samedi 24 septembre 2016

Great expectations from fewer collisions












CERN - European Organization for Nuclear Research logo.

September 24, 2016


Image above: Nicola Turini, deputy spokesperson for TOTEM, in front of one of the experiment’s so-called ‘Roman Pot’ detectors in the LHC tunnel. (Image: Maximilien Brice/CERN).

Usually, the motto of the LHC is ‘maximum luminosity’ (in other words, as many collisions as possible).

But this week, the LHC will ignore its motto, and perform special runs at very low luminosity for the TOTEM and ATLAS/ALFA experiments.

This is because scientists want to study a particular type of interaction, called “elastic scattering”. Elastic scattering is when two protons survive their encounter in the detector intact, without colliding head-on, so they don’t create new particles and only slightly change their direction. In normal LHC runs, this interaction is not observable, as the protons are more likely to crash into each other and create new particles.

These elastic interactions are precious to scientists, as they allow them to study the way protons are made up inside and also what part of the proton is actually responsible for this type of interaction. Indeed, we know that the protons are composite particles, made up of 3 quarks (two “up” and one “down”) ‘glued’ together by gluons. But we don’t know the exact disposition of these components, neither do we know how many or what particles are actually playing a role when two protons bounce off each other in elastic scatterings.

Eventually, these type of studies are also useful for understanding the dynamics of cosmic rays – high-energy particles that originate outside the Solar System that, while travelling towards the Earth’s surface, impact with its atmosphere to produce a shower of secondary particles.

TOTEM and ATLAS/ALFA run detectors located on both sides of two of the big LHC detectors, CMS for TOTEM, and ATLAS for ATLAS/ALFA. These special experiments study the protons as they come out of elastic scattering interactions at slightly-changed angles in respect to their initial trajectory (the so-called “forward region”).


Image above: Part of the ATLAS/ALFA experiment apparatus at Point 1 in the LHC tunnel.  (Image: Ronaldus Suykerbuyk/CERN).

One of the most fascinating physics goals of TOTEM is to get information on the probability that two protons pass completely through each other without interfering. This might appear awkward if you think of a proton as a billiard ball, but instead you have to try to imagine the two scattering protons as large ‘galaxies’ (made up inside of tiny moving particles) launched at high speed against each other: there is a finite probability that the two ‘galaxies' will pass through each other without the inner particles interacting significantly.

ALFA stands for Absolute Luminosity For ATLAS, and indeed its goal is to provide an independent estimate of the LHC luminosity by measuring this proton–proton elastic scattering at small angles.

For more information about TOTEM and ATLAS/ALFA and the LHC special physics run, read here: http://home.cern/cern-people/updates/2016/09/de-squeeze-beams-totem-and-atlasalfa

Note:

CERN, the European Organization for Nuclear Research, is one of the world’s largest and most respected centres for scientific research. Its business is fundamental physics, finding out what the Universe is made of and how it works. At CERN, the world’s largest and most complex scientific instruments are used to study the basic constituents of matter — the fundamental particles. By studying what happens when these particles collide, physicists learn about the laws of Nature.

The instruments used at CERN are particle accelerators and detectors. Accelerators boost beams of particles to high energies before they are made to collide with each other or with stationary targets. Detectors observe and record the results of these collisions.

Founded in 1954, the CERN Laboratory sits astride the Franco–Swiss border near Geneva. It was one of Europe’s first joint ventures and now has 22 Member States.

Related links:

TOTEM: https://home.web.cern.ch/about/experiments/totem

ATLAS/ALFA: http://atlas-project-lumi-fphys.web.cern.ch/atlas-project-lumi-fphys/ALFA/

For more information about European Organization for Nuclear Research (CERN), Visit: http://home.cern/

Images (mentioned), Text, Credits: CERN/Stefania Pandolfi.

Greetings, Orbiter.ch

ISS - Eye Scans, Orbital Plumbing and Story Time for Crew










ISS - Expedition 49 Mission patch.

September 24, 2016

Astronauts Kate Rubins and Takuya Onishi are continuing more eye checks today in the middle of day-long orbital plumbing work. Commander Anatoly Ivanishin packed trash in a resupply ship and researched a variety of Earth and space phenomena.

Rubins and Onishi scanned each other’s eyes today using an ultrasound. Doctors on the ground assisted the duo and will use the data to determine how living in space affects vision and the shape of the eye. The pair also participated in the Story Time From Space video series for children demonstrating simple physics experiments.


Image above: Japanese astronaut Takuya Onishi is at work inside the U.S. Destiny laboratory module. Image Credit: NASA.

Onishi spent most of his day replacing parts such as sensors and valves in the bathroom, or the Water and Hygiene Compartment, located in the Tranquility module. Rubins analyzed the quality of the station’s water supply and sampled for microbes, silica and organic material.

Ivanishin, a veteran cosmonaut on his second station mission, is getting the Progress 63 cargo craft ready for departure next month. He transferred cargo and trash to and from the resupply ship then updated the station’s inventory management system. The commander also spent some time exploring new ways to monitor natural disasters, how the digestive system adapts in space and detecting orbital debris and micrometeoroid impacts on the station.

