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  • richardmitnick 12:38 pm on April 15, 2017 Permalink | Reply
    Tags: , , , , , , Is there life on Saturn’s moon?, Saturn   

    From EarthSky: “Is there life on Saturn’s moon?” 

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    EarthSky
    April 15, 2017
    Daniela Breitman

    Enceladus, one of 62 moons in a confirmed orbit around Saturn, has been in the spotlight since the Cassini spacecraft began orbiting Saturn, weaving among its moons and rings, in 2004. It was only when Cassini turned its instruments toward Enceladus that we learned of the moon’s powerful geysers and subsurface saltwater ocean. This week, scientists made another fascinating announcement about this Saturn moon. They say they now have strong evidence for a habitable area on the floor of Enceladus’ ocean. Their paper on this subject was published in the peer-reviewed journal Science on April 13, 2017.

    The ocean of Enceladus is covered by a layer of surface ice. The moon’s geysers emerge from the subsurface ocean through cracks in the ice. When the Cassini spacecraft flew through plumes of gas and icy particles that make up Enceladus’ geysers on October 28, 2015, it detected a significant amount of molecular hydrogen. Scientists confirmed this week that the best explanation for this observation is that hydrothermal reactions occurring on Enceladus’ ocean floor. They may be similar to hydrogen-generating interactions taking place at Earth’s hydrothermal vents.

    This discovery means the small, icy moon Enceladus might have a source of chemical energy that could be useful for living microbes, if any exist there.

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    Scientists have suggested that water interacts with the rocky core of Enceladus, thereby producing hydrogen. The detection of molecular hydrogen in the plumes of Enceladus supports this idea. Image via NASA.

    Hydrothermal vents are common on Earth. They are fissures in the ocean crust through which geothermally heated water escapes. In other words, they are regions where water interacts with Earth’s magma. Earthly hydrothermal vents are home to many fascinating bacteria. Yellowstone’s Grand Prismatic Spring is an example of a hydrothermal area with a rich bacterial life.

    Life has not been discovered beneath the icy crust of Enceladus. But the detection of hydrogen is strong evidence that all the necessary conditions for life are present. Hunter Waite of the Southwest Research Institute in San Antonio and lead author of the new Enceladus study, said in a statement:

    Although we can’t detect life, we’ve found that there’s a food source there for it. It would be like a candy store for microbes.

    Microbes on Enceladus could produce their energy through a chemical reaction known as methanogenesis, which consists of burning hydrogen and carbon dioxide dissolved in the ocean water to form methane and water.

    This reaction is at the core of the development of life on Earth.

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    The so-called tiger stripes and geysers of Enceladus, photographed by the Cassini-Huygens probe in October, 2015. Image via NASA.

    NASA/ESA/ASI Cassini Spacecraft

    ESA Huygens Probe from Cassini landed on Titan

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    This Cassini image from 2005 shows Enceladus’ geysers – backlit – spewing into space. By flying the craft through the plume from geysers like this one, scientists obtained evidence for molecular hydrogen, possibly produced via hydrothermal processes on the floor on Enceladus’ ocean. Image via NASA.

    Scientists considered other explanations for Cassini spacecraft’s 2015 detection of molecular hydrogen within Enceladus’ geysers, for example, hydrogen leaking from the moon’s rocky core in ways other than hydrothermal reactions. The scientists who’ve studied these observations most closely, however, now feel that hydrothermal reactions are the best explanation.

    Liquid water, an energy source, and the right chemicals (carbon, hydrogen, nitrogen, oxygen, phosphorus and sulphur) are the three main requirements for life as we know it. Now scientists discovered all of these life-ingrediants – except phosphorus and sulphur – on Enceladus.

    The paper published in Science presents a detailed analysis of the possibility of methanogenesis on Enceladus. The calculations are inconclusive as to whether methanogenesis is happening or not around the hydrothermal vents of Enceladus. Nevertheless, this discovery is a big step in characterising the habitability of the ocean of Enceladus.

    Bottom line: In April, 2017, scientists announced that molecular hydrogen in the plumes of Enceladus, one of Saturn’s moons, may be due to methanogenesis, a process that implies microbial life.

    See the full article here .

