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  • richardmitnick 3:29 pm on October 20, 2014 Permalink | Reply
    Tags: Astrobiology, , , , , ,   

    From astrobio.net: ” Exomoons Could Be Abundant Sources Of Habitability” 

    Astrobiology Magazine

    Astrobiology Magazine

    Oct 20, 2014
    Elizabeth Howell

    With about 4,000 planet candidates from the Kepler Space Telescope data to analyze so far, astronomers are busy trying to figure out questions about habitability. What size planet could host life? How far from its star does it need to be? What would its atmosphere need to be made of?

    NASA Kepler Telescope

    Look at our own solar system, however, and there’s a big gap in the information we need. Most of the planets have moons, so surely at least some of the Kepler finds would have them as well. Tracking down these tiny worlds, however, is a challenge.

    Europa is one of the moons in our solar system that could host life. What about beyond the solar system? Credit: NASA/JPL/Ted Stryk

    A new paper in the journal Astrobiology, called Formation, Habitability, and Detection of Extrasolar Moons, goes over this mostly unexplored field of extrasolar research. The scientists do an extensive literature review of what is supposed about moons beyond the Solar System, and they add intriguing new results.

    A wealth of moons exist in our own solar system that could host life. Icy Europa, which is circling Jupiter, was recently discovered to have plumes of water erupting from its surface. Titan, in orbit around Saturn, is the only known moon with an atmosphere, and could have the precursor elements to life in its hydrocarbon seas that are warmed by Saturn’s heat. Other candidates for extraterrestrial hosts include Jupiter’s moons Callisto and Ganymede, as well as Saturn’s satellite Enceladus.

    Lead author René Heller, an astrophysicist at the Origins Institute at McMaster University, in Ontario, Canada, said some exomoons could be even better candidates for life than many exoplanets.

    “Moons have separate energy sources,” he said. “While the habitability of terrestrial planets is mostly determined by stellar illumination, moons also receive reflected stellar light from the planet as well as thermal emission from the planet itself.”

    Moreover, a planet like Jupiter — which hosts most of the moons in the Solar System that could support life — provides even more potential energy sources, he added. The planet is still shrinking and thereby converts gravitational energy into heat, so that it actually emits more light than it receives from the Sun, providing yet more illumination. Besides that, moons orbiting close to a gas giant are flexed by the planet’s gravity, providing potential tidal heating as an internal, geological heat source.

    Triton’s odd, melted appearance hint that the moon was captured and altered by Neptune. Credit: NASA

    Finding the first exomoon

    The first challenge in studying exomoons outside our Solar System is to actually find one. Earlier this year, NASA-funded researchers reported the possible discovery of such a moon, but this claim was ambiguous and can never be confirmed. That’s because it appeared as a one-time event, when one star passed in front of another, acting as a sort of gravitational lens that amplified the background star. Two objects popped out in the gravitational lens in the foreground — either a planet and a star, or a planet and an extremely heavy exomoon.

    For his part, Heller is convinced that exomoons are lurking in the Kepler data, but they have not been discovered yet. Only one project right now is dedicated to searching for exomoons, and is led by David Kipping at the Canadian Space Agency. His group has published several papers investigating 20 Kepler planets and candidates in total. The big restriction to their efforts is computational power, as their simulations require supercomputers.

    Another limiting factor is the number of observatories that can search for exomoons. To detect them, at least a handful of transits of the planet-moon system across their common host star would be required to absolutely make sure that the companion is a moon, Heller said. Also, the planet with the moon would have to be fairly far from its star, and decidedly not those close-in hot Jupiters that take only a few days to make an orbit. In that zone, the gravitational drag of the star would fatally perturb any moon’s orbit.

    Heller estimates that a telescope would need to stare constantly at the same patch of sky for several hundred days, minimum, to pick up an exomoon. Kepler fulfilled that obligation in spades with its four years of data gazing at the same spot in the sky, but astronomers will have to wait again for that opportunity.

    Because two of Kepler’s gyroscopes (pointing devices) have failed, Kepler’s new mission will use the pressure of the Sun to keep it steady. But it can only now point to the same region of the sky for about 80 days at at time because the telescope will periodically need to be moved so as not to risk placing its optics too close to the Sun.

    NASA’s forthcoming Transiting Exoplanet Survey Satellite [TESS} is only expected to look at a given field for 70 days. Further into the future, the European Space Agency’s PLAnetary Transits and Oscillations of stars (PLATO) will launch in 2024 for what is a planned six-year mission looking at several spots in the sky.



    “PLATO is the next step, with a comparable accuracy to Kepler but a much larger field of view and hopefully a longer field of view coverage,” Heller said.

    Clues in our solar system

    Thousands of exoplanets and exoplanet candidates have been discovered, but astronomers are still searching for exomoons. Credit: ESA – C. Carreau

    Heller characterizes moons as an under-appreciated feature of extrasolar planetary systems. Just by looking around us in the Solar System, he says, astronomers have been able to make crucial explanations about how the moons must have formed and evolved together with their planets. Moons thus carry information about the substructure of planet evolution, which is not accessible by planet observations alone.

    The Earth’s moon, for example, was likely formed when a Mars-sized object collided with the proto-Earth and produced a debris disk. Over time, that debris coalesced into our moon.

    While Heller says the literature mostly focuses on collision scenarios between an Earth-sized object and a Mars-sized object, he doesn’t see any reason why crashes on a bigger scale might not happen. Perhaps an Earth-sized object crashed into an object that was five times the mass of Earth, producing an extrasolar Earth-Earth binary planet system, he suggests.

