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

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

    Astrobiology Magazine

    Astrobiology Magazine

    Dec 22, 2014
    Adam Hadhazy

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

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

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

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

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

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

    Starved in the desert

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

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

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

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

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

    Living on the edge

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

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

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

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

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

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

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

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

    Letting nothing go to waste

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

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

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

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

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

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

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

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

    Delicate, yet steadfast

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

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

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

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

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

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

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

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

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

    See the full article here.

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

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

    Astrobiology Magazine

    Astrobiology Magazine

    Dec 20, 2014
    Source: Pensoft Publishers

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

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

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

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

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

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

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

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

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

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

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

    See the full article here.

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  • richardmitnick 11:11 am on December 10, 2014 Permalink | Reply
    Tags: , Astrobiology, , Redox   

    From astrobio.net: ” Reviewing Redox” 

    Astrobiology Magazine

    Astrobiology Magazine

    Dec 10, 2014 .
    Aaron L. Gronstal

    Chemical reactions are the stuff of life on Earth. They happen all the time, and in every living cell on our planet. Astrobiologists study this chemistry in order to determine the basic mechanisms behind life, and whether or not these mechanisms could operate on other worlds.

    Among these chemical reactions are redox reactions (also called oxidation-reduction reactions). These reactions occur when electrons are transferred between different species of molecule. In a way, they are similar to acid-base reactions, where positively and negatively charged ions are shuffled around.

    The transfer of electrons can make things interesting for microorganisms because it signifies energy. On Earth, there are microbes that take advantage of redox reactions to gain the energy they need to live. This ability can allow them to thrive independently from the energy produced by the Sun.

    Oxidation is the removal of one or more electrons from a substrate. Protons (H+) are often removed with the electrons. Reduction of a substrate refers to its gain of one or more electrons. Each time a substance is oxidized, another is simultaneously reduced. Credit: Midlands Technical College

    For astrobiologists, these microbes are an important example of how life might be able to survive in environments where sunlight isn’t necessarily an option on Earth and beyond. One such habitat is in the deep subsurface, where rocks and minerals can be plentiful… but sunlight is completely absent.

    The thing is, redox reactions don’t have to involve biology. They also occur naturally in nature (referred to as abiotic).

    Diagram of the iron cycle and its involvement in heavy metal immobilization. Credit: USGS

    In the case of iron (Fe), many of the redox reactions that were once thought to be entirely abiotic are now known to be mediated by microorganisms. This overlap can make it difficult to determine whether abiotic or biotic (microbially mediated) reactions are the most dominant in an environment.

    A new review published in the journal Nature Reviews: Microbiology outlines our current knowledge of the various chemical reactions that occur in the iron cycle on Earth. Iron redox reactions are broken down into those that are abiotic, and those that are known to involve microorganisms.

    The new paper could be a valuable resource for understanding how microbes are involved in cycling iron, and which of these reactions could provide energy for microbial communities to thrive.

    See the full article, with video, here.

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  • richardmitnick 2:42 pm on December 9, 2014 Permalink | Reply
    Tags: Astrobiology, , , , , ,   

    From SETI: “Answers Blowing in the Titan Wind” 

    SETI Institute

    Monday, December 08 2014
    Devon Burr
    University of Tennessee, Knoxville
    E-mail: dburr1@utk.edu
    Tel: +1 865-974-6010

    John Marshall
    SETI Institute
    E-mail: jmarshall@seti.org
    Tel: +1 650-325-2239

    Seth Shostak, Media Contact
    SETI Institute
    E-mail: seth@seti.org,
    Tel: +1 650 960-4530

    Using a specially engineered wind tunnel, scientists have solved a puzzle about wind-blown dunes on a world that has some striking similarities to our own.

    Titan wind tunnel with important components labelled. The downwind observation side port through which the data of record are observed is the rightmost of the labelled observation ports.

    Titan, Saturn’s largest moon, has both a thick atmosphere and lakes filled with methane and ethane, making it the only solar system body other than our own with liquid on its surface. In its lower latitudes, the Cassini orbiter has found wind-driven dunes reminiscent of those seen in the deserts of Earth, but hundreds of feet high and hundreds of miles in length.

