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  • richardmitnick 12:42 pm on September 26, 2014 Permalink | Reply
    Tags: Astrobiology, ,   

    From SETI: “To Find Alien Life, Expect the Unexpected” 


    SETI Institute

    temp

    Highlights of a Library of Congress symposium on first contact with extraterrestrial life

    September 25, 2014
    Dirk Schulze-Makuch

    Last week experts from a variety of fields answered a call from Steven Dick, the Baruch S. Blumberg NASA/Library of Congress Chair in Astrobiology at the Library of Congress, to meet for two days and discuss the possible discovery of extraterrestrial life and the impact such a discovery would have on society. The symposium consisted of individual talks and panel discussions, along with remarks by Rep. Lamar Smith, chair of the House science committee, Mary Voytek of NASA’s astrobiology program, and Steven Dick, who spoke on how far we have advanced our understanding.

    cows

    Some spectators from the media and “UFOlogists” in the audience may have been disappointed when Seth Shostak from the SETI Institute opened by stating that no signal from extraterrestrial intelligent beings has been discovered as yet. On the first afternoon I gave a talk about the “Landscape of Life,” which—as philosopher of science Carlos Mariscal put it—is extremely difficult to evaluate, since N still equals 1: There is only one biosphere we know of. And given that life on Earth is already extremely diverse, we can only image how diverse it would be in the universe.

    bio
    Description
    English: SeaWiFS Global Biosphere September 1997 – August 1998; This composite image gives an indication of the magnitude and distribution of global primary production, of both oceanic (mg/m3 chlorophyll a) and terrestrial (normalized difference land vegetation index), see Normalized Difference Vegetation Index (NVDI).
    Date 25 October 2005
    Source http://oceancolor.gsfc.nasa.gov/SeaWiFS/BACKGROUND/Gallery/index.html and from en:Image:Seawifs global biosphere.jpg
    Author Provided by the SeaWiFS Project, Goddard Space Flight Center and ORBIMAGE

    Neuroscientist Lori Marino continued with a presentation about the “Landscape of Intelligence” among animal species on Earth, and anthropologist John Traphagan spoke about how cultural and ethnic differences influence how we imagine aliens (and often reveal more about ourselves than about the aliens!). Marino pointed out that human interactions—such as historical encounters between aboriginal and western cultures—are often used as analogs for a first contact with extraterrestrials. A better analog, she says, would be our relationship with whales, dolphins, and other intelligent species on Earth.

    The morning session of the second day included philosopher Carol Cleland taking up a question that nicely complemented Marino’s talk: What would be the moral status of indigenous microbes on Mars or intelligent extraterrestrial animals? Philosopher Susan Schneider spoke about artificial intelligence and whether we might expect to contact not organic beings, but rather a “machine mind”—some sort of robot, android, or Borg. Brother Guy Consolmagno of the Vatican Observatory then considered the theological implications of first contact. To the question “Would you baptize an extraterrestrial?” he responded, “Only if he desires so!”

    The second day’s afternoon session included more elaboration on the theme of cultural bias in the field of astrobiology/SETI. Clearly, we’ll have to free ourselves of our own cultural mindsets to fathom what aliens really might be like. A technologically advanced octopus? A superior hive mind? Or maybe a smart, individually inclined warm-blooded animal like we see in the movies?

    Personally, I expect—based on evolutionary biology—a social predator, probably an omnivore (eating both animals and plants). There is a reason why cows are pretty stupid. They only need to graze and run away from predators. On the other hand, the predator has to be smart to eat the cow and anticipate its future movements. And of course, there’s always the possibility of swarm intelligence, as in my own sci-fi novel Alien Encounter.

    There was plenty to talk and think about at the meeting, and it’s not too soon to start the discussion. Some SETI researchers expect to detect intelligent signals within the next 25 years, given the current progress in technology. Who knows, perhaps we’re receiving the signals already, and just don’t see them or know how to interpret them!

    See the full article here.

    SETI Institute – 189 Bernardo Ave., Suite 100
    Mountain View, CA 94043
    Phone 650.961.6633 – Fax 650-961-7099
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  • richardmitnick 1:50 pm on September 25, 2014 Permalink | Reply
    Tags: Astrobiology, , Dust   

    From astrobio.net: ” Light Scattering on Dust Holds Clues to Habitability” 

    Astrobiology Magazine

    Astrobiology Magazine

    Sep 25, 2014
    Aaron L. Gronstal

    We are all made of dust. Dust particles can be found everywhere in space. Disks of dust and debris swirl around and condense to form stars, planets and smaller objects like comets, asteroids and dwarf planets. But what can dust tell us about life’s potential in the Universe?

