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Sonntag, 28. April 2013 - 17:30 Uhr

Planet Erde - Überflug von Saunders Island Wolstenholme Fjord

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IceBridge Survey Flight Over Saunders Island and Wolstenholme Fjord

This image of Saunders Island and Wolstenholme Fjord with Kap Atholl in the background was taken during an Operation IceBridge survey flight in April, 2013. Sea ice coverage in the fjord ranges from thicker, white ice seen in the background, to thinner grease ice and leads showing open ocean water in the foreground.

In March 2013, NASA's Operation IceBridge scientists began another season of research activity over Arctic ice sheets and sea ice. IceBridge, a six-year NASA mission, is the largest airborne survey of Earth's polar ice ever flown. It will yield an unprecedented three-dimensional view of Arctic and Antarctic ice sheets, ice shelves and sea ice. These flights will provide a yearly, multi-instrument look at the behavior of the rapidly changing features of the Greenland and Antarctic ice.

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Scientists and engineers with NASA's Operation IceBridge continued their work to gather vital information on Arctic ice with flights into areas not extensively covered in previous campaigns. With one sea ice flight and one ice sheet survey in the books, researchers are heading toward the end of the campaign and the last of the mission's high priority flights.

Greenland's Thule Air Base puts the NASA P-3B in range of large portions of Arctic sea ice, some of which IceBridge flew over on Apr. 22. This mission was a repeat of one from 2012 and aimed at sampling a large region of the Canada Basin between IceBridge survey lines flown out of and on the way back from Fairbanks, Alaska.

This mission also involved coordinating with a satellite that provides data for the Global Fiducials Library (GFL) at the U.S. Geological Survey. GFL is a collaborative effort between various academic institutions and U.S. government agencies that maintains a long-term record of high-resolution imagery of Arctic sea ice. On Apr. 22 and 23 a satellite was to capture images at 10 locations multiple times per day in the area of IceBridge's flight line, and IceBridge's goal was to survey that region on one of those two days. The objective of this collaboration was to see how feasible coordinating observations from multiple sources is and to find out what benefits there are in combining such measurements of Arctic sea ice cover.

Completing the Apr. 22 survey meant that IceBridge planners had two high-priority sea ice mission plans left, a survey farther south in the Canada Basin and a flight over the North Pole, which had been attempted and canceled earlier in the campaign. As is sometimes the case, weather had other plans. Unfavorable weather over the Canada Basin and a lack of suitable CryoSat-2 overpasses in the Arctic Ocean led mission planners to pass on the two sea ice flights and instead choose a flight over the north-central part of the ice sheet on Apr. 23.

The Apr. 23 flight was a new mission designed to fill in a gap in surface elevation and ice thickness coverage in north Greenland. On this survey, the P-3B flew two lines across the Greenland ice sheet, gathering data along the way. Once at the east coast researchers surveyed the centerlines of the Qeqertarsuap, Drachmann and Wordie glaciers. After returning to the west side of Greenland, the P-3B repeated parts of a coast-parallel survey line flown from 2010 to 2012 before returning to Thule Air Base.

Quelle: NASA


Tags: Saunders Island Wolstenholme Fjord 

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Samstag, 27. April 2013 - 18:47 Uhr

Raumfahrt - Cassini beobachtet Meteor Kollisionen mit Saturns Ringe

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Five images of Saturn's rings, taken by NASA's Cassini spacecraft between 2009 and 2012, show clouds of material ejected from impacts of small objects into the rings. Image credit: NASA/JPL-Caltech/Space Science Institute/Cornell

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PASADENA, Calif. -- NASA's Cassini spacecraft has provided the first direct evidence of small meteoroids breaking into streams of rubble and crashing into Saturn's rings.

These observations make Saturn's rings the only location besides Earth, the moon and Jupiter where scientists and amateur astronomers have been able to observe impacts as they occur. Studying the impact rate of meteoroids from outside the Saturnian system helps scientists understand how different planet systems in our solar system formed.

The solar system is full of small, speeding objects. These objects frequently pummel planetary bodies. The meteoroids at Saturn are estimated to range from about one-half inch to several yards (1 centimeter to several meters) in size. It took scientists years to distinguish tracks left by nine meteoroids in 2005, 2009 and 2012.

Details of the observations appear in a paper in the Thursday, April 25 edition of Science.