    This natural color composite was taken during the Cassini spacecraft’s April 16, 2005, flyby of Titan.
    NASA Cassini Spacecraft

    It is a combination of images taken through three filters that are sensitive to red, green and violet light. It shows approximately what Titan would look like to the human eye: a hazy orange globe surrounded by a tenuous, bluish haze. The orange color is due to the hydrocarbon particles which make up Titan’s atmospheric haze. This obscuring haze was particularly frustrating for planetary scientists following the NASA Voyager mission encounters in 1980-81. Fortunately, Cassini is able to pierce Titan’s veil at infrared wavelengths (see PIA06228). North on Titan is up and tilted 30 degrees to the right. The images to create this composite were taken with the Cassini spacecraft wide angle camera on April 16, 2005, at distances ranging from approximately 173,000 to 168,200 kilometers (107,500 to 104,500 miles) from Titan and from a Sun-Titan-spacecraft, or phase, angle of 56 degrees. Resolution in the images is approximately 10 kilometers per pixel. The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA’s Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging team is based at the Space Science Institute, Boulder, Colo. For more information about the Cassini-Huygens mission, visit http://saturn.jpl.nasa.gov and the Cassini imaging team home page, http://ciclops.org.

    Dunes are also known to exist on Venus and Mars, but Titan is unlike those worlds. This raises two questions: (a) what are the dunes made of, and (b) why do they appear to be formed in a direction opposite to that of Titan’s prevailing east-to-west winds?

    “The dunes are not made of silicates – sand – as on Earth or Mars,” says Devon Burr, a planetary scientist at the University of Tennessee, Knoxville and formerly with the SETI Institute, and lead author of a paper in the journal Nature describing the new results. “They’re hydrocarbons, and may possibly include particles of water ice that are coated with these organic materials.”

    While the source of this otherworldly sand remains a mystery, more puzzling is the direction of the winds producing the dunes. This direction can be deduced from the streamline appearance of the dunes when they wrap around high points, such as craters or mountains. These streamlines indicate winds that are more west-to-east, contrary to the prevailing easterlies.

    This conflict of reasonable expectation and appearance was solved when the research team realized that the usual models for wind transport need to be adjusted for Titan’s thicker atmosphere and more viscous sand. The team found that the threshold – or minimum – wind speed needed to transport Titan’s hydrocarbon-rich sand was higher than typical for the prevailing winds on that moon.

    Burr and her coauthors made this discovery using a wind tunnel that had been constructed in the 1980s for modeling aeolian physics on Venus, notes co-author John Marshall of the SETI Institute. “It was a bear to operate, but Dr. Burr’s refurbishment of the facility as a Titan simulator has tamed the beast. It is now an important addition to NASA’s arsenal of planetary simulation facilities.”

    This greater threshold wind speed solved the mystery of the dunes’ alignment. The winds on Titan occasionally reverse direction and dramatically increase in intensity due to the changing position of the Sun in its sky. Because the threshold wind speed is so high, only these stronger winds blowing from the west can move the sand and streamline the dunes.

    “This work highlights the fact that the winds that blow 95 percent of the time might have no effect on what we see,” Burr says. Much like the damage produced by infrequent, but “perfect” storms at sea, it is the relatively rare events that have shaped the dunes of this intriguing moon.

    The new research provides important insights into wind-borne transport on other bodies, both those with very thin atmospheres (Mars, Pluto and comets) and thick, such as might be encountered in Earth-like exoplanets.

    Burr says that these results also have down-to-Earth applications.

    “We see today sediment being wafted over the Sahara desert, across the Atlantic to South America. This wind-blow material accounts for much of the fertility of the Amazon Basin. So understanding this process is essential.”

    Wind transport dynamics are also important to unraveling climate changes in the past, including the ice ages, and the so-called “snowball Earth” episode when the entire planet was encased in ice and snow.

    Marshall says that the research “has raised many questions about Titan. There we have low gravity, a dense atmosphere, and light-weight materials – a recipe for unusual aeolian activity. Our work has just begun.”

    See the full article here.

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  • richardmitnick 9:51 am on December 9, 2014 Permalink | Reply
    Tags: Astrobiology, , , , ,   

    From NYT: “Curiosity Rover’s Quest for Clues on Mars” 

    New York Times

    The New York Times

    DEC. 8, 2014

    More than 3.5 billion years ago, a meteor slammed into Mars near its equator, carving a 96-mile depression now known as Gale Crater.

