Blogarchiv

Sonntag, 2. August 2015 - 22:00 Uhr

Raumfahrt-History - 1975: Vor 40 Jahren begann ISRO´s Raumfahrt in Indien

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Aus dem CENAP-Archiv:

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Quelle: CENAP-Archiv


Tags: Raumfahrt 

1367 Views

Sonntag, 2. August 2015 - 18:35 Uhr

UFO-Forschung-History - 24. August 1990: Podcast zu Fall Greifswald

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24.August 1990 über der Ostsee

Ursache und Identifikation der Greifswald-Lichter

Mehr darüber hier:

http://www.hjkc.de/_blog/2012/12/01/luftfahrt-/

/_blog/2012/12/01/ufo-forschung---ergaenzungabschluss-recherche-zu-fall-greifswald/

http://hjkc.de/_blog/2013/05/04/ufo-forschung---fall-greifswald-und-das-debakel-eines-degufo-militaer-historikers/%20Fall%20Greifswald

http://www.hjkc.de/_blog/2015/05/26/ufo-forschung---neues-ufo-video-aus-astrakhan--russland-zeigt-greifswald-manoever-fackeln/

Auf Grund des Bekanntheitsgrades der UFO-Fall´s Greifswald vor 25 Jahren, wollten wir nochmals ein Podcast zu unseren in den letzten Jahren statt gefundenen Nachrecherchen aufnehmen. Dieser Podcast haben wir  ( ui-Redaktion (Dennis Kirstein, Jochen Ickinger) und Hansjürgen Köhler/CENAP ) am Freitag, 31.07.2015 nun aufgezeichnet und Dennis Kirstein hat ihn nach dem Schnitt, heute auf der ui-Seite  zur Verfügung gestellt. Zu finden hier:

http://www.ufo-information.de/index.php/aktuelles/ufo-talk-podcast

CENAP-Mannheim




Tags: UFO-Forschung 

1457 Views

Sonntag, 2. August 2015 - 17:15 Uhr

Raumfahrt - Scott Kelly ONE-YEAR-MISSION im Bild

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Atascocita, TX 
These are not the droids you are looking for. 
I'm thinking this is about to get real. #YearInSpace
Last day in Star City is as the Inception riddle: waiting for a train, a train that'll take me far away #YearInSpace
Huge thanks to all that made this beautiful launch possible.
Good morning #Texas from the #ISS. Looks like #Houston and #Austin have some #weather headed your way. #YearInSpace
#Australia. You are very beautiful. Thanks for being there to brighten our day. #YearInSpace
#Patagonia never disappoints. #YearInSpace
Looks messy, but it's functional. Our #food table on the @space station. What's for breakfast? #YearInSpace
#Himalayas. What icy veins you have. #YearInSpace
Not sure what is going on on this beach in #Mexico but it's a striking image. #YearInSpace 
I can see my house (and @NASA_Johnson) from @Space_Station! #Houston #YearInSpace
#Tajikistan heights casting shadows. #YearInSpace
Congrats @SpaceX and @NASA team on a successful launch! Watched with my crewmates aboard #ISS. #YearInSpace
I've never heard of #Moa #Cuba but it's a very colorful place from @Space_Station. #YearInSpace
Great job @AstroSamantha and @AstroTerry capturing #SpaceX Dragon this morning! #YearInSpace
@AstroSamantha and I reflecting on #Dragon arrival. #YearInSpace
Africa. I wonder what these desert sands look like up close?#YearInSpace
My #bedroom aboard #ISS. All the comforts of #home. Well, most of them. #YearInSpace
Good morning from #ISS. This high altitude Central Asian lake looks like my morning cereal. #BreakfastOfChampions
I found these interesting waters on the US East Coast. #YearInSpace
Sometimes #Earth looks like another planet from @Space_Station. #YearInSpace
I wonder what they do here. #NorthAfrica #YearInSpace
#SaturdayMorning #coffee with my old friend #PlanetEarth. #YearInSpace
#SaturdayMorning #coffee with my old friend #PlanetEarth. #YearInSpace
Earth’s terrain from the @space_station looks like I've traveled to a parallel universe. #StarWarsDay #YearInSpace
The rising sun casts shadows upon the US #SouthWest this morning creating a striking image. #YearInSpace
Subtropical Storm #Ana churns off the East coast of USA. #Wx from @Space_Station. #YearInSpace
I don't know where in the US Southwest this is, but it sure is beautiful. #YearInSpace
#MtEtna Highest European active #volcano lives up to its Italian name Mongibello (beautiful mountain) from space too
New #SpaceGeo today! Download latest hi-res pics of my #geography trivia, or play to win: http://bit.ly/1K6wT6A
Looking down on #Earth, our nerve center. Good morning from the @space_station! #YearInSpace
Released #Dragon early this a.m. @ISS_Research on Earth. Mission success! Congrats & good night from @Space_Station!
RedSea. I'd sure like to jump into you this morning. #YearInSpace
#Pakistan. Is that a cloud over Karachi or cream in my coffee? Good morning from the @space_station! #YearInSpace
#SpaceGeo A: #Denmark #Norway #Sweden #Germany & #Poland. Two winners! Congrats to @TeacherWithTuba & @PC101!
Just flew over you #Honolulu #Hawaii. Happy #MemorialDay! #YearInSpace
Looks like parent and spawn from @space_station #YearInSpace
#SpaceGeo A: #NiagraFalls Long history of daredevils.1st to go over in a barrel was in 1901. Congrats @WilliamBum!
Saw this guy flying up through the #Noctilucentclouds this morning. #YearInSpace
This lake North East of the #Himalayas appears to be the bluest place on Earth from @Space_Station. #YearInSpace
#SpaceGeo The ripples of this coastal "vast place" are influenced not by the sea but by the fog. Name it!
Fair winds and following seas to my good friends @AstroTerry, @AstroSamantha, and @AntonAstrey. #YearInSpace
#SpaceSelfie before hatch closing. I'm going to miss these guys up here. Congrats on your safe return to #Earth!
There seems to be more green in the #African desert lately. This is a good thing. #YearInSpace
Sunrise #MondayMotivation. Good morning from @Space_Station!
Good afternoon #Dubai. You look much different than when I was there 25 years ago.
Day 83. Our galaxy from 250 miles away. Good night from @space_station! #YearInSpace
Day 85. Fiery #EarthArt. Good night from @Space_Station!
#EarthArt Interesting how meaningless squiggles are until they stand for something else. #YearInSpace
I've never seen this before- red #aurora. Spectacular! #YearInSpace
Day 88. #Sunset. With 16 of these a day, only 4,064 more to go. Good night from @space_station!
Good morning from 250 miles above the African desert. #YearInSpace
Day 92. #Aurora is back in town. Good night from @space_station! #YearInSpace
Watched #Dragon launch from @space_station Sadly failed Space is hard Teams assess below @NASAKennedy #YearInSpace
Earth rocks! Let's protect it. Happy #AsteroidDay from @space_station! #YearInSpace
Day 97. Good night, Moon. Good night from @Space_Station! #YearInSpace
#Bermuda, you're looking pretty good right now. #YearInSpace
The third time's the charm as the say! #Progress60 arrives overnight. Great news. #YearInSpace (with supplies!)
Christmas in July! Great gift for my 100th day in space! Only ~250 more to go (not that I’m counting) #YearInSpace
#Robonaut and I are happy to hear you are discussing important @ISS_Research at #ISSRDC to improve life on Earth.
#EarthArt The sun’s reflection appears to spill liquid metal onto this desert lake. #YearInSpace
SpaceGeo The root of this peninsula's name means "tooth" referencing its mountain peaks & triangular shape Name it!
#Athens, #Greece, #GoodMorning from @Space_Station. Wishing you the best. #YearInSpace
Bahamas, the strokes of your watercolors are always a refreshing sight. #YearInSpace.
Day 114. #Moon #Venus #Jupiter...#Earth Good night from @space_station! #YearInSpace
Day 118. Teaching @Astro_Kjell how to take night pics from the Cupola. Good night from @Space_Station! #YearInSpace
#EarthArt #Galapagos, I can see inside you. #YearInSpace
#Peru, your #Andes mountains always impress! #YearInSpace
Day 127. Sunset returns! Perfect end. Thanks again for joining me today. Good night from @space_station! #YearInSpace
Quelle: Scott Kelly, NASA

