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  • richardmitnick 2:08 pm on May 27, 2015 Permalink | Reply
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    From JPL: “NASA Begins Testing Mars Lander for Next Mission to Red Planet” 

    JPL

    May 27, 2015
    Media Contact
    Guy Webster
    Jet Propulsion Laboratory, Pasadena, Calif.
    818-354-6278
    guy.webster@jpl.nasa.gov

    Dwayne Brown
    NASA Headquarters, Washington
    202-358-1726
    dwayne.c.brown@nasa.gov

    1
    The solar arrays on NASA’s InSight lander are deployed in this test inside a clean room at Lockheed Martin Space Systems, Denver. This configuration is how the spacecraft will look on the surface of Mars. The image was taken on April 30, 2015.

    InSight, for Interior Exploration Using Seismic Investigations, Geodesy and Heat Transport, is scheduled for launch in March 2016 and landing in September 2016. It will study the deep interior of Mars to advance understanding of the early history of all rocky planets, including Earth.

    The InSight Project is managed by NASA’s Jet Propulsion Laboratory, Pasadena, California, for the NASA Science Mission Directorate, Washington. InSight is part of NASA’s Discovery Program, which is managed by NASA’s Marshall Space Flight Center in Huntsville, Alabama.

    2
    The Mars lander that NASA’s InSight mission will use for investigating how rocky planets formed and evolved is being assembled by Lockheed Martin Space Systems, Denver. In this scene from January 2015, Lockheed Martin spacecraft specialists are working on the lander in a clean room.

    4
    Spacecraft specialists in a clean room at Lockheed Martin Space Systems, Denver, are working on NASA’s InSight spacecraft in this January 2015 scene from the mission’s assembly and testing phase.

    At center is the cruise stage, which will serve multiple functions during the flight from Earth to Mars. In the background is the InSight lander.

    5
    In this February 2015 scene from a clean room at Lockheed Martin Space Systems, Denver, specialists are building the heat shield to protect NASA’s InSight spacecraft when it is speeding through the Martian atmosphere.

    7
    This parachute testing for NASA’s InSight mission to Mars was conducted inside the world’s largest wind tunnel, at NASA Ames Research Center, Moffett Field, California, in February 2015.

    The wind tunnel is 80 feet (24 meters) tall and 120 feet (37 meters) wide. It is part of the National Full-Scale Aerodynamics Complex, operated by the Arnold Engineering Development Center of the U.S. Air Force.

    8
    Engineers and technicians at Lockheed Martin Space Systems, Denver, run a test of deploying the solar arrays on NASA’s InSight lander in this April 30, 2015 image.

    9
    In this photo, the back shell of NASA’s InSight spacecraft is being lowered onto the mission’s lander, which is folded into its stowed configuration. The back shell and a heat shield form the aeroshell, which will protect the lander as the spacecraft plunges into the upper atmosphere of Mars. The photo was taken on April 29, 2015, in a spacecraft assembly clean room at Lockheed Martin Space Systems, Denver.

    10
    Spacecraft specialists at Lockheed Martin Space Systems, Denver, are preparing to attach the cruise stage of NASA’s InSight spacecraft to the top of the spacecraft’s back shell in this April 29, 2015, photo.

    The cruise stage will serve multiple functions during the flight from Earth to Mars. It has its own solar arrays, thrusters and radio antennas. It will be jettisoned shortly before the spacecraft enters the Martian atmosphere.

    12
    This photo shows the upper side of the cruise stage of NASA’s InSight spacecraft as specialists at Lockheed Martin Space Systems, Denver, attach it to the spacecraft’s back shell. The photo was taken on April 29, 2015.

    The cruise stage will serve multiple functions during the flight from Earth to Mars. It has its own solar arrays, thrusters and radio antennas. It will be jettisoned shortly before the spacecraft enters the Martian atmosphere.

    Testing is underway on NASA’s next mission on the journey to Mars, a stationary lander scheduled to launch in March 2016.

    The lander is called InSight, an abbreviation for Interior Exploration using Seismic Investigations, Geodesy and Heat Transport. It is about the size of a car and will be the first mission devoted to understanding the interior structure of the Red Planet. Examining the planet’s deep interior could reveal clues about how all rocky planets, including Earth, formed and evolved.

    The current testing will help ensure InSight can operate in and survive deep space travel and the harsh conditions of the Martian surface. The spacecraft will lift off from Vandenberg Air Force Base in California, and land on Mars about six months later.

    The technical capabilities and knowledge gained from Insight, and other Mars missions, are crucial to NASA’s journey to Mars, which includes sending astronauts to the Red Planet in the 2030s.

    “Today, our robotic scientific explorers are paving the way, making great progress on the journey to Mars,” said Jim Green, director of NASA’s Planetary Science Division at the agency’s headquarters in Washington. “Together, humans and robotics will pioneer Mars and the solar system.”

    During the environmental testing phase at Lockheed Martin’s Space Systems facility near Denver, the lander will be exposed to extreme temperatures, vacuum conditions of nearly zero air pressure simulating interplanetary space, and a battery of other tests over the next seven months. The first will be a thermal vacuum test in the spacecraft’s “cruise” configuration, which will be used during its seven-month journey to Mars. In the cruise configuration, the lander is stowed inside an aeroshell capsule and the spacecraft’s cruise stage – for power, communications, course corrections and other functions on the way to Mars — is fastened to the capsule.

    “The assembly of InSight went very well and now it’s time to see how it performs,” said Stu Spath, InSight program manager at Lockheed Martin Space Systems, Denver. “The environmental testing regimen is designed to wring out any issues with the spacecraft so we can resolve them while it’s here on Earth. This phase takes nearly as long as assembly, but we want to make sure we deliver a vehicle to NASA that will perform as expected in extreme environments.”

    Other tests include vibrations simulating launch and checking for electronic interference between different parts of the spacecraft. The testing phase concludes with a second thermal vacuum test in which the spacecraft is exposed to the temperatures and atmospheric pressures it will experience as it operates on the Martian surface.

    The mission’s science team includes U.S. and international co-investigators from universities, industry and government agencies.

    “It’s great to see the spacecraft put together in its launch configuration,” said InSight Project Manager Tom Hoffman at NASA’s Jet Propulsion Laboratory, Pasadena, California. “Many teams from across the globe have worked long hours to get their elements of the system delivered for these tests. There still remains much work to do before we are ready for launch, but it is fantastic to get to this critical milestone.”

    The InSight mission is led by JPL’s Bruce Banerdt. The Centre National d’Etudes Spatiales, France’s space agency, and the German Aerospace Center are each contributing a science instrument to the two-year scientific mission. InSight’s international science team includes researchers from Austria, Belgium, Canada, France, Germany, Japan, Poland, Spain, Switzerland, the United Kingdom and the United States.

    JPL, a division of the California Institute of Technology in Pasadena, manages InSight for NASA’s Science Mission Directorate in Washington. InSight is part of NASA’s Discovery Program, managed by the agency’s Marshall Space Flight Center in Huntsville, Alabama. Lockheed Martin Space Systems Company built the lander.

