Blogarchiv

Sonntag, 2. Dezember 2012 - 18:40 Uhr

Astronomie - Integral: Ein Jahrzehnt Erkundung des Gamma-Universums

 

 

-

This is an artist’s impression of ESA’s orbiting gamma-ray observatory, Integral. Credits: ESA

-

Europas großes Gammastrahlen-Observatorium Integral (International Gamma-Ray Astrophysics Laboratory) ist seit einem Jahrzehnt den energiereichsten Phänomenen des Universums auf der Spur. Im Visier stehen exotische Objekte, wie Schwarze Löcher, kollabierende Sterne oder die geheimnisvollen Gamma-Blitze, die stärksten bisher beobachteten Strahlungsausbrüche im Universum.

 
Integral ist eine internationale Gemeinschaftsmission, an der die ESA-Mitgliedsstaaten sowie die USA und Russland beteiligt sind. Als Flugkontrollzentrum fungiert das European Space Operations Centre ESOC in Darmstadt. 

Ambivalente Gammastrahlen
 
Gammastrahlen sind wesentlich energiereicher als Röntgenstrahlen und demzufolge für den Menschen höchst gefährlich. Glücklicherweise schützt uns die Erdatmosphäre vor dieser Strahlung. Erst die Raumfahrt ermöglichte der Astronomie dieses Fenster des elektromagnetischen Spektrums weit zu öffnen. Daher ist die Gamma-Astronomie eine recht junge, jedoch vielversprechende Wissenschaft.

Gammastrahlen treten immer bei außergewöhnlichen Ereignissen im Universum auf, beispielsweise bei gewaltigen Explosionen sowie Kollisionen von Sternen. Deren Beobachtung erlaubt uns wichtige Erkenntnisse über unbekannte Vorgänge im Weltraum.

Die ESA, die in der Gamma-Astronomie mit ihrem Satelliten COS-B (1975) Pionierarbeit leistete, hat mit Integral ihre führende Position auf diesem Gebiet gefestigt.

Einzigartiges Hightech-Observatorium
 
Das am 17. Oktober 2002 mit einer Proton-Trägerrakete vom Kosmodrom Baikonur (Kasachstan) gestartete 5 Meter hohe und 4 Tonnen schwere Observatorium erfasst die hochenergetische Gammastrahlung in den Tiefen des Alls. Auf seiner aktuell zwischen 3100 und 159 000 Kilometer hohen Umlaufbahn umkreist Integral einmal in drei Tagen die Erde. Das ermöglicht lange Beobachtungen außerhalb des irdischen Strahlungsgürtels.

Integral ist das leistungsfähigste und zugleich empfindlichste Gammastrahlen-Observatorium. An Bord befinden sich insgesamt vier wissenschaftliche Instrumente, von denen zwei für Observierungen im Gamma-Spektrum eingesetzt werden. Die anderen beiden Geräte dienen Beobachtungen im Röntgenspektralbereich sowie im sichtbaren Licht.

Alle Instrumente sind stets simultan auf einen Himmelssektor ausgerichtet. Dadurch lassen sich Gammastrahlungsquellen eindeutig identifizieren. Gleichzeitig können wertvolle Informationen über die im Blickfeld liegenden astronomischen Objekte erzielt werden. Die gewonnenen Daten und Bilder gehen an das Integral Science Data Centre (ISDC) ins schweizerische Versoix, werden dort aufbereitet und dann den Wissenschaftlern zur Verfügung gestellt.

Neue Erkenntnisse über das Gamma-Universum
 
Die Ergebnisse, die Integral bislang lieferte, sind außergewöhnlich. Von seltenen Sternen bis hin zu den „Fressgewohnheiten“ Schwarzer Löcher haben die scharfen Augen der vier Bordinstrumente alles registriert, was der Gammastrahlungsbereich aufzuweisen hat. Vor allem die im Zentrum unserer Milchstraße vorhandenen zahllosen hochenergetischen Röntgen- und Gammastrahlungsquellen wurden bis ins kleinste Detail dokumentiert. Hierzu gehören Röntgendoppelsterne mit zentralen Neutronensternen oder Schwarzen Löchern, Supernovae-Überreste und Pulsare. Viele dieser kosmischen Phänomene sind nur kurzzeitig sichtbar. Als Gammastrahlungsquellen können sie aber noch über einen sehr langen Zeitraum wahrgenommen werden.


Meilensteine der galaktischen Forschung
 
Integral entdeckte den am schnellsten rotierenden Neutronenstern der Galaxis: Der Gigant rotiert pro Sekunde 1122-mal um die eigene Achse. Erstmals gelang ein detaillierter Blick in das Schwarze Loch im Zentrum unserer Milchstraße. Das Observatorium bescherte den Astronomen zwei weitere Überraschungen: Integral fand energiearme kosmische Gammablitze sowie radioaktives Eisen.  

In der Explosionswolke der jungen Supernova 1987A entdeckte Integral radioaktives Titan-44 und zwar in einer Menge, die 100-mal größer ist als die Masse unserer Erde. Die Astronomen können mitverfolgen, wie Titan-44 allmählich zu Calcium zerfällt. Ein Element, das wir auch in unseren Knochen wiederfinden. Damit wird nachvollziehbar, wie wichtig Sternexplosionen sind. Sie haben jene schweren Elemente produziert, ohne die Leben auf der Erde nicht möglich wäre.

 

Atemberaubende Energiemengen
 
Die Antimateriewelt haben die Astronomen zwar noch nicht entdeckt, wohl aber das Gegenstück zum Elektron, das Positron. Beobachtungen von Integral zeigen nun, dass diese Partikel innerhalb unserer Galaxis ungleich verteilt sind.

Treffen Elektron und Positron aufeinander, löschen sich beide gegenseitig aus. Es kommt zur Annihilation, bei der Energie in Form von Gammastrahlung freigesetzt wird. Anhand der Integral-Daten ließ sich erstmals die bei der Annihilation von Elektronen und Positronen entstehende Gesamtenergiemenge berechnen. In jeder Sekunde werden im galaktischen Zentrum 15 Septillionen Teilchenpaare vernichtet. Das ist eine Zahl mit 42 Nullen. Die dabei freigesetzte Energie entspricht dem Sechstausendfachem der Leuchtstärke unserer Sonne.