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  • richardmitnick 7:54 am on September 28, 2016 Permalink | Reply
    Tags: , , Hidden Wonders, , , Saturn, surrounded by the icy lanes of its rings, The brilliant disk of Saturn   

    From JPL-Caltech: “Hidden Wonders” 

    NASA JPL Banner

    JPL-Caltech

    September 26, 2016
    No writer credit

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    No image caption. No image credit.

    NASA’s Cassini spacecraft looks toward the brilliant disk of Saturn, surrounded by the icy lanes of its rings. Faint wisps of cloud are visible in the atmosphere. At bottom, ring shadows trace delicate, curving lines across the planet.

    NASA/ESA/ASI Cassini Spacecraft
    NASA/ESA/ASI Cassini Spacecraft

    Prometheus (53 miles or 86 kilometers across) is just a few pixels wide in this view, barely visible as a dark speck in front of the planet, below the rings and to the left of center.

    Between April and September 2017, Cassini will plunge repeatedly through the gap that separates the planet from the rings.

    This view looks toward the sunlit side of the rings from about a degree above the ring plane. The image was taken in green light with the Cassini spacecraft wide-angle camera on July 21, 2016.

    The view was obtained at a distance of approximately 529,000 miles (852,000 kilometers) from Saturn and at a sun-Saturn-spacecraft, or phase, angle of 37 degrees. Image scale is 30 miles (50 kilometers) per pixel.

    The Cassini mission is a cooperative project of NASA, ESA (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. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colorado.

    For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov and http://www.nasa.gov/cassini. The Cassini imaging team homepage is at http://ciclops.org.

    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 2:18 pm on September 2, 2015 Permalink | Reply
    Tags: , , , Saturn   

    From JPL: “At Saturn, One of These Rings is not like the Others” 

    JPL

    September 2, 2015
    Preston Dyches
    Jet Propulsion Laboratory, Pasadena, Calif.
    818-354-7013
    preston.dyches@jpl.nasa.gov

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    Of the countless equinoxes Saturn has seen since the birth of the solar system, this one, captured here in a mosaic of light and dark, is the first witnessed up close by an emissary from Earth … none other than our faithful robotic explorer, Cassini.

    NASA Cassini Spacecraft
    Cassini

    Seen from our planet, the view of Saturn’s rings during equinox is extremely foreshortened and limited. But in orbit around Saturn, Cassini had no such problems. From 20 degrees above the ring plane, Cassini’s wide angle camera shot 75 exposures in succession for this mosaic showing Saturn, its rings, and a few of its moons a day and a half after exact Saturn equinox, when the sun’s disk was exactly overhead at the planet’s equator.

    The novel illumination geometry that accompanies equinox lowers the sun’s angle to the ring plane, significantly darkens the rings, and causes out-of-plane structures to look anomalously bright and to cast shadows across the rings. These scenes are possible only during the few months before and after Saturn’s equinox which occurs only once in about 15 Earth years. Before and after equinox, Cassini’s cameras have spotted not only the predictable shadows of some of Saturn’s moons (see PIA11657), but also the shadows of newly revealed vertical structures in the rings themselves (see PIA11665).

    Also at equinox, the shadows of the planet’s expansive rings are compressed into a single, narrow band cast onto the planet as seen in this mosaic. (For an earlier view of the rings’ wide shadows draped high on the northern hemisphere, see PIA09793.)

    The images comprising the mosaic, taken over about eight hours, were extensively processed before being joined together. First, each was re-projected into the same viewing geometry and then digitally processed to make the image “joints” seamless and to remove lens flares, radially extended bright artifacts resulting from light being scattered within the camera optics.

    At this time so close to equinox, illumination of the rings by sunlight reflected off the planet vastly dominates any meager sunlight falling on the rings. Hence, the half of the rings on the left illuminated by planetshine is, before processing, much brighter than the half of the rings on the right. On the right, it is only the vertically extended parts of the rings that catch any substantial sunlight.

    With no enhancement, the rings would be essentially invisible in this mosaic. To improve their visibility, the dark (right) half of the rings has been brightened relative to the brighter (left) half by a factor of three, and then the whole ring system has been brightened by a factor of 20 relative to the planet. So the dark half of the rings is 60 times brighter, and the bright half 20 times brighter, than they would have appeared if the entire system, planet included, could have been captured in a single image.