Related links:

Story Time From Space video series: http://www.nasa.gov/mission_pages/station/research/experiments/1287.html

Monitor natural disasters: http://www.energia.ru/en/iss/researches/study/12.html

Digestive system adapts in space: http://www.energia.ru/en/iss/researches/human/09.html

Orbital debris and micrometeoroid impacts: http://www.energia.ru/en/iss/researches/develop/16.html

Space Station Research and Technology: https://www.nasa.gov/mission_pages/station/research/index.html

International Space Station (ISS): https://www.nasa.gov/mission_pages/station/main/index.html

Image (mentioned), Text, Credits: NASA/Mark Garcia.

Greetings, Orbiter.ch

vendredi 23 septembre 2016

Weekly Recap From the Expedition Lead Scientist, Week of Sept. 12, 2016










ISS - Expedition 49 Mission patch.

Sept. 23, 2016

(Highlights: Week of Sept. 12, 2016) - The week began with moving day and ended with a handful of satellite deployments on the International Space Station.

On Sept. 12, NASA astronaut Kate Rubins disassembled and removed the hardware for the Effects of Microgravity on Stem Cell-Derived Cardiomyocytes (Heart Cells) investigation from the Microgravity Science Glovebox (MSG). Spaceflight can cause a variety of health issues with astronauts, which may become problematic the longer crew members stay in microgravity. The study looked at how human heart muscle tissue contracts, grows and changes genetically in microgravity and how those changes vary between subjects. Understanding how heart muscle cells, or cardiomyocytes, change in space can improve efforts to study disease, screen drugs and conduct cell replacement therapy for future space missions.


Image above: A pair of Planet Lab Dove satellites are ejected into orbit by the NanoRack CubeSat Deployer on the International Space Station. The satellites, each about the size of a shoebox, will take images of Earth. Image Credit: NASA.

Extended stays aboard the station are becoming more common, and future crews will stay in space for even longer periods as they travel on deep-space missions or a journey to Mars. Living without gravity’s influence for long periods can cause negative health effects such as muscle atrophy, including potential atrophy of heart muscle. The Heart Cells investigation cultured heart cells on the station for a month to determine how those muscle cells changed on a cellular and molecular level in space. Scientists hope the results will improve understanding of microgravity’s negative effects. Understanding changes to heart muscle cells could benefit cardiovascular research on Earth, where heart disease is a leading cause of death in many countries.

Rubins cleared out the Heart Cells investigation to make way for an ESA (European Space Agency) study into how molecules in liquid mixtures move in space where buoyancy-driven convection does not mask the more subtle molecular motions. The Selective Optical Diagnostics Instrument (SODI-DCMIX) will observe and measure the diffusion coefficient of liquid mixtures after a temperature gradient is established. Diffusion occurs at the molecular level as opposed to convection which occurs at the bulk level with entire masses, fronts, or regions of a gas or liquid moving somewhat as a unit.


Image above: An image taken from the International Space Station provides a nighttime view looking south at the Mediterranean Sea and the Strait of Gibraltar. A Russian Soyuz spacecraft (left) and Progress spacecraft (right) are in the foreground. Image Credit: NASA.

With convection eliminated in the weightlessness of space, the diffusion coefficient can be more accurately measured. Fluids and gases are never at rest, even if they appear to be when viewed by the naked eye. Molecules are constantly moving and colliding, even though there is no microscope powerful enough to see the phenomenon. SODI-DCMIX will study the Soret effect -- the movement of heat and mass that is caused by a difference in temperature. This is different from convection, where hotter, less dense matter rises upward compared to cooler, denser material.

Creating accurate models of how fluids heat is difficult. Measuring liquid mixtures at rest is not always possible on Earth, because heavier elements in a mixture will follow gravity and sink to the bottom. A mixture on the space station is free from the constraints of gravity, and will not separate. SODI-DCMIX exploits this fact to record temperatures of mixtures in space, using optical techniques to understand how molecules move in liquids. Understanding the fundamentals of thermodiffusion could help oil companies that use computer simulations to model and monitor underground oil reservoirs.


Image above: NASA Astronaut Kate Rubins installs an optical diagnostic instrument in the Microgravity Science Glovebox (MSG) as part of the Selective Optical Diagnostics Instrument (SODI-DCMIX) investigation. Image Credit: NASA.

JAXA (Japan Aerospace Exploration Agency) astronaut Takuya Onishi installed a series of eight Planet Lab-Dove satellites in the NanoRack CubeSat Deployer (NRCSD) using a special airlock in the Japanese Experiment Module (JEM). The NRCSD is a self-contained deployment system on the end of a robotic arm, called the JEM Remote Manipulating System (JRMS), mounted to the exterior of the station. It is a rectangular compartment that "ejects" very small satellites to place them into orbit. It provides a low-cost and frequent flight opportunity for industry and academia to put research satellites into space.

The eight Dove satellites -- each about the size of a shoebox -- were "launched" from the station by ground controllers to capture images of Earth from space. The images have several humanitarian and environmental applications, from monitoring deforestation and urbanization to improving natural disaster relief and agricultural yields in developing nations. The nanosatellite program engages the space community to enhance space-based global communication networks, and to conduct research on our climate and Earth’s atmosphere.

Progress was made on other investigations and facilities this week, including Plant RNA Regulation, Asia Try-Zero G, FLEX-2, Biomolecule Sequencer, Phase Change Heat Exchanger, Manufacturing Device, ELF.

