Blogarchiv

Sonntag, 8. September 2013 - 17:30 Uhr

Raumfahrt - CNES-Mikrosatellit Taranis soll Sprites (Höhen-Blitze) erforschen

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Taranis, eine besondere Mikrosatelliten Mission

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In Celtic ist Taranis der Gott des Himmels, Blitz und Donner. Ein treffend für einen Satelliten, die das Licht von Gewittern studieren wird jeder Winkel benannt. Seit mindestens zwei Jahren wird Taranis nehmen Zehntausende von Fotos mit Kameras und Photometer unter der Verantwortung des CNES und CEA, entwickelt und sollte daher den Katalog dieser seltsamen Phänomene (Trolle und Gnome, nicht formell identifiziert verbessern kann auch kommen größere Familie!) der Satellit wird auch mit X-ray-Detektoren und Gamma-, Elektronen-Detektoren und eine Reihe von elektromagnetischen Sensoren * ausgestattet werden. Sein Start in 2016, wird eifrig von Wissenschaftlern in aller Welt erwartet.

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Der Mikrosatellit Taranis wird im Jahre 2015 gestartet. Sein Ziel: die mysteriösen Lichterscheinungen, die explodieren und auf der Oberseite der Gewitterwolken sich ausbreiten zu untersuchen.

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Eine Gewitterwolke baut sich auf, spaltet ein Blitz den Himmel und beleuchtet die Wolke, die ihn geboren hat. Ein paar Kilometer über diesen Wolken, sind bunte und extrem kurze Blitze dabei ein wahres Feuerwerk zu zeigen. Diese sind "Vorübergehende Lichterscheinungen. "Während des Zweiten Weltkrieges, einige Piloten deuteten diese seltsame Blitze, manchmal bis 90 km hoch. Aber es war erst 1989, als Minnesota Forscher Beweise für ihre Existenz durch Fotografieren sorgten. Heute sind diese Phänomene besser bekannt: Es gibt blaue Strahlen, die aus dem Herzen der Wolken entstehen, orange Sprites und Elfen, große rote Halos dieser Form an der Oberseite der Atmosphäre.

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Vorübergehende Lichterscheinungen sind sehr energiereich. Sprites, zum Beispiel, sind 10-mal stärker als der Blitz. Trotz ihrer außerordentlichen Leistung, ist es schwierig, vom Boden aus zu studieren, weil sie sehr kurz sind - ein paar Millisekunden für den Sprites zu einigen hundert Millisekunden für blaue Strahlen - und werden oft von Wolken verdeckt. Der perfekte Ort, um zu sehen ist der Platz dort! Diese Blitze wurden von dem taiwanesischen FORMOSAT-2-Satelliten fotografiert, und von der Internationalen Raumstation ISS während des Französischen Mission * LSO. Aber bisher wurde keine Mission zur Untersuchung der Phänomene von Licht und Energie (Elektronen-, Gamma-und X-Flash), die sie begleiten gewidmet. Dies ist das Ziel des Satelliten Taranis, deren Projektmanagement durch CNES erfolgt.

6 Millisekunden Sprite. Credit: Steven Cummer, von der Duke University.

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Sprites aufgenommen von der ISS

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CNES-Mikrosatellit Taranis


The general objective of the TARANIS mission is to study magnetosphere-ionosphere-atmosphere coupling via transient processes. At the beginning of the project proposal, the transient processes considered were essentially sprites and their associated phenomena, hence the name TARANIS (Tool for the Analysis of RAdiation from lightNIng and Sprites). Today, all transient optical phenomena observed at an altitude of between 20 and 100 km (blue jets, red sprites, halos, elves, etc.) are covered by the term TLEs (Transient Luminous Events).

Furthermore, the study's reach has been extended to incorporate the transient precipitations and accelerations of energy electrons, regardless of whether they are directly linked to TLEs. The detection and the study of the gamma-ray and X-ray flashes probably associated to the TLEs, called TGFs (Terrestrial Gamma Flashes), are part of the mission objectives. In view of the satellite's orbit, emphasis is placed on medium and low latitudes, which, by definition, have been the focus of very few studies in the past.

The TARANIS mission has four main objectives:

Estimate the rate of occurrence of TLEs, TGFs and their associated emissions, highlight trigger factors
Characterise TGFs and runaway electrons that accelerate upwards in the atmosphere to the magnetosphere
Identify the effects of TLEs and TGFs on coupling between the ionosphere and the magnetosphere
Specify the role of precipitated electrons in coupling between the magnetosphere and the atmosphere.

Quelle: CNES


 

 
 

Tags: CNES-Mikrosatellit Taranis Sprites 

4800 Views

Samstag, 7. September 2013 - 17:24 Uhr

UFO-Forschung - Ist Komet ISON ein UFO? Flog bei LADEE-Start ein UFO vorbei?

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Is Comet ISON a UFO? Hubble's scientists do a reality check

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It's not at all certain that Comet ISON will turn out to be the "comet of the century," as hoped, but a couple of things are certain: It's not an alien spaceship, and it hasn't split up into three pieces.

Those were apparently questions on the minds of some folks last month, thanks to a flurry of videos and blog postings based on imagery from the Hubble Space Telescope's archives. The hoohah got hot enough to merit an official response, posted to the Space Telescope Science Institute's archive website and its ISON Blog.

It all started with a series of images captured by Hubble's Wide Field Camera 3 UVIS instrument on April 30. Various exposures were combined to produce a widely distributed color picture of Comet ISON against a background field of stars. When Internet sleuths took a close look at the archived image, it looked as if there were three separate objects hiding in the glare of ISON's coma.

Was ISON breaking up? Was the comet being escorted by two alien spacecraft? No. Just no.