    Another collision scenario likely took place at Uranus. The gas giant’s rotation is tilted about 90 degrees in its orbit around the Sun. In other words, it is rolling on its side. More intriguing, its two dozen moons follow Uranus’ rotational equator, and they do not orbit in the same plane as Uranus’ track around the Sun. This scenario suggests that Uranus was hit multiple times by huge objects instead of just once, Heller said.

    Examining mighty Jupiter’s moons gives astronomers a sense of how high temperatures were in the disk that formed the gas giant and its satellites, Heller added. Ganymede, for example, is an icy moon. Models indicate that beyond Ganymede’s orbit (at about 15 Jupiter radii) it is sufficiently cold for water to pass from the gas to the solid (ice) stage, so the regular moons in these regions are very water-rich compared to the inner, mostly rocky moons Io and Europa.

    “It sounds a bit technical, but we couldn’t have this information about planetary accretion if we did not have the moons today to observe,” Heller said.

    Some moons could also have been captured, such as Neptune’s large moon, Triton. The moon orbits in a direction opposite to other moons in Neptune‘s system (and in fact, opposite to the direction of other large moons in the Solar System.) Plus, its odd terrain suggests that it used to be a free-floating object that was captured by Neptune’s gravity. Neptune is so huge that it raised tides within the moon, reforming its surface.

    Even comparing the different types of moons around planets in the Solar System reveals different timescales of formation. Jupiter includes four moons similar in size to Earth’s moon (Europa, Callisto, Ganymede and Io), while the next largest planet in our solar system, Saturn, only has one large moon called Titan. Astronomers believe Saturn has only one large moon because the gas that formed objects in our solar system was more plentiful in Jupiter’s system to provide material for the moons to form.

    The gas abundance happened as a consequence of the huge gas giant creating a void in the material surrounding our young Sun, pulling the material in for its moons. Saturn was not quite large enough to do this, resulting in fewer large moons.

    More strange situations could exist beyond our solar system’s boundaries, but it will take a dedicated search to find exomoons. Once they are discovered, however, they will allow planet formation and evolution studies on a completely new level.

    This research was supported in part by the Natural Sciences and Engineering Research Council of Canada (NSERC), the Center for Exoplanets and Habitable Worlds, which is supported by the Pennsylvania State University, the Pennsylvania Space Grant Consortium, the National Science Foundation (NSF) the NASA Astrobiology Institute.

    See the full article here.


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  • richardmitnick 10:02 pm on October 18, 2014 Permalink | Reply
    Tags: Astrobiology, , , , , Methane Studies   

    From astrobio.net: “Scientists discover carbonate rocks are unrecognized methane sink” 

    Astrobiology Magazine

    Astrobiology Magazine

    Oct 18, 2014
    Andrew Thurber, 541-737-4500, athurber@coas.oregonstate.edu

    Since the first undersea methane seep was discovered 30 years ago, scientists have meticulously analyzed and measured how microbes in the seafloor sediments consume the greenhouse gas methane as part of understanding how the Earth works.

    The sediment-based microbes form an important methane “sink,” preventing much of the chemical from reaching the atmosphere and contributing to greenhouse gas accumulation. As a byproduct of this process, the microbes create a type of rock known as authigenic carbonate, which while interesting to scientists was not thought to be involved in the processing of methane.

    Methane bubbles pour out between rocks at the seep site. The white material at lower right is a type of bacterial colony commonly observed at methane seeps. Image courtesy of Deepwater Canyons 2013 Expedition, NOAA-OER/BOEM/USGS –

    That is no longer the case. A team of scientists has discovered that these authigenic carbonate rocks also contain vast amounts of active microbes that take up methane. The results of their study, which was funded by the National Science Foundation, were reported today in the journal Nature Communications.

    “No one had really examined these rocks as living habitats before,” noted Andrew Thurber, an Oregon State University marine ecologist and co-author on the paper. “It was just assumed that they were inactive. In previous studies, we had seen remnants of microbes in the rocks – DNA and lipids – but we thought they were relics of past activity. We didn’t know they were active.

    “This goes to show how the global methane process is still rather poorly understood,” Thurber added.

    A vast mussel community found on flat bottom as well as on rocks rising a meter or more off the seafloor. Image courtesy of Deepwater Canyons 2013 Expedition, NOAA-OER/BOEM/USGS

    Lead author Jeffrey Marlow of the California Institute of Technology and his colleagues studied samples from authigenic compounds off the coasts of the Pacific Northwest (Hydrate Ridge), northern California (Eel River Basin) and central America (the Costa Rica margin). The rocks range in size and distribution from small pebbles to carbonate “pavement” stretching dozens of square miles.

    “Methane-derived carbonates represent a large volume within many seep systems and finding active methane-consuming archaea and bacteria in the interior of these carbonate rocks extends the known habitat for methane-consuming microorganisms beyond the relatively thin layer of sediment that may overlay a carbonate mound,” said Marlow, a geobiology graduate student in the lab of Victoria Orphan of Caltech.

    These assemblages are also found in the Gulf of Mexico as well as off Chile, New Zealand, Africa, Europe – “and pretty much every ocean basin in the world,” noted Thurber, an assistant professor (senior research) in Oregon State’s College of Earth, Ocean, and Atmospheric Sciences.