Other human research investigations conducted this week include Dose Tracker, Fine Motor Skills, Habitability, Multi-Omics, and Space Headaches.

Related links:

Stem Cell-Derived Cardiomyocytes (Heart Cells): http://www.nasa.gov/mission_pages/station/research/experiments/1914.html

NanoRack CubeSat Deployer (NRCSD): http://www.nasa.gov/mission_pages/station/research/experiments/1350.html

Japanese Experiment Module (JEM): https://www.nasa.gov/mission_pages/station/structure/elements/jem.html

Planet Lab-Dove satellites: http://www.nasa.gov/mission_pages/station/research/experiments/1326.html

Plant RNA Regulation: http://www.nasa.gov/mission_pages/station/research/experiments/2019.html

Asia Try-Zero G: http://www.nasa.gov/mission_pages/station/research/experiments/2016.html

FLEX-2: http://www.nasa.gov/mission_pages/station/research/experiments/480.html

Biomolecule Sequencer: http://www.nasa.gov/mission_pages/station/research/experiments/2181.html

Phase Change Heat Exchanger: http://www.nasa.gov/mission_pages/station/research/experiments/2077.html

Manufacturing Device: http://www.nasa.gov/mission_pages/station/research/experiments/2198.html

ELF: http://www.nasa.gov/mission_pages/station/research/experiments/1999.html

Dose Tracker: http://www.nasa.gov/mission_pages/station/research/experiments/1933.html

Fine Motor Skills: http://www.nasa.gov/mission_pages/station/research/experiments/1767.html

Habitability: http://www.nasa.gov/mission_pages/station/research/experiments/1772.html

Multi-Omics: http://www.nasa.gov/mission_pages/station/research/experiments/1949.html

Space Headaches: http://www.nasa.gov/mission_pages/station/research/experiments/181.html

Space Station Research and Technology: https://www.nasa.gov/mission_pages/station/research/index.html

International Space Station (ISS): https://www.nasa.gov/mission_pages/station/main/index.html

Japan Aerospace Exploration Agency (JAXA): http://global.jaxa.jp/

Images (mentioned), Text, Credits: NASA/Vic Cooley, Lead Increment Scientist Expeditions 49 & 50/Kristine Rainey.

Greetings, Orbiter.ch

Hubble Views a Colorful Demise of a Sun-like Star












NASA - Hubble Space Telescope patch.

Sept. 23, 2016


This image, taken by the NASA/ESA Hubble Space Telescope, shows the colorful "last hurrah" of a star like our sun. The star is ending its life by casting off its outer layers of gas, which formed a cocoon around the star's remaining core. Ultraviolet light from the dying star makes the material glow. The burned-out star, called a white dwarf, is the white dot in the center. Our sun will eventually burn out and shroud itself with stellar debris, but not for another 5 billion years.

Our Milky Way Galaxy is littered with these stellar relics, called planetary nebulae. The objects have nothing to do with planets. Eighteenth- and nineteenth-century astronomers called them the name because through small telescopes they resembled the disks of the distant planets Uranus and Neptune. The planetary nebula in this image is called NGC 2440. The white dwarf at the center of NGC 2440 is one of the hottest known, with a surface temperature of more than 360,000 degrees Fahrenheit (200,000 degrees Celsius). The nebula's chaotic structure suggests that the star shed its mass episodically. During each outburst, the star expelled material in a different direction. This can be seen in the two bowtie-shaped lobes. The nebula also is rich in clouds of dust, some of which form long, dark streaks pointing away from the star. NGC 2440 lies about 4,000 light-years from Earth in the direction of the constellation Puppis.

The material expelled by the star glows with different colors depending on its composition, its density and how close it is to the hot central star. Blue samples helium; blue-green oxygen, and red nitrogen and hydrogen.

For more information about the Hubble Space Telescope, visit:

http://hubblesite.org/
http://www.nasa.gov/hubble
https://www.spacetelescope.org/

Image, Text, Credits: NASA, ESA, and K. Noll (STScI), Acknowledgment: The Hubble Heritage Team (STScI/AURA)/Karl Hille.

Greetings, Orbiter.ch

ALMA Explores the Hubble Ultra Deep Field














ALMA - Atacama Large Millimeter/submillimeter Array logo / ESA - Hubble Space Telescope logo.

22 September 2016

Deepest ever millimetre observations of early Universe

ALMA probes the Hubble Ultra Deep Field

International teams of astronomers have used the Atacama Large Millimeter/submillimeter Array (ALMA) to explore the distant corner of the Universe first revealed in the iconic images of the Hubble Ultra Deep Field (HUDF). These new ALMA observations are significantly deeper and sharper than previous surveys at millimetre wavelengths. They clearly show how the rate of star formation in young galaxies is closely related to their total mass in stars. They also trace the previously unknown abundance of star-forming gas at different points in time, providing new insights into the “Golden Age” of galaxy formation approximately 10 billion years ago.

The new ALMA results will be published in a series of papers appearing in the Astrophysical Journal and Monthly Notices of the Royal Astronomical Society. These results are also among those being presented this week at the Half a Decade of ALMA conference in Palm Springs, California, USA.

