, and the best way to do that is with life.”

    Scientists have used computer models to simulate the atmospheric chemistry on planets beyond our solar system (exoplanets) before, and the team used a similar model in its research. However, the researchers also developed a program to automatically compute the calculations thousands of times, so they could see the results with a wider range of atmospheric compositions and star types.

    In doing these simulations, the team made sure they balanced the reactions that could put oxygen molecules in the atmosphere with the reactions that might remove them from the atmosphere. For example, oxygen can react with iron on the surface of a planet to make iron oxides; this is what gives most red rocks their color. A similar process has colored the dust on Mars, giving the Red Planet its distinctive hue. Calculating the appearance of a balanced atmosphere is important because this balance would allow the atmosphere to persist for geological time scales. Given that planetary lifetimes are measured in billions of years, it’s unlikely astronomers will happen by chance to be observing a planet during a temporary surge of oxygen or methane lasting just thousands or even millions of years.

    It was important to make the calculations for a wide variety of cases, because the non-biological production of oxygen is subject to both the atmospheric and stellar environment of the planet. If there are a lot of gases that consume oxygen, such as methane or hydrogen, then any oxygen or ozone produced will be destroyed in the atmosphere.

    However, if the amount of oxygen-consuming gases is vanishingly small, the oxygen and the ozone might stick around for a while. Likewise, the production and destruction of oxygen, ozone, and methane is driven by chemical reactions powered by light, making the type of star important to consider as well. Different types of stars produce the majority of their light at specific colors.

    For example, massive, hot stars or stars with frequent explosive activity produce more ultraviolet light. “If there is more ultraviolet light hitting the atmosphere, it will drive these photochemical reactions more efficiently,” said Domagal-Goldman. “More specifically, different colors (or wavelengths) of ultraviolet light can affect oxygen and ozone production and destruction in different ways.”

    Astronomers detect molecules in exoplanet atmospheres by measuring the colors of light from the star the exoplanet is orbiting. As this light passes through the exoplanet’s atmosphere, some of it is absorbed by atmospheric molecules. Different molecules absorb different colors of light, so astronomers use these absorption features as unique “signatures” of the type and quantity of molecules present.

    “One of the main challenges in identifying life signatures is to distinguish between the products of life and those compounds generated by geological processes or chemical reactions in the atmosphere. For that we need to understand not only how life may change a planet but how planets work and the characteristics of the stars that host such worlds”, said Segura.

    The team plans to use this research to make recommendations about the requirements for future space telescopes designed to search exoplanet atmospheres for signs of alien life.

    “Context is key – we can’t just look for oxygen, ozone, or methane alone,” says Domagal-Goldman. “To confirm life is making oxygen or ozone, you need to expand your wavelength range to include methane absorption features. Ideally, you’d also measure other gases like carbon dioxide and carbon monoxide [a molecule with one carbon atom and one oxygen atom]. So we’re thinking very carefully about the issues that could trip us up and give a false-positive signal, and the good news is by identifying them, we can create a good path to avoid the issues false positives could cause. We now know which measurements we need to make. The next step is figuring out what we need to build and how to build it.”

    See the full article here.

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  • richardmitnick 12:02 pm on September 12, 2014 Permalink | Reply
    Tags: , Astrobiology,   

    From M.I.T.: “Wrinkles in time” 


    MIT News

    September 12, 2014
    Jennifer Chu | MIT News Office

    Take a walk along any sandy shoreline, and you’re bound to see a rippled pattern along the seafloor, formed by the ebb and flow of the ocean’s waves.

    wrinkle
    An example of fossilized wrinkles taken at the Upper Cambrian Big Cove Member of the Petit Jardin Formation, near Marches Point on the Port au Port Peninsula in western Newfoundland. Photo: S. Pruss

    Geologists have long observed similar impressions — in miniature — embedded within ancient rock. These tiny, millimeter-wide wrinkles have puzzled scientists for decades: They don’t appear in any modern environment, but seem to be abundant much earlier in Earth’s history, particularly following mass extinctions.