Richard White, principal investigator for the Mikulski Archive for Space Telescopes, explained that the image was a composite, created by averaging the data from three separate camera exposures. The three objects are just different views of Comet ISON's nucleus.

"The comet itself does not have three pieces," White wrote. "They are an artifact from adding up the separate exposures. The comet does not look the same in each exposure because both the comet and the Hubble telescope are moving during the exposure. The comet is blurred, just as a picture taken out the window of a moving car will be blurred."

Check out the full explanation, and to get the latest prognostications on how bright Comet ISON will get in November, check in with the ISON Facebook page as well as the Comets Mailing List and the Twitter hashtag #ISON.

This is a close-up from a composite Hubble image that has been manipulated to show what appear to be three objects. They're actually three exposures of the same object: Comet ISON.

This is the image of Comet ISON that incorporates the three exposures from April 30 to produce a color image.

Quelle: NBC

 

UFO bei LADEE-Start?

Und auch hierbei gibt es Entwarnung, kein UFO sondern nur lösendes Raketenteil zeigt dieses Fram aus Start-Video


3104 Views

Freitag, 6. September 2013 - 12:19 Uhr

Astronomie - Über Stuttgart dem Weltraumschrott auf der Spur

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Wenn bei gutem Wetter über dem Stuttgarter Talkessel die Dämmerung hereinbricht, macht sich ein kleines Team von Forschern des Deutschen Zentrums für Luft- und Raumfahrt (DLR) auf den Weg zur Sternwarte auf der Uhlandshöhe. Mit einem optischen Teleskop beobachten sie von dort aus Weltraumobjekte und vermessen deren Flugbahn. Dazu gehören Schrottteile, aber auch aktive Satelliten oder die internationale Raumstation ISS, die alle im niedrigen Orbit von bis zu eintausend Kilometern Höhe um die Erde kreisen. Mit Hilfe dieser Messungen entwickeln und erproben die Wissenschaftler des DLR-Instituts für Technische Physik eine neue Methode, um die Flugbahn von Schrottteilen genauer zu erfassen und so langfristig beispielsweise Zusammenstöße mit Satelliten zu verhindern.
Bild für Bild zur genauen Flugbahn
Die Forscher nutzen für ihre Messungen die Phase nach der Abend- und vor der Morgendämmerung, wenn das Sonnenlicht die Objekte vor einem dunklen Hintergrund beleuchtet. Im Gegensatz zu den Astronomen der Sternwarte, die nach Fixsternen Ausschau halten, müssen sich die DLR-Wissenschaftler dabei sputen: Denn die von ihnen beobachteten Gegenstände haben eine Geschwindigkeit von rund acht Kilometern pro Sekunde und sind über dem Stuttgarter Talkessel nur wenige Minuten sichtbar. Um dieses Zeitfenster optimal zu nutzen, fährt das speziell für diesen Zweck aufgebaute Spiegelteleskop in eine vorbestimmte Position und wartet auf das Objekt. Die dazu notwendigen Koordinaten liefert ein bestehendes Verzeichnis von Weltraumobjekten, das grob angibt, wann welcher Gegenstand am Himmel über Stuttgart zu sehen ist.
Sobald beispielsweise der erwartete Satellit durch das Sichtfeld des Teleskops fliegt, macht die angeschlossene Kamera eine Aufnahme. Dann fährt das Teleskop in die nächste Position, wartet auf den Satelliten und macht ein weiteres Bild. Pro Überflug entstehen auf diese Weise zehn bis zwanzig Aufnahmen. Mit ihrer Hilfe können die Forscher nun sehr präzise die Flugbahn des verfolgten Objekts bestimmen. Dazu vergleicht ein spezielles Computerprogramm automatisch die Position des auf den Aufnahmen festgehaltenen Gegenstands relativ zu den ebenfalls abgebildeten Sternen, deren Koordinaten bekannt sind.
Technologische Möglichkeiten der Detektion von Weltraumschrott ausloten
"Bereits jetzt können wir die auf der Uhlandshöhe gewonnen Daten nutzen, um bestehende Bahndaten von Weltraumobjekten in ihrer Genauigkeit zu verbessern", erläutert Wolfgang Riede, der das DLR-Projekt auf der Sternwarte leitet. "Hauptsächlich geht es uns aber darum, einen neuen technologischen Ansatz zu demonstrieren und weiter zu entwickeln, um immer kleinere Objekte, vor allem Weltraumschrott, zu erfassen und deren Flugbahn möglichst exakt zu bestimmen. Die Arbeiten auf der Uhlandshöhe sind dazu der erste Schritt", so Riede weiter.
Seit dem Start der Arbeiten im Frühjahr 2013 hat das Stuttgarter Wissenschaftlerteam um Wolfgang Riede bereits rund einhundert Weltraumobjekte beobachtet und vermessen. Die Bedingungen auf der Uhlandshöhe waren dabei besser als erhofft. Zwar beeinträchtigt die nachts hell erleuchtete Innenstadt die Messungen, allerdings sind die Turbulenzbedingungen wesentlich besser. Das heißt, die Temperaturunterschiede über dem Talkessel lenken die Lichtstrahlen nicht so stark ab wie erwartet. Zusätzlich erhalten die DLR-Forscher fachliche Unterstützung von den Mitgliedern des Vereins der Schwäbischen Sternwarte, die das Observatorium auf der Uhlandshöhe ehrenamtlich betreiben und der Öffentlichkeit zugänglich machen. Die Sternwarte liegt außerdem nahe am Stuttgarter DLR-Standort im Stadtteil Vaihingen. So können die Wissenschaftler schnell und flexibel auf die Wetterbedingungen reagieren und das System in Betrieb nehmen.
Detektion mittels Laser als nächster Schritt
In rund zwei Jahren wollen Wolfgang Riede und sein Team dann zum nächsten Schritt übergehen: "Bisher nutzen wir das Sonnenlicht in der Dämmerungsphase, um die Weltraumobjekte auszumachen, was wir im Fachjargon passiv-optische Detektion nennen. Um noch exaktere Messungen vornehmen zu können, wollen wir unsere Zielobjekte mit Hilfe eines Lasers anstrahlen – natürlich nur im augensicheren und von den Behörden genehmigten Betrieb", erklärt Riede die weiteren Planungen. Das Thema Weltraummüll wird die DLR-Wissenschaft also nicht nur in Stuttgart noch länger beschäftigen: Vom Schrott im All geht eine steigende Gefahr aus. Denn selbst kleine Schrotteile können bei einem Zusammenstoß verheerende Schäden anrichten. Gleichzeitig wächst der Anteil kleiner Müllobjekte jährlich um mehrere Zehntausend. Technologien, um diese Objekte genau zu verfolgen, tragen so dazu bei, die Sicherheit der bemannten und unbemannten Raumfahrt zu erhöhen.
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Spur eines geostationären Satelliten vor dem Adlernebel (Langzeitbelichtung)
Quelle: DLR