ALMA probes the Hubble Ultra Deep Field

In 2004 the Hubble Ultra Deep Field images — pioneering deep-field observations with the NASA/ESA Hubble Space Telescope — were published. These spectacular pictures probed more deeply than ever before and revealed a menagerie of galaxies stretching back to less than a billion years after the Big Bang. The area was observed several times by Hubble and many other telescopes, resulting in the deepest view of the Universe to date.

Astronomers using ALMA have now surveyed this seemingly unremarkable, but heavily studied, window into the distant Universe for the first time both deeply and sharply in the millimetre range of wavelengths [1]. This allows them to see the faint glow from gas clouds and also the emission from warm dust in galaxies in the early Universe.

The Hubble eXtreme Deep Field

ALMA has observed the HUDF for a total of around 50 hours up to now. This is the largest amount of ALMA observing time spent on one area of the sky so far.

One team led by Jim Dunlop (University of Edinburgh, United Kingdom) used ALMA to obtain the first deep, homogeneous ALMA image of a region as large as the HUDF. This data allowed them to clearly match up the galaxies that they detected with objects already seen with Hubble and other facilities.

ALMA deep view of part of the Hubble Ultra Deep Field

This study showed clearly for the first time that the stellar mass of a galaxy is the best predictor of star formation rate in the high redshift Universe. They detected essentially all of the high-mass galaxies [2] and virtually nothing else.

Jim Dunlop, lead author on the deep imaging paper sums up its importance: “This is a breakthrough result. For the first time we are properly connecting the visible and ultraviolet light view of the distant Universe from Hubble and far-infrared/millimetre views of the Universe from ALMA.”

ALMA deep view of part of the Hubble Ultra Deep Field

The second team, led by Manuel Aravena of the Núcleo de Astronomía, Universidad Diego Portales, Santiago, Chile, and Fabian Walter of the Max Planck Institute for Astronomy in Heidelberg, Germany, conducted a deeper search across about one sixth of the total HUDF [3].

“We conducted the first fully blind, three-dimensional search for cool gas in the early Universe,” said Chris Carilli, an astronomer with the National Radio Astronomy Observatory (NRAO) in Socorro, New Mexico, USA and member of the research team. “Through this, we discovered a population of galaxies that is not clearly evident in any other deep surveys of the sky.” [4]

Some of the new ALMA observations were specifically tailored to detect galaxies that are rich in carbon monoxide, indicating regions primed for star formation. Even though these molecular gas reservoirs give rise to the star formation activity in galaxies, they are often very hard to see with Hubble. ALMA can therefore reveal the “missing half” of the galaxy formation and evolution process.

ALMA probes the Hubble Ultra Deep Field

“The new ALMA results imply a rapidly rising gas content in galaxies as we look back further in time,” adds lead author of two of the papers, Manuel Aravena (Núcleo de Astronomía, Universidad Diego Portales, Santiago, Chile). “This increasing gas content is likely the root cause for the remarkable increase in star formation rates during the peak epoch of galaxy formation, some 10 billion years ago.”

The results presented today are just the start of a series of future observations to probe the distant Universe with ALMA. For example, a planned 150-hour observing campaign of the HUDF will further illuminate the star-forming potential history of the Universe.

“By supplementing our understanding of this missing star-forming material, the forthcoming ALMA Large Program will complete our view of the galaxies in the iconic Hubble Ultra Deep Field,” concludes Fabian Walter.

Notes:

[1] Astronomers specifically selected the area of study in the HUDF, a region of space in the faint southern constellation of Fornax (The Furnace), so ground-based telescopes in the southern hemisphere, like ALMA, could probe the region, expanding our knowledge about the very distant Universe.

Probing the deep, but optically invisible, Universe was one of the primary science goals for ALMA.

[2] In this context “high mass” means galaxies with stellar masses greater than 20 billion times that of the Sun ( 2 × 1010 solar masses). For comparison, the Milky Way is a large galaxy and has a mass of around 100 billion solar masses.

[3] This region of sky is about seven hundred times smaller than the area of the disc of the full Moon as seen from Earth. One of the most startling aspects of the HUDF was the vast number of galaxies found in such a tiny fraction of the sky.

[4] ALMA’s ability to see a completely different portion of the electromagnetic spectrum from Hubble allows astronomers to study a different class of astronomical objects, such as massive star-forming clouds, as well as objects that are otherwise too faint to observe in visible light, but visible at millimetre wavelengths.

The search is referred to as “blind” as it was not focussed on any particular object.

The new ALMA observations of the HUDF include two distinct, yet complementary types of data: continuum observations, which reveal dust emission and star formation, and a spectral emission line survey, which looks at the cold molecular gas fueling star formation. The second survey is particularly valuable because it includes information about the degree to which light from distant objects has been redshifted by the expansion of the Universe. Greater redshift means that an object is further away and seen farther back in time. This allows astronomers to create a three-dimensional map of star-forming gas as it evolves over cosmic time.

More information:

This research was presented in papers titled:

“A deep ALMA image of the Hubble Ultra Deep Field”, by J. Dunlop et al., to appear in the Monthly Notices of the Royal Astronomical Society.