    For addition information about the mission, visit:

    http://insight.jpl.nasa.gov

    More information about NASA’s journey to Mars is available online at:

    https://www.nasa.gov/topics/journeytomars

    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, 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 1:38 pm on May 27, 2015 Permalink | Reply
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    From Hubble: “Hubble Video Shows Shock Collision Inside Black Hole Jet” 

    NASA Hubble Telescope

    Hubble

    May 27, 2015
    CONTACT

    Felicia Chou
    NASA Headquarters, Washington, D.C.
    202-358-0257
    felicia.chou@nasa.gov

    Ray Villard
    Space Telescope Science Institute, Baltimore, Maryland
    410-338-4514
    villard@stsci.edu

    1
    Object Name: 3C 264
    Object Description: Active Radio Galaxy
    Constellation: Leo
    Distance: 300 million light-years (91 Mpc)

    The science team comprises: E. Meyer (STScI), M. Georganopoulos (UMBC/NASA GSFC), W.B. Sparks (STScI), E. Perlman (Florida Institute of Technology), R. van der Marel, J. Anderson (STScI), S.T. Sohn (JHU), J. Biretta (STScI), C. Norman (STScI/JHU), and M. Chiaberge (STScI/ESA).

    When you’re blasting though space at more than 98 percent of the speed of light, you may need driver’s insurance. Astronomers have discovered for the first time a rear-end collision between two high-speed knots of ejected matter from a super-massive black hole. This discovery was made while piecing together a time-lapse movie of a plasma jet blasted from a supermassive black hole inside a galaxy located 260 million light-years from Earth. [The “movie is presented on the original article. I could not make it work in this post.]

    The finding offers new insights into the behavior of “light-saber-like” jets that are so energized that they appear to zoom out of black holes at speeds several times the speed of light. This “superluminal” motion is an optical illusion due to the very fast real speed of the plasma, which is close to the universal maximum of the speed of light.

    Such extragalactic jets are not well understood. They appear to transport energetic plasma in a confined beam from the central black hole of the host galaxy. The new analysis suggests that shocks produced by collisions within the jet further accelerate particles and brighten the regions of colliding material.

    The video of the jet was assembled with two decades’ worth of NASA Hubble Space Telescope images of the elliptical galaxy NGC 3862, the sixth brightest galaxy and one of only a few active galaxies with jets seen in visible light. The jet was discovered in optical light by Hubble in 1992. NGC 3862 is in a rich cluster of galaxies known as Abell 1367.

    5
    NGC 3862 best image available

    3
    Abell 1367

    The jet from NGC 3862 has a string-of-pearls structure of glowing knots of material. Taking advantage of Hubble’s sharp resolution and long-term optical stability, Eileen Meyer of the Space Telescope Science Institute (STScI) in Baltimore, Maryland, matched archival Hubble images with a new, deep image taken in 2014 to better understand jet motions. Meyer was surprised to see a fast knot with an apparent speed of seven times the speed of light catch up with the end of a slower moving, but still superluminal, knot along the string.

    The resulting “shock collision” caused the merging blobs to brighten significantly.

    “Something like this has never been seen before in an extragalactic jet,” said Meyer. As the knots continue merging they will brighten further in the coming decades. “This will allow us a very rare opportunity to see how the kinetic energy of the collision is dissipated into radiation.”

    It’s not uncommon to see knots of material in jets ejected from gravitationally compact objects, but it is rare that motions have been observed with optical telescopes, and so far out from the black hole, thousands of light-years away. In addition to black holes, newly forming stars eject narrowly collimated streamers of gas that have a knotty structure. One theory is that material falling onto the central object is superheated and ejected along the object’s spin axis. Powerful magnetic fields constrain the material into a narrow jet. If the flow of the infalling material is not smooth, blobs are ejected like a string of cannon balls rather than a steady hose-like flow.

    Whatever the mechanism, the fast-moving knot will burrow its way out into intergalactic space. A knot launched later, behind the first one, may have less drag from the shoveled-out interstellar medium and catch up to the earlier knot, rear-ending it in a shock collision.

    Beyond the collision, which will play out over the next few decades, this discovery marks only the second case of superluminal motion measured at hundreds to thousands of light-years from the black hole where the jet was launched. This indicates that the jets are still very, very close to the speed of light even on distances that start to rival the scale of the host galaxy. These measurements can give insights into how much energy jets carry out into their host galaxy and beyond, which is important for understanding how galaxies evolve as the universe ages.

    Meyer is currently making a Hubble-image video of two more jets in the nearby universe, to look for similar fast motions. She notes that these kinds of studies are only possible because of the long operating lifetime of Hubble, which has now been looking at some of these jets for over 20 years.

    Extragalactic jets have been detected at X-ray and radio wavelengths in many active galaxies powered by central black holes, but only a few have been seen in optical light. Astronomers do not yet understand why some jets are seen in visible light and others are not.

    Meyer’s results are being reported in the May 28 issue of the journal Nature.

    See the full article here.

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    The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA’s Goddard Space Flight Center manages the telescope. The Space Telescope Science Institute (STScI), is a free-standing science center, located on the campus of The Johns Hopkins University and operated by the Association of Universities for Research in Astronomy (AURA) for NASA, conducts Hubble science operations.

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  • richardmitnick 12:55 pm on May 27, 2015 Permalink | Reply
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    From LBL: “Berkeley Lab Scientist Invents New Technique to Understand Cloud Behavior” 

    Berkeley Logo

    Berkeley Lab

    May 27, 2015
    Julie Chao (510) 486-6491

    1
    Berkeley Lab researchers David Romps and Rusen Oktem collected these images in Florida, showing 14 minutes of cloud movements.

    With two off-the-shelf digital cameras situated about 1 kilometer apart facing Miami’s Biscayne Bay, Lawrence Berkeley National Laboratory scientists David Romps and Rusen Oktem are collecting three-dimensional data on cloud behavior that have never been possible to collect before.

    The photos allow Romps, a climate scientist who specializes in clouds, to measure how fast the clouds rise, which in turn can shed light on a wide range of areas, ranging from lightning rates to extreme precipitation to the ozone hole. Perhaps most importantly, a better understanding of basic cloud behavior will allow scientists to improve global climate models.

    “We want to answer a very basic question: with what speeds do clouds rise through the atmosphere? This is very difficult to answer by any technology other than stereophotogrammetry,” he said. “Knowing their speeds is important for several reasons; the important one is that we lack a really basic understanding of what processes control these clouds, the levels they peter out at, and how buoyant they are.”

    While stereophotogrammetry, which uses photos to make 3D measurements of cloud boundaries, has been used before to study cloud behavior, Romps’ innovation was a technique that does not require a reference point, such as a mountain or other land-based feature. This allows scientists to study clouds over the open ocean.

    “We have a lot of measurements of clouds over land, but far fewer over the ocean,” Romps said. “The behavior can be quite different. For example, looking at satellite data, you see continental areas light up with a lot of lightning and oceans less so.”