Die bei der Annihilation freigesetzte Gammastrahlung zeigt eine starke Konzentration in Richtung des galaktischen Zentrums, jedoch ist noch völlig unklar welche Objekte die große Anzahl von Positronen erzeugen.

Erneute Missionsverlängerung möglich
 
Die ursprünglich auf fünf Jahre angesetzte Mission konnte aufgrund des sehr guten Zustandes des Observatoriums sowie der überaus erfolgreichen Forschungsergebnisse bereits dreimal verlängert werden, zuletzt bis zum 31. Dezember 2014. Die ESA hält sich eine Option für zusätzliche zwei Jahre offen, denn „wir hoffen auf weitere bahnbrechende Entdeckungen“, so Christoph Winkler, der überaus glückliche wissenschaftliche Leiter des Integral-Programms.
 

     

Kontrollraum der Integral-Mission im European Space Operations Centre (ESOC)der ESA in Darmstadt.

-

Quelle: ESA


3731 Views

Sonntag, 2. Dezember 2012 - 14:30 Uhr

Mars-Curiosity-Chroniken - Curiosity-News Sol 113-115

-

This image was taken by Mastcam: Right (MAST_RIGHT) onboard NASA's Mars rover Curiosity on Sol 113 (2012-11-30 08:51:56 UTC) .

.

This image was taken by Mastcam: Right (MAST_RIGHT) onboard NASA's Mars rover Curiosity on Sol 113 (2012-11-30 08:53:21 UTC) .

-

This image was taken by ChemCam: Remote Micro-Imager (CHEMCAM_RMI) onboard NASA's Mars rover Curiosity on Sol 113 (2012-11-30 06:41:22 UTC) .

.

This image was taken by Navcam: Right A (NAV_RIGHT_A) onboard NASA's Mars rover Curiosity on Sol 113 (2012-11-30 08:44:02 UTC) .

-

This image was taken by Navcam: Right A (NAV_RIGHT_A) onboard NASA's Mars rover Curiosity on Sol 113 (2012-11-30 08:46:39 UTC) .

-

This image was taken by Front Hazcam: Left A (FHAZ_LEFT_A) onboard NASA's Mars rover Curiosity on Sol 113 (2012-11-30 02:22:04 UTC) .

-

This image was taken by Mastcam: Left (MAST_LEFT) onboard NASA's Mars rover Curiosity on Sol 114 (2012-12-01 07:10:16 UTC) .

-

This image was taken by ChemCam: Remote Micro-Imager (CHEMCAM_RMI) onboard NASA's Mars rover Curiosity on Sol 114 (2012-12-01 05:14:33 UTC) .

.

This image was taken by Navcam: Right A (NAV_RIGHT_A) onboard NASA's Mars rover Curiosity on Sol 114 (2012-12-01 07:12:19 UTC) .

-

This image was taken by Navcam: Left A (NAV_LEFT_A) onboard NASA's Mars rover Curiosity on Sol 115 (2012-12-02 05:51:30 UTC) .

-

This image was taken by Front Hazcam: Left A (FHAZ_LEFT_A) onboard NASA's Mars rover Curiosity on Sol 115 (2012-12-02 03:41:14 UTC)

-

Fotos: NASA


3250 Views

Sonntag, 2. Dezember 2012 - 11:40 Uhr

Raumfahrt - Erfolgreicher Start von Sojus mit Pleiades 1B

 

-

Soyuz delivers from the Spaceport! Arianespace's medium-lift launcher orbits Pléiades 1B


December 1, 2012 – Soyuz Flight VS04

The maturity of Arianespace’s Soyuz launch system at French Guiana – and its confirmed role as a full-fledged member of the company’s launcher family – were demonstrated once again by tonight’s successful orbiting of the Pléiades 1B satellite from the Spaceport.

During a flight lasting 55 minutes, the Soyuz vehicle deployed its 970-kg. passenger into a targeted circular orbit of 695 km., inclined 98.2 deg., marking the medium-lift vehicle’s fourth mission from French Guiana since its introduction at this near-equatorial launch site in October 2011.

Pléiades 1B is a very-high-resolution dual-use satellite designed to provide optical imaging coverage for French and European defense ministries, institutions and civil users.  It joins the twin Pléiades 1A spacecraft that was launched in December 2011 on Arianespace’s second Soyuz mission from the Spaceport.  

Arianespace Chairman & CEO Jean-Yves Le Gall noted tonight’s launch was the ninth at French Guiana in 2012 for the company’s launcher family; following the lightweight Vega’s maiden flight in February; medium-lift  missions with Soyuz in October and today; along with heavy-lift Ariane 5 flights in March, May, July, August, September and November.

Le Gall thanked all involved in these successes, including the teams who work at the Spaceport for such an “impressive” year – during which a total of 23 primary and secondary payloads were placed into orbit from French Guiana.

The Pléiades 1A and 1B satellites launched by Arianespace create an optical observation system with great agility, a quick-response ground segment and daily revisit capability – offering a new generation of “real-world” satellite Earth imagery at a resolution of 70 cm.  Both Pléiades spacecraft are based on smaller, less expensive and more agile platforms than their predecessors – the highly-successful Spot satellite series that was lofted by Arianespace on its Ariane family launchers beginning in 1986.

France’s CNES space agency is prime contractor and architect for the Pléiades system, which is organized as part of a joint effort with Italy – whose Cosmo-Skymed satellite series delivers radar imaging coverage of the Earth. 

Pléiades program participants are the space agencies of France, Austria, Belgium, Spain and Sweden; along with the defense ministries of France, Italy and Spain.

The Pléiades 1A and 1B spacecraft were built by EADS’ Astrium division.

Arianespace will wrap-up its 2012 launch activity at the Spaceport with a year-ending Ariane 5 mission on December 19 to orbit the Mexsat Bicentenario and Skynet 5D satellites.