    Now MIT researchers have identified a mechanism by which such ancient wrinkles may have formed. Based on this mechanism, they posit that such fossilized features may be a vestige of microbial presence — in other words, where there are wrinkles, there must have been life.

    “You have about 3 billion years of Earth’s history where everything was microbial. The wrinkle structures were present, but don’t seem to have been all that common,” says Tanja Bosak, the Alfred Henry and Jean Morrison Hayes Career Development Associate Professor in MIT’s Department of Earth, Atmospheric and Planetary Sciences. “But it seems they become really abundant at the time when early animals were around. Knowing the mechanism of these features gives us a better sense of the environmental pressures these early animals were experiencing.”

    Bosak and her colleagues have published their study, led by postdoc Giulio Mariotti, in the journal Nature Geoscience.

    Sedimentary footprints

    Ancient sedimentary wrinkles can be found in rocks up to 575 million years old — from a time when the earliest animals may have arisen — in places such as Australia, Africa, and Canada.

    “Some of them look like wave ripples, and others look like raindrop impressions,” Mariotti says. “They’re shapes that remain in the sediment, like the footprint of a dinosaur.”

    Researchers have put forth multiple theories for how these shapes may have arisen. Some believe that ocean waves may have created such patterns, while others think the answer may lie in ancient sea foam.

    But the prevailing theory involves the presence of microbes: In a post-extinction world, microbial mats likely took over the seafloor in wide, leathery patches that were tough enough to withstand the overlying flow. As these mats were destroyed, they left small, lightweight microbial aggregates that shifted the underlying sand, creating wavelike patterns that were later preserved in sediment.

    A fragmentary sweet spot

    To test this last theory, Mariotti attempted to recreate the wrinkled patterns by growing microbial mats in custom-built wave tanks, partially filled with sand. To track his progress, he set up a camera to take time-lapse images of the tank. His initial results were successful — although, he admits, accidental.

    “I reproduced something that looked like wrinkle structures, although at first it wasn’t on purpose,” Mariotti says.

    In his first attempts to seed a tank with microbes, Mariotti obtained fragments of microbial mats from another wave tank in which microbes were growing at a moderate rate. After a few days, he spotted tiny, millimeter-wide ripples in the sand. Looking back at the time-lapse images, he discovered the mechanism: Fragments of microbial mats were rolling along the surface and, within a few hours, rearranging sediments to create wavelike patterns in the sand.

    Mariotti followed up on the observation with more controlled experiments with various wave conditions and microbial fragments, confirming that fragments, and not whole microbes, were forming the wrinkled features in the sediment.

    The results led the group to raise another question: What might have created such microbial fragments? Bosak says the likely answer is the early appearance of small animals, which may have grazed on microbial mats, ripping them into fragments in the process.

    “What we’re suggesting is that there may be some sort of sweet spot: You can’t have too many animals feeding, because then you lose microbial mats completely, but you need enough to produce these fragments,” Bosak says. “And that sweet spot could occur after a large marine extinction event.”

    Mariotti says the mechanism he’s identified may shed light on the environmental conditions early animals faced as they tried to gain a foothold following an extinction event. For example, early animals may have thrived in protected environments such as shallow lagoons, where microbial fragments might best create wrinkled patterns.

    “You need an environment where there’s not much energy, but still some wave motion, and close enough to the photic zone where you have light, so that microbial mats can grow,” Mariotti says. “Our finding may change how we see early animals.”

    David Bottjer, a professor of earth sciences at the University of Southern California, says knowing the mechanism by which these wrinkle structures formed is important not just for understanding life on Earth, but life on other planets as well.