Results from Cassini have already shown Saturn's rings act as very effective detectors of many kinds of surrounding phenomena, including the interior structure of the planet and the orbits of its moons. For example, a subtle but extensive corrugation that ripples 12,000 miles (19,000 kilometers) across the innermost rings tells of a very large meteoroid impact in 1983.

"These new results imply the current-day impact rates for small particles at Saturn are about the same as those at Earth -- two very different neighborhoods in our solar system -- and this is exciting to see," said Linda Spilker, Cassini project scientist at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "It took Saturn's rings acting like a giant meteoroid detector -- 100 times the surface area of the Earth -- and Cassini's long-term tour of the Saturn system to address this question."

The Saturnian equinox in summer 2009 was an especially good time to see the debris left by meteoroid impacts. The very shallow sun angle on the rings caused the clouds of debris to look bright against the darkened rings in pictures from Cassini's imaging science subsystem.

"We knew these little impacts were constantly occurring, but we didn't know how big or how frequent they might be, and we didn't necessarily expect them to take the form of spectacular shearing clouds," said Matt Tiscareno, lead author of the paper and a Cassini participating scientist at Cornell University in Ithaca, N.Y. "The sunlight shining edge-on to the rings at the Saturnian equinox acted like an anti-cloaking device, so these usually invisible features became plain to see."

Tiscareno and his colleagues now think meteoroids of this size probably break up on a first encounter with the rings, creating smaller, slower pieces that then enter into orbit around Saturn. The impact into the rings of these secondary meteoroid bits kicks up the clouds. The tiny particles forming these clouds have a range of orbital speeds around Saturn. The clouds they form soon are pulled into diagonal, extended bright streaks.

"Saturn's rings are unusually bright and clean, leading some to suggest that the rings are actually much younger than Saturn," said Jeff Cuzzi, a co-author of the paper and a Cassini interdisciplinary scientist specializing in planetary rings and dust at NASA's Ames Research Center in Moffett Field, Calif. "To assess this dramatic claim, we must know more about the rate at which outside material is bombarding the rings. This latest analysis helps fill in that story with detection of impactors of a size that we weren't previously able to detect directly."

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. NASA's Jet Propulsion Laboratory, Pasadena, Calif., a division of the California Institute of Technology, Pasadena, manages the Cassini-Huygens mission for NASA's Science Mission Directorate in Washington. JPL designed, developed and assembled the Cassini orbiter and its two onboard cameras. The imaging team consists of scientists from the United States, England, France and Germany. The imaging operations center is based at the Space Science Institute in Boulder, Colo.

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Quelle: NASA


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Samstag, 27. April 2013 - 10:20 Uhr

Raumfahrt - Action bei ISS durch Progress 49 und Progress 51

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10.04.2013

WASHINGTON -- NASA Television will broadcast an unpiloted Russian cargo ship's departure from the International Space Station on April 15 and the launch and docking of another April 24 and 26. 
The ISS Progress 49 resupply ship, which arrived at the station in late October, will depart the rear port of the station's Zvezda service module at 8:01 a.m. EDT, April 15. NASA TV coverage of the undocking will begin at 7:45 a.m. Progress 49 will reenter Earth's atmosphere several days later and burn up over the Pacific Ocean. 
Progress 49's departure will clear the way for the arrival of the ISS Progress 51 cargo craft. Loaded with more than 3 tons of food, fuel, supplies and experiment hardware for the six crew members aboard the orbital laboratory, Progress 51 is scheduled to launch from the Baikonur Cosmodrome in Kazakhstan at 6:12 a.m. (4:12 p.m. Kazakh time) Wednesday, April 24. NASA TV coverage of the launch will begin at 6 a.m. 
Progress 51 will take two days to catch up and rendezvous with the space station. It is scheduled to dock at 8:27 a.m. Friday, April 26. NASA TV coverage will begin at 7:45 a.m. 
Quelle: NASA
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Update: 24.04.2013
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Erfolgreicher Start von Russian Progress M-19M (51)
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Frams: NASA-TV
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Update: 26.04.2013
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The ship is scheduled to dock with the ISS at about 16:26 Moscow time on Friday, April 26. The ship is flying to the ISS by the standard two-day pattern, not a new six-hour one. A few previous supply ships, including Progress M-16M launched in August 2012, Progress M -17M launched in October 2012 and Progress M-18M launched in February 2013 reached the ISS within six hours.
Quelle: Roscosmos
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Update: 27.04.2013
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An unmanned cargo-carrying spacecraft successfully docked with the International Space Station Friday morning (April 26), despite a glitch in the capsule's navigation system.