Tags: Weltraumschrott 

3016 Views

Freitag, 6. September 2013 - 12:05 Uhr

Mars-Chroniken - Eine "strahlende" Schönheit - schwefelhaltige Sedimente im Krater Becquerel

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Ein Berg aus sulfathaltigen Sedimenten im Krater Becquerel

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Die aktuellen Bilder der vom DLR betriebenen hochauflösenden Stereokamera (HRSC) an Bord der ESA-Raumsonde Mars Express zeigen den Krater Becquerel, in dem sich ein fast 1000 Meter hoher Berg aus schwefelhaltigen Sedimentschichten befindet. Er zeugt von der bewegten Klimageschichte des Roten Planeten. Der Krater hat einen Durchmesser von 167 Kilometern, ist fast 4000 Meter tief und liegt in der Region Arabia Terra, die den Übergang vom Marshochland zum nördlichen Tiefland markiert.
In den letzten Jahren überflog Mars Express mehrmals diese Region. Vier dieser Überflugsaufnahmen der HRSC-Kamera wurden zu einem Bildmosaik zusammengesetzt, das Details von bis zu 17 Meter Größe erkennen lässt (Bild 2).
Benannt wurde der Krater nach dem französischen Physiker Antoine Henry Becquerel (1852-1908), der 1903 gemeinsam mit dem Ehepaar Marie und Pierre Curie für die Entdeckung der Radioaktivität mit dem Nobelpreis ausgezeichnet wurde und nach dem die physikalische Einheit für die radioaktive Aktivität benannt ist.
Auf dem Boden des Becquerel-Kraters befinden sich ungewöhnliche Sedimentstrukturen. Hierbei handelt es sich um geschichtete, helle Ablagerungen. Ganz ähnliche Ablagerungen gibt es auch im Krater Gale, in dem der NASA-Rover Curiosity am 6. August 2012 gelandet ist. Untersuchungen haben ergeben, dass die hellen Ablagerungen in dieser Region aus sulfathaltigen Gesteinen bestehen, die zum Teil wasserhaltig sind. Sulfate sind Salze der Schwefelsäure wie zum Beispiel Gips und entstehen auf der Erde bei der Verdunstung von Wasser. Im Krater Becquerel bilden diese Sedimentstapel einen fast 1000 Meter hohen Berg mit sanft geneigten Hängen und einer flachen Kuppe.
Auf der Suche nach dem Prozess, der die Sulfatablagerungen erzeugt
Die in der Region Arabia Terra relativ häufig anzutreffenden Sulfate lassen vermuten, dass ein großräumig agierender Prozess für ihre Entstehung verantwortlich ist. Es wird angenommen, dass sich diese Sedimente durch ein Zusammenspiel von austretendem Grundwasser in tief liegenden Gebieten (zum Beispiel in Einschlagskratern) und von Wind transportiertem Staub, möglicherweise in Kombination mit Ascheablagerungen, gebildet haben. Die Schichtenabfolge wird dabei auf jahreszeitliche Klimaschwankungen oder Änderungen des Klimas des Mars über größere Zeiträume durch die periodische Schwankung der Rotationsachse des Planeten zurückgeführt. Diese und andere Theorien werden in der Fachwelt intensiv debattiert, da für eine abschließende Antwort noch immer stichhaltige Argumente und Informationen vom Boden fehlen. Hier könnte auch der Rover Curiosity durch seine Untersuchung des Gale-Kraters wichtige Erkenntnisse liefern.
Der Wind erodiert die Sedimente im Laufe der Zeit
Auf den Bildern 1, 3 und 4 sieht man sehr deutlich die Schichtung innerhalb des hellen Sedimentbergs. Vermutlich war einst der gesamte Kraterboden von diesen Sedimenten bedeckt. Sulfathaltige Gesteine sind relativ anfällig für Verwitterung, so dass im Laufe von möglicherweise mehr als drei Milliarden Jahren ein Großteil der geschichteten Sedimentlagen durch die Kraft des Windes abgetragen wurde und ein abgeschliffener und abgerundeter Berg zurückblieb.
Die dunklen Flächen in den Bildern sind Oberflächen, die von einer Schicht aus basaltischen Sanden bedeckt sind. Diese Sande haben wahrscheinlich ihren Ursprung in vulkanischer Asche und bilden auf dem Mars vielerorts imposante Dünenfelder.
Bildverarbeitung und das HRSC-Experiment der Mars Express-Mission
Die Farbdraufsicht (Bild 2) wurde aus dem senkrecht auf die Marsoberfläche gerichteten Nadirkanal und den Farbkanälen der HRSC erstellt; die perspektivischen Schrägansichten (Bilder 1 und 3) wurden aus den Stereokanälen der HRSC berechnet. Das Anaglyphenbild (Bild 4), das bei Betrachtung mit einer Rot-Blau- oder Rot-Grün-Brille einen dreidimensionalen Eindruck der Landschaft vermittelt, wurde aus dem Nadirkanal und einem Stereokanal abgeleitet. Die in Regenbogenfarben kodierte Aufsicht (Bild 5) beruht auf einem digitalen Geländemodell der Region, von dem sich die Topographie der Landschaft ableiten lässt.
Die High Resolution Stereo Kamera wurde am Deutschen Zentrum für Luft- und Raumfahrt (DLR) entwickelt und in Kooperation mit industriellen Partnern gebaut (EADS Astrium, Lewicki Microelectronic GmbH und Jena-Optronik GmbH). Das Wissenschaftsteam unter Leitung des Principal Investigator (PI) Prof. Dr. Ralf Jaumann besteht aus 40 Co-Investigatoren, die aus 33 Institutionen und zehn Nationen stammen. Die Kamera wird vom DLR-Institut für Planetenforschung in Berlin-Adlershof betrieben. Die hier gezeigten Darstellungen wurden vom Institut für Geologische Wissenschaften der FU Berlin in Zusammenarbeit mit dem DLR-Institut für Planetenforschung in Berlin erstellt. 
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Senkrechte Draufsicht auf den Krater Becquerel
Windfahnen, Winderosion und Windablagerungen am Krater Becquerel
Anaglyphenbild des Kraters Becquerel
Topographische Bildkarte des Kraters Becquerel
Topographische Übersichtkarte von Arabia Terra
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Quelle: DLR, ESA