“The ALMA Spectroscopic Survey in the Hubble Ultra Deep Field: Search for the [CII] Line and Dust Emission in 6 < z < 8 Galaxies”, by M. Aravena et al., to appear in the Astrophysical Journal.

“The ALMA Spectroscopic Survey in the Hubble Ultra Deep Field: Molecular Gas Reservoirs in High-Redshift Galaxies”, by R. Decarli et al., to appear in the Astrophysical Journal.

“The ALMA Spectroscopic Survey in the Hubble Ultra Deep Field: CO Luminosity Functions and the Evolution of the Cosmic Density of Molecular Gas”, by R. Decarli et al., to appear in the Astrophysical Journal.

“The ALMA Spectroscopic Survey in the Hubble Ultra Deep Field: Continuum Number Counts, Resolved 1.2-mm Extragalactic Background, and Properties of the Faintest Dusty Star Forming Galaxies”, by M. Aravena et al., to appear in the Astrophysical Journal.

“The ALMA Spectroscopic Survey in the Hubble Ultra Deep Field: Survey Description”, by F. Walter et al., to appear in the Astrophysical Journal.

“The ALMA Spectroscopic Survey in the Hubble Ultra Deep Field: the Infrared excess of UV-selected z= 2-10 Galaxies as a Function of UV-continuum Slope and Stellar Mass”, by R. Bouwens et al., to appear in the Astrophysical Journal.

“The ALMA Spectroscopic Survey in the Hubble Ultra Deep Field: Implication for spectral line intensity mapping at millimeter wavelengths and CMB spectral distortions”, by C. L. Carilli et al. to appear in the Astrophysical Journal.

The teams are composed of:

M. Aravena (Núcleo de Astronomía, Universidad Diego Portales, Santiago, Chile), R. Decarli (Max-Planck Institut für Astronomie, Heidelberg, Germany), F. Walter (Max-Planck Institut für Astronomie, Heidelberg, Germany; Astronomy Department, California Institute of Technology, USA; NRAO, Pete V. Domenici Array Science Center, USA), R. Bouwens (Leiden Observatory, Leiden, The Netherlands; UCO/Lick Observatory, Santa Cruz, USA), P.A. Oesch (Astronomy Department, Yale University, New Haven, USA), C.L. Carilli (Leiden Observatory, Leiden, The Netherlands; Astrophysics Group, Cavendish Laboratory, Cambridge, UK), F.E. Bauer (Instituto de Astrofísica, Pontificia Universidad Católica de Chile, Santiago, Chile; Millennium Institute of Astrophysics, Chile; Space Science Institute, Boulder, USA), E. Da Cunha (Research School of Astronomy and Astrophysics, Australian National University, Canberra, Australia; Centre for Astrophysics and Supercomputing, Swinburne University of Technology, Hawthorn, Australia), E. Daddi (Laboratoire AIM, CEA/DSM-CNRS-Université Paris Diderot, Orme des Merisiers, France), J. Gónzalez-López (Instituto de Astrofísica, Pontificia Universidad Católica de Chile, Santiago, Chile), R.J. Ivison (European Southern Observatory, Garching bei München, Germany; Institute for Astronomy, University of Edinburgh, Edinburgh, UK), D.A. Riechers (Cornell University, 220 Space Sciences Building, Ithaca, USA), I. Smail (Institute for Computational Cosmology, Durham University, Durham, UK), A.M. Swinbank (Institute for Computational Cosmology, Durham University, Durham, UK), A. Weiss (Max-Planck-Institut für Radioastronomie, Bonn, Germany), T. Anguita (Departamento de Ciencias Físicas, Universidad Andrés Bello, Santiago, Chile; Millennium Institute of Astrophysics, Chile), R. Bacon (Université Lyon 1, Saint Genis Laval, France), E. Bell (Department of Astronomy, University of Michigan, USA), F. Bertoldi (Argelander Institute for Astronomy, University of Bonn, Bonn, Germany), P. Cortes (Joint ALMA Observatory - ESO, Santiago, Chile; NRAO, Pete V. Domenici Array Science Center, USA), P. Cox (Joint ALMA Observatory - ESO, Santiago, Chile), J. Hodge (Leiden Observatory, Leiden, The Netherlands), E. Ibar (Instituto de Física y Astronomía, Universidad de Valparaíso, Valparaiso, Chile), H. Inami (Université Lyon 1, Saint Genis Laval, France), L. Infante (Instituto de Astrofísica, Pontificia Universidad Católica de Chile, Santiago, Chile), A. Karim (Argelander Institute for Astronomy, University of Bonn, Bonn, Germany), B. Magnelli (Argelander Institute for Astronomy, University of Bonn, Bonn, Germany), K. Ota (Kavli Institute for Cosmology, University of Cambridge, Cambridge, UK; Cavendish Laboratory, University of Cambridge, UK), G. Popping (European Southern Observatory, Garching bei München, Germany), P. van der Werf (Leiden Observatory, Leiden, The Netherlands), J. Wagg (SKA Organization, Cheshire, UK), Y. Fudamoto (European Southern Observatory, Garching bei München, Germany; Universität-Sternwarte München, München, Germany), D. Elbaz (Laboratoire AIM, CEA/DSM-CNRS-Universite Paris Diderot, France), S. Chapman (Dalhousie University, Halifax, Nova Scotia, Canada), L.Colina (ASTRO-UAM, UAM, Unidad Asociada CSIC, Spain), H.W. Rix (Max-Planck Institut für Astronomie, Heidelberg, Germany), Mark Sargent (Astronomy Centre, University of Sussex, Brighton, UK), Arjen van der Wel (Max-Planck Institut für Astronomie, Heidelberg, Germany)