    3
    Berkeley Lab researchers Rusen Oktem (left) and David Romps

    The technique was detailed in a paper published last year in the Journal of Atmospheric and Oceanic Technology, titled Stereophotogrammetry of Oceanic Clouds. Co-authors include Berkeley Lab computing experts Oktem, James Lee, Aaron Thomas, and Prabhat, and Paquita Zuidema of the University of Miami.

    The paper describes how to set up and calibrate the two cameras; Romps and his team also devised algorithms to automate the 3D reconstruction, quickly finding feature points and matching them. The accuracy of the technique was validated with lidar and radiosondes.

    With images taken every 10 to 30 seconds, “we can really start to look at the full lifecycle of clouds,” said Romps, who has a joint appointment in UC Berkeley’s Department of Earth and Planetary Science. His technique also offers far higher spatial and temporal resolution than other technologies.

    The Department of Energy’s Atmospheric Radiation Measurement (ARM) program has funded a second set of cameras at its Southern Great Plains site in Oklahoma, the largest and most extensive climate research site in the world. Across about 55,000 square miles, clusters of lidar, radar, and other sophisticated monitoring equipment gather massive amounts of data to study the effects of aerosols, precipitation, surface fluxes, and clouds on the global climate.

    3
    One of the cameras looking over Miami’s Biscayne Bay.

    Using stereophotogrammetry, Romps has measured the speeds of shallow clouds rising through the atmosphere at 1 to 3 meters per second and of deeper clouds rising at speeds in excess of 10 meters per second. “The updraft speeds play an important role in the microphysics, general precipitation, and aerosol processing, which all impact climate simulations,” he said.

    Updraft speeds can also impact lightning rates, as faster clouds tend to produce more lightning. And if clouds are fast enough they can penetrate the stratosphere. “They can throw out water vapor and ice, which sets the humidity of the stratosphere, and that has an impact both because water vapor is greenhouse gas and also because water vapor, through a sequence of events, has an effect on the ozone hole,” Romps said.

    The largest source of uncertainty in today’s climate models is clouds. “We are still seeking a fundamental theory for moist convection, or what we call convection with phase changes. Without that theory, it is difficult to construct more accurate parameterizations [or models] of clouds that go into global climate models,” Romps said. “Stereophotogrammetry can provide very useful information in this quest.”

    The next steps are to combine the stereophotogrammetric data with other observations at the ARM site to answer basic questions about cloud life cycles. In particular, Romps and colleagues want to understand what environmental conditions can be used to forecast the sizes, speeds, depths, and lifetimes of convective clouds.

    Romps and Oktem are also developing new techniques to automate the reconstruction of three-dimensional cloud features. Until now, stereophotogrammetry has been a labor-intensive process, but their new algorithms have been used on supercomputers to rapidly reconstruct 35 million cloud features from a three-month period. “The development of these new algorithms makes stereophotogrammetry a tool that can now be used on a regular basis,” Romps said.

    See the full article here.

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    A U.S. Department of Energy National Laboratory Operated by the University of California

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  • richardmitnick 10:13 am on May 27, 2015 Permalink | Reply
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    From LLNL: “Lawrence Livermore scientists move one step closer to mimicking gamma-ray bursts” 


    Lawrence Livermore National Laboratory

    May. 26, 2015

    Anne M Stark
    stark8@llnl.gov (link sends e-mail)
    925-422-9799

    1
    The Centaurus A galaxy, at a distance of about 12 million light years from Earth, contains a gargantuan jet blasting away from a central supermassive black hole. In this image, red, green and blue show low, medium and high-energy X-rays. Photo courtesy NASA/CXC/U. Birmingham/M. Burke et al.

    Using ever more energetic lasers, Lawrence Livermore researchers have produced a record high number of electron-positron pairs, opening exciting opportunities to study extreme astrophysical processes, such as black holes and gamma-ray bursts.

    By performing experiments using three laser systems — Titan at Lawrence Livermore, Omega-EP at the Laboratory for Laser Energetics (link is external) and Orion at Atomic Weapons Establishment (link is external) (AWE) in the United Kingdom — LLNL physicist Hui Chen and her colleagues created nearly a trillion positrons (also known as antimatter particles). In previous experiments at the Titan laser in 2008, Chen’s team had created billions of positrons.

    Positrons, or “anti-electrons,” are anti-particles with the same mass as an electron but with opposite charge. The generation of energetic electron-positron pairs is common in extreme astrophysical environments associated with the rapid collapse of stars and formation of black holes. These pairs eventually radiate their energy, producing extremely bright bursts of gamma rays. Gamma-ray bursts (GRBs) are the brightest electromagnetic events known to occur in the universe and can last from ten milliseconds to several minutes. The mechanism of how these GRBs are produced is still a mystery.

    In the laboratory, jets of electron-positron pairs can be generated by shining intense laser light into a gold foil. The interaction produces high-energy radiation that will traverse the material and create electron-positron pairs as it interacts with the nucleus of the gold atoms. The ability to create a large number of positrons in a laboratory, by using energetic lasers, opens the door to several new avenues of antimatter research, including the understanding of the physics underlying extreme astrophysical phenomena such as black holes and gamma-ray bursts.

    “The goal of our experiments was to understand how the flux of electron-positron pairs produced scales with laser energy,” said Chen, who along with former Lawrence Fellow Frederico Fiuza (now at SLAC National Accelerator Laboratory), co-authored the article appearing in the May 18 edition of Physical Review Letters.

    “We have identified the dominant physics associated with the scaling of positron yield with laser and target parameters, and we can now look at its implication for using it to study the physics relevant to gamma-ray bursts,” Chen said. “The favorable scaling of electron-positron pairs with laser energy obtained in our experiments suggests that, at a laser intensity and pulse duration comparable to what is available, near-future 10-kilojoule-class lasers would provide 100 times higher antimatter yield.”

    The team used these scaling results obtained experimentally together with first-principles simulations to model the interaction of two electron positron pairs for future laser parameters. “Our simulations show that with upcoming laser systems, we can study how these energetic pairs of matter-antimatter convert their energy into radiation,” Fiuza said. “Confirming these predictions in an experiment would be extremely exciting.”

    Antimatter research could reveal why more matter than antimatter survived the Big Bang at the start of the universe. There is considerable speculation as to why the observable universe is apparently almost entirely matter, whether other places are almost entirely antimatter, and what might be possible if antimatter could be harnessed. Normal matter and antimatter are thought to have been in balance in the very early universe, but due to an “asymmetry” the antimatter decayed or was annihilated, and today very little antimatter is seen.

    In future work, the researchers plan to use the National Ignition Facility [NIF] to conduct laser antimatter experiments to study the physics of relativistic pair shocks in gamma-ray bursts by creating even higher fluxes of electron-positron pairs.

    LLNL NIF
    NIF

    The research was funded by LLNL’s Laboratory Directed Research and Development program and the LLNL Lawrence Fellowship.