-

-

Frams von Start

-

Quelle: arianespace/CNES


3333 Views

Samstag, 1. Dezember 2012 - 23:30 Uhr

Raumfahrt - Sojus mit Pleiades 1B startklar am Sonntag

-

Arianespace's fourth Soyuz for launch from the Spaceport in French Guiana is now undergoing final checkout for a November 30 evening liftoff following installation of its Pleiades 1B observation satellite atop the medium-lift vehicle.
Pleiades 1B's mating with Soyuz occurred during the second half of yesterday, only hours after this Russian-built vehicle was rolled out to the launch pad in the Spaceport's northwestern sector.
The satellite was fitted as part of an integrated payload "stack," consisting of the very-high-resolution optical spacecraft, the Fregat upper stage that will place it into a circular orbit, and the Soyuz ST fairing.
This activity occurred inside the 53-meter-tall mobile gantry that provides a protected environment for the vertical payload installation - which is one of the main differences in launcher handling at the Spaceport compared to the horizontal processing of vehicles on Soyuz launch sites at the Baikonur Cosmodrome in Kazakhstan and Plesetsk Cosmodrome in Russia.
The dual-use Pleiades 1B spacecraft has a fueled mass of approximately 1 metric ton, and is designed to offer optical imaging coverage for French and European defense ministries, institutions and civil users.
Operating from a 695-km. circular orbit, it will join the twin Pleiades 1A satellite launched by Arianespace last December on Soyuz' second mission from the Spaceport. Both spacecraft were built by the Astrium division of EADS.
France's CNES space agency is prime contractor and architect for the Pleiades system, which is part of a joint effort with Italy's Cosmo-Skymed satellite series, which provides radar imaging coverage of the Earth.
Participants in the Pleiades program are the space agencies of France, Austria, Belgium, Spain and Sweden; along with the defense ministries of France, Italy and Spain.
-
-
The integrated payload “stack” – consisting of Pléiades 1B, the Fregat upper stage and Soyuz ST fairing – is aligned for its subsequent hoisting to the mobile gantry’s upper levels (photo at left).  After reaching the work stand area in the gantry’s top section, the payload “stack” is then moved into position for mating to the Soyuz launcher
-
-
Quelle: arianespace
-
Update: 1.12.2012
-

3263 Views

Samstag, 1. Dezember 2012 - 18:00 Uhr

Astronomie - Wie viele möglichen Alien Zivilisationen gibt es?

-

Claudio Maccone revisits the Drake Equation. Image Credit: SETI League

Frank Drake writes out his formula for estimating alien life in the galaxy, the Drake Equation.

-

During the space age, 1961 was a special year: the Russian cosmonaut Yuri Gagarin became the first man to orbit Earth, while the American astronomer Frank Drake developed the now famous Drake Equation. This equation estimates the number of detectable extraterrestrial civilizations in our Milky Way galaxy, supposing our present electromagnetic detection methods. The Drake equation states:

N =  Ns x fp x ne x fl x fi x fc x fL

N = number of alien civilizations in the Milky Way
Ns  = estimated number of stars in the Milky Way;
fp = fraction or percentage of these stars with planets on its orbits;
ne = average number of these planets with potential to host life as we know it;
fl = percentage of these planets that actually develop life;
fi = percentage of these planets that actually develop intelligence on human level;
fc = percentage of these civilizations that actually develop electromagnetic radiation emitting technologies;
fL  = percentage of these civilizations that keep emitting electromagnetic signals to space. This factor is extremely dependent on the lifetime a civilization remains electromagnetic communicative.

Looking to the Drake equation factors, it is obvious that none can be precisely determined by modern science. More than that, as we move from the left to right in the equation, estimating each factor becomes more controversial. The later terms are highly speculative, and the values one may attribute to each of them might tell more about a person’s beliefs than about scientific facts.

But the Drake equation must not be evaluated only by the numerical values it produces. Some say the Drake equation is a way to organize our ignorance. By exposing the extraterrestrial intelligence hypothesis mathematically, we limit the real possibilities to each term and approach the final answer: how many alien civilizations are there?

The L term is considered the most important one in Drake equation. We have no idea how long a technological civilization can last. Even if only one extraterrestrial civilization lasts for billions of years, or becomes immortal, the L factor would be enough to reduce Drake’s equation to N = L. Actually, Frank Drake recognizes this in his license plate: “ NEQLSL

Among dozens of papers written about the Drake Equation, some have suggested new considerations for the formula. One such paper stands out for adding well-established probabilistic principles from statistics. In 2010, the Italian astronomer Claudio Maccone published in the journal Acta Astronautica the Statistical Drake Equation (SDE). It is mathematically more complex and robust than the Classical Drake Equation (CDE).

The SDE is based on the Central Limit Theorem, which states that given the enough number of independent random variables with finite mean and variance, those variables will be normally distributed as represented by a Gaussian or bell curve in a plot. In this way, each of the seven factors of the Drake Equation become independent positive random variables. In his paper, Maccone tested his SDE using values usually accepted by the SETI community, and the results may be good news for the “alien hunters”.

Although the numerical results were not his objective, Maccone estimated with his SDE that our galaxy may harbor 4,590 extraterrestrial civilizations. Assuming the same values for each term the Classical Drake Equation estimates only 3,500. So the SDE adds more than 1,000 civilizations to the previous estimate.

Another SDE advantage is to incorporate the standard variation concept, which shows how much variation exists from the average value. In this case the standard variation concept is pretty high: 11,195. In other words, besides human society, zero to 15,785 advanced technological societies could exist in the Milky Way.

If those galactic societies were equally spaced, they could be at an average distance of 28,845 light-years apart. That’s too far to have a dialogue with them, even through electromagnetic radiation traveling in the speed of light. So, even with such a potentially high number of advanced civilizations, interstellar communication would still be a major technological challenge.

Still, according to SDE, the average distance we should expect to find any alien intelligent life form may be 2,670 light-years from Earth. There is a 75% chance we could find ET between 1,361 and 3,979 light-years away.

500 light-years away, the chance of detecting any signal from an advanced civilization approaches zero. And that is exactly the range in which our present technology is searching for extraterrestrial radio signals. So, the “Great Silence” detected by our radio telescopes is not discouraging at all. Our signals just need to travel a little farther – at least 900 light years more – before they have a high chance of coming across an advanced alien civilization.