K. Sheth (NASA Headquarters, Washington DC, USA), Roberto Neri (IRAM, Saint-Martin d’Hères, France), O. Le Fèvre (Aix Marseille Université, Laboratoire d’Astrophysique de Marseille, Marseille, France), M. Dickinson (Steward Observatory, University of Arizona, USA), R. Assef (Núcleo de Astronomía, Universidad Diego Portales, Santiago, Chile), I. Labbé (Leiden Observatory, Leiden University, Netherlands), S. Wilkins (Astronomy Centre, University of Sussex, Brighton, UK), J.S. Dunlop (University of Edinburgh, Royal Observatory, Edinburgh, United Kingdom), R.J. McLure (University of Edinburgh, Royal Observatory, Edinburgh, United Kingdom), A.D. Biggs (ESO, Garching, Germany), J.E. Geach (University of Hertfordshire, Hatfield, United Kingdom), M.J. Michałowski (University of Edinburgh, Royal Observatory, Edinburgh, United Kingdom), W. Rujopakarn (Chulalongkorn University, Bangkok, Thailand), E. van Kampen (ESO, Garching, Germany), A. Kirkpatrick (University of Massachusetts, Amherst, Massachusetts, USA), A. Pope (University of Massachusetts, Amherst, Massachusetts, USA), D. Scott (University of British Columbia, Vancouver, British Columbia, Canada), T.A. Targett (Sonoma State University, Rohnert Park, California, USA), I. Aretxaga (Instituto Nacional de Astrofísica, Optica y Electronica, Mexico), J.E. Austermann (NIST Quantum Devices Group, Boulder, Colorado, USA), P.N. Best (University of Edinburgh, Royal Observatory, Edinburgh, United Kingdom), V.A. Bruce (University of Edinburgh, Royal Observatory, Edinburgh, United Kingdom), E.L. Chapin (Herzberg Astronomy and Astrophysics, National Research Council Canada, Victoria, Canada), S. Charlot (Sorbonne Universités, UPMC-CNRS, UMR7095, Institut d’Astrophysique de Paris, Paris, France), M. Cirasuolo (ESO, Garching, Germany), K.E.K. Coppin (University of Hertfordshire, College Lane, Hatfield, United Kingdom), R.S. Ellis (ESO, Garching, Germany), S.L. Finkelstein (The University of Texas at Austin, Austin, Texas, USA), C.C. Hayward (California Institute of Technology, Pasadena, California, USA), D.H. Hughes (Instituto Nacional de Astrofísica, Optica y Electronica, Mexico), S. Khochfar (University of Edinburgh, Royal Observatory, Edinburgh, United Kingdom), M.P. Koprowski (University of Hertfordshire, College Lane, Hatfield, United Kingdom), D. Narayanan (Haverford College, Haverford, Pennsylvania, USA), C. Papovich (Texas A & M University, College Station, Texas, USA), J.A. Peacock (University of Edinburgh, Royal Observatory, Edinburgh, United Kingdom), B. Robertson (University of California, Santa Cruz, Santa Cruz, California, USA), T. Vernstrom (Dunlap Institute for Astronomy and Astrophysics, University of Toronto, Toronto, Ontario, Canada), G.W. Wilson (University of Massachusetts, Amherst, Massachusetts, USA) and M. Yun (University of Massachusetts, Amherst, Massachusetts, USA).

The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership of ESO, the U.S. National Science Foundation (NSF) and the National Institutes of Natural Sciences (NINS) of Japan in cooperation with the Republic of Chile. ALMA is funded by ESO on behalf of its Member States, by NSF in cooperation with the National Research Council of Canada (NRC) and the National Science Council of Taiwan (NSC) and by NINS in cooperation with the Academia Sinica (AS) in Taiwan and the Korea Astronomy and Space Science Institute (KASI).

ALMA construction and operations are led by ESO on behalf of its Member States; by the National Radio Astronomy Observatory (NRAO), managed by Associated Universities, Inc. (AUI), on behalf of North America; and by the National Astronomical Observatory of Japan (NAOJ) on behalf of East Asia. The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.

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”.

Links:

Research paper 1 (Dunlop, J. S. et al.): http://www.eso.org/public/archives/releases/sciencepapers/eso1633/eso1633a.pdf

Research paper 2 (Aravena, M. et al.): http://www.eso.org/public/archives/releases/sciencepapers/eso1633/eso1633b.pdf

Research paper 3 (Decarli, R. et al.): http://www.eso.org/public/archives/releases/sciencepapers/eso1633/eso1633c.pdf

Research paper 4 (Decarli, R. et al.): http://www.eso.org/public/archives/releases/sciencepapers/eso1633/eso1633d.pdf

Research paper 5 (Aravena, M. et al.): http://www.eso.org/public/archives/releases/sciencepapers/eso1633/eso1633e.pdf

Research paper 6 (Walter, F. et al.): http://www.eso.org/public/archives/releases/sciencepapers/eso1633/eso1633f.pdf