    Curiosity Cradled by Gale Crater
    NASA’s Curiosity rover landed in the Martian crater known as Gale Crater, which is approximately the size of Connecticut and Rhode Island combined. A green dot [?]shows where the rover landed, well within its targeted landing ellipse, outlined in blue.
    This oblique view of Gale, and Mount Sharp in the center, is derived from a combination of elevation and imaging data from three Mars orbiters. The view is looking toward the southeast. Mount Sharp rises about 3.4 miles (5.5 kilometers) above the floor of Gale Crater.
    The image combines elevation data from the High Resolution Stereo Camera on the European Space Agency’s Mars Express orbiter, image data from the Context Camera on NASA’s Mars Reconnaissance Orbiter, and color information from Viking Orbiter imagery. There is no vertical exaggeration in the image.
    Image credit: NASA/JPL-Caltech/ESA/DLR/FU Berlin/MSSS
    Date 13 August 2012
    Source http://www.nasa.gov/images/content/676519main_pia16058-full_full.jpg
    Author NASA/JPL-Caltech/ESA/DLR/FU Berlin/MSSS
    That was unremarkable. Back then, Mars, Earth and other bodies in the inner solar system were regularly pummeled by space rocks, leaving crater scars large and small.
    What was remarkable was what happened after the impact.

    Some scientists think Gale Crater was once fully buried with sediment and that winds excavated most of it, leaving an 18,000-foot mountain in the middle. (The colors represent different elevations.) Credit European Space Agency

    Even though planetary scientists disagree on exactly what that was, they can clearly see the result: a mountain rising more than three miles from the floor of Gale.
    More remarkable still, the mountain is layer upon layer of sedimentary rock.
    The layered rock drew the attention of the scientists who chose Gale as the destination for NASA’s Curiosity rover, a mobile laboratory the size of a Mini Cooper.
    Now, more than two years after arriving on Mars, Curiosity is climbing the mountain.

    NASA Mars Curiosity Rover

    ESA Mars Express Orbiter
    ESA/Mars Express

    NASA Viking

    In sedimentary rock, each layer encases the geological conditions of the time it formed, each a page from the book of Mars’ history. As Curiosity traverses the layers, scientists working on the $2.5 billion mission hope to read the story of how young Mars, apparently once much warmer and wetter, turned dry and cold in what John P. Grotzinger, the project scientist, calls “the great desiccation event.”

    Dr. Grotzinger remembers the first time he heard about Gale. “I looked at it, and immediately I’m like, ‘This is a fantastic site,’ ” he said. “What’s that mountain in the middle?”

    Aeolis Mons

    Officially, the name is Aeolis Mons, but mission scientists call it Mount Sharp in homage to Robert P. Sharp, a prominent geologist and Mars expert at the California Institute of Technology who died in 2004.

    On Earth, mountains rise out of volcanic eruptions or are pushed upward by plate tectonics, the collision of pieces of the planet’s crust.

    Mars lacks plate tectonics, and volcanoes do not spew out of sedimentary rock. So how did this 18,000-foot mountain form?

    In the late 1990s, NASA’s Mars Global Surveyor spacecraft was sending back images of the Martian surface far sharper than those from earlier missions, like Mariner and Viking.

    NASA Mars Global Surveyor
    NASA/Mars Global Surveyor

    Kenneth S. Edgett and Michael C. Malin of Malin Space Science Systems, the San Diego company that built Global Surveyor’s camera, saw fine layered deposits at many places on Mars, including Gale. In 2000, they offered the hypothesis that they were sedimentary, cemented into rock.

    Indeed, Dr. Edgett said, it appeared that Gale Crater had been fully buried with sediment and that later winds excavated most of it, leaving the mountain in the middle.

    Imagine carving out of an expanse as large as 1.5 Delawares — a mound as tall, from base to peak, as Mount McKinley in Alaska, the tallest mountain in North America at 20,237 feet.

    Dr. Edgett asserts that that is plausible on Mars. He points to other Martian craters of similar size that remain partly buried. “There are places where this did happen, so it’s not ridiculous to think this is what happened at Gale,” he said.

    Still, in 2007 Gale had been discarded from the list of potential landing sites for Curiosity, because observations from orbit did not show strong evidence for water-bearing minerals in the rocks. NASA’s Mars mantra for the past two decades has been “Follow the water,” because water is an essential ingredient for life.

    Dr. Grotzinger asked Ralph E. Milliken, then a postdoc in his research group at Caltech, to take a closer look at Gale. With data from an instrument on NASA’s Mars Reconnaissance Orbiter that can identify minerals in the rocks below, Dr. Milliken showed the presence of clays at the base of Mount Sharp as well as other minerals that most likely formed in the presence of water.

    “The fact we have this mountain, and it’s not all the same stuff — the mineralogy is changing from one layer to the next — that gives us the hope that maybe those minerals are recording the interaction of the water and the atmosphere and the rocks,” said Dr. Milliken, now a geologist at Brown.