    “It has been suggested that if a Martian rover was scanning sedimentary rocks that had been deposited underwater, and it saw wrinkle structures, that this could mean that there was microbial life present when the rocks were deposited,” says Bottjer, who was not involved in the work. “This study provides experimental evidence that, indeed, microbial fragments derived from microbial mats would be necessary to produce wrinkle structures. So, as a ‘biomarker’ indicating that microbial life would have existed on Mars, this strengthens the case for wrinkle structures, if they are found.”

    This research was partially supported by NASA and the National Science Foundation.

    See the full article, with video, here.

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  • richardmitnick 7:37 am on September 10, 2014 Permalink | Reply
    Tags: Astrobiology, ,   

    From Astrobiology: “A single evolutionary road may lead to Rome” 

    Astrobiology Magazine

    Astrobiology Magazine

    Sep 10, 2014
    Contact(s): Layne Cameron Media Communications office: (517) 353-8819 cell: (765) 748-4827 Layne.Cameron@cabs.msu.edu , Jason Gallant Zoology office: (517) 884-7756 jgallant@msu.edu, Michigan State University

    A well-known biologist once theorized that many roads led to Rome when it comes to two distantly related organisms evolving a similar trait. A new paper, published in Nature Communications, suggests that when it comes to evolving some traits – especially simple ones – there may be a shared gene, one road, that’s the source.

    jg
    Jason Gallant, MSU zoologist, shows that a single evolutionary road may lead to Rome. Photo by G.L. Kohuth – See more at: http://www.astrobio.net/topic/origins/origin-and-evolution-of-life/single-evolutionary-road-may-lead-rome/#sthash.d9t39bd2.dpuf

    Jason Gallant, MSU zoologist and the paper’s first author, focused on butterflies to illustrate his metaphorical roadmap on evolutionary traits. Butterfly wings are important biological models. While some butterflies are poisonous and notify their predators via colorful wing markings, others are nontoxic but have evolved similar color patterns to avoid being eaten.

    Many scientists, including the famed Ernst Mayr, favored the “many roads” theory. This was largely attributed to being unable to identify a shared gene for such traits. Gallant, Sean Mullen, co-author and Boston University biologist, and their collaborators, however, were able to pinpoint the single gene responsible for two different families of butterflies’ flashy markings.

    The North American and South American species last had a common ancestor more than 65 million years ago. So, rather than evolve these traits independently using two unique mechanisms, the genetic control of particular butterfly markings can be traced to a single gene present in their ancient ancestors, said Gallant, who also teamed with Arnaud Martin and Bob Reed from Cornell University, and Marcus Kronforst from the University of Chicago.

    “This result represents the culmination of a decade’s worth of effort, but we identified the mechanism for a single aspect of wing patterns in a lineage,” Gallant said. “Is this the rule or the exception? For simple traits, it’s beginning to look like it could be the rule. The jury is still out on complicated traits, but there may be fewer roads leading to Rome than we once thought.”

    The decade-long journey began as a butterfly mapping study and later involved the 30,000 genes that comprise white admiral butterflies and red-spotted purple butterflies in North America. They are the same species of butterflies, but to a common observer, they look completely unrelated.

    bf
    Jason Gallant, MSU zoologist, studied butterflies to illustrate his metaphorical roadmap on evolutionary traits. Photo by G.L. Kohuth

    In the southern United States, the red-spotted purples [Limenitis arthemis] have dark-blue wings that mimic the poisonous pipevine swallowtail. The white admirals [also Limenitis arthemis], with distinctive white bands on their wings, reside in northern climes where the swallowtail is not found. A hybrid of the two can be found in a region near Pennsylvania.

    rsp
    Red Spotted Purple

    wa
    White admiral

    Out of the 30,000 genes, Gallant, Mullen and their team narrowed the candidates to three. In one of these genes, WntA, they discovered the presence of a retrotransposon, a DNA virus of sorts, which appears to cause the deviations in wing pattern.

    “It’s the same type of DNA ‘virus’ that causes random-colored kernels in Indian corn,” Gallant said. “It was present in 100 percent of the red-spotted purples, 50 percent of the hybrids and zero percent of the white admirals; I’ve never seen such clean data like this – ever.”