    Astrobiologists study dust particles in space for many reasons. The behavior of particles in planet-forming disks yields clues about how planets form and evolve. Studying the composition of dust can help us understand the conditions that lead to habitability on those planets.

    But how do you determine if dust contains molecules that may be important for the origin of life, or other materials that could be used to construct habitable environments?

    Shining the Light

    Astrobiologists study dust in space by watching light coming from dusty regions. As a light wave interacts with the tiny particles, the light is scattered. This scattering causes changes in the light wave. These can include an effect called circular polarization (CP).

    A light wave can be roughly imagined as a single line that wiggles up and down. If circular polarization occurs, this line rotates as the wave moves. On paper, the effect looks a bit like a slinky or an old-fashioned spiral telephone chord.

    “Discussions on what causes circular polarization (CP) observed in dusty objects can be seen quite often in scientific papers,” said Ludmilla Kolokolova, a senior research scientist at the University of Maryland’s Department of Astronomy. “Among the most popular explanations of the CP formation are scattering of light on aligned elongated/irregular dust particles, or on the particles that contain homochiral molecules.”

    line
    The electric field vectors of a traveling circularly polarized electromagnetic wave. Credit: Wikimedia Commons

    It’s the potential role of homochiral molecules that makes this process particularly interesting for astrobiology.

    Chirality refers to molecules that are identical, but can exist in forms that are mirror-images of one another. It’s similar to a person’s left and right hands. They are both hands and are made up of the same five fingers, but the arrangement of the fingers defines each hand as either left or right. Homochirality means that even though both right- and left-hand forms of an object are possible, only one is found in the environment. This is often the case for some molecules used to build life on Earth.

    Many molecules used in life — including sugars and amino acids — can theoretically exist in both left and right-handed forms. However, life on Earth has a preference for only one type. Amino acids, for example, are typically found in the left-handed form. The introduction of right-handed amino acids actually causes cells to die.

    If light has passed through dust in space and experienced CP formation, it could tell astronomers whether or not that dust contains homochiral molecules, which could be an indictor of interest to astrobiologists.

    Right-handed/clockwise circularly polarized light displayed with and without the use of components. This would be considered left-handed/counter-clockwise circularly polarized if defined from the point of view of the source rather than the receiver. Credit: Wikimedia Commons

    cp
    Right-handed/clockwise circularly polarized light displayed with and without the use of components. This would be considered left-handed/counter-clockwise circularly polarized if defined from the point of view of the source rather than the receiver. Credit: Wikimedia Commons

    Dust isn’t only present in planet and star-forming disks. Comets in the Solar System shed dust as they orbit the Sun, and dust in the atmospheres of extrasolar planets can also affect light by reflecting it. Studying how CP occurs in each of these cases, and whether or not homochiral molecules are involved, could aid in the study of these astrobiologically significant objects.

    “If we learn how to separate CP caused by alignment from CP caused by homochirality, we get a good tool in the search for pre-biological and biological materials in space, especially in circumstellar disks and exoplanets,” Kolokolova told Astrobiology Magazine.

    Raise Your Hand

    Kolokolova and Lev Nagdimunov (an undergraduate when the study was made, and now a research assistant in Kolokolova’s group at the University of Maryland) used computer models to study the behavior of light waves in order to see if they could spot a difference in CP caused by alignment of the light wave on elongated dust particles, and CP caused by interactions with homochiral molecules.

    amino
    Amino acids, sugars and other chiral molecules come in two varieties that are mirror images of each other. Credit: NASA

    “One way to answer what causes CP in this or that case is to see which mechanism is more realistic for the given environment,” said Kolokolova. “For example, in star forming regions, alignment in magnetic fields looks more realistic. However, this is not so obvious for comets, and will be even more difficult to determine in the case of observing CP in exoplanets.”

    At first glance, the two types of CP look very similar. Looking at the two light beams head on, they appear identical.

    “Unfortunately a simple way to distinguish between these two mechanism based on the difference in the phase function of their CP cannot be used. ‘Phase function’ is dependent on phase angle, and phase angle is the angle between the star (Sun), dust particle, and observer (Earth),” explained Kolokolova. “The phase functions for aligned particles and homochiral molecules are quite similar and, within the errors of observations, almost indistinguishable.”

    With computer modelling, the team found a slight difference in the exact backscatter and forward scatter directions of light that becomes circularly polarized by alignment versus homochirality. The team hopes that by watching how light is backscattered and forward scattered by dust, they can identify specific signatures for each of the two cases.