Tags: HRSC ESA-Raumsonde Mars Express Mars Krater Becquerel 

2952 Views

Freitag, 6. September 2013 - 09:34 Uhr

Astronomie - Auf der Spur Kälteste Braune Zwerge

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Coldest Brown Dwarfs Blur Lines between Stars and Planets
Cambridge, MA - Astronomers are constantly on the hunt for ever-colder star-like bodies, and two years ago a new class of objects was discovered by researchers using NASA's WISE space telescope. However, until now no one has known exactly how cool their surfaces really are - some evidence suggested they could be room temperature.
A new study shows that while these brown dwarfs, sometimes called failed stars, are indeed the coldest known free-floating celestial bodies, they are warmer than previously thought with temperatures about 250-350 degrees Fahrenheit.
To reach such low surface temperatures after cooling for billions of years means that these objects can only have about 5 to 20 times the mass of Jupiter. Unlike the Sun, these objects' only source of energy is from their gravitational contraction, which depends directly on their mass.
"If one of these objects was found orbiting a star, there is a good chance that it would be called a planet," says Trent Dupuy, a Hubble Fellow at the Harvard-Smithsonian Center for Astrophysics. But because they probably formed on their own and not in a proto-planetary disk, astronomers still call these objects brown dwarfs even if they are "planetary mass."
Characterizing these cold brown dwarfs is challenging because they emit most of their light at infrared wavelengths, and they are very faint due to their small size and low temperature.
To get accurate temperatures, astronomers need to know the distances to these objects. "We wanted to find out if they were colder, fainter, and nearby or if they were warmer, brighter, and more distant," explains Dupuy. Using NASA's Spitzer Space Telescope, the team determined that the brown dwarfs in question are located at distances 20 to 50 light-years away.
To determine the distances to these objects the team measured their parallax - the apparent change in position against background stars over time. As the Spitzer Space Telescope orbits the Sun its perspective changes and nearby objects appear to shift back and forth slightly. The same effect occurs if you hold up a finger in front of your face and close one eye and then the other. The position of your finger seems to shift when viewed against the distant background.
But even for these relatively nearby brown dwarfs, the parallax motion is small. "To be able to determine accurate distances, our measurements had to be the same precision as knowing the position of a firefly to within 1 inch from 200 miles away," explains Adam Kraus, professor at the University of Texas at Austin and the other author of the study.
The new data also present new puzzles to astronomers that study cool, planet-like atmospheres. Unlike warmer brown dwarfs and stars, the observable properties of these objects don't seem to correlate as strongly with temperature. This suggests increased roles for other factors, such as convective mixing, in driving the chemistry at the surface. They also find evidence for disappearing alkali elements that are likely getting incorporated into noxious clouds.
This study examined the initial sample of the coldest brown dwarfs discovered in the WISE survey data. Additional objects discovered in the past two years remain to be studied and will hopefully shed light on some of these outstanding issues.
A paper describing these results, authored by Dupuy and Kraus, appears in the Sept. 5, 2013 issue of Science Express online.
Headquartered in Cambridge, Mass., the Harvard-Smithsonian Center for Astrophysics (CfA) is a joint collaboration between the Smithsonian Astrophysical Observatory and the Harvard College Observatory. CfA scientists, organized into six research divisions, study the origin, evolution and ultimate fate of the universe.
Quelle: CfA
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2781 Views