    The study is important, scientists say, because the rock-based microbes potentially may consume a huge amount of methane. The microbes were less active than those found in the sediment, but were more abundant – and the areas they inhabit are extensive, making their importance potential enormous. Studies have found that approximately 3-6 percent of the methane in the atmosphere is from marine sources – and this number is so low due to microbes in the ocean sediments consuming some 60-90 percent of the methane that would otherwise escape.

    Methane gas bubbles rise from the seafloor – this type of activity, originally noticed by the Okeanos Explorer in 2012 on a multibeam sonar survey, is what led scientists to the area. Image courtesy of Deepwater Canyons 2013 Expedition, NOAA-OER/BOEM/USGS

    Now those ratios will have to be re-examined to determine how much of the methane sink can be attributed to microbes in rocks versus those in sediments. The distinction is important, the researchers say, because it is an unrecognized sink for a potentially very important greenhouse gas.

    “We found that these carbonate rocks located in areas of active methane seeps are themselves more active,” Thurber said. “Rocks located in comparatively inactive regions had little microbial activity. However, they can quickly activate when methane becomes available.

    “In some ways, these rocks are like armies waiting in the wings to be called upon when needed to absorb methane.”

    The ocean contains vast amounts of methane, which has long been a concern to scientists. Marine reservoirs of methane are estimated to total more than 455 gigatons and may be as much as 10,000 gigatons carbon in methane. A gigaton is approximate 1.1 billion tons.

    By contrast, all of the planet’s gas and oil deposits are thought to total about 200-300 gigatons of carbon.

    See the full article here.


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  • richardmitnick 5:54 pm on October 13, 2014 Permalink | Reply
    Tags: Astrobiology, , , , , ,   

    From astrobio.net: “Violent Eruptions in Mercury’s Past Could Hold Clues to Its Formation” 

    Astrobiology Magazine

    Astrobiology Magazine

    Oct 13, 2014
    Nola Taylor Redd

    Volcanoes on Mercury may have been more explosive than previously anticipated, and they may have erupted more recently, as well.

    Bright deposits around a line of volcanic vents suggest that the eruptions were explosive events.
    Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

    Scientists examining volcanic deposits on the surface of the planet using NASA’s MESSENGER spacecraft found evidence of explosive activity as recently as a billion years ago. Previous studies of the cratering of other lava flows placed most volcanic activity at more than 3.5 billion years in the past.

    NASA Messenger satellite

    Rocky planets like Mercury in orbit around other stars could have similar volcanic activity, releasing volatiles useful for the evolution of life at the surface. With temperatures ranging from -280 to 800 degrees Fahrenheit (-173 to 427 degrees Celsius), Mercury is not habitable, but similar rocky bodies around smaller, cooler stars would lie in their star’s habitable zone, the region where liquid water could exist on the surface.

    In fact, volcanism on the hot planet bears a strong similarity to volcanism on the Moon, which scientists say is surprising because of their differences.

    “Both Mercury and the Moon are a lot smaller than the Earth, and so will have cooled more than Earth since their formation. For that reason, a lot of models would not predict volcanism within the last two billion years,” lead author Rebecca Thomas of The Open University, in the United Kingdom, told Astrobiology Magazine by email.

    Kuniyoshi, a fresh crater on Mercury less than a billion years old, contains volcanic vents in its rim and walls. Because the vents would not have survived the impact, scientists concluded they must be younger than the billion-year-old crater. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

    Thomas added:

    “The fact that they both have evidence for such volcanism, despite their very different internal structures and geological histories, suggests either that our thermal models are wrong, or that there is a common cause for the prolongation of such volcanic activity.”

    The research was published in the journal Geophysical Research Letters in September 2014.

    Tiny glass beads

    When NASA’s Mariner 10 flew by Mercury in 1974, it captured features later identified as lava plains created by effusive volcanism, where lava flows from a vent in the ground. In 2009, studies by the MESSENGER probe identified irregular pits on the rocky planet with deposits that were redder than the planetary average when seen in visible and near-infrared wavelengths. Scientists identified the reddish material as deposits formed by explosive volcanism.

    NASA Mariner 10
    NASA/Mariner 10

    After identifying the first pyroclastic deposits, scientists searched other regions for indications of explosive volcanism. Thomas and her team found 150 groups of volcanic pits with bright red deposits to indicate that the lava had violently burst through the crust. Using craters to determine the age of the deposits, they found that they occurred between 4.1 billion years ago— not long after the planet’s birth — up to about a billion years ago.

    The volcanos formed aren’t steep-sided cones like those often identified on Earth. Instead, the deposits form a ring around the vent out to approximately 3.5 miles (6 kilometers), and then a zone of thin deposits spread out about three times as far, Thomas said.

    MESSENGER celebrated a decade in space last August. Credit: NASA

    Although the deposits Thomas and her team searched for appear redder than the rest of the planet, they are so dark they would look black against the bright surface of the Moon, she said. Ejected material near the vents may have been so hot that it welded together on landing, looking more like lava flows or gobs of melted wax. Farther out, the magma fragments would have had more time to cool before landing, forming small glass spheres that resemble fine beads. On the Moon, these spherules come in many colors, depending on changes in the composition.

    “When the Apollo 17 astronauts went to the Moon, they found orange-colored soil, and they realized that tiny glass spheres from a volcanic eruption were what made it look orange,” Laura Kerber, of NASA’s Jet Propulsion Laboratory, told Astrobiology Magazine in an email.