After its launch from the Baikonur Cosmodrome in Kazakhstan on Wednesday, the Russian Progress 51 spacecraft failed to deploy one of the two antennas used for the Kurs automated docking system. Russian ground controllers were able to reposition the antenna, allowing the automated docking to go ahead as planned.

Russian cosmonauts Pavel Vinogradov and Roman Romanenko kept an eye on Progress as it moved into position.

Quelle: Roscosmos

 
 

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Samstag, 27. April 2013 - 10:10 Uhr

Astronomie - Einstein behält Recht Ein rekordverdächtiger Pulsar betritt Neuland bei der Überprüfung der Allgemeine Relativitätstheorie

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Astronomen haben mit dem Very Large Telescope und Radioteleskopen auf der ganzen Welt ein bizarres Sternenpaar entdeckt und näher untersucht. Es besteht aus dem bislang massereichsten Neutronenstern, dessen Entdeckung als bestätigt gilt, und einem ihn umkreisenden Weißen Zwerg. Dieses kuriose neuentdeckte Doppelsternsystem ermöglicht es, die Theorie Einsteins zur Gravitation - die Allgemeine Relativitätstheorie - auf eine Art und Weise zu überprüfen, die bisher nicht möglich war. Die neuen Beobachtungen stimmen genau mit den Vorhersagen der Allgemeinen Relativitätstheorie überein und sind nicht konsistent mit einigen alternativen Theorien. Die Ergebnisse werden am 26. April 2013 in der Fachzeitschrift Science veröffentlicht.

Ein internationales Wissenschaftlerteam hat ein exotisches Doppeltsternsystem entdeckt: Es besteht aus einem winzigen, jedoch ungewöhnlich schweren Neutronenstern, der sich 25 mal pro Sekunde um sich selber dreht und alle zweieinhalb Stunden von einem Weißen Zwerg umkreist wird. Der Neutronenstern ist ein Pulsar, der Radiowellen abstrahlt, die dann auf der Erde mit Hilfe von Radioteleskopen empfangen werden können. Obwohl dieses ungewöhnliche Paar an sich schon sehr interessant ist, stellt es zusätzlich ein einzigartiges Testobjekt zur Überprüfung der Grenzen physikalischer Theorien dar.

Der Pulsar trägt den Namen PSR J0348+0432 und ist das Überbleibsel einer Supernovaexplosion. Bei einen Durchmesser von nur 20 Kilometern hat er die doppelte Masse der Sonne, demnach sind in das Volumen eines Zuckerwürfels mehr als eine Milliarde Tonnen Materie gepresst. Die Schwerkraft auf seiner Oberfläche ist mehr als 300 Milliarden mal stärker als auf der Erde. Sein Begleitstern, ein Weißer Zwerg, ist nur geringfügig weniger exotisch. Er ist das Überbleibsel eines deutlich leichteren Sterns, der seine Atmosphäre verloren hat und nun langsam abkühlt.  

Ich habe das Doppelsystem mit dem Very Large Telescope der ESO beobachtet um nach Veränderungen in der Lichtkurve des Weißen Zwergs zu suchen, die durch seine Bewegung um den Pulsar verursacht werden", erklärt John Antoniadis, Doktorand am Max-Planck-Institut für Radioastronomie (MPIfR) in Bonn und Erstautor des Fachartikels. „Schon bei einer ersten Vor-Ort-Analyse konnte ich erkennen, dass der Pulsar ein ziemliches Schwergewicht ist. Er ist doppelt so schwer wie die Sonne, was ihn zum massereichsten Neutronenstern macht, den wir kennen. Das macht ihn zu einem exzellenten Testobjekt für Grundlagenphysik."

Einsteins Allgemeine Relativitätstheorie, die die Gravitation als Folge der Krümmung der Raumzeit durch das Vorhandensein von Masse und Energie erklärt, hat bislang allen Überprüfungen standgehalten, seit sie vor fast einem Jahrhundert veröffentlicht wurde. Dennoch bietet sie keine allumfassende Erklärung für sämtliche Vorgänge im Kosmos und wird letztlich Teil einer umfangreicheren Theorie werden müssen [1].