Freitag, 6. September 2013 - 09:23 Uhr

Astronomie - Veränderung in der Heliosphäre durch ( Interstellaren ) Wind

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Cosmic voyager. Moving at some 23 kilometers per second, the solar system journeys through a cluster of thin gas clouds.
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As Earth and the other planets orbit the sun, the solar system itself travels through space. Its slow journey is taking it though a wispy expanse of gas called the Local Interstellar Cloud. Now, astronomers have discovered signs of potential turbulence in the cloud, indicated by a shift in direction of helium atoms that flow into the solar system. If the shift is real and continues for hundreds to thousands of years—a dicey extrapolation—it could be a harbinger of more dramatic changes in our solar system, notes study co-author David McComas of the Southwest Research Institute in San Antonio.
The finding, which McComas, Priscilla Frisch of the University of Chicago, and their colleagues report in the 6 September issue of Science, could foreshadow a change in the heliosphere, the vast bubble that shields the solar system from harmful cosmic rays. The heliosphere consists of charged particles blown out by the sun in the so-called solar wind. The size and shape of the heliosphere depends on the balance between the outward push of the solar wind and the inward pressure from gas in the Local Interstellar Cloud—the interstellar wind.
To detect the wind shift, researchers drew on measurements by 11 spacecraft and satellites that have recorded directly or indirectly the flow of helium atoms into the solar system. Many kinds of atoms infiltrate the heliosphere, but helium is a particularly good tracer for all of them because it is abundant and typically survives in its uncharged, atomic state all the way to Earth’s orbit, Frisch says.
So far, the apparent change in direction is small, about 4° to 9° over the past 40 years. But if it continues to shift direction and flips to the other side of the solar system, the heliosphere could be substantially distorted, notes astronomer William Reach of the Universities Space Research Association at NASA’s Ames Research Center in Moffett Field, California, who is not a member of the study. A smaller heliosphere would let in a greater a number of galactic cosmic rays, which are harmful to life on Earth.
Jeff Linsky of the University of Boulder, Colorado, who is not a member of the team, says that the new result, if confirmed, indicates that the heliosphere is emerging from the Local Interstellar Cloud into another region, with a different wind direction. Frisch disagrees and thinks that it's small-scale turbulence. Either way, the finding will provide "interesting new twists" to modeling of the solar wind's interactions with the cloud, comments Gary Zank of the University of Alabama, Huntsville. In addition, simply having the ability to record such changes in the solar system’s environment “is a really big deal,” McComas says.
Quelle: AAAS
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DURHAM, N.H. – Scientists, including University of New Hampshire astrophysicists involved in NASA’s Interstellar Boundary Explorer (IBEX) mission, have discovered that the particles streaming into the solar system from interstellar space have likely changed direction over the last 40 years.
The finding helps scientists map our location within the Milky Way galaxy and is crucial for understanding our place in the cosmos through the vast sweep of time—where we've come from, where we're currently located, and where we're going in our journey through the galaxy.
Additionally, scientists now gain deeper insight into the dynamic nature of the interstellar winds, which has major implications on the size, structure, and nature of our sun's heliosphere—the gigantic bubble that surrounds our solar system and helps shield us from dangerous incoming galactic radiation.
The results, based on data spanning four decades from 11 different spacecraft, including IBEX, were published in the journal Science September 5, 2013.
“It was very surprising to find that changes in the interstellar flow show up on such short time scales because interstellar clouds are astronomically large,” says Eberhard Möbius, UNH principal scientist for the IBEX mission and co-author on the Science paper. Adds Möbius, “However, this finding may teach us about the dynamics at the edges of these clouds—while clouds in the sky may drift along slowly, the edges often are quite fuzzy and dynamic. What we see could be the expression of such behavior.”
The data from the IBEX spacecraft show that neutral interstellar atoms are flowing into the solar system from a different direction than previously observed. Interstellar atoms flow past the Earth as the interstellar cloud surrounding the solar system passes the sun at 23 kilometers per second (50,000 miles per hour).
The latest IBEX measurements of the interstellar wind direction differed from those made by the Ulysses spacecraft in the 1990s. That difference led the IBEX team to compare the IBEX measurements to data gathered by 11 spacecraft between 1972 and 2011. The scientists wanted to gather as much evidence from as many sources as possible to determine whether the newer instruments simply provided more accurate results, or whether the wind direction itself changed over the years.
The various sets of observations relied on three different methods to measure the incoming interstellar wind. IBEX and Ulysses directly measured neutral helium atoms as they coursed through the inner solar system. IBEX's measurements are close to Earth, while Ulysses' measurements were taken between 1.3 and 2 times further from the sun.
In the final analysis, the direction of the wind obtained most recently by IBEX data differs from the direction obtained from the earlier measurements, which strongly suggests the wind itself has changed over time.
“Prior to this study, we were struggling to understand why our current measurements from IBEX differed from those of the past,” says co-author Nathan Schwadron, lead scientist for the IBEX Science Operations Center at UNH. “We are finally able to resolve why these fundamental measurements have been changing with time: we are moving through a changing interstellar medium.” 
The paper, “Decades-long Changes of the Interstellar Wind Through our Solar System,” includes IBEX team members from the University of Chicago, the Space Research Centre of the Polish Academy of Sciences, the Southwest Research Institute, the University of Texas in San Antonio, UNH, Dartmouth College, Central Arizona College, the University of California at Berkeley, and NASA’s Jet Propulsion Laboratory. 
IBEX is part of NASA’s series of low-cost, rapidly developed Small Explorer space missions. Southwest Research Institute in San Antonio leads the IBEX mission with teams of national and international partners. NASA’s Goddard Space Flight Center in Greenbelt, Md., manages the Explorers Program for NASA’s Science Mission Directorate in Washington.
The University of New Hampshire, founded in 1866, is a world-class public research university with the feel of a New England liberal arts college. A land, sea, and space-grant university, UNH is the state's flagship public institution, enrolling 12,200 undergraduate and 2,300 graduate students.
Quelle:  University of New Hampshire 