    Were water conditions there becoming more acidic? Was there oxygen in the water? “That’s something we can assess with the rover on the ground,” Dr. Milliken said.

    Since its landing on Mars in August 2012, Curiosity took a detour to explore a section named http://en.wikipedia.org/wiki/Yellowknife_Bay,_Mars
    and discovered geological signs that Gale was once habitable, perhaps a freshwater lake.

    Geologic feature of Yellowknife Bay informally known as Shaler. The outcrop displays prominent cross-bedding, a feature indicative of water flows

    After that, the rover drove to Mount Sharp, with only brief stops for science. To date, the rover, operated by NASA’s Jet Propulsion Laboratory in Pasadena, Calif., has driven more than six miles, taken more than 104,000 pictures and fired more than 188,000 shots from a laser instrument that vaporizes rock and dirt to identify what they are made of.

    In September, Curiosity drilled its first hole in an outcrop of Mount Sharp and identified the iron mineral hematite in a rock. That was the first confirmation on the ground for a Gale mineral that had been first identified from orbit.

    When Curiosity reaches rocks containing clays, which form in waters with a neutral pH, that will be the most promising place to look for organic molecules, the carbon compounds that could serve as the building blocks of life, particularly if the rover can maneuver into a spot shielded from radiation. (It does not have instruments that directly test for life, past or present.)

    The orbiter also detected magnesium sulfate salts, which Dr. Milliken described as possibly similar to Epsom salts.

    A 1999 Hubble telescope image showing Mars at a distance of 54 million miles from Earth. Credit NASA

    NASA Hubble Telescope
    NASA/ESA Hubble

    That layer appears to be roughly as old as sulfates that NASA’s older Opportunity rover discovered on the other side of Mars. If Mount Sharp sulfates turn out to be the same, that could reflect global changes in the Martian climate. Or they could be different, suggesting broad regional variations in Martian conditions.

    NASA Mars Opportunity Rover

    “We’re finally beginning the scientific exploration of Mount Sharp,” Dr. Milliken said. “That was the goal.”

    Along the way, Curiosity may also turn up clues to the origins of Mount Sharp. While Dr. Edgett thinks Gale Crater filled to the brim before winds excavated the mountain, others, like Edwin S. Kite, a postdoctoral researcher at Princeton who is moving to the University of Chicago as a professor, think the mountain formed as a mound, with winds blowing layers of sand together that then were cemented by transient water. “Can you build up a pile like that without necessarily filling up the whole bowl with water?” Dr. Kite said. “Perhaps just a little bit of snow melt as the pile grows up.”

    He said the layers of Mount Sharp dip outward at the edges, as in an accumulating mound; they are not flat, as would be expected if they were lake sediments subsequently eroded by wind.

    Dr. Grotzinger thinks that both could have happened: that Gale Crater partly filled, then emptied to form the lower half of Mount Sharp, and a different process formed the upper portion. A sharp divide between the upper and lower parts of the mountain is suggestive.

    On Monday, during a NASA telephone news conference, Dr. Grotzinger and other members of the science team described new data suggesting long-lived lakes in the crater. The deposits at Yellowknife Bay could have been part of an ancient lake filled by streams flowing from the crater rim. As Curiosity drove toward Mount Sharp, it appeared to be traveling down a stack of accumulated deltas — angled layers where river sediment emptied into a standing body of water — and yet it was heading uphill. That pattern could have occurred if the water level were rising over time, and Mount Sharp was not there yet.

    That does not mean Gale was continually filled with water, but it suggests repeated wet episodes. “We don’t imagine that this environment was a single lake that stood for millions of years,” Dr. Grotzinger said, “but rather a system of alluvial fans, deltas and lakes and dry deserts that alternated probably for millions if not tens of millions of years as a connected system.”

    Ashwin Vasavada, the deputy project scientist, said that to explain the episodes of a lake-filled Gale crater, “the climate system must have been loaded with water.”

    But answers will remain elusive. “We’re not going to solve this one with the rover,” Dr. Edgett said. “We’re not going to solve this one with our orbiter data. We’re going to be scratching our heads a hundred years from now. Unless we could send some people there.”

    As successful as the NASA Mars rovers have been, their work is limited and slow. Curiosity’s top speed is not quite a tenth of a mile per hour. What might be obvious at a glance to a human geologist, who can quickly crack open a rock to peer at the minerals inside, could take days or weeks of examination by Curiosity.

    “I’d like to think it would take only a few months,” Dr. Edgett said of solving Mount Sharp’s mysteries, “with a few people on the ground.”