    An excess of left-handed amino acids has been found in a few meteorites, including the Murchison meteorite, which landed in Australia in 1969. Credit: NASA

    met
    An excess of left-handed amino acids has been found in a few meteorites, including the Murchison meteorite, which landed in Australia in 1969.
    Credit: NASA

    “Using these results, we can plan observations directed to search for prebiological/biological materials in space, especially in disks and exoplanets,” said Kolokolova. “And they can be used in studies of the origin of homochirality; for example, through a survey of homochiral molecules in cosmic dust of different ages.”

    Kolokolova also points out that identifying homochiral molecules in space can provide important clues about the origins of life. Evidence from meteorites supports the idea that the origin of left-handed himochirality in amino acids used by biology on Earth is related to conditions in the early Solar System. If the dust that formed our solar system only contained left-handed amino acids, it could explain why life on Earth developed a preference for these molecules in the first place. A survey of cosmic dust could reveal that homochirality is Universal, but that doesn’t mean that every system would be just like ours.

    “It is likely that on other worlds, right-handed amino acids could dominate,” said Kolokolova. “It depends on the properties of the original magnetic field that aligned dust particles in star-forming regions.”

    This work was supported by the Exobiology & Evolutionary Biology element of the NASA Astrobiology Program.

    See the full article here.

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  • richardmitnick 8:26 pm on September 21, 2014 Permalink | Reply
    Tags: Astrobiology, ,   

    From astrobio.net: “New Hadrosaur Noses into Spotlight” 

    Astrobiology Magazine

    Astrobiology Magazine

    Sep 21, 2014
    Source: NC State University
    Terry Gates | 773.750.7714
    Mick Kulikowski | 919.515.8387
    Tracey Peake | 919.515.6142

    Call it the Jimmy Durante of dinosaurs – a newly discovered hadrosaur with a truly distinctive nasal profile. The new dinosaur, named Rhinorex condrupus by paleontologists from North Carolina State University and Brigham Young University, lived in what is now Utah approximately 75 million years ago during the Late Cretaceous period.

    had

    Rhinorex, which translates roughly into “King Nose,” was a plant-eater and a close relative of other Cretaceous hadrosaurs like Parasaurolophus and Edmontosaurus. Hadrosaurs are usually identified by bony crests that extended from the skull, although Edmontosaurus doesn’t have such a hard crest (paleontologists have discovered that it had a fleshy crest). Rhinorex also lacks a crest on the top of its head; instead, this new dinosaur has a huge nose.

    Terry Gates, a joint postdoctoral researcher with NC State and the North Carolina Museum of Natural Sciences, and colleague Rodney Sheetz from the Brigham Young Museum of Paleontology, came across the fossil in storage at BYU. First excavated in the 1990s from Utah’s Neslen formation, Rhinorex had been studied primarily for its well-preserved skin impressions. When Gates and Sheetz reconstructed the skull, they realized that they had a new species.

    “We had almost the entire skull, which was wonderful,” Gates says, “but the preparation was very difficult. It took two years to dig the fossil out of the sandstone it was embedded in – it was like digging a dinosaur skull out of a concrete driveway.”

    Based on the recovered bones, Gates estimates that Rhinorex was about 30 feet long and weighed over 8,500 lbs. It lived in a swampy estuarial environment, about 50 miles from the coast. Rhinorex is the only complete hadrosaur fossil from the Neslen site, and it helps fill in some gaps about habitat segregation during the Late Cretaceous.

    “We’ve found other hadrosaurs from the same time period but located about 200 miles farther south that are adapted to a different environment,” Gates says. “This discovery gives us a geographic snapshot of the Cretaceous, and helps us place contemporary species in their correct time and place. Rhinorex also helps us further fill in the hadrosaur family tree.”

    When asked how Rhinorex may have benefitted from a large nose Gates said, “The purpose of such a big nose is still a mystery. If this dinosaur is anything like its relatives then it likely did not have a super sense of smell; but maybe the nose was used as a means of attracting mates, recognizing members of its species, or even as a large attachment for a plant-smashing beak. We are already sniffing out answers to these questions.”

    The researchers’ results appear in the Journal of Systematic Palaeontology

    See the full article here.