Physiker haben daher auch andere Theorien der Gravitation ausgearbeitet, deren Vorhersagen von jenen der Allgemeinen Relativitätstheorie abweichen. Für einige dieser Alternativen würden sich die Unterschiede nur in extrem starken Gravitationsfeldern zeigen, wie sie im Sonnensystem nicht zu finden sind. In Bezug auf die Gravitation ist PSR J0348+0432 ein wahrhaft außergewöhnliches Objekt, sogar im Vergleich zu anderen Pulsaren, die bislang in Hochpräzesionsexperimenten zur Überprüfung Einsteins Allgemeiner Relativitätstheorie verwendet wurden [2]. In solch starken Gravitationsfeldern können kleine Änderungen in der Masse zu großen Veränderungen in der Raumzeit um ein solches Objekt führen. Bis jetzt wussten Astronomen nicht, was bei der Anwesenheit eines solch massereichen Neutronensterns wie PSR J0348+0432 passieren würde. Dieses Objekt bietet daher die einzigartige Gelegenheit, die Experimente auf eine neue Ebene zu bringen. 

Das Astronomenteam hat die Beobachtungsdaten, die mit dem Very Large Telescope von dem Weißen Zwerg aufgenommen wurden, mit den präzisen Messungen der Pulsationszeiten des Pulsars von Radioteleskopen kombiniert [3]. Enge Doppelsternsysteme strahlen Gravitationswellen ab und verlieren dadurch Energie. Dies führt dazu, dass sich die Umlaufzeit geringfügig ändert. Die Vorhersagen für die Änderung der Umlaufzeit sind sehr unterschiedlich für die Allgemeine Relativitätstheorie und andere konkurrierende Theorien. 

Unsere Beobachtungen im Radiobereich sind sehr präzise, so dass wir in der Lage waren eine Änderung in der Umlaufzeit von einem Achtmillionstel einer Sekunde pro Jahr zu messen. Und das ist genau das, was Einsteins Theorie vorhersagt", ergänzt Paulo Freire, ein Mitglied des Teams.

Die neuen Messungen stellen aber erst den Beginn einer detaillierten Studie dieses einzigartigen Objektes dar. In Zukunft werden Astronomen dieses Objekt nutzen, um die Allgemeine Relativitätstheorie mit immer höherer Genauigkeit zu überprüfen.

Endnoten

[1] Die Allgemeine Relativitätstheorie ist nicht mit der Quantenmechanik, der anderen großen Theorie der Physik des 20. Jahrhunderts, vereinbar.  Die Allgemeine Relativitätstheorie sagt zudem unter gewissen Umständen Singularitäten voraus. Dort streben einige Größen gegen unendlich, so wie es bei einem Schwarzen Loch der Fall ist. 

[2] Der erste Pulsar in einem Doppelsternsystem namens PSR B1913+16 wurde von Joseph Hooton Taylor, Jr. und Russell Hulse entdeckt, die dafür im Jahre 1993 den Physik-Nobelpreis erhielten. Sie hatten sorgfältig Änderungen der Eigenschaften dieses bemerkenswerten Objekts vermessen und konnten zeigen, dass diese genau mit den Energieverlusten durch Abstrahlung von Gravitationswellen übereinstimmen, wie sie von der Allgemeinen Relativitätstheorie vorhergesagt werden.

[3] Diese Arbeit basiert sowohl auf Daten der Radioteleskope Effelsberg, Arecibo und Greene Bank als auch auf Mesungen im sichtbaren Licht mit dem Very Large Telescope der ESO und dem William-Herschel-Teleskop.

Weitere Informationen

Die hier vorgestellten Ergebnisse von John Antoniadis et al. erscheinen am 26. April 2013 unter dem Titel “A Massive Pulsar in a Compact Relativistic Orbit"in der Fachzeitschrift Science.