Gaussian or bell curve showing the probability of finding the nearest extra terrestrial civilization from Earth. Credit: Maccone (2010)

-

Quelle: SETI


3410 Views

Samstag, 1. Dezember 2012 - 17:00 Uhr

Planet Erde - Erste Hyperspectral-Fotos von Auroras

-

First-ever hyperspectral images of Earth's auroras
New camera provides tantalizing clues of new atmospheric phenomenon

-

The aurora as seen as a color composite image from the NORUSCA II camera. Three bands were combined to make the image. Each band was assigned a different color -- red, green, and blue -- to enhance the features of the aurora for analysis.
-
Hoping to expand our understanding of auroras and other fleeting atmospheric events, a team of space-weather researchers designed and built NORUSCA II, a new camera with unprecedented capabilities that can simultaneously image multiple spectral bands, in essence different wavelengths or colors, of light. The camera was tested at the Kjell Henriksen Observatory (KHO) in Svalbard, Norway, where it produced the first-ever hyperspectral images of auroras—commonly referred to as "the Northern (or Southern) Lights"—and may already have revealed a previously unknown atmospheric phenomenon.
Details on the camera and the results from its first images were published today in the Optical Society's (OSA) open-access journal Optics Express.
Auroras, nature's celestial fireworks, are created when charged particles from the Sun penetrate Earth's magnetic field. These shimmering displays in the night sky reveal important information about the Earth-Sun system and the way our planet responds to powerful solar storms. Current-generation cameras, however, are simply light buckets—meaning they collect all the light together into one image—and lack the ability to separately capture and analyze multiple slivers of the visible spectrum. That means if researchers want to study auroras by looking at specific bands or a small portion of the spectrum they would have to use a series of filters to block out the unwanted wavelengths.
The new NORUSCA II hyperspectral camera achieves the same result without any moving parts, using its advanced optics to switch among all of its 41 separate optical bands in a matter of microseconds, orders of magnitude faster than an ordinary camera. This opens up new possibilities for discovery by combining specific bands of the same ethereal phenomenon into one image, revealing previously hidden details.
"A standard filter wheel camera that typically uses six interference filters will not be able to spin the wheel fast enough compared to the NORUSCA II camera," said Fred Sigernes of the University Centre in Svalbard (UNIS), Norway. "This makes the new hyperspectral capability particularly useful for spectroscopy, because it can detect specific atmospheric constituents by their unique fingerprint, or wavelengths, in the light they emit."
These spectral signatures can then reveal subtle changes in atmospheric behavior, such as the ionization of gases during auroras. This form of multispectral imaging also will enable scientists to better classify auroras from background sky emissions and study the way they cluster in the atmosphere.
-
The red arrow points to the unidentified low-intensity wave pattern, which the researchers suspect is an auroral-generated wave interaction with airglow. For contrast, the blue arrow points to the faint emission of the Milky Way.
-
A New Phenomenon
On Jan. 24, 2012, during the inaugural research campaign of NORUSCA II, a major solar flare jettisoned a burst of high-energy particles known as a Coronal Mass Ejection (CME). The CME eventually slammed into Earth's magnetic field, producing magnificent auroras and a chance to fully test the new camera.
The researchers were able to image the aurora in unprecedented clarity through a layer of low altitude clouds, which would have thwarted earlier-generation instruments (see Image 1). The camera also revealed something unexpected—a very faint wave pattern of unknown origin in the lower atmosphere (see Image 2). The wave pattern resembles "airglow"—the natural emission of light by Earth's atmosphere. Airglow can be produced by a variety of known sources, including cosmic rays striking the upper atmosphere and chemical reactions. Its concurrent appearance with the aurora suggests that it may also be caused by a previously unrecognized source.
"After the January CME, we think we saw an auroral-generated wave interaction with airglow," said Sigernes. This would be an entirely new phenomenon and if confirmed, would be the first time airglow has been associated with auroras.
"Our new all-sky camera opens up new frontiers of discovery and will help in the detection of auroras and the understanding of how our Sun impacts the atmosphere here on Earth. Additional development and commissioning will also hopefully verify our intriguing first results," concludes Sigernes.
-
This shows an aurora appearing in the night sky at the Kjell Henriksen Observatory in Svalbard, Norway. Taken November 2010.
-
Quelle:Optical Society of America