    See the full article, with interactive features, here.

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  • richardmitnick 7:45 pm on December 8, 2014 Permalink | Reply
    Tags: , Astrobiology,   

    From astrobio.net: “How Did Life Become Complex, And Could It Happen Beyond Earth?” 

    Astrobiology Magazine

    Astrobiology Magazine

    Dec 8, 2014
    Elizabeth Howell

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

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

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

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

    Shopping for life in the Solar System

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

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

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

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

    Rosenzweig’s research developed out of previous NASA grants over the past six years.

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

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

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

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

    Applications beyond Earth

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

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

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

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

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

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

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

    See the full article here.

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  • richardmitnick 1:56 pm on December 8, 2014 Permalink | Reply
    Tags: Astrobiology, , , , , ,   

    From JPL: “NASA’s Curiosity Rover Finds Clues to How Water Helped Shape Martian Landscape” 


    December 8, 2014
    Guy Webster
    Jet Propulsion Laboratory, Pasadena, Calif.

    Dwayne Brown
    NASA Headquarters, Washington

    Observations by NASA’s Curiosity Rover indicate Mars’ Mount Sharp was built by sediments deposited in a large lake bed over tens of millions of years.


    NASA Mars Curiosity Rover

    This interpretation of Curiosity’s finds in Gale Crater suggests ancient Mars maintained a climate that could have produced long-lasting lakes at many locations on the Red Planet.

    “If our hypothesis for Mount Sharp holds up, it challenges the notion that warm and wet conditions were transient, local, or only underground on Mars,” said Ashwin Vasavada, Curiosity deputy project scientist at NASA’s Jet Propulsion Laboratory in Pasadena, California. “A more radical explanation is that Mars’ ancient, thicker atmosphere raised temperatures above freezing globally, but so far we don’t know how the atmosphere did that.”

    Why this layered mountain sits in a crater has been a challenging question for researchers. Mount Sharp stands about 3 miles (5 kilometers) tall, its lower flanks exposing hundreds of rock layers. The rock layers – alternating between lake, river and wind deposits — bear witness to the repeated filling and evaporation of a Martian lake much larger and longer-lasting than any previously examined close-up.

    “We are making headway in solving the mystery of Mount Sharp,” said Curiosity Project Scientist John Grotzinger of the California Institute of Technology in Pasadena. “Where there’s now a mountain, there may have once been a series of lakes.”

    Curiosity currently is investigating the lowest sedimentary layers of Mount Sharp, a section of rock 500 feet (150 meters) high, dubbed the Murray formation. Rivers carried sand and silt to the lake, depositing the sediments at the mouth of the river to form deltas similar to those found at river mouths on Earth. This cycle occurred over and over again.

    “The great thing about a lake that occurs repeatedly, over and over, is that each time it comes back it is another experiment to tell you how the environment works,” Grotzinger said. “As Curiosity climbs higher on Mount Sharp, we will have a series of experiments to show patterns in how the atmosphere and the water and the sediments interact. We may see how the chemistry changed in the lakes over time. This is a hypothesis supported by what we have observed so far, providing a framework for testing in the coming year.”

    After the crater filled to a height of at least a few hundred yards, or meters, and the sediments hardened into rock, the accumulated layers of sediment were sculpted over time into a mountainous shape by wind erosion that carved away the material between the crater perimeter and what is now the edge of the mountain.

    On the 5-mile (8-kilometer) journey from Curiosity’s 2012 landing site to its current work site at the base of Mount Sharp, the rover uncovered clues about the changing shape of the crater floor during the era of lakes.

    “We found sedimentary rocks suggestive of small, ancient deltas stacked on top of one another,” said Curiosity science team member Sanjeev Gupta of Imperial College in London. “Curiosity crossed a boundary from an environment dominated by rivers to an environment dominated by lakes.”

    Despite earlier evidence from several Mars missions that pointed to wet environments on ancient Mars, modeling of the ancient climate has yet to identify the conditions that could have produced long periods warm enough for stable water on the surface.

    NASA’s Mars Science Laboratory Project uses Curiosity to assess ancient, potentially habitable environments and the significant changes the Martian environment has experienced over millions of years. This project is one element of NASA’s ongoing Mars research and preparation for a human mission to the planet in the 2030s.

    “Knowledge we’re gaining about Mars’ environmental evolution by deciphering how Mount Sharp formed will also help guide plans for future missions to seek signs of Martian life,” said Michael Meyer, lead scientist for NASA’s Mars Exploration Program at the agency’s headquarters in Washington.