    Chen and Fiuza were joined by Anthony Link, Andy Hazi, Matt Hill, David Hoarty, Steve James, Shaun Kerr, David Meyerhofer, Jason Myatt, Jaebum Park, Yasuhiko Sentoku and Jackson Williams from LLNL, AWE, University of Alberta, University of Rochester and University of Nevada, Reno.

    See the full article here.

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  • richardmitnick 9:20 am on May 27, 2015 Permalink | Reply
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    From phys.org: “Discovery shows what the solar system looked like as a ‘toddler'” 

    physdotorg
    phys.org

    May 27, 2015
    No Writer Credit

    1
    Left: Image of HD 115600 showing a bright debris ring viewed nearly edge-on and located just beyond a Pluto-like distance to the star. Right: A model of the HD 115600 debris ring on the same scale. Credit: T. Currie

    Astronomers have discovered a disc of planetary debris surrounding a young sun-like star that shares remarkable similarities with the Kuiper Belt that lies beyond Neptune, and may aid in understanding how our solar system developed.

    2
    Kuiper Belt

    An international team of astronomers, including researchers from the University of Cambridge, has identified a young planetary system which may aid in understanding how our own solar system formed and developed billions of years ago.

    Using the Gemini Planet Imager (GPI) at the Gemini South telescope in Chile, the researchers identified a dTisc-shaped bright ring of dust around a star only slightly more massive than the sun, located 360 light years away in the Centaurus constellation.

    Gemini Planet Imager
    GPI

    Gemini South telescope
    Gemini South

    The disc is located between about 37 and 55 Astronomical Units (3.4 – 5.1 billion miles) from its host star, which is almost the same distance as the solar system’s Kuiper Belt is from the sun. The brightness of the disc, which is due to the starlight reflected by it, is also consistent with a wide range of dust compositions including the silicates and ice present in the Kuiper Belt.

    The Kuiper Belt lies just beyond Neptune, and contains thousands of small icy bodies left over from the formation of the solar system more than four billion years ago. These objects range in size from specks of debris dust, all the way up to moon-sized objects like Pluto – which used to be classified as a planet, but has now been reclassified as a dwarf planet.

    The star observed in this new study is a member of the massive 10-20 million year-old Scorpius-Centaurus OB association, a region similar to that in which the sun was formed. The disc is not perfectly centred on the star, which is strong indication that it was likely sculpted by one or more unseen planets. By using models of how planets shape a debris disc, the team found that ‘eccentric’ versions of the giant planets in the outer solar system could explain the observed properties of the ring.

    “It’s almost like looking at the outer solar system when it was a toddler,” said principal investigator Thayne Currie, an astronomer at the Subaru Observatory in Hawaii.

    The current theory on the formation of the solar system holds that it originated within a giant molecular cloud of hydrogen, in which clumps of denser material formed. One of these clumps, rotating and collapsing under its own gravitation, formed a flattened spinning disc known as the solar nebula. The sun formed at the hot and dense centre of this disc, while the planets grew by accretion in the cooler outer regions. The Kuiper Belt is believed to be made up of the remnants of this process, so there is a possibility that once the new system develops, it may look remarkably similar to our solar system.

    “To be able to directly image planetary birth environments around other stars at orbital distances comparable to the solar system is a major advancement,” said Dr Nikku Madhusudhan of Cambridge’s Institute of Astronomy, one of the paper’s co-authors. “Our discovery of a near-twin of the Kuiper Belt provides direct evidence that the planetary birth environment of the solar system may not be uncommon.”

    This is the first discovery with the new cutting-edge Gemini instrument. “In just one of our many 50-second exposures we could see what previous instruments failed to see in more than 50 minutes,” said Currie.

    The star, going by the designation HD 115600, was the first object the research team looked at. “Over the next few years, I’m optimistic that GPI will reveal many more debris discs and young planets. Who knows what strange, new worlds we will find,” Currie added.

    The paper is accepted for publication in The Astrophysical Journal Letters.

    See the full article here.

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    Phys.org™ (formerly Physorg.com) is a leading web-based science, research and technology news service which covers a full range of topics. These include physics, earth science, medicine, nanotechnology, electronics, space, biology, chemistry, computer sciences, engineering, mathematics and other sciences and technologies. Launched in 2004, Phys.org’s readership has grown steadily to include 1.75 million scientists, researchers, and engineers every month. Phys.org publishes approximately 100 quality articles every day, offering some of the most comprehensive coverage of sci-tech developments world-wide. Quancast 2009 includes Phys.org in its list of the Global Top 2,000 Websites. Phys.org community members enjoy access to many personalized features such as social networking, a personal home page set-up, RSS/XML feeds, article comments and ranking, the ability to save favorite articles, a daily newsletter, and other options.

     
  • richardmitnick 7:59 am on May 27, 2015 Permalink | Reply
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    From Caltech: “Using Radar Satellites to Study Icelandic Volcanoes and Glaciers” 

    Caltech Logo
    Caltech

    05/26/2015
    Kimm Fesenmaier

    1
    This Landsat 8 image, acquired on September 6, 2014, is a false-color view of the Holuhraun lava field north of Vatnajökull glacier in Iceland. The image combines shortwave infrared, near infrared, and green light to distinguish between cooler ice and steam and hot extruded lava. The Bárðarbunga caldera, visible in the lower left of the image under the ice cap, experienced a large-scale collapse starting in mid-August. Credit: USGS

    NASA LandSat 8
    Landsat 8

    On August 16 of last year, Mark Simons, a professor of geophysics at Caltech, landed in Reykjavik with 15 students and two other faculty members to begin leading a tour of the volcanic, tectonic, and glaciological highlights of Iceland. That same day, a swarm of earthquakes began shaking the island nation—seismicity that was related to one of Iceland’s many volcanoes, Bárðarbunga caldera, which lies beneath Vatnajökull ice cap.

    2
    Bárðarbunga

    As the trip proceeded, it became clear to scientists studying the event that magma beneath the caldera was feeding a dyke, a vertical sheet of magma slicing through the crust in a northeasterly direction. On August 29, as the Caltech group departed Iceland, the dike triggered an eruption in a lava field called Holuhraun, about 40 kilometers (roughly 25 miles) from the caldera just beyond the northern limit of the ice cap.

    Although the timing of the volcanic activity necessitated some shuffling of the trip’s activities, such as canceling planned overnight visits near what was soon to become the eruption zone, it was also scientifically fortuitous. Simons is one of the leaders of a Caltech/JPL project known as the Advanced Rapid Imaging and Analysis (ARIA) program, which aims to use a growing constellation of international imaging radar satellites that will improve situational awareness, and thus response, following natural disasters. Under the ARIA umbrella, Caltech and JPL/NASA had already formed a collaboration with the Italian Space Agency (ASI) to use its COSMO-SkyMed (CSK) constellation (consisting of four orbiting X-Band radar satellites) following such events.