2981 Views

Donnerstag, 5. September 2013 - 15:30 Uhr

Raumfahrt - China startet Chang'e-3-Mond-Lander noch dieses Jahr

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29.08.2013

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China to launch lunar probe for landing mission

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China's Chang'e-3 lunar probe is scheduled to be launched at the end of this year for a moon landing mission, the State Administration of Science, Technology and Industry for National Defence announced on Wednesday.
"Chang'e-3 has officially entered its launch stage, following its research and manufacture period," said a statement released by the administration after Wednesday's meeting on the mission.
The mission will see a Chinese space probe land on a celestial body for the first time.
"The Chang'e-3 mission makes best use of a plethora of innovative technology. It is an extremely difficult mission, that carries great risk," said Ma Xingrui, head of China's space exploration body and chief commander of the lunar program.
The Chang'e-3 mission is the second phase of China's lunar program which includes orbiting, landing and returning to Earth, following the successes of the Chang'e-2 missions, which include plotting a high-resolution, full-coverage lunar map.
Chang'e-3's carrier rocket has successfully gone through its first test while the launch pad, control and ground application systems are ready for the mission.
Chang'e-3 will be launched from the Xichang Satellite Launch Center in southwest China.
Quelle: CHINA-NEWS
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Update: 5.09.2013
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Moon landing mission to use "secret weapons"
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Multiple "secret weapons" will be used on China's Chang'e-3 lunar probe, scheduled to launch at the end of this year for a moon landing mission, a key scientist said on Wednesday.
The mission will see a Chinese orbiter soft-land on a celestial body for the first time.
In addition to several cameras, Chang'e-3 will carry a near-ultraviolet astronomical telescope to observe stars, the galaxy and the universe from the moon, said Ouyang Ziyuan, a senior advisor to China's lunar program.
The telescope will observe the universe "farther and clearer" and will possibly bring new discoveries since there will be no disturbance from the aerosphere, ionosphere and magnetosphere on the moon, offering views free from interference from human activity, pollution and the magnetic field, said Ouyang.
He said at the First Beijing International Forum on Lunar and Deep-space Exploration held on Sept. 3-6 that the lander also carries an extreme ultraviolet camera, which will be used on the moon for the first time to monitor the transformation of the earth's plasmasphere and the planet's environmental change.
The Chang'e-3 moon rover will roam the moon's surface to patrol and explore the satellite.
Radar will be attached to the bottom of the rover to explore 100 to 200 meters beneath the moon's surface, which is unprecedented, said Ouyang.
Chang'e-3 has officially entered its launch stage, following research and manufacturing periods. It will be launched from the Xichang Satellite Launch Center in southwest China.
"The Chang'e-3 mission makes use of a plethora of innovative technologies. It is an extremely difficult mission that carries great risk," Ma Xingrui, head of China's space exploration body and chief commander of the lunar program, said last month.
The Chang'e-3 mission is the second phase of China's lunar program, which includes orbiting, landing and returning to Earth. It follows the successes of the Chang'e-2 missions, which include plotting a high-resolution, full-coverage lunar map.
Chang'e-3's carrier rocket has successfully gone through its first test, while the launch pad, control and ground application systems are ready for the mission.
China's deep-space exploration should go beyond the moon, and the country's scientists are actively preparing to implement plans to explore Mars, Venus and asteroids, said Ye Peijian, chief scientist of the Chang'e-3 program.
"Scientists are always prepared to conduct deep-space exploration and will do it after conditions permit," said Ye.
Ouyang said the scientific goals of solar system exploration include searching for extraterrestrial life; deepening understanding of Earth by exploring Mars, Venus and Jupiter; investigating the impact on Earth caused by solar activity and asteroid strikes; searching for new energies and resources; and preparing for mankind's future development.
Quelle: ChIna-News

Tags: Chinas Change-3 lunar probe 

2711 Views

Donnerstag, 5. September 2013 - 13:45 Uhr

UFO-Forschung - Himmelsphänomene

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Himmelsphänomen über Mannheim

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Fotos: ©-hjkc
Kondensstreifeneffekt am Westhimmel. Der sich im auflösen befindliche Kondensstreifen wurde durch die gerade untergegangene Sonne noch angestrahlt und ergab den Eindruck einer Meteoritenspur.
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Tags: Himmelsphänomene 

3252 Views

Mittwoch, 4. September 2013 - 09:04 Uhr

Astronomie - Blanco Teleskop in Chile startet Dunkle Energie Studie

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The Dark Energy Camera photographs galaxies from its perch on the Blanco telescope in Chile.