    See the full article here.

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    NASA JPL Campus

    Jet Propulsion Laboratory (JPL) is a federally funded research and development center and NASA field center located in the San Gabriel Valley area of Los Angeles County, California, United States. Although the facility has a Pasadena postal address, it is actually headquartered in the city of La Cañada Flintridge [1], on the northwest border of Pasadena. JPL is managed by the nearby California Institute of Technology (Caltech) for the National Aeronautics and Space Administration. The Laboratory’s primary function is the construction and operation of robotic planetary spacecraft, though it also conducts Earth-orbit and astronomy missions. It is also responsible for operating NASA’s Deep Space Network.

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  • richardmitnick 9:49 am on December 5, 2014 Permalink | Reply
    Tags: , Astrobiology, , , , ,   

    From Cornell: “Finding infant earths and potential life just got easier” 

    Cornell Bloc

    Cornell University

    Dec. 4, 2014
    Contact: Syl Kacapyr
    Phone: (607) 255-7701

    Among the billions and billions of stars in the sky, where should astronomers look for infant Earths where life might develop? New research from Cornell University’s Institute for Pale Blue Dots shows where – and when – infant Earths are most likely to be found. The paper by research associate Ramses M. Ramirez and director Lisa Kaltenegger, The Habitable Zones of Pre-Main-Sequence Stars will be published in the Jan. 1, 2015, issue of Astrophysical Journal Letters.



    [Above from] Images and study: https://cornell.box.com/infantearths

    “The search for new, habitable worlds is one of the most exciting things human beings are doing today and finding infant Earths will add another fascinating piece to the puzzle of how ‘Pale Blue Dots’ work” says Kaltenegger, associate professor of astronomy in Cornell’s College of Arts and Sciences.

    The researchers found that on young worlds the Habitable Zone – the orbital region where water can be liquid on the surface of a planet and where signals of life in the atmosphere can be detected with telescopes – turns out to be located further away from the young stars these worlds orbit than previously thought.

    “This increased distance from their stars means these infant planets should be able to be seen early on by the next generation of ground-based telescopes,” says Ramirez. “They are easier to spot when the Habitable Zone is farther out, so we can catch them when their star is really young.”

    Moreover, say the researchers, since the pre-main sequence period for the coolest stars is long, up to 2.5 billion years, it’s possible that life could begin on a planet during its sun’s early phase and then that life could move to the planet’s subsurface (or underwater) as the star’s luminosity decreases.

    “In the search for planets like ours out there, we are certainly in for surprises. That’s what makes this search so exciting,” says Kaltenegger.

    To enable researchers to more easily find infant earths, the paper by Kaltenegger and Ramirez offers estimates for where one can find habitable infant Earths. As reference points, they also assess the maximum water loss for rocky planets that are at equivalent distances to Venus, Earth and Mars from our Sun.

    Ramirez and Kaltenegger also found that during the early period of a solar system’s development, planets that end up being in the Habitable Zone later on, when the star is older, initially can lose the equivalent of several hundred oceans of water or more if they orbit the coolest stars. However, even if a runaway greenhouse effect is triggered – when a planet absorbs more energy from the star than it can radiate back to space, resulting in a rapid evaporation of surface water – a planet could still become habitable if water is later delivered to the planet, after the runaway phase ends.

    “Our own planet gained additional water after this early runaway phase from a late, heavy bombardment of water-rich asteroids,” says Ramirez. “Planets at a distance corresponding to modern Earth or Venus orbiting these cool stars could be similarly replenished later on.”

    Ramirez and Kaltenegger’s research was supported by the Institute for Pale Blue Dots and the Simons Foundation.

    See the full article here.

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    Once called “the first American university” by educational historian Frederick Rudolph, Cornell University represents a distinctive mix of eminent scholarship and democratic ideals. Adding practical subjects to the classics and admitting qualified students regardless of nationality, race, social circumstance, gender, or religion was quite a departure when Cornell was founded in 1865.

    Today’s Cornell reflects this heritage of egalitarian excellence. It is home to the nation’s first colleges devoted to hotel administration, industrial and labor relations, and veterinary medicine. Both a private university and the land-grant institution of New York State, Cornell University is the most educationally diverse member of the Ivy League.

    On the Ithaca campus alone nearly 20,000 students representing every state and 120 countries choose from among 4,000 courses in 11 undergraduate, graduate, and professional schools. Many undergraduates participate in a wide range of interdisciplinary programs, play meaningful roles in original research, and study in Cornell programs in Washington, New York City, and the world over.