    Through the ASI/ARIA collaboration, the managers of CSK agreed to target the activity at Bárðarbunga for imaging using a technique called interferometric synthetic aperture radar (InSAR). As two CSK satellites flew over, separated by just one day, they bounced signals off the ground to create images of the surface of the glacier above the caldera. By comparing those two images in what is called an interferogram, the scientists could see how the glacier surface had moved during that intervening day. By the evening of August 28, Simons was able to pull up that first interferogram on his cell phone. It showed that the ice above the caldera was subsiding at a rate of 50 centimeters (more than a foot and a half) a day—a clear indication that the magma chamber below Bárðarbunga caldera was deflating.

    The next morning, before his return flight to the United States, Simons took the data to researchers at the University of Iceland who were tracking Bárðarbunga’s activity.

    “At that point, there had been no recognition that the caldera was collapsing. Naturally, they were focused on the dyke and all the earthquakes to the north,” says Simons. “Our goal was just to let them know about the activity at the caldera because we were really worried about the possibility of triggering a subglacial melt event that would generate a catastrophic flood.”

    Luckily, that flood never happened, but the researchers at the University of Iceland did ramp up observations of the caldera with radar altimetry flights and installed a continuous GPS station on the ice overlying the center of the caldera.

    Last December, Icelandic researchers published a paper in Nature about the Bárðarbunga event, largely focusing on the dyke and eruption. Now, completing the picture, Simons and his colleagues have developed a model to describe the collapsing caldera and the earthquakes produced by that action. The new findings appear in the journal Geophysical Journal International.

    “Over a span of two months, there were more than 50 magnitude-5 earthquakes in this area. But they didn’t look like regular faulting—like shearing a crack,” says Simons. “Instead, the earthquakes looked like they resulted from movement inward along a vertical axis and horizontally outward in a radial direction—like an aluminum can when it’s being crushed.”

    To try to determine what was actually generating the unusual earthquakes, Bryan Riel, a graduate student in Simons’s group and lead author on the paper, used the original one-day interferogram of the Bárðarbunga area along with four others collected by CSK in September and October. Most of those one-day pairs spanned at least one of the earthquakes, but in a couple of cases, they did not. That allowed Riel to isolate the effect of the earthquakes and determine that most of the subsidence of the ice was due to what is called aseismic activity—the kind that does not produce big earthquakes. Thus, Riel was able to show that the earthquakes were not the primary cause of the surface deformation inferred from the satellite radar data.

    “What we know for sure is that the magma chamber was deflating as the magma was feeding the dyke going northward,” says Riel. “We have come up with two different models to explain what was actually generating the earthquakes.”

    In the first scenario, because the magma chamber deflated, pressure from the overlying rock and ice caused the caldera to collapse, producing the unusual earthquakes. This mechanism has been observed in cases of collapsing mines (e.g., the Crandall Canyon Mine in Utah).

    The second model hypothesizes that there is a ring fault arcing around a significant portion of the caldera. As the magma chamber deflated, the large block of rock above it dropped but periodically got stuck on portions of the ring fault. As the block became unstuck, it caused rapid slip on the curved fault, producing the unusual earthquakes.

    “Because we had access to these satellite images as well as GPS data, we have been able to produce two potential interpretations for the collapse of a caldera—a rare event that occurs maybe once every 50 to 100 years,” says Simons. “To be able to see this documented as it’s happening is truly phenomenal.”

    Additional authors on the paper, The collapse of Bárðarbunga caldera, Iceland, are Hiroo Kanamori, John E. and Hazel S. Smits Professor of Geophysics, Emeritus, at Caltech; Pietro Milillo of the University of Basilicata in Potenza, Italy; Paul Lundgren of JPL; and Sergey Samsonov of the Canada Centre for Mapping and Earth Observation. The work was supported by a NASA Earth and Space Science Fellowship and by the Caltech/JPL President’s and Director’s Fund.

    See the full article here.

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    The California Institute of Technology (commonly referred to as Caltech) is a private research university located in Pasadena, California, United States. Caltech has six academic divisions with strong emphases on science and engineering. Its 124-acre (50 ha) primary campus is located approximately 11 mi (18 km) northeast of downtown Los Angeles. “The mission of the California Institute of Technology is to expand human knowledge and benefit society through research integrated with education. We investigate the most challenging, fundamental problems in science and technology in a singularly collegial, interdisciplinary atmosphere, while educating outstanding students to become creative members of society.”
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  • richardmitnick 7:00 am on May 27, 2015 Permalink | Reply
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    From ESO: “A Bubbly Cosmic Celebration” 


    European Southern Observatory

    27 May 2015
    Richard Hook
    ESO Public Information Officer
    Garching bei München, Germany
    Tel: +49 89 3200 6655
    Cell: +49 151 1537 3591
    Email: rhook@eso.org

    1

    In the brightest region of this glowing nebula called RCW 34, gas is heated dramatically by young stars and expands through the surrounding cooler gas. Once the heated hydrogen reaches the borders of the gas cloud, it bursts outwards into the vacuum like the contents of an uncorked champagne bottle — this process is referred to as champagne flow. But the young star-forming region RCW 34 has more to offer than a few bubbles; there seem to have been multiple episodes of star formation within the same cloud.

    This new image from ESO’s Very Large Telescope (VLT) in Chile shows a spectacular red cloud of glowing hydrogen gas behind a collection of blue foreground stars. Within RCW 34 — located in the southern constellation of Vela — a group of massive young stars hide in the brightest region of the cloud [1]. These stars have a dramatic effect on the nebula. Gas exposed to strong ultraviolet radiation — as occurs in the heart of this nebula — becomes ionised, meaning that the electrons have escaped the hydrogen atoms.

    Hydrogen is treasured by cosmic photographers because it glows brightly in the characteristic red colour that distinguishes many nebulae and allows them to create beautiful images with bizarre shapes. It is also the raw material of dramatic phenomena such as champagne flow. But ionised hydrogen also has an important astronomical role: it is an indicator of star-forming regions. Stars are born from collapsing gas clouds and therefore abundant in regions with copious amounts of gas, like RCW 34. This makes the nebula particularly interesting to astronomers studying stellar birth and evolution.

    Vast amounts of dust within the nebula block the view of the inner workings of the stellar nursery. deeply embedded in these clouds. RCW 34 is characterised by extremely high extinction, meaning that almost all of the visible light from this region is absorbed before it reaches Earth. Despite hiding away from direct view, astronomers can use infrared telescopes, to peer through the dust and study the nest of embedded stars.

    Looking behind the red colour reveals that there are a lot of young stars in this region with masses only a fraction of that of the Sun. These seem to clump around older, more massive stars at the centre, while only a few are distributed in the outskirts. This distribution has led astronomers to believe that there have been different episodes of star formation within the cloud. Three gigantic stars formed in the first event that then triggered the formation of the less massive stars in their vicinity [2].

    This image uses data from the FOcal Reducer and low dispersion Spectrograph (FORS) instrument attached to the VLT, which were acquired as part of the ESO Cosmic Gems programme [3].

    ESO FORS1
    FORS1

    Notes

    [1] RCW 34 is also known as Gum 19 and is centred on the brilliant young star called V391 Velorum.