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  • richardmitnick 5:05 pm on September 20, 2014 Permalink | Reply
    Tags: , Astrobiology, , Fossil Record   

    From astrobio.net: “Meteorite that doomed the dinosaurs helped the forests bloom” 

    Astrobiology Magazine

    Astrobiology Magazine

    Sep 20, 2014
    Source: PLOS
    No Writer Credit

    66 million years ago, a 10-km diameter chunk of rock hit the Yukatan peninsula near the site of the small town of Chicxulub with the force of 100 teratons of TNT. It left a crater more than 150 km across, and the resulting megatsunami, wildfires, global earthquakes and volcanism are widely accepted to have wiped out the dinosaurs and made way for the rise of the mammals. But what happened to the plants on which the dinosaurs fed?

    A new study led by researchers from the University of Arizona reveals that the meteorite impact that spelled doom for the dinosaurs also decimated the evergreen flowering plants to a much greater extent than their deciduous peers. They hypothesize that the properties of deciduous plants made them better able to respond rapidly to chaotically varying post-apocalyptic climate conditions. The results are publishing on September 16 in the open access journal PLOS Biology.

    Applying biomechanical formulae to a treasure trove of thousands of fossilized leaves of angiosperms — flowering plants excluding conifers — the team was able to reconstruct the ecology of a diverse plant community thriving during a 2.2 million-year period spanning the cataclysmic impact event, believed to have wiped out more than half of plant species living at the time. The fossilized leaf samples span the last 1,400,000 years of the Cretaceous and the first 800,000 of the Paleogene.

    The researchers found evidence that after the impact, fast-growing, deciduous angiosperms had replaced their slow-growing, evergreen peers to a large extent. Living examples of evergreen angiosperms, such as holly and ivy, tend to prefer shade, don’t grow very fast and sport dark-colored leaves.

    “When you look at forests around the world today, you don’t see many forests dominated by evergreen flowering plants,” said the study’s lead author, Benjamin Blonder. “Instead, they are dominated by deciduous species, plants that lose their leaves at some point during the year.”

    leaf
    Seen here is a Late Cretaceous specimen from the Hell Creek Formation, morphotype HC62, taxon ”Rhamnus” cleburni. Specimens are housed at the Denver Museum of Nature and Science in Denver, Colorado. Credit: Image credit: Benjamin Blonder.

    Blonder and his colleagues studied a total of about 1,000 fossilized plant leaves collected from a location in southern North Dakota, embedded in rock layers known as the Hell Creek Formation, which at the end of the Cretaceous was a lowland floodplain crisscrossed by river channels.

    The collection consists of more than 10,000 identified plant fossils and is housed primarily at the Denver Museum of Nature and Science. “When you hold one of those leaves that is so exquisitely preserved in your hand knowing it’s 66 million years old, it’s a humbling feeling,” said Blonder.

    “If you think about a mass extinction caused by catastrophic event such as a meteorite impacting Earth, you might imagine all species are equally likely to die,” Blonder said. “Survival of the fittest doesn’t apply — the impact is like a reset button. The alternative hypothesis, however, is that some species had properties that enabled them to survive.

    “Our study provides evidence of a dramatic shift from slow-growing plants to fast-growing species,” he said. “This tells us that the extinction was not random, and the way in which a plant acquires resources predicts how it can respond to a major disturbance. And potentially this also tells us why we find that modern forests are generally deciduous and not evergreen.”

    Previously, other scientists found evidence of a dramatic drop in temperature caused by dust from the impact. “The hypothesis is that the impact winter introduced a very variable climate,” Blonder said. “That would have favored plants that grew quickly and could take advantage of changing conditions, such as deciduous plants.”

    “We measured the mass of a given leaf in relation to its area, which tells us whether the leaf was a chunky, expensive one to make for the plant, or whether it was a more flimsy, cheap one,” Blonder explained. “In other words, how much carbon the plant had invested in the leaf.” In addition the researchers measured the density of the leaves’ vein networks, a measure of the amount of water a plant can transpire and the rate at which it can acquire carbon.

    “There is a spectrum between fast- and slow-growing species,” said Blonder. “There is the ‘live fast, die young’ strategy and there is the ‘slow but steady’ strategy. You could compare it to financial strategies investing in stocks versus bonds.” The analyses revealed that while slow-growing evergreens dominated the plant assemblages before the extinction event, fast-growing flowering species had taken their places afterward.

    See the full article here.

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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.

    ScienceDaily is one of the Internet’s most popular science news web sites. Since starting in 1995, the award-winning site has earned the loyalty of students, researchers, healthcare professionals, government agencies, educators and the general public around the world. Now with more than 3 million monthly visitors, ScienceDaily generates nearly 15 million page views a month and is steadily growing in its global audience.

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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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