Research paper 7 (Bouwens, R. et al.): http://www.eso.org/public/archives/releases/sciencepapers/eso1633/eso1633g.pdf

Research paper 8 (Carilli, C. L. et al.): http://www.eso.org/public/archives/releases/sciencepapers/eso1633/eso1633h.pdf

NRAO press release: https://public.nrao.edu/2016-alma-hudf

Max Planck Institute for Astronomy press release (English | German):
http://www.mpia.de/news/science/2016-11-alma-udf
http://www.mpia.de/aktuelles/wissenschaft/2016-11-alma-udf

Photos of ALMA: http://www.eso.org/public/images/archive/search/?adv=&subject_name=Atacama%20Large%20Millimeter/submillimeter%20Array

NASA/ESA Hubble Space Telescope: http://www.spacetelescope.org/

Images, Text, Credits: ALMA (ESO/NAOJ/NRAO)/NASA/ESA/J. Dunlop et al. and S. Beckwith (STScI) and the HUDF Team/NASA, ESA, G. Illingworth, D. Magee, and P. Oesch (University of California, Santa Cruz), R. Bouwens (Leiden University), and the HUDF09 Team/B. Saxton (NRAO/AUI/NSF); ALMA (ESO/NAOJ/NRAO); NASA/ESA Hubble/Video: NASA/ESA/ESO/J. Dunlop.

Best regards, Orbiter.ch

Summer Fireworks on Rosetta Comet












ESA - Rosetta Mission patch.

23 September 2016

Brief but powerful outbursts seen from Comet 67P/Churyumov–Gerasimenko during its most active period last year have been traced back to their origins on the surface.

In the three months centred around the comet’s closest approach to the Sun, on 13 August 2015, Rosetta’s cameras captured 34 outbursts.

Comet outbursts

These violent events were over and above regular jets and flows of material seen streaming from the comet’s nucleus. The latter switch on and off with clockwork repeatability from one comet rotation to the next, synchronised with the rise and fall of the Sun’s illumination.

By contrast, outbursts are much brighter than the usual jets – sudden, brief, high-speed releases of dust. They are typically seen only in a single image, indicating that they have a lifetime shorter than interval between images – typically 5–30 minutes.

A typical outburst is thought to release 60–260 tonnes of material in those few minutes.

On average, the outbursts around the closest approach to the Sun occurred once every 30 hours – about 2.4 comet rotations. Based on the appearance of the dust flow, they can be divided into three categories.

One type is associated with a long, narrow jet extending far from the nucleus, while the second involves a broad, wide base that expands more laterally. The third category is a complex hybrid of the other two.

Guide to comet activity (Click on the image for enlarge)

“As any given outburst is short-lived and only captured in one image, we can’t tell whether it was imaged shortly after the outburst started, or later in the process,” notes Jean-Baptiste Vincent, lead author of the paper published today in Monthly Notices of the Astronomical Society .

“As a result, we can’t tell if these three types of plume ‘shapes’ correspond to different mechanisms, or just different stages of a single process.

"But if just one process is involved, then the logical evolutionary sequence is that an initially long narrow jet with dust is ejected at high speed, most likely from a confined space.

"Then, as the local surface around the exit point is modified, a larger fraction of fresh material is exposed, broadening the plume ‘base’.

"Finally, when the source region has been altered so much as not to be able to support the narrow jet anymore, only a broad plume survives.”

Summer outburst sources (Click on the image for enlarge)

The other key question is how these outbursts are triggered.

The team found that just over half of the events occurred in regions corresponding to early morning, as the Sun began warming up the surface after many hours in darkness.

The rapid change in local temperature is thought to trigger thermal stresses in the surface that might lead to a sudden fracturing and exposure of volatile material. This material rapidly heats up and vaporises explosively.

The other events occurred after local noon – after illumination of a few hours.

These outbursts are attributed to a different cause, where the cumulative heat makes its down to pockets of ‘volatiles’ buried beneath the surface, again causing sudden heating and an explosion.

“The fact that we have clear morning and noon outbursts points to at least two different ways of triggering an outburst,” says Jean-Baptiste.

But it is also possible that yet another cause is involved in some outbursts.

“We found that most of the outbursts seem to originate from regional boundaries on the comet, places where there are changes in texture or topography in the local terrain, such as steep cliffs, pits or alcoves,” adds Jean-Baptiste.

Cliff collapse and comet activity

 Indeed, the fact that boulders or other debris are also seen around the regions identified as the sources of the outbursts confirms that these areas are particularly susceptible to erosion.

While slowly eroding cliff faces are thought to be responsible for some of the regular, long-lived jet features, a weakened cliff edge may also suddenly collapse at any time, night or day. This collapse would reveal substantial amounts of fresh material and could lead to an outburst even when the region is not exposed to sunlight.

At least one of the events studied took place in local darkness and may be linked to cliff collapse.

“Studying the comet over a long period of time has given us the chance to look into the difference between ‘normal’ activity and short-lived outbursts, and how these outbursts may be triggered,” says Matt Taylor, ESA’s Rosetta project scientist.

“Studying how these phenomena vary as the comet progresses along its orbit around the Sun give us new insight into how comets evolve during their lifetimes.”