    Kerber, who was not involved in the new research, studies explosive volcanism on Mars, Mercury and Earth.

    Identifying these features on Mercury has been what Kerber calls “a special challenge.” On the Moon, the presence of iron allowed scientists to map different minerals. But on the surface of Mercury, there is so little iron that identifying the composition of the crust is more difficult.

    “MESSENGER has several instruments, such as an X-ray spectrometer, and a gamma ray and neutron spectrometer, which allow us to learn about Mercury’s composition in other ways,” Kerber said. “Still, it would be great for us to have a sample of Mercury here on the Earth to study up close. Many amazing discoveries have been made using the pyroclastic beads that the Apollo astronauts brought back from the Moon.”

    “A Roman Candle firework”

    Although most of the volcanism on Mercury took the form of slow-moving lava, some of it was quite violent.

    “In explosive volcanism, gases that were originally dissolved in the magma rip it apart when it reaches the lower-pressure conditions of the planet’s surface,” Thomas said.

    “Chunks of magma, blocks ripped from the vent wall, and finer ash are ejected violently. On Earth, these would be the most destructive eruptions.”

    A close-up view of the crater Rudaki by MESSENGER shows the nearby plains that were formed by volcanic flows on the surface of Mercury. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

    Kerber compares the process to the physics involved in a carbonated beverage. In a can of soda, the carbon dioxide is pushed into liquid form while under high pressure. When the bottle is opened and the pressure released, bubbles form as the carbon dioxide jumps back into the gas phase.

    Materials known as volatiles, elements or compounds likely to enter the gas phase when heated, act similar to the soda’s carbon dioxide. More volatiles result in more gas, making the eruption more likely to be explosive.

    In addition, scientists think that an impact early in the planet’s lifetime evaporated most of the crust, vaporizing most of its volatile components.

    “So the presence of explosive volcanism on Mercury is a little bit surprising,” Kerber said.

    While the slow creeping lava from effusive eruptions might bear a strong resemblance to flows seen at the Kilauea volcano in Hawaii,the more explosive eruptions on Mercury would differ from those on Earth.

    Mercury is a smaller planet, with lower gravity, which means material ejected from a volcano on the hot rocky planet would fly farther than if it spewed from an Earth-based eruption at the same speed.

    Mercury also has almost no atmosphere, compared to the thick one surrounding Earth, which means that there would be no air pressure to keep the gas from spreading. As a result, Kerber said, the gases would expand more rapidly and explosively than they would on Earth. The lack of atmosphere would also keep the particles traveling in a straightforward trajectory, without the effects of turbulence or wind.

    “On Mercury, you would not see billowing ash clouds as on Earth. Instead, it would be like a Roman Candle firework, with glowing fragments spraying out in every direction,” Thomas said.

    The fiery yellow spots shown in these images of Mercury are a series of pyroclastic vents believed to be one source of explosive eruptions on the planet. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

    Mercurys around other suns

    Volcanism can help scientists understand a planet’s composition, internal structure and even how it formed. As Mercury cools, it contracts, creating features known as “wrinkle ridges” as the crust pulls closer together. This contraction, along with the cooling, is one reason scientists thought it unlikely that volcanic activity would have continued into the later part of the planet’s geological history, Thomas said.

    Such deposits may be present on exoplanets — planets orbiting other stars — if they, too, are rocky bodies without an atmosphere. According to Kerber, the farther a planet is from a star, the more volatiles it is likely to have. Similarly, larger planets cool slower, also suggesting more volcanic activity.

    Recent studies have suggested that rocky planets like Mercury orbiting stars smaller and dimmer than the sun—a class known as ‘M dwarfs’—would be able to host photosynthesis on their surface.

    “If an exoplanet of a similar size were in its star’s habitable zone, the heat from the volcanic eruption is a good source of energy, and the volcanic-bearing compounds it releases to the surface can be used as nutrients,” Thomas said.

    Exoplanets could also help to clear up the mystery of Mercury’s formation, as scientists come to understand the internal composition of other small, close-orbiting rocky planets.

    Mercury stands out from other planets in the Solar System because it has a massive iron core that dominates its interior. Less than 20 percent of the radius of the planet is taken up by the crust and mantle.

    The irregularly shaped pit within the crater To Ngoc Van is thought to have formed through explosive volcanism. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

    Some models propose that the over-sized core is due to an impact early in its life — the same impact that scientists thought would have evaporated the majority of the volatiles when most of the crust and mantle were lost. Most of the iron remained, but in the planet’s core rather than at its surface. Others suggest it formed this way due to its close orbit around the Sun.

    “In fact, this is one of the most exciting things we could learn by looking at exoplanets that are also close to their star. Was a planet like Mercury inevitable at that distance from the Sun, or is it the result of a massive catastrophe?” Thomas said.

    See the full article here.


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  • richardmitnick 7:00 pm on October 2, 2014 Permalink | Reply
    Tags: Astrobiology, , , , , ,   

    From Ethan Siegel: “Preparing for Alien Life” 

    Starts with a bang
    Starts with a Bang

    Oct 2, 2014
    Ethan Siegel

    “Language… has created the word ‘loneliness’ to express the pain of being alone. And it has created the word ‘solitude’ to express the glory of being alone.” -Paul Tillich

    Recently, the John Templeton Foundation ran a series of articles asking one of the biggest questions of all: Are We Alone in the Universe? One of the articles in particular I was a big fan of, but would have liked to seen go longer and more in-depth. You see, we have every reason to not only believe that some form of life is quite common in the Universe, but that if we get lucky, we’re going to find it in the next two decades, tops.