Die beteiligten Wissenschaftler sind John Antoniadis (Max-Planck-Institut für Radioastronomie [MPIfR], Bonn), Paulo C. C. Freire (MPIfR), Norbert Wex (MPIfR), Thomas M. Tauris (Argelander-Institut für Astronomie, Bonn; MPIfR), Ryan S. Lynch (McGill University, Montreal, Kanada), Marten H. van Kerkwijk (University of Toronto, Kanada), Michael Kramer (MPIfR; Jodrell Bank Centre for Astrophysics, University of Manchester, Großbritanien), Cees Bassa (Jodrell Bank), Vik S. Dhillon (University of Sheffield, Großbritanien), Thomas Driebe (Deutsches Zentrum für Luft- und Raumfahrt, Bonn), Jason W. T. Hessels (ASTRON, niederländisches Institut für Radioastronomie, Dwingeloo; Universiteit van Amsterdam, Niederlande), Victoria M. Kaspi (McGill University), Vladislav I. Kondratiev (ASTRON; Lebedev Physical Institute, Moskau, Russland), Norbert Langer (Argelander-Institut für Astronomie), Thomas R. Marsh (University of Warwick, Großbritanien), Maura A. McLaughlin (West Virginia University), Timothy T. Pennucci (Department of Astronomy, University of Virginia) Scott M. Ransom (National Radio Astronomy Observatory, Charlottesville, USA), Ingrid H. Stairs (University of British Columbia, Vancouver, Kanada), Joeri van Leeuwen (ASTRON; Universiteit van Amsterdam), Joris P. W. Verbiest (MPIfR), David G. Whelan (Department of Astronomy, University of Virginia).  

Die Europäische Südsternwarte ESO (European Southern Observatory) ist die führende europäische Organisation für astronomische Forschung und das wissenschaftlich produktivste Observatorium der Welt. Getragen wird die Organisation durch ihre 15 Mitgliedsländer: Belgien, Brasilien, Dänemark, Deutschland, Finnland, Frankreich, Großbritannien, Italien, die Niederlande, Österreich, Portugal, Spanien, Schweden, die Schweiz und die Tschechische Republik. Die ESO ermöglicht astronomische Spitzenforschung, indem sie leistungsfähige bodengebundene Teleskope entwirft, konstruiert und betreibt. Auch bei der Förderung internationaler Zusammenarbeit auf dem Gebiet der Astronomie spielt die Organisation eine maßgebliche Rolle. Die ESO betreibt drei weltweit einzigartige Beobachtungsstandorte in Nordchile: La Silla, Paranal und Chajnantor. Auf dem Paranal betreibt die ESO mit dem Very Large Telescope (VLT) das weltweit leistungsfähigste Observatorium für Beobachtungen im Bereich des sichtbaren Lichts und zwei Teleskope für Himmelsdurchmusterungen: VISTA, das größte Durchmusterungsteleskop der Welt, arbeitet im Infraroten, während das VLT Survey Telescope (VST) für Himmelsdurchmusterungen ausschließlich im sichtbaren Licht konzipiert ist. Die ESO ist der europäische Partner bei den neuartigen Teleskopverbund ALMA, dem größten astronomischen Projekt überhaupt. Derzeit entwickelt die ESO ein Großteleskop mit 39 Metern Durchmesser für Beobachtungen im Bereich des sichtbaren und Infrarotlichts, das einmal das größte optische Teleskop der Welt werden wird: das European Extremely Large Telescope (E-ELT).

Quelle: ESO


Tags: Einstein Allgemeine Relativitätstheorie 

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Samstag, 27. April 2013 - 10:00 Uhr

Raumfahrt - Vier Satelliten erfolgreich mit Langer Marsch Rakete gestartet

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A Chinese Long March rocket blasted off from a remote desert launch base Friday with a high-resolution Earth imaging payload and Ecuador's first satellite. 

The Long March 2D rocket fired its hydrazine-fueled main engine at 0413 GMT (12:13 a.m. EDT) Friday and muscled off the launch pad at the Jiuquan space center in northwest China, powered by more than 650,000 pounds of thrust for the first two-and-a-half minutes of flight.

Liftoff occurred at 12:13 p.m. Beijing time.

The first stage engine gave way to the launcher's second stage to boost the mission's satellite passengers into orbit, where the payloads were released about 13 minutes after liftoff. The rocket was targeting a 422-mile-high sun-synchronous orbit optimized for imaging of Earth.

The flight's prime objective was deploying the Gaofen 1 Earth observation satellite, a civil remote sensing satellite launched to help Chinese officials respond to disasters, survey natural resources, plot urban growth and support national security applications, according to the state-run Xinhua news agency.

Gaofen 1 is the first of up to six similar remote sensing satellites planned for launch through 2015.

Data from the Gaofen satellites will be used by civilian agencies within the Chinese government, including the Ministry of Land and Resources, the Ministry of Agriculture, and the Ministry of Environmental Protection, Xinhua reported.

Gaofen means "high resolution" in Chinese.

Moments after the Gaofen 1 satellite separated from the rocket, a cache of smaller passengers was supposed to be ejected into orbit.