Tags: Raumfahrt 

1845 Views

Sonntag, 2. August 2015 - 09:53 Uhr

Astronomie - Doppelsternsystem mittels Pulsar-Gammastrahlung präzise vermessen

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Max-Planck-Forscher finden Hinweise auf Aktivitätszyklen des Begleitsterns
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Pulsare sind schnell rotierende, kompakte Überreste von Explosionen massereicher Sterne. Beobachten lassen sie sich anhand der Bündel aus Radio- und Gammastrahlung, die sie wie kosmische Leuchttürme ins All senden. Forscher des Max-Planck-Instituts für Gravitationsphysik (Albert-Einstein-Institut, AEI) in Hannover haben nun ein Doppelsternsystem mit einem schnell rotierenden, sogenannten Millisekundenpulsar ganz genau vermessen. Die Wissenschaftler analysierten Archiv-Daten des Gamma-Weltraumteleskops Fermi mit neuen Methoden präziser als zuvor möglich. Dabei entdeckten sie Schwankungen in der Umlaufzeit des wechselwirkenden Doppelsternsystems, die sich durch magnetische Aktivitätszyklen des Begleitsterns erklären lassen.
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Im Doppelsternsystem umlaufen der Pulsar und sein Begleitstern den gemeinsamen Schwerpunkt in nur 4,6 Stunden. Der Begleiter wird durch die Strahlung (magenta) des Pulsars einseitig erhitzt und langsam verdampft. Das Doppelsternsystem und der Begleiter sind maßstabsgerecht abgebildet, der Pulsar wurde vegrößert. 
© Knispel/AEI/SDO/AIA/NASA/DSS
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0FGL J2339.8–0530 – diese Zeichenkombination ist der Katalogname eines Himmelsobjekts, welches das Large Area Telescope (LAT) an Bord des Fermi Gamma-ray Space Telescope bereits im Jahr 2009 als Quelle intensiver Gammastrahlung identifizierte. Beobachtungen in anderen Wellenlängenbereichen in den Folgejahren legten nahe, dass sich dahinter ein Millisekundenpulsar verbirgt, der mit einem Begleitstern den gemeinsamen Schwerpunkt in etwa 4,6 Stunden umrundet.
Erst im Jahr 2014 konnte der Pulsar als „PSR J2339–0533“ anhand seiner Radiostrahlung nachgewiesen werden. Die Beobachtung im Radiobereich wird dadurch erschwert, dass der Pulsar mit seinem Begleitstern wechselwirkt – er erhitzt seinen Begleiter und verdampft ihn dadurch. So ist das Doppelsternsystem von Gaswolken erfüllt, die die Radiostrahlung absorbieren und den Pulsar zeitweise unsichtbar machen. Um das System vollständig zu charakterisieren, wären regelmäßige Beobachtungen über mehrere Jahre notwendig.
Durchblick mit Gammastrahlung 
Die Gammastrahlung von PSR J2339–0533 hingegen durchdringt die Gaswolken und erlaubt so dessen Untersuchung. „Die vom Fermi-LAT registrierten Ankunftszeiten der einzelnen Gammaphotonen hängen von den physikalischen Eigenschaften der Sterne und ihrer Bahnen ab“, erläutert Holger Pletsch, Leiter einer unabhängigen Forschungsgruppe am AEI und Erstautor der in The Astrophysical Journal erschienen Studie.
Im Umkehrschluss lässt sich aus der Analyse der Ankunftszeiten eine präzise Vermessung der Doppelsternsystems konstruieren. „Nach den ersten Radiobeobachtungen hatten wir einen Ansatzpunkt, anhand der umfangreichen Fermi-LAT-Archivdaten der letzten sechs Jahre sofort einen hochauflösenden Blick auf das System zu werfen“, sagt Pletsch.
Präzise Messungen mit neuen Methoden
Entscheidend war dabei der Einsatz neuer Analyse-Algorithmen. „Im Gegensatz zu bisherigen Verfahren, die stets die Ankunftszeiten mehrerer Gammaphotonen mitteln und so zeitliche Auflösung verlieren, basiert unsere Methode auf den Ankunftszeiten einzelner Photonen“, sagt Colin Clark, Doktorand in Pletschs Arbeitsgruppe und Koautor. „Dadurch können wir die physikalischen Eigenschaften des Doppelsternsystems noch genauer ermitteln, vor allem Effekte auf kürzeren Zeitskalen.“
Die Ergebnisse von Pletsch und Clark liefern eine ganz genaue Vermessung von PSR J2339–0533, seinem Begleiter und ihren Bahnen umeinander. Es handelt sich um die erste hochpräzise Vermessung eines solchen wechselwirkenden Doppelsternsystems mittels der Gammastrahlung eines Millisekundenpulsars. Die Forscher reizen dabei die Zeitauflösung des Fermi-LAT, die etwa bei Millionstelsekunden liegt, aufs Äußerste aus.