    Let me explain.

    Image credit: Robert Gendler of http://www.robgendlerastropics.com/Biography.html, of the Rosette_Nebula.

    Everywhere we look in the Universe, we see evidence that the same cosmic story is unfolding, from nearby stars to neighboring galaxies to distant clusters across the Universe. We see the same laws of physics, the same physical phenomena, and a shared history that cuts across the billions of light years that separate us.

    We see a Universe that began from a hot, dense, expanding state,

    Image credit: NASA / Goddard Space Flight Center, via http://cosmictimes.gsfc.nasa.gov/universemashup/archive/pages/expanding_universe.html.

    where matter won out over antimatter,

    Image credit: me, with the background by Christof Schaefer.

    where stable atomic nuclei and then neutral atoms formed,

    Image credit: Universe Adventure, © 2005 LBNL Physics Division.

    where gravitational collapse caused the first stars to form,

    Image credit: The Coronet Cluster, X-ray/IR composite, via NASA/CXC/J. Forbrich, NASA/JPL-Caltech L.Allen (Harvard-Smithsonian CfA), IRAC GTO.

    where the heavy elements formed in their cores were recycled back into interstellar space when those stars died in supernova explosions,

    Image credit: Supernova Remnant 1E 0102.2–7219, via NASA / CXC / MIT / SAO / STScI / J. DePasquale / D.Dewey et al., at http://www.cfa.harvard.edu/imagelist/2009-16.

    where complex molecules arose from multiple generations of stars spilling their innards back into deep space,
    Image credit: NASA, ESA, CXC, SSC, and STScI.

    where later generations of stars formed with planets, moons, asteroids and comets around them,

    Image credit: Avi M. Mandell, NASA.

    and where the ingredients essential to life are ubiquitous.

    This is the consistent cosmic story that we see cutting across the entire observable Universe, from nearby stars to distant nebulae to the galactic center to other galaxies, as far as our technology allows us to observe. Over the last two decades, we’ve discovered the first planets around Sun-like stars [exoplanets]. While initially we tended to discover hot, giant planets in close orbits around their stars, that turned out to be solely because those types of planets are the easiest to observe: they causes the largest “rocking motion” (or stellar wobble) of their parent star due to gravitation, and they also block the most amount of light if they happen to have the right alignment to transit in front of their star’s disk relative to our line-of-sight.

    It’s the planets and planetary candidates that are found via this latter method — the planetary transit — that are likely to be the first planets found that harbor life. This isn’t because planets that transit in front of their stars relative to us are more likely to contain life, but rather because it’s easiest to detect a surefire sign of life using this method.

    Even though there are many conceivable chemical reactions that can give rise to life, and many possible signatures that life would leave behind as a by-product, there are a great many abiotic processes that we’d have to rule out. In addition, there are a great many properties of Earth that — although we could see them from a distant star — aren’t necessarily indicators of life.

    From a long distance away, we could find, with a large enough telescope, that Earth contained:

    oceans and continents,
    an active, variable-cloud-cover atmosphere, and
    polar icecaps that grew and shrank with the seasons.

    But none of those are necessarily indicative of life. However, there is a signature that Earth possesses that, as far as we know, couldn’t occur on a planet that didn’t have life.

    Image credit: Ziurys et al. 2006, NRAO Newsletter, 109, 11.

    You see, every atom and molecule in existence has a signature spectrum that’s unique to that configuration. Hydrogen, helium, lithium and all the elements of the periodic table have specific wavelengths of light that they absorb and emit, corresponding to the atomic transitions that can occur within those atoms, with all other transitions being forbidden. This is true of molecules as well, including the nitrogen, water vapor, carbon dioxide and ozone in the Earth’s atmosphere.

    Periodic Tbale of elements

    All of those molecules could be the result of either organic or inorganic processes, but there’s one component of Earth’s atmosphere that couldn’t have arisen through inorganic processes, and that’s oxygen.

    Image credit: Fran Bagenal of Colorado, via http://lasp.colorado.edu/~bagenal/3720/CLASS5/5Spectroscopy.html.

    There are only a few ways to produce oxygen abiotically, mostly from the high-energy dissociation of other molecules, and even then that only produces it in trace amounts. Here on Earth, however, our atmosphere is a tremendous 21% oxygen, and that percentage has been signficant (at 10% or above) for some two billion years. Although not every planet that has life on it will have a large oxygen content in its atmosphere, every planet that has a large oxygen content in its atmosphere has, at the very least, a history of life that gave rise to that oxygen!

    So how, then, would we detect oxygen on a planetary atmosphere?

    Image credit: H. Rauer et al.: Potential Biosignatures in super-Earth Atmospheres. Astronomy & Astrophysics, February 16, 2011.

    We couldn’t do it the same way we do it here on Earth; the light coming from an individual, rocky planet in another solar system is far too faint to be seen with not only existing telescope technology, but with any of the telescopes proposed to be built over the next generation. But we are expecting huge upgrades in telescope technology over the next decade or two: the largest, most powerful telescope in space will go from Hubble, at 2.4 meters in diameter, to James Webb, which will have a primary mirror that’s 6.5 meters in diameter, with five times the light-gathering power!

    NASA Hubble Telescope
    NASA/ESA Hubble

    NASA Webb Telescope

    Image credit: NASA.