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High in the Chilean Andes, a massive project to probe the nature of dark energy has begun.
The Dark Energy Survey (DES) launched on 31 August at the 4-metre Blanco telescope at the Cerro Tololo Inter-American Observatory. It is one of several new pushes to explore the physical properties of dark energy, the mysterious force that is driving the universe to expand at an ever-faster rate.
Over the course of five years, the DES will map 300 million galaxies over one-eighth of the night sky. Its backbone is a 570-megapixel digital camera (pictured, right), designed to capture sharp images of galaxies and galaxy clusters. Such high resolution is essential because the DES measures weak gravitational lensing, the phenomenon in which light from distant cosmic objects is subtly distorted by the gravity of matter between them and Earth.
Weak lensing can be hard to spot. A competing Japanese-led survey, which uses the Hyper Suprime-Cam in Hawaii, relies on an even more detailed, 870-megapixel camera. That camera is mounted on a larger machine, the 8.2-metre Subaru telescope, and so it can image fainter galaxies than the DES can. The DES covers more area on the sky, however. Both surveys aim to measure enough weak lensing to map matter across the universe — a three-dimensional web that can reveal the fingerprints of dark energy through time.
Along with weak lensing, the DES has a couple of other tools in its arsenal. To beef up the matter map, it will count galaxy clusters at different distances from Earth. And it will probe for distant supernovae, whose otherwise reference light is dimmed as the universe expands. This technique was originally used to discover the accelerating cosmic expansion, and netted its scientists the 2011 Nobel Prize in physics.
The DES also hopes to muscle in on the territory of studying sound waves in the early universe. Its sky maps could reveal the effects of pressure waves frozen in place some 370,000 years after the big bang. Those results, in turn, could shed light on how the expansion rate of the universe changed over time, presumably driven by dark energy.
But other approaches have a head start in this arena. The ongoing BOSS survey and its planned successor, BigBOSS, focus on taking spectra of these acoustic waves, known as baryon acoustic oscillations. BOSS has already mapped these cosmic ripples and provided some of the tightest constraints on dark energy through time.
Quelle: nature-news
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Blanco-4M
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Why is the universe speeding up?
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In 1998, two teams of astronomers studying distant supernovae made the remarkable discovery that the expansion of the universe is speeding up. Yet, according to Einstein's theory of General Relativity, gravity should lead to a slowing of the expansion. To explain cosmic acceleration, cosmologists are faced with two possibilities: Either 75% of the universe exists in an exotic form, now called dark energy, that exhibits a gravitational force opposite to the attractive gravity of ordinary matter, or General Relativity must be replaced by a new theory of gravity on cosmic scales.
The Dark Energy Survey (DES) is designed to probe the origin of the accelerating universe and help uncover the nature of dark energy by measuring the 14-billion-year history of cosmic expansion with high precision. More than 120 scientists from 23 institutions in the United States, Spain, the United Kingdom, Brazil, and Germany are working on the project. This collaboration is building an extremely sensitive 570-Megapixel digital camera, DECam, and will mount it on the Blanco 4-meter telescope at Cerro Tololo Inter-American Observatory high in the Chilean Andes. Starting in Sept. 2012 and continuing for five years, DES will survey a large swath of the southern sky out to vast distances in order to provide new clues to this most fundamental of questions.
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Dark Energy Survey begins five-year mission to map southern sky in tremendous detail
Tonight, as the sun sinks below the horizon, the world’s most powerful digital camera will once again turn its gleaming eye skyward. Tonight, and for hundreds of nights over the next five years, a team of physicists and astronomers from around the globe will use this remarkable machine to try to answer some of the most fundamental questions about our universe.
On Aug. 31, the Dark Energy Survey (DES) officially began. Scientists on the survey team will systematically map one-eighth of the sky (5000 square degrees) in unprecedented detail. The start of the survey is the culmination of 10 years of planning, building and testing by scientists from 25 institutions in six countries.
The survey’s goal is to find out why the expansion of the universe is speeding up, instead of slowing down due to gravity, and to probe the mystery of dark energy, the force believed to be causing that acceleration.
“The Dark Energy Survey will explore some of the most important questions about our existence,” said James Siegrist, associate director for High Energy Physics at the U.S. Department of Energy’s Office of Science. “In five years’ time, we will be far closer to the answers, and far richer in our knowledge of the universe.”
“With the start of the survey, the work of more than 200 collaborators is coming to fruition,” said DES Director Josh Frieman of the U.S. Department of Energy’s Fermi National Accelerator Laboratory. “It’s an exciting time in cosmology, when we can use observations of the distant universe to tell us about the fundamental nature of matter, energy, space and time.”
The main tool of the survey is the Dark Energy Camera, a 570-megapixel digital camera built at Fermilab in Batavia, Ill., and mounted on the 4-meter Victor M. Blanco telescope at the National Science Foundation’s Cerro Tololo Inter-American Observatory in the Andes Mountains in Chile. The camera includes five precisely shaped lenses, the largest nearly a yard across, that together provide sharp images over its entire field of view.
The Dark Energy Camera is the most powerful survey instrument of its kind, able to see light from more than 100,000 galaxies up to 8 billion light-years away in each snapshot.
“The start of the Dark Energy Survey is an important milestone,” said CTIO Director Nicole van der Bliek. “The Dark Energy Camera, in conjunction with the Blanco telescope here at CTIO, will greatly increase our understanding of the forces that control the expansion of our universe.”
Over five years, the survey will obtain color images of 300 million galaxies and 100,000 galaxy clusters and will discover 4,000 new supernovae, many of which were formed when the universe was half its current size. The data collected will be processed at the National Center for Supercomputing Applications (NCSA) at the University of Illinois in Urbana and then delivered to collaboration scientists and the public.
“NCSA is pleased to be producing and distributing the refined data products that will enable this science,” said Don Petravick, principal investigator of the DES Data Management Operation.
The survey’s observations will not be able to see dark energy directly. However, by studying the expansion of the universe and the growth of large-scale structure over time, the survey will give scientists the most precise measurements to date of the properties of dark energy.
“We’re looking at this big galaxy map of the universe as a way of finding evidence for dark energy and characterizing its nature with cosmic epoch,” said Ofer Lahav of University College London and head of the DES Science Committee. “An even more challenging goal for DES is to tell if what causes the acceleration of the universe is indeed dark energy, or something entirely different."
The survey will use four methods to probe dark energy:
Counting galaxy clusters. While gravity pulls mass together to form galaxies, dark energy pulls it apart. The Dark Energy Camera will see light from 100,000 galaxy clusters billions of light-years away. Counting the number of galaxy clusters at different points in time sheds light on this cosmic competition between gravity and dark energy.
Measuring supernovae. A supernova is a star that explodes and becomes as bright as an entire galaxy of billions of stars. By measuring how bright they appear on Earth, we can tell how far away they are. Scientists can use this information to determine how fast the universe has been expanding since the star’s explosion. The survey will discover 4000 of these supernovae, which exploded billions of years ago in galaxies billions of light-years away.
Studying the bending of light. When light from distant galaxies encounters dark matter in space, it bends around the matter, causing those galaxies to appear distorted in telescope images. The survey will measure the shapes of 200 million galaxies, revealing the cosmic tug of war between gravity and dark energy in shaping the lumps of dark matter throughout space.
Using sound waves to create a large-scale map of expansion over time. When the universe was less than 400,000 years old, the interplay between matter and light set off a series of sound waves traveling at nearly two-thirds the speed of light. Those waves left an imprint on how galaxies are distributed throughout the universe. The survey will measure the positions in space of 300 million galaxies to find this imprint and use it to infer the history of cosmic expansion.
The Dark Energy Survey is supported by funding from the U.S. Department of Energy Office of Science; the National Science Foundation; funding agencies in the United Kingdom, Spain, Brazil, Germany and Switzerland; and the participating institutions.
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DECam
The Dark Energy Survey officially began on Aug. 31. Using the powerful Dark Energy Camera, scientists will map a portion of the sky in unprecedented detail, seeking answers to the mystery of dark energy.
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Composite DECam image (combining images from 4 filters) of the cluster of galaxies RXJ 2248-4431. Bright points with horizontal white lines are stars in our own galaxy.
Quelle: DES