  • richardmitnick 5:48 pm on December 3, 2014 Permalink | Reply
    Tags: Astrobiology, , , , , , ,   

    From ESA: “The quest for organic molecules on the surface of 67P/C-G” 

    European Space Agency

    From The Rosetta Blog

    ESA Rosetta spacecraft

    This blog post is contributed by Ian Wright and his colleagues from the Ptolemy team.

    Ptolemy on Philae Lander

    For scientists engaged with large complex projects like Rosetta, there is always a delightful period early on when, unbound by practical realities, it is possible to dream. And so it was that at one time the scientists were thinking about having a lander with the capability to hop around a comet’s surface. In this way it would be possible to make measurements from different parts of the comet.

    Interestingly, this unplanned opportunity presented itself on 12 November 2014, when Philae landed not once but three times on Comet 67P/Churyumov-Gerasimenko.

    Comet 67P/Churyumov-Gerasimenko

    The Ptolemy instrument on Philae is a compact mass spectrometer designed to measure the composition of the materials making up 67P/C-G, with a particular focus on organic molecules and mineral components. Earlier in 2014, Ptolemy had collected data at distances of 15,000, 13,000, 30, 20, and 10 km from the comet, while Philae was still attached to Rosetta.

    But from 12 to 14 November, along with some other instruments on the lander, Ptolemy had the chance to operate at more than one location on the comet’s surface.
    Rosetta’s OSIRIS narrow-angle camera images of Philae’s first touchdown on the comet. Credit: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA


    Ptolemy performed its first ‘sniffing’ measurements on the comet just after the initial touchdown of Philae. At almost exactly the same moment, the OSIRIS camera on Rosetta was imaging Philae flying back above the surface after the first bounce.

    Later, once Philae had stopped at its final landing site, Ptolemy then made six subsequent sets of measurements, sniffing the comet’s atmosphere at the surface between 13 and 14 November. Finally, a slightly different experiment was also conducted on 14 November, which was completed only 45 minutes before Philae went into hibernation as its primary battery was exhausted.

    For this “last gasp” experiment, the team used a specialised oven, the so-called “CASE” oven, to determine the composition of volatiles (and perhaps any particulates) that had accumulated in it. The Ptolemy team also used the same opportunity to reconfigure their analytical procedures, to see if they could make some isotopic measurements. Unfortunately, there was no chance to use Ptolemy in conjunction with SD2, as this was confined to the sister instrument, COSAC, given the limited power and time available.

    The experiments conducted by Ptolemy on the surface of Comet 67P/C-G. Table courtesy of the Ptolemy team.

    Because of the relatively high power consumption of Ptolemy, it was a race against the clock. The battery had to hold out, both to perform the measurements and to relay the data back to Rosetta and then home. For those involved, it’s hard to describe the shared emotions on that day, helplessly watching a voltage heading towards the end-stop.

    Scientists from the Ptolemy team at the Lander Control Centre at DLR in Cologne, Germany, during the night between 14 and 15 November 2014, just before Philae went into hibernation. Photo courtesy of Ian Wright.

    Nevertheless, the very good news is that Ptolemy definitely returned data from its various stops on the comet. However, the data are complex and will require careful analysis: this will take time. Also, because the instrument was operated in ways that hadn’t initially been planned for, it will be necessary to go back into the laboratory to run some simulated tests, to ensure that the on-comet data obtained in similar configurations can be understood.

    In the first instance, however, the team will be concentrating on the data acquired immediately after the first touchdown. It will be fascinating to compare the rich spectrum of organic compounds detected by Ptolemy with the measurements made by COSAC about 14 minutes later.

    The Ptolemy team has lots of questions. Exactly what organic compounds are present and in what ratios? How did things change between the various sets of measurements? What does these data tell us about the composition of the 10–20 cm depth of surface dust that got kicked up during the first bounce? And what can these materials tell us about the fundamental make-up of comets?

    The team is looking forward to making these analyses over the coming months and sharing the results with you.

    See the full article here.

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    The European Space Agency (ESA), established in 1975, is an intergovernmental organization dedicated to the exploration of space, currently with 19 member states. Headquartered in Paris, ESA has a staff of more than 2,000. ESA’s space flight program includes human spaceflight, mainly through the participation in the International Space Station program, the launch and operations of unmanned exploration missions to other planets and the Moon, Earth observation, science, telecommunication as well as maintaining a major spaceport, the Guiana Space Centre at Kourou, French Guiana, and designing launch vehicles. ESA science missions are based at ESTEC in Noordwijk, Netherlands, Earth Observation missions at ESRIN in Frascati, Italy, ESA Mission Control (ESOC) is in Darmstadt, Germany, the European Astronaut Centre (EAC) that trains astronauts for future missions is situated in Cologne, Germany, and the European Space Astronomy Centre is located in Villanueva de la Cañada, Spain.