    For comparison, a different species of South American butterflies, studied by researchers from Cornell and the University of Chicago, were folded into the experiment. This species is separated by a mountain range rather than a continent, but the genetic patterns were the same. The group with dark wing markings had a deletion in the WntA gene in the same spot that the retrotransposon occurred in the North American butterflies.

    When asked to comment on the significance of the work, Mullen stated the main goal of evolutionary biology is to understand the origin and maintenance of biodiversity. Within this context, a major unanswered question is whether or not evolution is predictable, and, if so, over what evolutionary time scales?

    “We addressed this question by identifying the specific genetic changes responsible for the repeated evolution of similar color pattern traits in two butterfly lineages that last shared a common ancestor some 65 million years ago,” he said. “Surprisingly, we found that changes in the expression of the same gene during development were responsible in both cases. This result implies an unprecedented level of predictability in the evolutionary process over deep time.”

    Since this evolutionary trait was triggered, perhaps somewhat accidentally, it stirs questions as to what other changes are taking place before our eyes.

    “Copying errors and genomic viruses directly lead to the wing patterns of these beautiful butterflies,” Gallant said. “It’s these accidents that allow the evolutionary process to move forward. When I look over a field of butterflies, it makes me wonder what types of ‘mistakes’ are happening right now that may lead to important evolutionary changes years from now? What evolutionary processes will we someday be able to predict?”

    See the full article here.

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  • richardmitnick 2:44 pm on September 9, 2014 Permalink | Reply
    Tags: , Astrobiology, ,   

    From Astrobiology: “New Study Revisits Miller-Urey Experiment at the Quantum Level” 

    Astrobiology Magazine

    Astrobiology Magazine

    Sep 9, 2014
    Johnny Bontemps

    New Study Revisits Miller-Urey Experiment at the Quantum Level
    By Johnny Bontemps – Sep 9, 2014

    spark
    The famous spark discharge experiment was designed to mimic lightning and the atmosphere of early Earth.

    For the first time, researchers have reproduced the results of the Miller-Urey experiment in a computer simulation, yielding new insight into the effect of electricity on the formation of life’s building blocks at the quantum level.

    exp
    The experiment

    In 1953, American chemist Stanley Miller had famously electrified a mixture of simple gas and water to simulate lightning and the atmosphere of early Earth. The revolutionary experiment—which yielded a brownish soup of amino acids—offered a simple potential scenario for the origin of life’s building blocks. Miller’s work gave birth to modern research on pre-biotic chemistry and the origins of life.

    For the past 60 years, scientists have investigated other possible energy sources for the formation of life’s building blocks, including ultra violet light, meteorite impacts, and deep sea hydrothermal vents.

    sm
    Stanley Miller, 1999 Credit: James A. Sugar

    In this new study, Antonino Marco Saitta, of the Université Pierre et Marie Curie, Sorbonne, in Paris, France and his colleagues wanted to revisit Miller’s result with electric fields, but from a quantum perspective.

    Saitta and study co-author Franz Saija, two theoretical physicists, had recently applied a new quantum model to study the effects of electric fields on water, which had never been done before. After coming across a documentary on Miller’s work, they wondered whether the quantum approach might work for the famous spark-discharge experiment.

    The method would also allow them to follow individual atoms and molecules through space and time—and perhaps yield new insight into the role of electricity in Miller’s work.

    “The spirit of our work was to show that the electric field is part of it,” Saitta said, “without necessarily involving lightning or a spark.”

    Their results are published this week in the scientific journal Proceedings of the National Academy of Sciences.

    An Alternate Route

    As in the original Miller experiment, Saitta and Saija subjected a mixture of molecules containing carbon, nitrogen, oxygen and hydrogen atoms to an electric field. As expected, the simulation yielded glycine, an amino acid that is one of the simplest building blocks for proteins, and one the most abundant products in the original Miller experiment.