    In addition to that, the current generation of 8-to-10 meter ground-based telescopes will be superseded by 20-to-35 meter telescopes, providing not only additional light-gathering power but also increased resolution. Examples include the Giant Magellan Telescope, the Thirty Meter Telescope and the European Extremely Large Telescope projects.

    Giant Magellan TelescopeGiant Magellan Interior
    Giant Magellan Telescope

    TMT Schematic


    This improvement in sensitivity means we’re going to be able to detect smaller effects, find smaller planets around larger stars, and many other advances. But perhaps the greatest advance towards finding a planet with oxygen on it — and hence, life — will occur where we have rocky, Earth-sized planets transiting in front of their stars.

    Image credit: NASA / JPL-Caltech, via http://www.nasa.gov/centers/goddard/news/topstory/2007/cloudy_world.html.

    You see, when a planet passes in front of its star, it not only blocks a fraction of the starlight coming from the star, it also allows a tiny amount of that starlight to pass through the planet’s atmosphere, streaming on into the Universe towards us! Just as the Moon turns red during an eclipse because sunlight passes through the Earth’s atmosphere, so should we be able to see tiny absorption signatures corresponding to different elements when distant starlight passes through a transiting planet’s atmosphere.

    So far, with present technology, we’ve been able to find signatures like water in the atmospheres of Neptune-sized planets.

    Image credit: Harvard Smithsonian Center for Astrophysics, illustration of Planet HAT-P-11b.

    But what the next generation of telescope advances should bring us is the ability to find those same types of signatures around Earth-sized planet, and we should be able to find those signatures around stars up to perhaps 25-to-30 light years away, or conceivably even farther! Given that we have some 300 stars within that conservative distance alone, and given that some of those planetary systems are bound to have a fortuitous alignment with our line-of-sight, we’re going to have the first opportunity, if oxygen-producing life is really abundant in the Universe, to find our first planet with alien life within a single generation.

    Image credit: NASA / NSF / Lynette Cook. Via http://www.nasa.gov/topics/universe/features/gliese_581_feature.html.

    If the Universe is kind to us, the first signs of life beyond our Solar System will not only teach us that we’re not alone, but that the optimists have it right. Life might not only exist on planets other than Earth, it might be more common than most of us have dared to dream.

    See the full article, with video, here.

    Starts With A Bang! is a blog/video blog about cosmology, physics, astronomy, and anything else I find interesting enough to write about. I am a firm believer that the highest good in life is learning, and the greatest evil is willful ignorance. The goal of everything on this site is to help inform you about our world, how we came to be here, and to understand how it all works. As I write these pages for you, I hope to not only explain to you what we know, think, and believe, but how we know it, and why we draw the conclusions we do. It is my hope that you find this interesting, informative, and accessible.

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  • richardmitnick 2:43 pm on October 1, 2014 Permalink | Reply
    Tags: Astrobiology, , , , ,   

    From Cassini: “Swirling Cloud at Titan’s Pole is Cold and Toxic “ 

    NASA Cassini Spacecraft


    Scientists analyzing data from NASA’s Cassini mission have discovered that a giant, toxic cloud is hovering over the south pole of Saturn’s largest moon, Titan, after the atmosphere there cooled dramatically.

    Spectral Map of Titan with Polar Vortex. These two views of Saturn’s moon Titan show the southern polar vortex, a huge, swirling cloud that was first observed by NASA’s Cassini spacecraft in 2012.
    The view at left is a spectral map of Titan obtained with the Cassini Visual and Infrared Mapping Spectrometer (VIMS) on Nov. 29, 2012. The inset image is a natural-color close-up of the polar vortex taken by Cassini’s wide-angle camera.


    Three distinct components are evident in the VIMS image, represented by different colors: the surface of Titan (orange, near center), atmospheric haze along the limb (light green, at top) and the polar vortex (blue, at lower left).

    To the VIMS instrument, the spectrum of the southern polar vortex shows a remarkable difference with respect to other portions of Titan’s atmosphere: a signature of frozen hydrogen cyanide molecules (HCN). This discovery has suggested to researchers that the atmosphere of Titan’s southern hemisphere is cooling much faster than expected. Observing seasonal shifts like this in the moon’s climate is a major goal for Cassini’s current extended mission.

    The scientists found that this giant polar vortex contains frozen particles of the toxic compound hydrogen cyanide, or HCN.

    “The discovery suggests that the atmosphere of Titan’s southern hemisphere is cooling much faster than we expected,” said Remco de Kok of Leiden Observatory and SRON Netherlands Institute for Space Research, lead author of the study published today in the journal Nature.

    Titan is the only moon in the solar system that is cloaked in a dense atmosphere. Like our home planet, Earth, Titan experiences seasons. As it makes its 29-year orbit around the sun along with Saturn, each season lasts about seven Earth years. The most recent seasonal switch occurred in 2009, when winter gave way to spring in the northern hemisphere, and summer transitioned to autumn in the southern hemisphere.

    In May 2012, while Titan’s southern hemisphere was experiencing autumn, images from Cassini revealed a huge swirling cloud, several hundred miles across, taking shape above Titan’s south pole. This polar vortex appears to be an effect of the change of season.

    A puzzling detail about the swirling cloud is its altitude, some 200 miles (about 300 kilometers) above Titan’s surface, where scientists thought the temperature was too warm for clouds to form. “We really didn’t expect to see such a massive cloud so high in the atmosphere,” said de Kok.