    [2] The most massive very bright stars have short lives — measured in millions of years — but the less massive ones have lives longer than the current age of the Universe.

    [3] The ESO Cosmic Gems programme is an outreach initiative to produce images of interesting, intriguing or visually attractive objects using ESO telescopes, for the purposes of education and public outreach. The programme makes use of telescope time that cannot be used for science observations. All data collected may also be suitable for scientific purposes, and are made available to astronomers through ESO’s science archive.

    3
    Around the star-formation region Gum 19 (RCW 34)

    See the full article here.

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    ESO is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive ground-based astronomical observatory by far. It is supported by 16 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland and the United Kingdom, along with the host state of Chile. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world’s most advanced visible-light astronomical observatory and two survey telescopes. VISTA works in the infrared and is the world’s largest survey telescope and the VLT Survey Telescope is the largest telescope designed to exclusively survey the skies in visible light. ESO is a major partner in ALMA, the largest astronomical project in existence. And on Cerro Armazones, close to Paranal, ESO is building the 39-metre European Extremely Large Telescope, the E-ELT, which will become “the world’s biggest eye on the sky”.

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  • richardmitnick 5:23 pm on May 26, 2015 Permalink | Reply
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    From CFHT: “Faint Galaxies found Hiding in the Virgo Cluster” 

    CFHT icon
    Canada France Hawaii Telescope

    May 26, 2015

    Science Contact information
    James Taylor
    University of Waterloo
    taylor@uwaterloo.ca

    Dr. Laura Ferrarese
    NGVS Principal Investigator
    laura.ferrarese@nrc-cnrc.gc.ca

    Media Contact information
    Leslie Sage
    CASCA Press Officer
    cascapressofficer@gmail.com

    Mary Beth Laychak
    CFHT Outreach Program Manager
    mary@cfht.hawaii.edu

    1
    Example of a Low Surface Brightness Galaxy in the Virgo cluster. These galaxies are very hard to detect and the LSB mode on MegaCam enabled the possibility of such detections.

    A recent survey using the Canada-France-Hawaii Telescope has discovered hundreds of new galaxies in the Virgo Cluster, the nearest large cluster of galaxies.

    2
    Virgo Cluster showing the diffuse light between member galaxies. Messier 87 is the largest galaxy (lower left)

    Most are extremely faint “dwarf” galaxies, objects hundreds of thousands of times less massive than our own galaxy, the Milky Way, and amongst the faintest galaxies known in the Universe. The Virgo cluster appears to be home to far more of such faint systems than the “Local Group” of galaxies to which the Milky Way belongs, suggesting that galaxy formation on small scales may be more complicated than previously thought, and that our Local Group may not be a typical corner of the universe.

    3
    The Local Group of galaxies. The Milky Way and Andromeda are the most massive galaxies by far.

    The discovery has been announced by the “Next Generation Virgo Cluster Survey” (NGVS) team and is based on data collected, over the course of 6 years, with Megacam, a 340 Megapixel camera operating at the Canada France Hawaii Telescope and capable of observing, in a single shot, a one square degree field of view (equivalent to 4 full moons). Taking advantage of MegaCam’s wide angle coverage, the NGVS team was able to observe the Virgo cluster in its entirety, covering an area of the sky equivalent to over 400 full moons, at a depth and resolution that significantly exceed those of any existing surveys of the cluster. The resulting mosaic, comprising nearly 40 billion pixels, is the deepest, widest contiguous field ever seen is such detail.

    To exploit the full power of the data, Laura Ferrarese, Lauren McArthur and Patrick Cote of the National Research Council of Canada developed a sophisticated data analysis technique that allowed them to discover many times more galaxies than were known previously, including some of the faintest and most diffuse objects ever detected.

    Virgo is the nearest large cluster of galaxies, roughly 50 Million light-years away from us. Whereas the Milky Way forms part of a relatively small group of galaxies, the “Local Group”, spread over the nearest few million light-years, Virgo contains dozens of bright galaxies and thousands of fainter ones. In the Local Group, the current theories of galaxy formation suggest there should be hundreds or thousands of dwarf galaxies, but fewer than 100 have been detected. Clusters such as Virgo were known to be richer hunting grounds for dwarfs, but only recently has the NGVS made it possible to set firm constraints on their numbers.

    To understand the implications of these new discoveries, Jonathan Grossauer and James Taylor at the University of Waterloo ran computer simulations of clusters like Virgo, to see how many bound concentrations of dark matter they should contain at the present day. Comparing the numbers and masses of dark matter clumps to the population of galaxies discovered by the NGVS, they find a very simple pattern, where the ratio of stellar to dark matter mass changes slowly going from the smallest to the largest galaxies. It seems that in Virgo, there could be a simple relationship between dark matter mass and galaxy brightness, valid over a factor of 100,000 in stellar mass.

    This is not the case in the Local Group: the low mass dark matter clumps that would be occupied by galaxies in Virgo, do not seem to have been capable of forming galaxies in the Local Group. So why are the two environments so different? A follow-up study with higher-resolution simulations by the NGVS survey team will explore how galaxies are spatially distributed throughout the cluster, to seek more clues to the mystery of dwarf galaxy formation.

    See the full article here.

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    The CFH observatory hosts a world-class, 3.6 meter optical/infrared telescope. The observatory is located atop the summit of Mauna Kea, a 4200 meter, dormant volcano located on the island of Hawaii. The CFH Telescope became operational in 1979. The mission of CFHT is to provide for its user community a versatile and state-of-the-art astronomical observing facility which is well matched to the scientific goals of that community and which fully exploits the potential of the Mauna Kea site.

     
  • richardmitnick 4:35 pm on May 26, 2015 Permalink | Reply
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    From JPL: “NASA’s Europa Mission Begins with Selection of Science Instruments” 

    JPL

    May 26, 2015
    Preston Dyches
    Jet Propulsion Laboratory, Pasadena, Calif.
    818-354-7013
    preston.dyches@jpl.nasa.gov

    Dwayne Brown
    NASA Headquarters, Washington
    202-358-1726
    dwayne.c.brown@nasa.gov

    NASA Europa
    This artist’s rendering shows a concept for a future NASA mission to Europa in which a spacecraft would make multiple close flybys of the icy Jovian moon, thought to contain a global subsurface ocean. Credit: NASA/JPL-Caltech

    NASA has selected nine science instruments for a mission to Jupiter’s moon Europa, to investigate whether the mysterious icy moon could harbor conditions suitable for life.

    NASA’s Galileo mission yielded strong evidence that Europa, about the size of Earth’s moon, has an ocean beneath a frozen crust of unknown thickness.

    NASA Galileo
    Galileo

    If proven to exist, this global ocean could have more than twice as much water as Earth. With abundant salt water, a rocky sea floor, and the energy and chemistry provided by tidal heating, Europa could be the best place in the solar system to look for present day life beyond our home planet.