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  • richardmitnick 7:31 pm on December 1, 2014 Permalink | Reply
    Tags: , Astrobiology, , ,   

    From astrobio.net: ” The emergence of modern sea ice cover in the Arctic Ocean, 2.6 million years ago” 

    Astrobiology Magazine

    Astrobiology Magazine

    Dec 1, 2014
    No Writer Credit
    Source Center for Arctic Gas Hydrate, Climate and Environment

    Four or five million years ago, the extent of sea ice cover in Arctic was much smaller than it is today. The maximum winter extent did not reach its current location until around 2.6 million years ago. This new knowledge can now be used to improve future climate models.

    Investigating Arctic sea ice. Photo: Thomas A. Brown and Simon T. Belt

    “We have not seen an ice free period in the Arctic Ocean for 2,6 million years. However, we may see it in our lifetime. The new IPCC report shows that the expanse of the Arctic ice cover has been quickly shrinking since the 70-ies, with 2012 being the year of the sea ice minimum”, says marine geologist Jochen Knies.

    In an international collaborative project, Jochen Knies has studied the trend in the sea ice extent in the Arctic Ocean from 5.3 to 2.6 million years ago. That was the last time the Earth experienced a long period with a climate that, on average, was warm before cold ice ages began to alternate with mild interglacials.

    “When we studied molecules from certain plant fossils preserved in sediments at the bottom of the ocean, we found that large expanses of the Arctic Ocean were free of sea ice until four million years ago,” Knies tells us.

    “Later, the sea ice gradually expanded from the very high Arctic before reaching, for the first time, what we now see as the boundary of the winter ice around 2.6 million years ago,” says Jochen Knies.

    Satellite data reveal how the new record low Arctic sea ice extent, from Sept. 16, 2012, compares to the average minimum extent over the past 30 years (in yellow). Image: NASA

    The research is of great interest because present-day global warming is strongly tied to a shrinking ice cover in the Arctic Ocean. By the end of the present century, the Arctic Ocean seems likely to be completely free of sea ice, especially in summer.

    This may be of major significance for the entire planet ‘s climate system. Polar oceans, their temperature and salinity, are important drivers for world ocean circulation that distributes heat in the oceans. It also affects the heat distribution in the atmosphere. Trying to anticipate future changes in this finely tuned system, is a priority for climate researchers. For that they use climate modeling , which relies on good data.

    “Our results can be used as a tool in climate modelling to show us what kind of climate we can expect at the turn of the next century. There is no doubt that this will be one of many tools the UN Climate Panel will make use of, too. The extent of the ice in the Arctic has always been very uncertain but, through this work, we show how the sea ice in the Arctic Ocean developed before all the land-based ice masses in the Northern Hemisphere were established,” Jochen Knies explains.

    A deep well into the ocean floor northwest of Spitsbergen was the basis for this research. It was drilled as part of the International Ocean Drilling Programme, (IODP), to determine the age of the ocean-floor sediments in the area. Then, by analysing the sediments for chemical fossils made by certain microscopic plants that live in sea ice and the surrounding oceans, Knies and his co-workers were able to fingerprint the environmental conditions as they changed through time.

    A microphotograph of sea-ice diatoms (Pleurosigma stuxbergii), which scientists study to describe the extent of sea ice in the Arctic. Photo: Thomas A. Brown and Simon T. Belt

    “One thing these layers of sediment enable us to do is to “read” when the sea ice reached that precise point,” Jochen Knies tells us.

    The scientists believe that the growth of sea ice until 2.6 million years ago was partly due to the considerable exhumation of the land masses in the circum-Arctic that occurred during this period. “Significant changes in altitudes above sea level in several parts of the Arctic, including Svalbard and Greenland, with build-up of ice on land, stimulated the distribution of the sea ice,” Jochen Knies says.

    “In addition, the opening of the Bering Strait between America and Russia and the closure of the Panama Canal in central America at the same time resulted in a huge supply of fresh water to the Arctic, which also led to the formation of more sea ice in the Arctic Ocean,” Jochen Knies adds.

    All the large ice sheets in the Northern Hemisphere were formed around 2.6 million years ago.

    The results of this new study are published in Nature Communications.

    • See the full article here.


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