    Keen to understand what could give rise to this mysterious cloud, the scientists dove into Cassini’s observations and found an important clue in the spectrum of sunlight reflected by Titan’s atmosphere.

    A spectrum splits the light from a celestial body into its constituent colors, revealing signatures of the elements and molecules present. Cassini’s visual and infrared mapping spectrometer (VIMS) maps the distribution of chemical compounds in Titan’s atmosphere and on its surface.

    “The light coming from the polar vortex showed a remarkable difference with respect to other portions of Titan’s atmosphere,” says de Kok. “We could clearly see a signature of frozen HCN molecules.”

    As a gas, HCN is present in small amounts in the nitrogen-rich atmosphere of Titan. Finding these molecules in the form of ice was surprising, as HCN can condense to form frozen particles only if the atmospheric temperature is as cold as minus 234 degrees Farenheit (minus 148 degrees Celsius). This is about 200 degrees Fahrenheit (about 100 degrees Celsius) colder than predictions from current theoretical models of Titan’s upper atmosphere.

    To check whether such low temperatures were actually possible, the team looked at observations from Cassini’s composite infrared spectrometer (CIRS), which measures atmospheric temperature at different altitudes. Those data showed that the southern hemisphere of Titan has been cooling rapidly, making it possible to reach the cold temperature needed to form the giant toxic cloud seen on the south pole.

    Atmospheric circulation has been drawing large masses of gas towards the south since the change of season in 2009. As HCN gas becomes more concentrated there, its molecules shine brightly at infrared wavelengths, cooling the surrounding air in the process. Another factor contributing to this cooling is the reduced exposure to sunlight in Titan’s southern hemisphere as winter approaches there.

    “These fascinating results from a body whose seasons are measured in years rather than months provide yet another example of the longevity of the remarkable Cassini spacecraft and its instruments,” said Earl Maize, Cassini project manager at NASA’s Jet Propulsion Laboratory in Pasadena, California. “We look forward to further revelations as we approach summer solstice for the Saturn system in 2017.”

    See the full article here.

    Cassini completed its initial four-year mission to explore the Saturn System in June 2008 and the first extended mission, called the Cassini Equinox Mission, in September 2010. Now, the healthy spacecraft is seeking to make exciting new discoveries in a second extended mission called the Cassini Solstice Mission.

    The mission’s extension, which goes through September 2017, is named for the Saturnian summer solstice occurring in May 2017. The northern summer solstice marks the beginning of summer in the northern hemisphere and winter in the southern hemisphere. Since Cassini arrived at Saturn just after the planet’s northern winter solstice, the extension will allow for the first study of a complete seasonal period.

    Cassini launched in October 1997 with the European Space Agency’s Huygens probe. The probe was equipped with six instruments to study Titan, Saturn’s largest moon. It landed on Titan’s surface on Jan. 14, 2005, and returned spectacular results.

    Meanwhile, Cassini’s 12 instruments have returned a daily stream of data from Saturn’s system since arriving at Saturn in 2004.

    Among the most important targets of the mission are the moons Titan and Enceladus, as well as some of Saturn’s other icy moons. Towards the end of the mission, Cassini will make closer studies of the planet and its rings.

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  • richardmitnick 7:50 pm on September 30, 2014 Permalink | Reply
    Tags: , Astrobiology, , , , ,   

    From Astronomy: “New molecule found in space connotes life origins” 

    Astronomy magazine

    Astronomy Magazine

    September 29, 2014
    No Writer Credit
    Cornell University, Ithaca, New York

    Like finding a molecular needle in a cosmic haystack, astronomers have detected radio waves emitted by isopropyl cyanide.

    Hunting from a distance of 27,000 light-years, astronomers have discovered an unusual carbon-based molecule — one with a branched structure — contained within a giant gas cloud in interstellar space. Like finding a molecular needle in a cosmic haystack, astronomers have detected radio waves emitted by isopropyl cyanide. The discovery suggests that the complex molecules needed for life may have their origins in interstellar space.

    Dust and molecules in the central region of our galaxy: The background image shows the dust emission in a combination of data obtained with the APEX telescope and the Planck space observatory at a wavelength around 860 micrometers. The organic molecule iso-propyl cyanide with a branched carbon backbone (i-C3H7CN, left) as well as its straight-chain isomer normal-propyl cyanide (n-C3H7CN, right) were both detected with the Atacama Large Millimeter/submillimeter Array in the star-forming region Sgr B2, about 300 light years away from the galactic center Sgr A*.
    MPIfR/A. Weiß (background image); University of Cologne/M. Koerber (molecular models); MPIfR/A. Belloche (montage)

    Using the Atacama Large Millimeter/submillimeter Array (ALMA), researchers studied the gaseous star-forming region Sagittarius B2.

    ALMA Array

    Organic molecules usually found in these star-forming regions consist of a single “backbone” of carbon atoms arranged in a straight chain. But the carbon structure of isopropyl cyanide branches off, making it the first interstellar detection of such a molecule, said Rob Garrod from Cornell University in Ithaca, New York.

    This detection opens a new frontier in the complexity of molecules that can be formed in interstellar space and that might ultimately find their way to the surfaces of planets, said Garrod. The branched carbon structure of isopropyl cyanide is a common feature in molecules that are needed for life — such as amino acids, which are the building blocks of proteins. This new discovery lends weight to the idea that biologically crucial molecules, like amino acids that are commonly found in meteorites, are produced early in the process of star formation — even before planets such as Earth are formed.