    A typical intermediate in the formation of amino acids is the small molecule formaldehyde.

    form
    Formaldehyde – A typical intermediate in the formation of amino acids.

    But their approach also yielded some unexpected results. In particular, their model suggested that the formation of amino acids in the Miller scenario might have occurred via a more complex chemical pathway than previously thought.

    A typical intermediate in the formation of amino acids is the small molecule formaldehyde. But their simulation showed that when subjected to an electric field, the reaction favored a different intermediate, the molecule formamide.

    It turns out, formamide could have not only played a crucial role in the formation of life’s building blocks on Earth, but also elsewhere.

    “We weren’t looking for it, or expecting it,” Saitta said. “We only learned after the fact, by reviewing the scientific literature, that it’s an important clue in prebiotic chemistry.”

    For instance, formamide has recently been shown to be a key ingredient in making some of the building blocks of RNA, notably guanine, in the presence of ultra violet light.

    Formamide has also recently been observed in space—notably in a comet and in a solar-type proto star. Earlier research has also shown that formamide can form when comets or asteroids impact the Earth.

    Their model suggested that the formation of amino acids in the Miller scenario might have occurred via a more complex chemical pathway than previously thought.

    forma
    Formamide – In their computer model, the reaction favored this more complex intermediate.

    “The possibility of new routes to make amino acids without a formaldehyde intermediate is novel and gaining ground, especially in extraterrestrial contexts,” the authors wrote. “The presence of formamide might be a most telling fingerprint of abiotic terrestrial and extraterrestrial amino acids.”

    However, Jeff Bada, who was a graduate student of Miller’s in the 1960s and spent his career working of the origin of life, remains skeptical about their results and theoretical approach.

    “Their model might not meaningfully represent what happens in a solution,” he says. “We know there’s a lot of formaldehyde made in the spark discharge experiment. I don’t think the formamide reaction would be significant in comparison to the traditional reaction.”

    But Saitta points out that formamide is very unstable, so it may not last long enough to be observed in real Miller experiments. “In our simulation, formamide always formed spontaneously. And it was some sort of crucible—it would either break up into water and hydrogen cyanide, or combine with other molecules and form the amino acid glycine.”

    Life’s Origin–on the Rocks?

    Another key insight from their study is that the formation of some of life’s building blocks may have occurred on mineral surfaces, since most have strong natural electric fields.

    “The electric field of mineral surfaces can be easily 10 or 20 times stronger than the one in our study,” Saitta said. “The problem is that it only acts on a very short range. So to feel the effects, molecules would have to be very close to the surface.”

    “I think that this work is of great significance,” said François Guyot, a geochemist at the French Museum of Natural History.

    “Regarding the mineral surfaces, strong electric fields undoubtedly exist at their immediate proximity. And because of their strong role on the reactivity of organic molecules, they might enhance the formation of more complex molecules by a mechanism distinct from the geometrical concentration of reactive species, a mechanisms often proposed when mineral surfaces are invoked for explaining the formation of the first biomolecules.”

    One of the leading hypotheses in the field of life’s origin suggests that important prebiotic reactions may have occurred on mineral surfaces. But so far scientists don’t fully understand the mechanism behind it.

    “Nobody has really looked at electric fields on mineral surfaces,” Saitta said. “My feeling is that there’s probably something to explore there.”

    See the full article here.

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  • richardmitnick 3:44 pm on September 7, 2014 Permalink | Reply
    Tags: , Astrobiology, , titanosaurs   

    From Astrobiology- “T. Rex times seven: New dinosaur species is discovered in Argentina” 

    Astrobiology Magazine

    Astrobiology Magazine

    Sep 7, 2014
    Source: National Science Foundation (NSF)
    Maria C. Zacharias, NSF, (703) 292-8454, mzachari@nsf.gov
    Rachel Ewing, Drexel University, (215) 895-2614, re39@drexel.edu

    big
    The reconstructed skeleton and body silhouette of Dreadnoughtus, showing fossil bones that were found in white. Credit: Lacovara et al.