    The moon Janus (179 kilometers, 111 miles across) is on the lower left of this image. Epimetheus (113 kilometers, 70 miles across) appears near the middle bottom. Pandora (81 kilometers, 50 miles across) orbits outside the rings on the right of the image. The small moon Atlas (30 kilometers, 19 miles across) orbits inside the thin F ring on the right of the image. The brightnesses of all the moons, relative to the planet, have been enhanced between 30 and 60 times to make them more easily visible. Other bright specks are background stars. Spokes — ghostly radial markings on the B ring — are visible on the right of the image.

    This view looks toward the northern side of the rings from about 20 degrees above the ring plane.

    The images were taken on Aug. 12, 2009, beginning about 1.25 days after exact equinox, using the red, green and blue spectral filters of the wide angle camera and were combined to create this natural color view. The images were obtained at a distance of approximately 847,000 kilometers (526,000 miles) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 74 degrees. Image scale is 50 kilometers (31 miles) 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 operations center is based at the Space Science Institute in Boulder, Colo.

    Fast Facts:

    › A study suggests the particles in one section of Saturn’s rings are denser than elsewhere, possibly due to solid, icy cores.

    › The findings could mean that particular ring is much younger than the rest.

    When the sun set on Saturn’s rings in August 2009, scientists on NASA’s Cassini mission were watching closely. It was the equinox — one of two times in the Saturnian year when the sun illuminates the planet’s enormous ring system edge-on. The event provided an extraordinary opportunity for the orbiting Cassini spacecraft to observe short-lived changes in the rings that reveal details about their nature.

    Like Earth, Saturn is tilted on its axis. Over the course of its 29-year-long orbit, the sun’s rays move from north to south over the planet and its rings, and back again. The changing sunlight causes the temperature of the rings — which are made of trillions of icy particles — to vary from season to season. During equinox, which lasted only a few days, unusual shadows and wavy structures appeared and, as they sat in twilight for this brief period, the rings began to cool.

    In a recent study published in the journal Icarus, a team of Cassini scientists reported that one section of the rings appears to have been running a slight fever during equinox. The higher-than-expected temperature provided a unique window into the interior structure of ring particles not usually available to scientists.

    “For the most part, we can’t learn much about what Saturn’s ring particles are like deeper than 1 millimeter below the surface. But the fact that one part of the rings didn’t cool as expected allowed us to model what they might be like on the inside,” said Ryuji Morishima of NASA’s Jet Propulsion Laboratory, Pasadena, California, who led the study.

    The researchers examined data collected by Cassini’s Composite Infrared Spectrometer during the year around equinox. The instrument essentially took the rings’ temperature as they cooled. The scientists then compared the temperature data with computer models that attempt to describe the properties of ring particles on an individual scale.

    What they found was puzzling. For most of the giant expanse of Saturn’s rings, the models correctly predicted how the rings cooled as they fell into darkness. But one large section — the outermost of the large, main rings, called the A ring — was much warmer than the models predicted. The temperature spike was especially prominent in the middle of the A ring.

    To address this curiosity, Morishima and colleagues performed a detailed investigation of how ring particles with different structures would warm up and cool down during Saturn’s seasons. Previous studies based on Cassini data have shown Saturn’s icy ring particles are fluffy on the outside, like fresh snow. This outer material, called regolith, is created over time, as tiny impacts pulverize the surface of each particle. The team’s analysis suggested the best explanation for the A ring’s equinox temperatures was for the ring to be composed largely of particles roughly 3 feet (1 meter) wide made of mostly solid ice, with only a thin coating of regolith.

    “A high concentration of dense, solid ice chunks in this one region of Saturn’s rings is unexpected,” said Morishima. “Ring particles usually spread out and become evenly distributed on a timescale of about 100 million years.”

    The accumulation of dense ring particles in one place suggests that some process either placed the particles there in the recent geologic past or the particles are somehow being confined there. The researchers suggest a couple of possibilities to explain how this aggregation came to be. A moon may have existed at that location within the past hundred million years or so and was destroyed, perhaps by a giant impact. If so, debris from the breakup might not have had time to diffuse evenly throughout the ring. Alternatively, they posit that small, rubble-pile moonlets could be transporting the dense, icy particles as they migrate within the ring. The moonlets could disperse the icy chunks in the middle A ring as they break up there under the gravitational influence of Saturn and its larger moons.