The secondary payloads included three CubeSats: Ecuador's first satellite, a spacecraft built by students in Turkey, and a technology demonstration platform from Argentina.

The Ecuadorian satellite - named NEE-01 Pegasus - is outfitted with a camera to stream live video from orbit in partnership with EarthCam, a company which broadcasts views from cameras worldwide on the Internet. The CubeSat will also transmit data and audio messages to the ground.

The cube-shaped satellite, measuring about 4 inches on each side, was developed by the Ecuadorian Civilian Space Agency, a non-profit, privately-funded organization set up in 2007.

Ecuadorian President Rafael Correa watched the launch from a control center in Guayaquil, the country's largest city, and congratulated the space agency on the launch.

Ronnie Nader, head of the space agency's space operations, tweeted: "Welcome to the sky, NEE-01 Pegasus. Welcome to space Ecuador."

The toaster-sized Turksat-3USAT spacecraft was built in a joint effort between Turksat, Turkey's communications satellite operator, and the Istanbul Technical University. The satellite carries a transponder to communicate with amateur radio hobbyists.

The CubeBug 1 satellite, sponsored by Argentina's Ministry of Science, Technology and Productive Innovation, will test custom-designed components in a small five-pound spacecraft, according to its builders.

Quelle: CHINANEWS


3316 Views

Samstag, 27. April 2013 - 09:43 Uhr

Astronomie - Supernova Staub fiel auf die Erde in antarktischen Meteoriten

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A section of the LaPaz Icefield 031117 meteorite, courtesy of NASA

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Two primitive meteorites collected in Antarctica appear to contain grains of silica—the stuff of quartz and sand—forged in an ancient supernova that predates the birth of the solar system. In fact, some researchers believe that it was just such a stellar explosion that triggered the formation of the solar system from a cloud of dust and gas billions of years ago. Whether or not the Antarctic meteorites contain a record of that fateful cataclysm, they do contain a supernova by-product that has never before been found on Earth.

Researchers have identified so-called presolar grains in several primitive meteorites, which more or less preserve the chemistry of the raw materials from which they formed at the dawn of the solar system. Some presolar grains spilled into the molecular cloud that would become the solar system from nearby supernovae, and some seem to have arrived on the winds expelled from aging stars.

Presolar grains stand out from the rest because of their unusual mix of chemical isotopes, “which cannot be explained by any known process acting in the solar system,” according to a study in the May 1 issue of the Astrophysical Journal Letters. “Their isotopic compositions can only be explained by nuclear reactions occurring in stellar environments.”

In the new study, Pierre Haenecour of Washington University in St. Louis and his colleagues analyzed two meteorites collected in Antarctica in 2003, each named for a geographic feature near the spot where the meteorite fell. (Antarctica makes an ideal hunting ground for dark-colored meteorites, which stand out clearly against the ice fields.) Grove Mountains 021710, found by a Chinese expedition, and LaPaz Icefield 031117, collected by U.S. searchers, each harbor presolar grains of silica (SiO2), the researchers found, as evidenced by the grains’ enrichment in a heavy isotope of oxygen known as oxygen 18. That signature points to the grains’ formation in a type II supernova—the explosion initiated by the collapse of a massive star’s core. Other researchers had spotted presolar silica in meteorites before, but those grains had different isotopic signatures that indicated that they came from an aging star called an asymptotic giant branch (AGB) star rather than from a supernova.

The conclusion by Haenecour and his colleagues that a supernova seeded our corner of space with silica grains, among other types of dust, lends laboratory support to a 2008 study, using the Spitzer Space Telescope, that spotted the possible spectral signature of silica in the remnant of a supernova that exploded in the Milky Way so recently that its light reached Earth just 300 or so years ago.

Amassing and analyzing these presolar grains is more than just an exercise in interstellar history—a shock wave from a nearby supernova or the gentler expulsions of an AGB star could have stirred a cloud of dust and gas to collapse into the system of sun and planets that we inhabit today. Collecting presolar detritus allows astrophysicists a glimpse into the violent inner workings of dying stars and may ultimately help pinpoint just how the solar system came to be.

About the Author: John Matson is an associate editor at Scientific American focusing on space, physics and mathematics.


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Samstag, 27. April 2013 - 09:30 Uhr

Raumfahrt - Erfolgreicher Sojus-2-1b Start mit neuen GLONASS-M-Satelliten

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Russia has successfully launched a satellite for the GLONASS navigation system from its northern Plesetsk Cosmodrome, the Defense Ministry reported on Friday.