Tags: The Dark Energy Survey DECam Blanco Telescope Chile 

3011 Views

Dienstag, 3. September 2013 - 23:46 Uhr

Raumfahrt - Cassini sieht die Explosive Kraft eines Saturn-Sturms

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This set of images from NASA's Cassini mission shows the turbulent power of a monster Saturn storm. The visible-light image in the back, obtained on Feb. 25, 2011, by Cassini's imaging camera, shows the turbulent clouds churning across the face of Saturn. The inset infrared image, obtained a day earlier, by Cassini's visual and infrared mapping spectrometer, shows the dredging up of water and ammonia ices from deep in Saturn's atmosphere.
Image Credit: NASA/JPL-Caltech/SSI/Univ. of Arizona/Univ. of Wisconsin
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A monster storm that erupted on Saturn in late 2010 – as large as any storm ever observed on the ringed planet -- has already impressed researchers with its intensity and long-lived turbulence. A new paper in the journal Icarus reveals another facet of the storm's explosive power: its ability to churn up water ice from great depths. This finding, derived from near-infrared measurements by NASA's Cassini spacecraft, is the first detection at Saturn of water ice. The water originates from deep in Saturn's atmosphere.
"The new finding from Cassini shows that Saturn can dredge up material from more than 100 miles [160 kilometers]," said Kevin Baines, a co-author of the paper who works at the University of Wisconsin-Madison and NASA's Jet Propulsion Laboratory, Pasadena, Calif. "It demonstrates in a very real sense that typically demure-looking Saturn can be just as explosive or even more so than typically stormy Jupiter." Water ice, which originates from deep in the atmosphere of gas giants, doesn't appear to be lofted as high at Jupiter.
Monster storms rip across the northern hemisphere of Saturn once every 30 years or so, or roughly once per Saturn year. The first hint of the most recent storm first appeared in data from Cassini's radio and plasma wave subsystem on Dec. 5, 2010. Soon after that, it could be seen in images from amateur astronomers and from Cassini's imaging science subsystem. The storm quickly grew to superstorm proportions, encircling the planet at about 30 degrees north latitude for an expanse of nearly 190,000 miles (300,000 kilometers).
The new paper focuses on data gathered by Cassini's visual and infrared mapping spectrometer on Feb. 24, 2011. The team, led by Lawrence Sromovsky, also of the University of Wisconsin, found that cloud particles at the top of the great storm are composed of a mix of three substances: water ice, ammonia ice, and an uncertain third constituent that is possibly ammonium hydrosulfide. The observations are consistent with clouds of different chemical compositions existing side-by-side, though it is more likely that the individual cloud particles are composed of two or all three of the materials.
The classic model of Saturn’s atmosphere portrays it as a layered sandwich of sorts, with a deck of water clouds at the bottom, ammonia hydrosulfide clouds in the middle, and ammonia clouds near the top. Those layers are just below an upper tropospheric haze of unknown composition that obscures almost everything.
But this storm appears to have disrupted those neat layers, lofting up water vapor from a lower layer that condensed and froze as it rose. The water ice crystals then appeared to become coated with more volatile materials like ammonium hydrosulfide and ammonia as the temperature decreased with their ascent, the authors said.
“We think this huge thunderstorm is driving these cloud particles upward, sort of like a volcano bringing up material from the depths and making it visible from outside the atmosphere,” said Sromovsky. “The upper haze is so optically thick that it is only in the stormy regions where the haze is penetrated by powerful updrafts that you can see evidence for the ammonia ice and the water ice. Those storm particles have an infrared color signature that is very different from the haze particles in the surrounding atmosphere.”
In understanding the dynamics of this Saturn storm, researchers realized that it worked like the much smaller convective storms on Earth, where air and water vapor are pushed high into the atmosphere, resulting in the towering, billowing clouds of a thunderstorm. The towering clouds in Saturn storms of this type, however, were 10 to 20 times taller and covered a much bigger area. They are also far more violent than an Earth storm, with models predicting vertical winds of more than about 300 mph (500 kilometers per hour) for these rare giant storms.
The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. JPL manages the mission for NASA's Science Mission Directorate, Washington. The California Institute of Technology in Pasadena manages JPL for NASA. The VIMS team is based at the University of Arizona in Tucson.
Quelle: NASA

Tags: Saturn-Storms Cassini 

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