Notes for Editors:

“Summer fireworks on Comet 67P ,” by J.-B. Vincent et al is accepted for publication in Monthly Notices of the Royal Astronomical Society: http://mnras.oxfordjournals.org/content/early/2016/09/21/mnras.stw2409.abstract?keytype=ref&ijkey=UIAL2LRvx5X72Qi

This article also uses information from “ Are fractured cliffs the source of cometary dust jets? Insights from OSIRIS/Rosetta at 67P ,” by J.-B. Vincent et al, published in Astronomy & Astrophysics 2015: http://www.aanda.org/articles/aa/abs/2016/03/aa27159-15/aa27159-15.html

Of the 34 outbursts, 26 were detected with the OSIRIS narrow-angle camera, three with the OSIRIS wide-angle camera, and five with the Navigation Camera.

Related links:

Comet viewer tool: http://sci.esa.int/comet-viewer/

Where is Rosetta?: http://sci.esa.int/where_is_rosetta/

For more information about Rosetta mission, visit: http://www.esa.int/Our_Activities/Space_Science/Rosetta

Rosetta overview: http://www.esa.int/Our_Activities/Space_Science/Rosetta_overview

Rosetta in depth: http://sci.esa.int/rosetta

Images, Text, Credits: OSIRIS: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA; NavCam: ESA/Rosetta/NavCam – CC BY-SA IGO 3.0/Based on J.-B. Vincent et al (2015).

Best regards, Orbiter.ch

jeudi 22 septembre 2016

Scientists and Engineers Evaluate Orion Radiation Protection Plan











NASA - Orion Spacecraft patch.

Sept. 22, 2016

video
Orion Backstage: Evaluating Orion Radiation Protection Plan for Astronauts

When astronauts in Orion venture far beyond Earth into deep space, they will expand humanity’s frontier and push the boundaries of exploration. While the spacecraft is designed with systems and materials to keep the crew safe during their journey, leaving the protection of Earth’s magnetosphere exposes astronauts to a radiation environment in space that scientists and engineers at Johnson Space Center in Houston are working hard to protect against.

NASA works to protect astronauts from radiation and limit their exposure over time because chronic effects can, for example, include an increased risk of cancer. To limit risks in Orion, the team is developing a way to make use of the mass on board the spacecraft to protect the crew and recently conducted evaluations at Johnson to test procedures for getting astronauts into their protective environment as quickly as possible.

“Our goal is to limit the risk of radiation exposure over an astronaut’s lifetime,” said Kerry Lee, radiation system manager for Orion. “It’s not likely you’d see acute effects of radiation during a mission or immediately upon return, but we are concerned about long term effects. Our work aims to mitigate risks due to radiation without adding mass to the vehicle.”


Image above: Engineers conducted testing in a representative Orion to evaluate procedures that will be used to protect astronauts during radiation events in space. Image Credit: NASA.

Orion will be equipped with a radiation-sensing instrument integrated into the vehicle called the Hybrid Electronic Radiation Assessor, or HERA, to provide a warning if crew members need to take shelter in the case of a radiation event, such as a solar flare. To protect themselves, astronauts will position themselves in the central part of the crew module largely reserved for storing items they’ll need during flight and create a shelter using the stowage bags on board. The method protects the crew by increasing mass directly surrounding them, and therefore making a denser environment that solar particles would have to travel through, while not adding mass to the crew module itself.

If the warning were to sound, the crew would create the shelter within an hour and in some cases would need to stay inside for as long as 24 hours. Using the stowage bags on board that will contain supplies, food and water, in combination with Orion’s seats will allow astronauts making the shelter to strategically place denser bags in areas of the vehicle with less radiation-protecting materials. For example, the bottom of Orion where the heat shield and service module are attached will provide more shielding than other areas, and stowage bags can be used for parts of the spacecraft’s interior with less shielding.


Image above: The crew will use stowage bags on board Orion during missions to deep space to create a dense shelter. Image Credit: NASA.

“A big part of the evaluation was assessing how coordinated the crew could be given the procedures we’re establishing for them,” said Jessica Vos, deputy health and medical technical authority for Orion. “The real meat of it was evaluating how effective we could be with our procedures given that the crew may not have a lot of warning.”

The evaluation also included assessing ways to tie down the stowage bags, where to locate tubing to provide air to the shelter and the best ways to get in and out of it. After evaluating test results, NASA will further develop the procedures and conduct additional testing.

Orion capsule and ATV Service Module. Image Credits: NASA & ESA

Orion will launch atop NASA’s powerful Space Launch System rocket to deep space destinations on NASA’s journey to Mars. It’s first mission, Exploration Mission-1, will send an uncrewed Orion about 40,000 miles beyond the moon in late 2018.

Related links:

Exploration Mission-1: http://orbiterchspacenews.blogspot.ch/2014/12/liftoff-orion-begins-new-era-in-space.html

Johnson Space Center: https://www.nasa.gov/centers/johnson/home/index.html

Journey to Mars: https://www.nasa.gov/topics/journeytomars/index.html

Orion Spacecraft: https://www.nasa.gov/exploration/systems/orion/index.html

Images (mentioned), Video, Text, Credits: NASA/JSC/Mark Garcia.

Greetings, Orbiter.ch