3436 Views

Samstag, 1. Dezember 2012 - 16:16 Uhr

Planet Erde - NASA´s Hurricane Mission

-

NASA's HS3 Hurricane Mission Ends for 2012

-

NASA's 2012 Hurricane and Severe Storms Sentinel, or HS3, mission came to an end Nov. 6 when a NASA unmanned Global Hawk aircraft flew a final data-collection mission in the North Pacific Ocean over a large storm in preparation for next year's campaign.
The primary activity of the 2012 HS3 mission included a NASA Global Hawk aircraft that flew from NASA's Wallops Flight Facility in Wallops Island, Va., in September to investigate the environment and cloud structure of hurricanes Leslie and Nadine in the Atlantic Ocean with more than 148 hours flown over six science flights. A second Global Hawk equipped to examine hurricane precipitation and wind structure was unable to deploy to Wallops before the end of the hurricane campaign, but successfully completed its maiden science research voyage in the Pacific flight.
The Global Hawk departed from NASA's Dryden Flight Research Center on Edwards Air Force Base, Calif., Nov. 5 and flew along the Pacific Coast to as far north as Washington state. The aircraft flew over four Pacific Ocean buoys and a low pressure system south of the Aleutian Islands in Alaska. The 24.2-hour flight allowed for testing of several instruments that will be flown during the 2013 HS3 campaign. All three instruments operated well and collected good data.
Testing the HIWRAP Instrument 
One of the instruments on this HS3 journey was the High-altitude Imaging Wind and Rain Airborne Profiler, or HIWRAP. This system maps 3-D winds and precipitation within hurricanes and other severe weather events. Gerry Heymsfield is the principal investigator for the HIWRAP and is a research meteorologist at NASA's Goddard Space Flight Center in Greenbelt, Md.
"HIWRAP measured precipitation and Doppler winds in the weather front associated with the low pressure system," Heymsfield said. "The vertical structure of this front is very interesting in preliminary looks since it was in a data sparse region of the Pacific. We are really excited about looking at this data in more detail. While this data was not from a tropical weather system that we are interested in for HS3, the flight nevertheless allowed us to test upgrades to HIWRAP such as real time plots that are very promising for future flights."
Testing the HIRAD Instrument
A second instrument that flew on this final 2012 HS3 flight was the Hurricane Imaging Radiometer, or HIRAD. HIRAD is an instrument that measures surface wind speeds and rain rates using its rectangular antenna to track storm-induced fluctuations on the ocean’s surface. The antenna measures microwaves emitted by the ocean surface that are increased by the storm. As winds move across the surface of the sea they generate white, frothy foam. This sea foam causes the ocean surface to emit increasingly large amounts of microwave radiation. HIRAD measures that microwave energy and, in doing so, allows scientists to deduce how powerfully the wind is blowing. 
With HIRAD’s unique capabilities, the two-dimensional structure of the surface wind field can be much more accurately determined than current operational capabilities allow. 
"The Pacific flight was a major step in the development and validation of the algorithms that retrieve wind and rain measurements from the microwave brightness temperatures," said HIRAD Principal Investigator Tim Miller of NASA's Marshall Space Flight Center in Huntsville, Ala.
HAMSR
The High Altitude MMIC (Monolithic Microwave Integrated Circuits) Sounding Radiometer (HAMSR) instrument was also tested during this flight over the Pacific Ocean. For HS3, HAMSR will provide measurements of the moist thermodynamic state (e.g. temperature, water vapor) and precipitation structure in and around a tropical cyclone, which are important measurements for understanding the storm dynamics and evolution.
During the Pacific Global Hawk flight, the HAMSR quick-look temperature and water vapor profiles showed a transition from warmer, moister air to cold, dry polar air as the plane traversed a front associated with a low pressure system centered in the Gulf of Alaska.
"Because HAMSR operates at microwave frequencies, it readily penetrates the clouds that are prevalent in the core regions of hurricanes, which allows us to map out the temperature, water vapor, cloud and precipitation structure there," said Bjorn Lambrigtsen, HAMSR principal investigator at NASA's Jet Propulsion Laboratory, Pasadena, Calif. He noted that infrared sounders are "blinded" by those clouds, and dropsondes only give sparse spot samples -- and neither measures precipitation or cloud structure.
HAMSR and the other two instruments previously flew in NASA's 2010 Genesis and Rapid Intensification Processes (GRIP) hurricane mission. During GRIP, the HIRAD flew aboard a WB-57 aircraft and HIWRAP was mounted in a NASA Global Hawk. 
The HS3 mission is an Earth Venture mission funded by NASA’s Science Mission Directorate in Washington, D.C. Earth Venture missions are managed by NASA’s Earth System Science Pathfinder Program at the agency’s Langley Research Center in Hampton, Va. The HS3 mission is managed by the Earth Science Project Office at NASA’s Ames Research Center in Moffett Field, Calif. The principal investigator (lead scientist) Scott Braun is from NASA Goddard.
-
The Global Hawk departed from NASA Dryden on Nov. 6 and flew along the Pacific Coast to as far north as Washington state. During the 24.2-hour flight, the aircraft flew over four Pacific Ocean buoys and a low-pressure system south of the Aleutian Islands in Alaska.
Credit: NASA
-
HIWRAP radar reflectivity quicklook from the Nov. 6 flight. The plot region covers precipitation associated with a Pacific frontal system. The precipitation slopes upward with height over the colder air to the west (left side of the plot).Credit: NASA/Gerry Heymsfield
-
Quelle: NASA