    “Europa has tantalized us with its enigmatic icy surface and evidence of a vast ocean, following the amazing data from 11 flybys of the Galileo spacecraft over a decade ago and recent Hubble observations suggesting plumes of water shooting out from the moon,” said John Grunsfeld, associate administrator for NASA’s Science Mission Directorate in Washington. “We’re excited about the potential of this new mission and these instruments to unravel the mysteries of Europa in our quest to find evidence of life beyond Earth.”

    NASA’s fiscal year 2016 budget request includes $30 million to formulate a mission to Europa. The mission would send a solar-powered spacecraft into a long, looping orbit around the gas giant Jupiter to perform repeated close flybys of Europa over a three-year period. In total, the mission would perform 45 flybys at altitudes ranging from 16 miles to 1,700 miles (25 kilometers to 2,700 kilometers).

    The payload of selected science instruments includes cameras and spectrometers to produce high-resolution images of Europa’s surface and determine its composition. An ice penetrating radar will determine the thickness of the moon’s icy shell and search for subsurface lakes similar to those beneath Antarctica. The mission also will carry a magnetometer to measure strength and direction of the moon’s magnetic field, which will allow scientists to determine the depth and salinity of its ocean.

    A thermal instrument will scour Europa’s frozen surface in search of recent eruptions of warmer water, while additional instruments will search for evidence of water and tiny particles in the moon’s thin atmosphere. NASA’s Hubble Space Telescope observed water vapor above the south polar region of Europa in 2012, providing the first strong evidence of water plumes. If the plumes’ existence is confirmed – and they’re linked to a subsurface ocean – it will help scientists investigate the chemical makeup of Europa’s potentially habitable environment while minimizing the need to drill through layers of ice.

    Last year, NASA invited researchers to submit proposals for instruments to study Europa. Thirty-three were reviewed and, of those, nine were selected for a mission that will launch in the 2020s.

    “This is a giant step in our search for oases that could support life in our own celestial backyard,” said Curt Niebur, Europa program scientist at NASA Headquarters in Washington. “We’re confident that this versatile set of science instruments will produce exciting discoveries on a much-anticipated mission.”

    The NASA selectees are:

    Plasma Instrument for Magnetic Sounding (PIMS) — principal investigator Dr. Joseph Westlake of Johns Hopkins Applied Physics Laboratory (APL), Laurel, Maryland. This instrument works in conjunction with a magnetometer and is key to determining Europa’s ice shell thickness, ocean depth, and salinity by correcting the magnetic induction signal for plasma currents around Europa.

    Interior Characterization of Europa using Magnetometry (ICEMAG) — principal investigator Dr. Carol Raymond of NASA’s Jet Propulsion Laboratory (JPL), Pasadena, California. This magnetometer will measure the magnetic field near Europa and – in conjunction with the PIMS instrument – infer the location, thickness and salinity of Europa’s subsurface ocean using multi-frequency electromagnetic sounding.

    Mapping Imaging Spectrometer for Europa (MISE) — principal investigator Dr. Diana Blaney of JPL. This instrument will probe the composition of Europa, identifying and mapping the distributions of organics, salts, acid hydrates, water ice phases, and other materials to determine the habitability of Europa’s ocean.

    Europa Imaging System (EIS) — principal investigator Dr. Elizabeth Turtle of APL. The wide and narrow angle cameras on this instrument will map most of Europa at 50 meter (164 foot) resolution, and will provide images of areas of Europa’s surface at up to 100 times higher resolution.

    Radar for Europa Assessment and Sounding: Ocean to Near-surface (REASON) — principal investigator Dr. Donald Blankenship of the University of Texas, Austin. This dual-frequency ice penetrating radar instrument is designed to characterize and sound Europa’s icy crust from the near-surface to the ocean, revealing the hidden structure of Europa’s ice shell and potential water within.

    Europa Thermal Emission Imaging System (E-THEMIS) — principal investigator Dr. Philip Christensen of Arizona State University, Tempe. This “heat detector” will provide high spatial resolution, multi-spectral thermal imaging of Europa to help detect active sites, such as potential vents erupting plumes of water into space.

    MAss SPectrometer for Planetary EXploration/Europa (MASPEX) — principal investigator Dr. Jack (Hunter) Waite of the Southwest Research Institute (SwRI), San Antonio. This instrument will determine the composition of the surface and subsurface ocean by measuring Europa’s extremely tenuous atmosphere and any surface material ejected into space.

    Ultraviolet Spectrograph/Europa (UVS) — principal investigator Dr. Kurt Retherford of SwRI. This instrument will adopt the same technique used by the Hubble Space Telescope to detect the likely presence of water plumes erupting from Europa’s surface. UVS will be able to detect small plumes and will provide valuable data about the composition and dynamics of the moon’s rarefied atmosphere.

    SUrface Dust Mass Analyzer (SUDA) — principal investigator Dr. Sascha Kempf of the University of Colorado, Boulder. This instrument will measure the composition of small, solid particles ejected from Europa, providing the opportunity to directly sample the surface and potential plumes on low-altitude flybys.

    Separate from the selectees listed above, the SPace Environmental and Composition Investigation near the Europan Surface (SPECIES) instrument has been chosen for further technology development. Led by principal investigator Dr. Mehdi Benna at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, this combined neutral mass spectrometer and gas chromatograph will be developed for other mission opportunities.

    NASA’s Science Mission Directorate in Washington conducts a wide variety of research and scientific exploration programs for Earth studies, space weather, the solar system and the universe.

    For more information about Europa, visit:

    http://go.nasa.gov/europanews

    See the full article here.

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    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, 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 4:08 pm on May 26, 2015 Permalink | Reply
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    From Symmetry: “A goldmine of scientific research” 

    Symmetry

    May 26, 2015
    Amelia Williamson Smith

    1
    Photo by Anna Davis

    The underground home of the LUX dark matter experiment has a rich scientific history.

    There’s more than gold in the Black Hills of South Dakota. For longer than five decades, the Homestake mine has hosted scientists searching for particles impossible to detect on Earth’s surface.

    It all began with the Davis Cavern.

    In the early 1960s, Ray Davis, a nuclear chemist at Brookhaven National Laboratory designed an experiment to detect particles produced in fusion reactions in the sun. The experiment would earn him a share of the Nobel Prize in Physics in 2002.

    Davis was searching for neutrinos, fundamental particles that had been discovered only a few years before. Neutrinos are very difficult to detect; they can pass through the entire Earth without bumping into another particle. But they are constantly streaming through us. So, with a big enough detector, Davis knew he could catch at least a few.

    Davis’ experiment had to be done deep underground; without the shielding of layers of rock and earth it would be flooded by the shower of cosmic rays also constantly raining from space.

    Davis put his first small prototype detector in a limestone mine near Akron, Ohio. But it was only about half a mile underground, not deep enough.

    “The only reason for mining deep into the earth was for something valuable like gold,” says Kenneth Lande, professor of physics at the University of Pennsylvania, who worked on the experiment with Davis. “And so a gold mine became the obvious place to look.”