    Scientists have discovered and described a new supermassive dinosaur species with the most complete skeleton ever found of its type. At 85 feet long and weighing about 65 tons in life, Dreadnoughtus schrani is the largest land animal for which a body mass can be accurately calculated.

    Its skeleton is exceptionally complete, with over 70 percent of the bones, excluding the head, represented. Because all previously discovered super-massive dinosaurs are known only from relatively fragmentary remains, Dreadnoughtus offers an unprecedented window into the anatomy and biomechanics of the largest animals to ever walk the Earth.

    “Dreadnoughtus schrani was astoundingly huge,” said Kenneth Lacovara, an associate professor in Drexel University’s College of Arts and Sciences, who discovered the Dreadnoughtus fossil skeleton in southern Patagonia in Argentina and led the excavation and analysis. “It weighed as much as a dozen African elephants or more than seven T. rex. Shockingly, skeletal evidence shows that when this 65-ton specimen died, it was not yet full grown. It is by far the best example we have of any of the most giant creatures to ever walk the planet.”

    kl
    Kenneth Lacovara surrounded by the skeleton of Dreadnoughtus schrani. Credit: Kenneth Lacovara

    Lacovara and colleagues published the detailed description of their discovery, defining the genus and species Dreadnoughtus schrani, in the journal Scientific Reports from the Nature Publishing Group today. The new dinosaur belongs to a group of large plant eaters known as titanosaurs. The fossil was unearthed over four field seasons from 2005 through 2009 by Lacovara and a team including Lucio M. Ibiricu of the Centro Nacional Patagonico in Chubut, Argentina; the Carnegie Museum of Natural History’s Matthew Lamanna, and Jason Poole of the Academy of Natural Sciences of Drexel University, as well as many current and former Drexel students and other collaborators. These included three current NSF Graduate Research Fellows–current GRF Kristyn Voegele, and former GRFs Elena Schroeter and Paul Ullmann–all co-authors of this paper.

    tibia
    Kenneth Lacovara with the tibia (shinbone) and humerus (upper arm bone) from Dreadnoughtus schrani. Credit: Drexel University

    “The quality of this specimen has allowed us to study this new species in numerous aspects giving us closer to a holistic view than is possible for most dinosaur species,” said Voegele. “This could only be accomplished by collaborating with multiple experts–and without this collaboration our knowledge of this taxon would be fragmentary and not live up to the completeness and quality of the specimen. The NSF GRFP has enabled myself and two fellow collaborators to preform detailed analyses of this new species.”

    “The fellowship awarded in 2013 acknowledged Kristyn’s scientific potential, and supports her contributions to this exciting discovery,” said Gisele Muller-Parker, program director for the Graduate Research Fellowship Program. “In addition to her research on dinosaur anatomy and biomechanics, Kristyn has been involved in a variety of related outreach activities, including an annual Community Dig Day and a Fossil Discovery Station for school visits at a fossil site in New Jersey.”

    team
    Excavation team, left to right: Jason Poole, Christopher Coughenour, Alison Moyer, Kenneth Lacovara, Lucio Ibiricu, Jason Schein, Yanko Kamerbeek. Credit: Kenneth Lacovara

    NSF funding also included an Earth Sciences award of the Geobiology and Low-Temperature Geochemistry program.

    See the full article, with video, here.