3544 Views

Samstag, 1. Dezember 2012 - 15:55 Uhr

Raumfahrt - Messenger-Sonde findet Eis auf Merkur

-

Mercury's North Polar Region Acquired By The Arecibo Observatory
A radar image of Mercury's north polar region acquired by the Arecibo Observatory. Yellow areas denote regions of high radar reflectivity. Since their discovery in 1992, these polar deposits have been hypothesized to consist of water ice trapped in permanently shadowed areas near Mercury’s north and south pole, but other explanations for the polar deposits have also been suggested. Polar stereographic projection. From J. K. Harmon et al., Icarus, 211, 37–50 (2011).
Image Credit: National Astronomy and Ionosphere Center, Arecibo Observatory
-
New observations by the MESSENGER spacecraft provide compelling support for the long-held hypothesis that Mercury harbors abundant water ice and other frozen volatile materials in its permanently shadowed polar craters. 
Three independent lines of evidence support this conclusion: the first measurements of excess hydrogen at Mercury's north pole with MESSENGER's Neutron Spectrometer, the first measurements of the reflectance of Mercury's polar deposits at near-infrared wavelengths with the Mercury Laser Altimeter (MLA), and the first detailed models of the surface and near-surface temperatures of Mercury's north polar regions that utilize the actual topography of Mercury's surface measured by the MLA. These findings are presented in three papers published online today in Science Express. 
Given its proximity to the Sun, Mercury would seem to be an unlikely place to find ice. But the tilt of Mercury's rotational axis is almost zero — less than one degree — so there are pockets at the planet's poles that never see sunlight. Scientists suggested decades ago that there might be water ice and other frozen volatiles trapped at Mercury's poles. 
The idea received a boost in 1991, when the Arecibo radio telescope in Puerto Rico detected unusually radar-bright patches at Mercury's poles, spots that reflected radio waves in the way one would expect if there were water ice. Many of these patches corresponded to the location of large impact craters mapped by the Mariner 10 spacecraft in the 1970s. But because Mariner saw less than 50 percent of the planet, planetary scientists lacked a complete diagram of the poles to compare with the images. 
MESSENGER's arrival at Mercury last year changed that. Images from the spacecraft's Mercury Dual Imaging System taken in 2011 and earlier this year confirmed that radar-bright features at Mercury's north and south poles are within shadowed regions on Mercury's surface, findings that are consistent with the water-ice hypothesis. 
Now the newest data from MESSENGER strongly indicate that water ice is the major constituent of Mercury's north polar deposits, that ice is exposed at the surface in the coldest of those deposits, but that the ice is buried beneath an unusually dark material across most of the deposits, areas where temperatures are a bit too warm for ice to be stable at the surface itself. 
MESSENGER uses neutron spectroscopy to measure average hydrogen concentrations within Mercury's radar-bright regions. Water-ice concentrations are derived from the hydrogen measurements. "The neutron data indicate that Mercury's radar-bright polar deposits contain, on average, a hydrogen-rich layer more than tens of centimeters thick beneath a surficial layer 10 to 20 centimeters thick that is less rich in hydrogen," writes David Lawrence, a MESSENGER Participating Scientist based at The Johns Hopkins University Applied Physics Laboratory and the lead author of one of the papers. "The buried layer has a hydrogen content consistent with nearly pure water ice." 
Data from MESSENGER's Mercury Laser Altimeter (MLA) — which has fired more than 10 million laser pulses at Mercury to make detailed maps of the planet's topography — corroborate the radar results and Neutron Spectrometer measurements of Mercury's polar region, writes Gregory Neumann of the NASA Goddard Space Flight Center. In a second paper, Neumann and his colleagues report that the first MLA measurements of the shadowed north polar regions reveal irregular dark and bright deposits at near-infrared wavelength near Mercury's north pole. 
"These reflectance anomalies are concentrated on poleward-facing slopes and are spatially collocated with areas of high radar backscatter postulated to be the result of near-surface water ice," Neumann writes. "Correlation of observed reflectance with modeled temperatures indicates that the optically bright regions are consistent with surface water ice."
The MLA also recorded dark patches with diminished reflectance, consistent with the theory that the ice in those areas is covered by a thermally insulating layer. Neumann suggests that impacts of comets or volatile-rich asteroids could have provided both the dark and bright deposits, a finding corroborated in a third paper led by David Paige of the University of California, Los Angeles. 
Paige and his colleagues provided the first detailed models of the surface and near-surface temperatures of Mercury's north polar regions that utilize the actual topography of Mercury's surface measured by the MLA. The measurements "show that the spatial distribution of regions of high radar backscatter is well matched by the predicted distribution of thermally stable water ice," he writes. 
According to Paige, the dark material is likely a mix of complex organic compounds delivered to Mercury by the impacts of comets and volatile-rich asteroids, the same objects that likely delivered water to the innermost planet.The organic material may have been darkened further by exposure to the harsh radiation at Mercury's surface, even in permanently shadowed areas. 
This dark insulating material is a new wrinkle to the story, says Sean Solomon of the Columbia University's Lamont-Doherty Earth Observatory, principal investigator of the MESSENGER mission. "For more than 20 years the jury has been deliberating on whether the planet closest to the Sun hosts abundant water ice in its permanently shadowed polar regions. MESSENGER has now supplied a unanimous affirmative verdict." 
"But the new observations have also raised new questions," adds Solomon. "Do the dark materials in the polar deposits consist mostly of organic compounds? What kind of chemical reactions has that material experienced? Are there any regions on or within Mercury that might have both liquid water and organic compounds? Only with the continued exploration of Mercury can we hope to make progress on these new questions." 
-
A Mosaic of MESSENGER Images of Mercury's North Polar Region
Tradar image of Mercury's north polar region from Image 2.1 is shown superposed on a mosaic of MESSENGER images of the same area. All of the larger polar deposits are located on the floors or walls of impact craters. Deposits farther from the pole are seen to be concentrated on the north-facing sides of craters. Updated from N. L. Chabot et al., Journal of Geophysical Research, 117, doi: 10.1029/2012JE004172 (2012). 
Image Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington/National Astronomy and Ionosphere Center, Arecibo Observatory
-
Permanently Shadowed Polar Craters
Shown in red are areas of Mercury’s north polar region that are in shadow in all images acquired by MESSENGER to date. Image coverage, and mapping of shadows, is incomplete near the pole. The polar deposits imaged by Earth-based radar are in yellow (from Image 2.1), and the background image is the mosaic of MESSENGER images from Image 2.2. This comparison indicates that all of the polar deposits imaged by Earth-based radar are located in areas of persistent shadow as documented by MESSENGER images. Updated from N. L. Chabot et al., Journal of Geophysical Research, 117, doi: 10.1029/2012JE004172 (2012). 
Image Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington/National Astronomy and Ionosphere Center, Arecibo Observatory
-
Quelle: NASA