    “This particular result is fascinating because it suggests that the middle of Saturn’s A ring may be much younger than the rest of the rings,” said Linda Spilker, Cassini project scientist at JPL and a co-author of the study. “Other parts of the rings may be as old as Saturn itself.”

    During its final series of close orbits to Saturn, Cassini will directly measure the mass of the planet’s main rings for the first time, using gravity science. Scientists will use the mass of the rings to place constraints on their age.

    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 5:28 pm on August 15, 2015 Permalink | Reply
    Tags: , , Saturn,   

    From U Liecester: “Scientists solve planetary ring riddle” 

    U leicester Bloc

    U Leicester

    Aug 05, 2015
    pt91

    University of Leicester study suggests universal particle distribution of Saturn’s rings

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    Study suggests planetary rings have a universal particle distribution
    Study solves ‘amazing’ mathematical inverse cubes law of particle size distribution

    In a breakthrough study, an international team of scientists, including Professor Nikolai Brilliantov from the University of Leicester, has solved an age-old scientific riddle by discovering that planetary rings, such as those orbiting Saturn, have a universally similar particle distribution.

    The study, which is published in the academic journal Proceedings of the National Academy of Sciences (PNAS), also suggests that Saturn’s rings are essentially in a steady state that does not depend on their history.

    Professor Brilliantov from the University of Leicester’s Department of Mathematics explained: “Saturn’s rings are relatively well studied and it is known that they consist of ice particles ranging in size from centimetres to about ten metres. With a high probability these particles are remains of some catastrophic event in a far past, and it is not surprising that there exists debris of all sizes, varying from very small to very large ones.

    “What is surprising is that the relative abundance of particles of different sizes follows, with a high accuracy, a beautiful mathematical law ‘of inverse cubes’. That is, the abundance of 2 metre-size particles is 8 times smaller than the abundance of 1 metre-size particles, the abundance of 3 metre-size particles is 27 times smaller and so on. This holds true up to the size of about 10 metres, then follows an abrupt drop in the abundance of particles. The reason for this drastic drop, as well as the nature of the amazing inverse cubes law, has remained a riddle until now.

    “We have finally resolved the riddle of particle size distribution. In particular, our study shows that the observed distribution is not peculiar for Saturn’s rings, but has a universal character. In other words, it is generic for all planetary rings which have particles to have a similar nature.”

    Most of the planets in the Solar System have smaller bodies, or satellites, that orbit a planet. Some of them, such as Saturn, Jupiter, Uranus and Neptune, additionally possess planetary rings – a collection of still smaller bodies of different sizes that also orbit a planet. It is likely that planetary rings also exist beyond the Solar System.

    Large asteroids, such as Chariklo and Chiron, only a few hundred kilometres in diameter, are also surrounded by rings.

    Professor Brilliantov added: “The rather general mathematical model elaborated in the study with the focus on Saturn’s rings may be successfully applied to other systems, where particles merge, colliding with slow velocities and break into small pieces colliding with large impact speeds.

    “Such systems exist in nature and industry and will exhibit a beautiful law of inverse cubes and drop in large particle abundance in their particle size distribution.”

    The study Size distribution of particles in Saturn’s rings from aggregation and fragmentation published in PNAS is available at: http://dx.doi.org/10.1073/pnas.1503957112

    See the full article here.

    Please help promote STEM in your local schools.

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    U Leicester Campus

    The University of Leicester (Listeni/ˈlɛstə/ LES-tər) is a public research university based in Leicester, England. The main campus is south of the city centre, adjacent to Victoria Park.

    The university has established itself as a leading research-led university and has been named University of the Year of 2008 by the Times Higher Education.[5] The University of Leicester is also the only university ever to have won a Times Higher Education award in seven consecutive years. In 2016, the university ranked 24th in the The Complete University Guide and 32nd in the The Guardian. Recent REF 2014, the University of Leicester ranked 49th among 126 universities.[6] The 2012 QS World University Rankings also placed Leicester eighth in the UK for research citations.[7]

    The university is most famous for the invention of genetic fingerprinting and for the discovery of the remains of King Richard III.

     
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