    But there was no precedent for hosting a particle physics experiment in such a place. “There was no case where a physics group would appear at a working mine and say, ‘Can we move in please?’”

    Davis approached the Homestake Mining Company anyway, and the company agreed to excavate a cavern for the experiment.

    BNL funded the experiment. In 1965, it was installed in a cavern 4850 feet below the surface.

    The detector consisted of a 100,000-gallon tank of chlorine atoms. Davis had predicted that as solar neutrinos passed through the tank, one would occasionally collide with a chlorine atom, changing it to an argon atom. After letting the detector run for a couple of months at a time, Davis’ team would flush out the tank and count the argon atoms to determine how many neutrino interactions had occurred.

    “The detector had approximately 1031 atoms in it. One argon atom was produced every two days,” Lande says. “To design something that could do that kind of extraction was mind-boggling.”

    2
    Ray Davis. Courtesy of: Brookhaven National Laboratory

    A different kind of laboratory

    During the early years of the Davis experiment, around 2000 miners worked at the mine, along with engineers and geologists. The small group of scientists working on the Davis experiment would travel down into the mine with them.

    To go down the shaft to the 4850-foot level, they would get into what was called the “cage,” a 4.4-foot by 12.5-foot metal conveyance that held 36 people. The ride down, lit only by the glow of a couple of headlamps, took about five minutes, says Tom Regan, former operations safety manager and now safety consultant, who worked as a student laborer in the mine during the early years of the Davis experiment.

    Once they reached the 4850-foot level, the scientists walked across a rock dump. “It was guarded so a person couldn’t fall down the hole,” Regan says. “But you had to sometimes wait for a production train of rock or even loads of supplies or men or materials.”

    The Davis Cavern was 24 feet long, 24 feet wide, and 30 feet high. A small room off to the side held the group’s control system. “We were basically out of touch with the rest of the world when we were underground,” Lande says. “There was no difference between day and night, heat and cold, and snow and sunshine.”

    The miners and locals from Lead, South Dakota—the community surrounding the mine—were welcoming of the scientists and interested in their work, Lande says. “We’d go out to dinner at the local restaurant and we’d hear this hot conversation in the next booth, and they would be discussing black holes and neutron stars. So science became the talk of the small town.”

    4
    Davis Cavern, during the solar neutrino experiment. Photo by: Anna Davis

    The solar neutrino problem

    As the experiment began taking data, Davis’ group found they were detecting only about one-third the number of neutrinos predicted—a discrepancy that became known as the “solar neutrino problem.”

    Davis described the situation in his Nobel Prize biographical sketch: “My opinion in the early years was that something was wrong with the standard solar model; many physicists thought there was something wrong with my experiment.”

    However, every test of the experiment confirmed the results, and no problems were found with the model of the sun. Davis’ group began to suspect it was instead a problem with the neutrinos.

    This suspicion was confirmed in 2001, when the Sudbury Neutrino Observatory experiment [SNO] in Canada determined that as solar neutrinos travel through space, they oscillate, or change, between three flavors—electron, muon and tau. By the time neutrinos from the sun reach the Earth, they are an equal mixture of the three types.

    Sudbury Neutrino Observatory
    SNO

    The Davis experiment was sensitive only to electron neutrinos, so it was able to detect only one-third of the neutrinos from the sun. The solar neutrino problem was solved.

    5
    Davis Cavern, during a more recent expansion. Photo by: Matthew Kapust, Sanford Underground Research Facility

    A different kind of gold

    The Davis experiment ran for almost 40 years, until the mine closed in 2003.

    But the days of science in the Davis Cavern weren’t over. In 2006, the mining company donated Homestake to the state of South Dakota. It was renamed the Sanford Underground Research Facility.

    In 2009, many former Homestake miners became technicians on a $15.2 million project to renovate the experimental area. They completed the new 30,000-square-foot Davis Campus in 2012.

    Although scientists still ride in the cage to get down to the 4850-foot level of the mine, once they arrive it looks completely different.

    “It’s a very interesting contrast,” says Stanford University professor Thomas Shutt of SLAC National Accelerator Laboratory. “Going into the mine, it’s all mining carts, rust and rock, and then you get down to the Davis Campus, and it’s a really state-of-the-art facility.”

    The campus now contains block buildings with doors and windows. It has its own heating and air conditioning system, ventilation system, humidifiers and dust filters.

    The original Davis Cavern has been expanded and now houses the Large Underground Xenon experiment, the most sensitive detector yet searching for what many consider the most promising candidate for a type of dark matter particle.

    LUX Dark matter
    LUX

    Shielded from distracting background particles this far underground, scientists hope LUX will detect the rare interaction of dark matter particles with the nucleus of xenon atoms in the 368-kilogram tank.

    Another cavern nearby was excavated as part of the Davis Campus renovation project and now holds the Majorana Demonstrator experiment, which will soon start to examine whether neutrinos are their own antimatter partners.

    Majorano Demonstrator Experiment
    Majorano Demonstrator Experiment

    LUX began taking data in 2013. It is currently on its second run and will continue through spring 2016.

    After its current run, LUX will be replaced by the LUX-ZEPLIN, or LZ, experiment, which will be 50 times bigger in usable mass and several hundred times more sensitive than the current LUX results.

    LZ project
    LZ

    Science in the mine is still the talk of the town in Lead, says Carmen Carmona, an assistant project scientist at the University of California, Santa Barbara, who works on LUX. “When you go out on the streets and talk to people—especially the families of the miners from the gold mine days—they want to know how it is working underground now and how the experiment is going.”

    The spirit of cooperation between the mining community, the science community and the public community lives on, Regan says.

    “It’s been kind of a legacy to provide the beneficial space and be good neighbors and good hosts,” Regan says. “Our goal is for them to succeed, so we do everything we can to help and provide the best and safest place for them to do their good science.”

    6
    In 2010, Sanford Lab enlarged the Davis Cavern to support the Large Underground Xenon experiment. Matthew Kapust, Sanford Underground Research Facility

    7
    This cavern is being outfitted for the Compact Accelerator System Performing Astrophysical Research. CASPAR will use a low-powered accelerator to study what happens when stars die. Matthew Kapust, Sanford Underground Research Facility

    8
    Davis Cavern undergoes outfitting for the LUX experiment. Matthew Kapust, Sanford Underground Research Facility

    9
    Each day scientists working at the the Davis Campus pass this area, known as the Big X. The entrance to the Davis Campus is to the left; Yates Shaft is to the right. Matthew Kapust, Sanford Underground Research Facility

    10
    LUX researchers install the detector at the 4850 level. Matthew Kapust, Sanford Underground Research Facility

    11
    The Majorana Demonstrator experiment requires a very strict level of cleanliness. Researcher work in full clean room garb and assemble their detectors inside nitrogen-filled glove boxes. Matthew Kapust, Sanford Underground Research Facility

    12
    The LUX detector was built in a clean room on the surface and then brought underground. Matthew Kapust, Sanford Underground Research Facility

    See the full article here.

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    Symmetry is a joint Fermilab/SLAC publication.


     
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