3397 Views

Samstag, 1. Dezember 2012 - 14:00 Uhr

UFO-Forschung - Ufo-Effekte durch Raketen-Starts

-

Chinese skywatchers marveled this month over mysterious rays of light in the night sky, and now sharp-eyed analysts are saying those UFO sightings were sparked by a European Ariane 5 rocket that launched two telecommunication satellites from French Guiana.
Amateur astronomers in China's Sichuan and Yunnan provinces reported seeing the weird phenomenon on Nov. 11. They watched as a luminous object moved through the heavens, shimmering with rays or rings of light. The reports made a splash on Chinese news websites such as Sina.com, as well as the Astronomy.com.cn discussion forum.
"It is certainly a UFO," one forum poster wrote in Chinese. Another wrote that the UFO was a "blessing from another planet." (I couldn't determine how that comment was meant, because my machine-translation software doesn't have a sarcasm filter.)
For a while, Chinese experts speculated that the object might have been a comet — but skywatchers soon figured out that the sightings occurred less than an hour after Arianespace sent the Eutelsat 21B and Star One C3 satellites into orbit (from the European Space Agency's South American spaceport, where it was still Nov. 10).
"The detailed analysis of the height of the UFO and the timing of observation leads me to conclude that this was the ESC-A upper stage, 30 minutes after all the fuel leaked out via passification," a Hong Kong observer known as Galactic Penguin SST reported last week on the NASASpaceflight.com forum.
Today, Want China Times said that the Beijing UFO Research Society has reached a similar conclusion.
"The 'rays' were most likely the rocket jettisoning boosters or other parts and entering low Earth orbit after being launched 30 minutes previously," the Taiwan-based online publication reported. It's also possible that the swirls of light came from fuel or vapor emanating from the upper stage. Such explanations are consistent with a host of other rocket-related UFO sightings over the years, including Russian rocket stages that have been spotted over the Middle East and Scandinavia.
-
Raketen-Ufo-Effekt im Oktober 2009
-
A spectacular spiral light show in the sky above Norway on Wednesday was caused by a Russian missile that failed just after launch, according to Russia's defense ministry.
When the rocket motor spun out of control, it likely created the heavenly spiral of white light near where the missile was launched from a submarine in the White Sea.
The Russian Defense Ministry confirmed that a Bulava ballistic missile test had failed.
"It has been established ... that the missile's first two stages worked as normal, but there was a technical malfunction at the next, third, stage of the trajectory," Reuters quoted a Defense Ministry spokesman as saying.
Paal Brekke, a senior adviser at the Norwegian Space Centre Drammensvn, told Space.com that the cloud was "very spectacular."
"When we looked at the videos people submitted to the media, we quickly concluded that it looked like a rocket or missile out of control, thus the spiraling effect," Brekke said. "I think this is the first time we have seen such a display from a launch failure."
The phenomenon was seen by people all over northern Norway.
"It was a fairly stunning display, and we were really surprised to see it so well-observed," Brekke said.
Viewers described an eerie white cloud with a piercing blue-green beam coming out of it.
6 real-life 'X-Files'"It consisted initially of a green beam of light similar in color to the aurora with a mysterious rotating spiral at one end," Nick Banbury of Harstad, Norway, told Spaceweather.com. "This spiral then got bigger and bigger until it turned into a huge halo in the sky with the green beam extending down to Earth."
Banbury said he saw the lights on his way to work between 7:50 and 8 a.m. local time, or 1:50 to 2 a.m. ET Wednesday.
"We are used to seeing lots of auroras here in Norway, but this was different," he said.
Before the missile test was confirmed, many people suggested the bright light pattern might have been a UFO. Russia finally admitted to the accident, which is an embarrassing mishap for a rocket that had already failed six of 13 previous tests, according to the BBC.
The Bulava missile is designed to carry six individually targeted nuclear warheads over a range of up to 6,200 miles (10,000 km), the BBC reported. The missile had been touted as Russia's newest technological breakthrough to support its nuclear deterrent, but the numerous failures have led to second thoughts.
"This is a catastrophe ... Huge funds were siphoned off from Russia's moribund navy for the Bulava project. In fact, billions of dollars have been flushed down the drain," Alexander Khramchikhin, chief analyst at the Moscow-based Institute of Military and Political Analysis, told Reuters.
Analysts criticize Moscow's hurry to build the Bulava, as it already has a highly reliable Soviet-built Sineva submarine-based ballistic missile. They also question awarding the Bulava contract to the Moscow Institute of Thermal Technology, which has never before built missiles for submarines.
-
In an ironic encore, yet another secret military missile test has sparked widespread UFO reports from surprised ground witnesses.
On Dec. 9, a Russian Bulava missile was launched from a submarine within sight of northern Norway, resulting in a spectacular spiral display and a spate of UFO sightings.
This week's UFO reports apparently were sparked by a Chinese missile that was fired to intercept another missile in flight, for the first time in the nation's history.
Witnesses in China's inland provinces of Xinjiang and Gansu weren’t as well equipped with cameras as last month's Norwegian witnesses were, so the only images reaching the West merely show fuzzy-colored clouds and streaks. The military secrecy surrounding China's missile test is so tight that Beijing officials seem to be at a loss as to how to respond to the reports.
As with December's Russian missile test, cases such as these underscore how important it is for intelligence agencies to seek out and evaluate reports of unidentified flying objects from countries of interest. For decades, such reports from the Soviet Union and China might have provided hints about top-secret military missiles and space weapons. The stories would be most valuable precisely because the unidentified flying objects were not true “UFOs” at all.
Great leap for China's missile shield 
China’s latest military space maneuver came to light on Monday when a single-sentence news item was released by the Xinhua news agency. “China conducted a test on ground-based midcourse missile interception within its territory on Monday,” Xinhua reported. An hour later, two sentences were added: “The test has achieved the expected objective. The test is defensive in nature and is not targeted at any country.”
No other details have been released. The names, or even the generic types, of missiles weren’t given. The locations of the two missile launches — for the target and the interceptor — were never specified, nor was the time of their launches. In contrast, Moscow quickly provided such data for last month's missile test.
Advertise | AdChoices
Speculation in the Western press went on for days without converging on any consensus, except that the warhead had been a ‘hit-to-kill’ guided missile, probably closely related to the anti-satellite warhead used three years earlier to smash a derelict Chinese satellite. The altitude of the intercept and the maximum speed of any target missile was not clear.
Hints from the hinterland 
Chinese military officials are well aware of the extent to which the U.S. military officials (and to a lesser degree the Russians) keep a close watch on their activities. China has an active program of camouflage and misdirection to hide their secrets.
Civilian UFO reports, however, don't always follow the program. UFO Web sites in China and overseas began picking up detailed reports from ground observers, telling of an amazing celestial light show that occurred about an hour before Beijing's first official announcement.
Six real-life 'X-Files'At a coal mine in eastern Xinjiang, an engineer named Ma reported: “I and my 45 colleagues from the mine came out. I suddenly sensed the color of the sky becoming ever brighter. In the southwest there were clusters of green, moving toward the east slowly. …  Blue light issued waves that rotated for several minutes, and then came down on a nearby mountain.” 
A man named Daw who lives in Mori county, on the Mongolian border, said: "My friends and I  were walking home. Suddenly we saw the sky had a bright spot in the west, it was spinning in clockwise movement toward the south. It was surrounded by a white fog that constantly expanded. In the center there also appeared a blue iris that expanded, then gradually faded and finally disappeared. "
A man named Shi who worked in the Grand Canyon Park in Xinjiang's Tian Shan Mountains said "there was a light in the sky, a light blue ball, a horizontally fast-moving ball of light. Then it collided with an unknown object, resulting in an explosion, and this produced two white circular light waves."
A worker at the Jiuquan space center in Gansu province provided a detailed report about a "white circular structure about the size of dozens of moons." The worker said the display "quickly expanded to half of the sky, and then gradually faded."
After wondering whether the flash was a nuclear explosion, the worker said "my colleagues and I then guessed that it may be an alien voyager from another planet." The display lasted just two or three minutes, the worker said.
Decoding the narratives 
Space and missile experts will now be working with these and other stories, and with whatever photographs manage to slip out of China. The information may help supplement much more detailed measurements from U.S. military assets. The result could provide significant insights into the nature of the interceptor’s kill mechanism and the range of its potential target missiles.
Some caution is still prudent. So far there's no confirmation from U.S. military intelligence sources that the Chinese missile test did in fact occur at about 8 p.m. local time (7 a.m. ET) on Monday, when the UFO sightings were made. However, the timing is consistent with the way Beijing released information about the test.
It might turn out to be a complete coincidence, and the reports might be due to something else entirely — even a real flying saucer. But the Chinese have a long history of reporting space and missile events as UFOs, and with the Norway experience so fresh in our minds, reaching a similar conclusion is reasonable.
The eyewitnesses got quite a thrill, as have UFO buffs who are welcoming this latest news as further proof of the imminence of alien arrivals on Earth. The Chinese military teams who pulled off the intercept have every reason to feel proud of the successful mission.
If the UFO reports and the missile test reports indeed refer to the same event, the people least happy about the whole affair could well be China's security forces — who may have seriously underestimated how well their own people are watching the skies, and how quickly they can report their observations.
NBC News space analyst James Oberg spent 22 years at the Johnson Space Center as a Mission Control operator and an orbital designer. He is the author of nine books on space policy and phenomena, including "Space Power Theory" and "UFOs and Outer Space Mysteries."
-
An eerie spiral light show in the pre-dawn sky over Australia early Saturday prompted a flood of UFO reports to local news stations, but was likely just the remnants of a new private rocket launched by an American millionaire, according to Australian media reports.
The bright sky spiral appeared before sunrise on Saturday over New South Wales, Queensland and the Australia Capital Territory (ACT), with witnesses describing it as a "lollipop-type swirl," the Australia Broadcasting Corp. (ABC) reported.
"The spiral looked like a bright light shining through some clouds in a spiral shape, except the edges of the spiral were very sharp and defined unlike what a cloud might look like," Baden West, who snapped photos of the spiral before it faded from view, told SPACE.com in an e-mail. "It was also very large, much bigger than any photo makes it look and in terms of brightness. It looked like it was about as bright as a full moon but all the light was coming from a much smaller point."
One witness, James Butcher of Canberra, told ABC that the spiral light appeared to have a yellow hue.
Another skywatcher described the sky apparition as a "huge revolving moon," according to ABC.
But despite claims of otherworldly origins, the phenomenon was likely created by the new Falcon 9 rocket launched from Cape Canaveral, Fla., by Space Exploration Technologies (SpaceX), a California-based spaceflight company led by millionaire PayPal co-founder Elon Musk.
"I heard people in Australia thought UFOs were visiting :)," SpaceX's millionaire founder Elon Musk told SPACE.com in an e-mail. "The venting of propellants, which is done to ensure that an overpressure event doesn't produce orbital debris, created a temporary halo caught the sun at just the right angle for a great view from Australia.  I thought the pictures looked really cool." [See the sky spiral.]
Professional skywatchers quickly suggested that SpaceX's first Falcon 9 rocket may be the source of the sky spiral, ABC reported
"The fact that you've got the rotation, the spiral effect, is very reminiscent of the much widely reported sightings from Norway and Russia last year, which both turned out to be a Bulava missile which was being adjusted in its orbit," Geoffrey Whyatt of the Sydney Observatory told ABC. "So possibly a rocket, I would say, having some sort of gyroscopic stability rocket fired on its side."
The Bulava missile spiral occurred in December 2009 and also set off a flurry of UFO reports from observers on the ground, as well as resulting in spectacular photos.
The new Falcon 9 blasted off Friday afternoon from Cape Canaveral Air Force Station on a successful test flight that reached an orbit of about 155 miles (250 km) above Earth.
SpaceX plans to use the two-stage Falcon 9 rocket to launch its own Dragon spacecraft on unmanned cargo flights to the International Space Station for NASA under a $1.6 billion contract with the U.S. space agency.
Musk also hopes to add an emergency launch escape system to the 180-foot (55-meter) tall rocket and refit the Dragon spacecraft to launch astronauts into space.
NASA plans to retire its three aging space shuttles later this year after two final missions and rely on commercial spacecraft to send astronauts and cargo into orbit.
-
Quelle: space