    Garrod, along with Arnaud Belloche and Karl Menten, both of the Max Planck Institute for Radio Astronomy, and Holger Müller of the University of Cologne, sought to examine the chemical makeup of Sagittarius B2, a region close to the Milky Way’s galactic center and an area rich in complex interstellar organic molecules.

    With ALMA, the group conducted a full spectral survey looking for fingerprints of new interstellar molecules — with sensitivity and resolution 10 times greater than previous surveys.

    The purpose of the ALMA Observatory is to search for cosmic origins through an array of 66 sensitive radio antennas from the high elevation and dry air of northern Chile’s Atacama Desert. The array of radio telescopes works together to form a gigantic “eye” peering into the cosmos.

    “Understanding the production of organic material at the early stages of star formation is critical to piecing together the gradual progression from simple molecules to potentially life-bearing chemistry,” said Belloche.

    About 50 individual features for isopropyl cyanide and 120 for normal-propyl cyanide — its straight-chain sister molecule — were identified in the ALMA spectrum of the Sagittarius B2 region. The two molecules — isopropyl cyanide and normal-propyl cyanide — are also the largest molecules yet detected in any star-forming region.

    See the full article here..

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  • richardmitnick 5:41 pm on September 30, 2014 Permalink | Reply
    Tags: Astrobiology, , , , , ,   

    From SPACE.com: “Search for Alien Life Should Target Water, Oxygen and Chlorophyll” 

    space-dot-com logo


    September 30, 2014
    Mike Wall

    The next generation of space telescopes hunting for signs of extraterrestrial life should focus on water, then oxygen and then alien versions of the plant chemical chlorophyll, a new study suggests.

    In the past 20 years or so, astronomers have confirmed the existence of nearly 2,000 worlds outside Earth’s solar system. Many of these exoplanets lie in the habitable zones of stars, areas potentially warm enough for the worlds to harbor liquid water on their surfaces. Astrobiologists hope that life may someday be spotted on such alien planets, since there is life pretty much everywhere water exists on Earth.

    One strategy to discover signs of such alien life involves looking for ways that organisms might change a world’s appearance. For example, chemicals typically shape what are known as the spectra seen from planets by adding or removing wavelengths of light. Alien-hunting telescopes could look for spectra that reveal chemicals associated with life. In other words, these searches would focus on biosignatures — chemicals or combinations of chemicals that life could produce, but that processes other than life could not or would be unlikely to create.

    Astrophysicists Timothy Brandt and David Spiegel at the Institute for Advanced Study in Princeton, New Jersey, sought to see how challenging it might be to conclusively identify signatures of water, oxygen and chlorophyll — the green pigment that plants use to convert sunlight to energy — on a distant twin of Earth using a future off-Earth instrument such as NASA’s proposed Advanced Technology Large-Aperture Space Telescope (ATLAST).

    8-meter monolithic mirror telescope (credit: MSFC Advanced Concepts Office)
    16-meter segmented mirror telescope (credit: Northrop Grumman Aerospace Systems & NASA/STScI)
    two conceptual schemes for ATLAST

    The scientists found that water would be the easiest to detect.

    “Water is a very common molecule, and I think a mission to take spectra of exoplanets should certainly look for water,” said Brandt, the lead study author. “Indeed, we have found water in a few gas giants more massive than Jupiter orbiting other stars.”

    In comparison, oxygen is more difficult to detect than previously thought, requiring scientific instruments approximately twice as sensitive as those needed to detect water and significantly better at discriminating between similar colors of light.

    “Oxygen, however, has only been a large part of Earth’s atmosphere for a few hundred million years,” Brandt said. “If we see it in an exoplanet, it probably points to life, but not finding oxygen certainly does not mean that the planet is sterile.”

    Although a well-designed space telescope could detect water and oxygen on a nearby Earth twin, the astrophysicists found the instrument would need to be significantly more sensitive, or very lucky, to see chlorophyll. Identifying this chemical typically requires scientific instruments about six times more sensitive than those needed for oxygen. Chlorophyll becomes as detectable as oxygen only when an exoplanet has a lot of vegetation and/or little in the way of cloud cover, researchers said.

    Chlorophyll slightly reddens the light from Earth. If extraterrestrial life does convert sunlight to energy as plants do, scientists expect that the alien process might use a different pigment than chlorophyll. But alien photosynthesis could also slightly redden planets, just as chlorophyll does.

    “Light comes in packets called photons, and only photons with at least a certain amount of energy are useful for photosynthesis,” Brandt said. Chlorophyll reflects photons that are too red and low in energy to be used for photosynthesis, and it may be reasonable to assume that extraterrestrial pigments would do the same thing, Brandt noted.

    The researchers suggest a strategy for discovering Earthlike alien life that first looks for water, then oxygen on the more favorable planets and finally chlorophyll on only the most exceptionally promising worlds.

    “The goal of a future space telescope will be primarily to detect water and oxygen on a planet around a nearby star,” Brandt said. “The construction and launch of such a telescope will probably cost at least $10 billion and won’t happen for at least 20 years — a lot of technology development needs to happen first — but it could be the most exciting mission of my lifetime.”

    Brandt and Spiegel detailed their findings online Sept. 1 in the journal Proceedings of the National Academy of Sciences.

    See the full article here.

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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


    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.


    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.

    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.”

    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

    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 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

    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.


    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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