The GLONASS-M satellite was launched by a Soyuz 2-1b rocket on Friday morning Moscow time, Space Forces spokesman Col. Alexei Zolotukhin said.

After reaching a designated orbit, the satellite will complete several weeks of commissioning and testing before entering regular service.

GLONASS is Russia’s answer to the US Global Positioning System, or GPS, and is designed for both military and civilian use.

The new spacecraft will join the GLONASS system of 23 operational satellites, two spacecraft undergoing in-orbit maintenance and three orbital spares as well as a new-generation GLONASS-K in test flight, according to the Defense Ministry.

The GLONASS satellite constellation, which was initially completed in 1995, suffered from insufficient financing that eventually caused gaps in coverage. But a renewed commitment to the system saw full global coverage restored by 2011.


2951 Views

Donnerstag, 25. April 2013 - 23:20 Uhr

Astronomie - "Spechtel-Alarm" - Partielle Mondfinsternis am 25.April 2013

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23.04.2013

Grafik: Thomas Baer, Arnold Barmettler. Partielle Mondfinsternis am 25. April 2013
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Finsternisfans müssen sich den Abend des 25. April 2013 in der Agenda anstreichen. Es ist keine spektakuläre Mondfinsternis, die ab 21:52 Uhr MESZ für kurze 32 Minuten partiell wird, aber dennoch interessant, da die Erdschattenvergrösserung, bedingt durch die Erdatmosphäre, zur Partialität beiträgt.Die Finsternis beginnt mit dem Eintritt des Mondes in den Halbschatten der Erde unbemerkt bereits um 20:02 Uhr MESZ - der Mond ist dann verbreitet noch unter Horizont und geht erst während der Halbschattenfinsternis auf. Erst mit der Zeit wird auch der flüchtige Betrachter feststellen, wie sich die Mondscheibe im oberen linken Sektor in Bezug auf den Horizont allmählich einzutrüben beginnt.
Quelle: astro-info
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Update: 24.04.2013
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Vollmond 24 Stunden vor partielle Mondfinsternis
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Update: 25.04.2013
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Live-Fotos von partielle Mondfinsternis folgen:.
 
 
 
 
 
 

3063 Views

Donnerstag, 25. April 2013 - 15:45 Uhr

Mars-Chroniken - Curiosity und Mars in 3D

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Mars Stereo View from 'John Klein' to Mount Sharp -- Raw
Left and right eyes of the Navigation Camera (Navcam) in NASA's Curiosity Mars rover took the dozens of images combined into this stereo scene of the rover and its surroundings. The component images were taken during the 166th, 168th and 169th Martian days, or sols, of Curiosity's work on Mars (Jan. 23, 25 and 26, 2013). The scene appears three dimensional when viewed through red-blue glasses with the red lens on the left. It spans 360 degrees, with Mount Sharp on the southern horizon. 
In the center foreground, the rover's arm holds the tool turret above a target called "Wernecke" on the "John Klein" patch of pale-veined mudstone. On Sol 169, Curiosity used its dust-removing brush and Mars Hand Lens Imager (MAHLI) on Wernecke. About two weeks later, Curiosity used its drill at a point about 1 foot (30 centimeters) to the right of Wernecke to collect the first drilled sample from the interior of a rock on Mars. This anaglyph was made with the images as captured by the Curiosity. Another version with the seams in the sky eliminated and cropped for optimal 3-D viewing can be seen at PIA16925.
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Mars Stereo View from 'John Klein' to Mount Sharp
Left and right eyes of the Navigation Camera (Navcam) in NASA's Curiosity Mars rover took the dozens of images combined into this stereo scene of the rover and its surroundings. The component images were taken during the 166th, 168th and 169th Martian days, or sols, of Curiosity's work on Mars (Jan. 23, 25 and 26, 2013). The scene appears three dimensional when viewed through red-blue glasses with the red lens on the left. It spans 360 degrees, with Mount Sharp on the southern horizon. 
In the center foreground, the rover's arm holds the tool turret above a target called "Wernecke" on the "John Klein" patch of pale-veined mudstone. On Sol 169, Curiosity used its dust-removing brush and Mars Hand Lens Imager (MAHLI) on Wernecke. About two weeks later, Curiosity used its drill at a point about 1 foot (30 centimeters) to the right of Wernecke to collect the first drilled sample from the interior of a rock on Mars. Seams have been eliminated from the sky portion of the mosaic to better simulate the vista a person standing on Mars would see. The mosaic has been cropped to reduce areas of extreme disparities between the views from the left and right eyes, which make viewing the 3-D anaglyph difficult. Another version of this anaglyph made from the images as captured by Curiosity is available at