3671 Views

Samstag, 1. Dezember 2012 - 00:05 Uhr

Mars-Curiosity-Chroniken - Curiosity-News Sol 111+112

-

This image was taken by Navcam: Right A (NAV_RIGHT_A) onboard NASA's Mars rover Curiosity on Sol 111 (2012-11-28 06:05:34 UTC)

-

This image was taken by Navcam: Right A (NAV_RIGHT_A) onboard NASA's Mars rover Curiosity on Sol 111 (2012-11-28 05:11:45 UTC) .

-

This image was taken by Navcam: Right A (NAV_RIGHT_A) onboard NASA's Mars rover Curiosity on Sol 111 (2012-11-28 05:15:21 UTC) . 
-
This image was taken by Navcam: Right A (NAV_RIGHT_A) onboard NASA's Mars rover Curiosity on Sol 111 (2012-11-28 06:00:45 UTC) . 
-
This image was taken by Navcam: Left A (NAV_LEFT_A) onboard NASA's Mars rover Curiosity on Sol 111 (2012-11-28 06:00:45 UTC) .
-
This image was taken by Front Hazcam: Left A (FHAZ_LEFT_A) onboard NASA's Mars rover Curiosity on Sol 111 (2012-11-28 05:56:06 UTC) .
-
This image was taken by Front Hazcam: Left A (FHAZ_LEFT_A) onboard NASA's Mars rover Curiosity on Sol 111 (2012-11-28 05:56:06 UTC) .
-
This image was taken by ChemCam: Remote Micro-Imager (CHEMCAM_RMI) onboard NASA's Mars rover Curiosity on Sol 112 (2012-11-29 04:36:02 UTC) . 
-
This image was taken by Front Hazcam: Left A (FHAZ_LEFT_A) onboard NASA's Mars rover Curiosity on Sol 112 (2012-11-29 01:42:29 UTC) . 
-
Fotos: NASA

3185 Views


Weitere 10 Nachrichten nachladen...