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  • richardmitnick 3:38 pm on September 6, 2014 Permalink | Reply
    Tags: Astrobiology, , Oxygen   

    From Astrobiology: “Geologists re-write Earth’s evolutionary history books” 

    Astrobiology Magazine

    Astrobiology Magazine

    Sep 6, 2014

    Oxygen-producing life forms appeared at least 60 million years earlier than previously thought

    rock
    The study site landscape is shown with boulders of the ancient soil in the foreground. Credit: Quentin Crowley

    Geologists from Trinity College Dublin have rewritten the evolutionary history books by finding that oxygen-producing life forms were present on Earth some 3 billion years ago – a full 60 million years earlier than previously thought. These life forms were responsible for adding oxygen (O2) to our atmosphere, which laid the foundations for more complex life to evolve and proliferate.

    Working with Professors Joydip Mukhopadhyay and Gautam Ghosh and other colleagues from the Presidency University in Kolkata, India, the geologists found evidence for chemical weathering of rocks leading to soil formation that occurred in the presence of O2.

    Using the naturally occurring uranium-lead isotope decay system, which is used for age determinations on geological time-scales, the authors deduced that these events took place at least 3.02 billion years ago. The ancient soil (or paleosol) came from the Singhbhum Craton of Odisha, and was named the ‘Keonjhar Paleosol’ after the nearest local town.

    The pattern of chemical weathering preserved in the paleosol is compatible with elevated atmospheric O2 levels at that time. Such substantial levels of oxygen could only have been produced by organisms converting light energy and carbon dioxide to O2 and water. This process, known as photosynthesis, is used by millions of different plant and bacteria species today.

    hand
    Hand sample of 3.02 billion year old soil.

    It was the proliferation of such oxygen-producing species throughout Earth’s evolutionary trajectory that changed the composition of our atmosphere – adding much more O2 – which was as important for the development of ancient multi-cellular life as it is for us today.

    Quentin Crowley, Ussher Assistant Professor in Isotope Analysis and the Environment in the School of Natural Sciences at Trinity, is senior author of the journal article that describes this research which has just been published online in the world’s top-ranked Geology journal, Geology.

    He said: “This is a very exciting finding, which helps to fill a gap in our knowledge about the evolution of the early Earth. This paleosol from India is telling us that there was a short-lived pulse of atmospheric oxygenation and this occurred considerably earlier than previously envisaged.”

    The early Earth was very different to what we see today. Our planet’s early atmosphere was rich in methane and carbon dioxide and had only very low levels of O2. The widely accepted model for evolution of the atmosphere states that O2 levels did not appreciably rise until about 2.4 billion years ago. This ‘Great Oxidation Event‘ event enriched the atmosphere and oceans with O2, and heralded one of the biggest shifts in evolutionary history.

    rock2
    Paleosol – lower part and pale coloured – locally quarried for the mineral pyrophyllite.

    Micro-organisms were certainly present before 3.0 billion years ago but they were not likely capable of producing O2 by photosynthesis. Up until very recently however, it has been unclear if any oxygenation events occurred prior to the Great Oxidation Event and the argument for an evolutionary capability of photosynthesis has largely been based on the first signs of an oxygen build-up in the atmosphere and oceans.

    “It is the rare examples from the rock record that provide glimpses of how rocks weathered,” added Professor Crowley. “The chemical changes which occur during this weathering tell us something about the composition of the atmosphere at that time. Very few of these ‘paleosols’ have been documented from a period of Earth’s history prior to 2.5 billion years ago. The one we worked on is at least 3.02 billion years old, and it shows chemical evidence that weathering took place in an atmosphere with elevated O2 levels.”

    There was virtually no atmospheric O2 present 3.4 billion years ago, but recent work from South African paleosols suggested that by about 2.96 billion years ago O2 levels may have begun to increase. Professor Crowley’s finding therefore moves the goalposts back at least 60 million years, which, given humans have only been on the planet for around a tenth of that time, is not an insignificant drop in the evolutionary ocean.

    Professor Crowley concluded: “Our research gives further credence to the notion of early and short-lived atmospheric oxygenation.

    This particular example is the oldest known example of oxidative weathering from a terrestrial environment, occurring about 600 million years before the Great Oxidation Event that laid the foundations for the evolution of complex life.”

    See the full article here.

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