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Donnerstag, 25. April 2013 - 10:00 Uhr

Planet Erde - Forscher haben einen Ausbruch von hochenergetischer Strahlung als "Dark Lightning" unmittelbar vor einem Blitz der als gewöhnlicher Blitz bekannt identifiziert.

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Scientists Detect 'Dark Lightning' Energy Burst Linked to Visible Lightning

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Researchers have identified a burst of high-energy radiation known as 'dark lightning" immediately preceding a flash of ordinary lightning. The new finding provides observational evidence that the two phenomena are connected, although the exact nature of the relationship between ordinary bright lightning and the dark variety is still unclear, the scientists said.

"Our results indicate that both these phenomena, dark and bright lightning, are intrinsic processes in the discharge of lightning," said Nikolai Østgaard, who is a space scientist at the University of Bergen in Norway and led the research team.
He and his collaborators describe their findings in an article recently accepted in Geophysical Research Letters -- a journal of the American Geophysical Union.
Dark lightning is a burst of gamma rays produced during thunderstorms by extremely fast moving electrons colliding with air molecules. Researchers refer to such a burst as a terrestrial gamma ray flash.
Dark lightning is the most energetic radiation produced naturally on Earth, but was unknown before 1991. While scientists now know that dark lightning naturally occurs in thunderstorms, they do not know how frequently these flashes take place or whether visible lightning always accompanies them.
In 2006, two independent satellites -- one equipped with an optical detector and the other carrying a gamma ray detector -- coincidentally flew within 300 kilometers (186 miles) of a Venezuelan storm as a powerful lightning bolt exploded within a thundercloud. Scientists were unaware then that a weak flash of dark lightning had preceded the bright lightning.
But last year, Østgaard and his colleagues discovered the previously unknown gamma ray burst while reprocessing the satellite data. "We developed a new, improved search algorithm…and identified more than twice as many terrestrial gamma flashes than originally reported," said Østgaard. He and his team detected the gamma ray flash and a discharge of radio waves immediately preceding the visible lightning.
"This observation was really lucky," Østgaard said. "It was fortuitous that two independent satellites -- which are traveling at 7 kilometers per second (4.3 miles per second) -- passed right above the same thunderstorm right as the pulse occurred." A radio receiver located 3,000 kilometers (1864 miles) away at Duke University in Durham, North Carolina detected the radio discharge.
The satellites' observations combined with radio-wave data provided the information that Østgaard and his team used to reconstruct this ethereal electrical event, which lasted 300 milliseconds.
Østgaard and his team suspect that the flash of dark lightning was triggered by the strong electric field that developed immediately before the visible lightning. This strong field created a cascade of electrons moving at close to the speed of light. When those relativistic electrons collided with air molecules, they generated gamma rays and lower energy electrons that were the main electric current carrier that produced the strong radio pulse before the visible lightning.
Dark and bright lightning may be intrinsic processes in the discharge of lightning, Østgaard said, but he stressed that more research needs to be done to elucidate the link.
The European Space Agency is planning on launching the Atmospheric Space Interactions Monitor (ASIM) within the next three years, which will be able to better detect both dark and visible lightning from space, said Østgaard, who is part of the team that is building the ASIM gamma-ray detector.
Dark lightning has remained a perplexing phenomenon due to scientific limitations and a dearth of measurements, Østgaard explained.
"Dark lightning might be a natural process of lightning that we were completely unaware of before 1991," he noted. "But it is right above our heads, which makes it very fascinating."
A grant from the European Research Council and the Research Council of Norway funded this research.
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Three images, left to right, of the same thundercloud depict a less-than-10-milliseconds-long sequence of events: (left) formation within the cloud of a small channel, or ‘leader,’ of electrical conductivity (yellow line) with weak emission of radio signals (ripples), to (middle) a burst of both dark lightning (pink) and radio waves (larger ripples), to (right) a discharge of bright lightning and more radio waves. (Credit: Studio Gohde)
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Quelle: American Geophysical Union

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