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Die magnetische Aktivität des Begleiters beeinflusst die Umlaufzeit im Doppelsternsystem. Das schwankende Magnetfeld des Begleiters mit dem Plasma im Sterninneren und verformt ihn (rechts). Mit der Form des Sterns ändert sich auch sein Gravitationsfeld, was wiederum die Bahn des Pulsars beeinflusst und die beobachteten Schwankungen (links) der Umlaufzeit erklärt. Das Doppelsternsystem und der Begleiter sind maßstabsgerecht abgebildet, der Pulsar wurde stark vergrößert, ebenso die Verformung des Begleiters.
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Magnetische Aktivität lässt die Umlaufzeit schwanken
Die Ergebnisse zeigen eine überraschende Schwankung der Umlaufzeit. „Wir waren erstaunt, dass die Umlaufzeit langsam nach oben und unten um den Mittelwert von 4,6 Stunden schwankt. Die Änderungen liegen in der Größenordnung von wenigen Tausendstelsekunden, was verglichen mit der Messgenauigkeit von Millionstelsekunden aber enorm viel ist“, sagt Clark. „Das ist so als würde die Jahreslänge auf der Erde um ein Dutzend Sekunden schwanken.“
Als wahrscheinlichste Ursache erachten die Wissenschaftler winzige Veränderungen in der Form des Begleitsterns, die durch dessen magnetische Aktivität hervorgerufen werden. Ähnlich wie unsere Sonne durchläuft der Begleiter demnach Aktivitätszyklen. Das dabei schwankende Magnetfeld wechselwirkt mit dem Plasma im Sterninneren und verformt ihn. Mit der Form des Sterns ändert sich auch sein Gravitationsfeld, was wiederum die Bahn des Pulsars beeinflusst und die beobachteten Schwankungen der Umlaufzeit erklärt.
„In der Zukunft kann die Kombination von weiteren Beobachtungen mit optischen Teleskopen uns helfen, den Zusammenhang zwischen Sternaktivität und Schwankungen der Umlaufzeit zu belegen“, sagt Pletsch. Diese könnte außerdem zum besseren Verständnis des Doppelsternsystem beitragen. „Die Fermi-LAT-Beobachtungen des Pulsars lassen uns gewissermaßen in das Innere des Begleitsterns blicken. Vielleicht lässt sich damit zukünftig sogar die Art des Magnetfeld-Dynamos im Begleiter ermitteln.“
Pulsare
Neutronensterne sind Exoten. Sie bestehen aus Materie, die viel dichter gepackt ist als gewöhnlich, mit einer Dichte vergleichbar der eines Atomkerns. Ein Stern von etwa der Masse unserer Sonne hätte so einen Durchmesser von rund 30 Kilometer.
Außerdem besitzen Pulsare extrem starke Magnetfelder. Entlang der Magnetfeldlinien beschleunigte, geladene Teilchen senden elektromagnetische Strahlung in verschiedenen Wellenlängenbereichen aus: Diese Strahlung ist in Richtung der Magnetfeldachse kegelartig gebündelt. Dreht sich der Neutronenstern nun um seine Rotationsachse, die relativ zur Magnetfeldachse geneigt ist – und das ist der Regelfall –, so beleuchten die Strahlungskegel wie ein Leuchtturm das Universum. Der Neutronenstern ist dann als Pulsar sichtbar. Die Pulsare rotieren im Sekunden- bis Millisekundentakt so präzise, dass sie als die zuverlässigsten Uhren überhaupt gelten.
Erstmals wurden diese kosmischen Leuchtfeuer im Jahre 1967 von Jocelyn Bell Burnell als Radiopulsare entdeckt. Inzwischen sind außerdem Röntgen- und Gammapulsare bekannt. Auch wenn sich nicht alle Pulsare in allen Frequenzbereichen beobachten lassen, gehen die Wissenschaftler davon aus, dass sie über das gesamte elektromagnetische Spektrum verteilt Energie abstrahlen.
Gamma- und Radiopulsare
Jedoch sind die Mechanismen, welche die Strahlung in den verschiedenen Frequenzbereichen erzeugen, noch nicht vollständig verstanden. Die Forscher vermuten, dass die energieärmeren Radiowellen an den Magnetfeldpolen zu einem engeren Lichtkegel gebündelt werden als die hoch energetische Gammastrahlung. Nun wird aber die meiste Strahlung entlang der Kegelhülle ausgesendet. Da die Kegel in diesem Modell je nach Art der Strahlung unterschiedlich stark aufgefächert sind, verlassen Radio- und Gammastrahlung den Pulsar in unterschiedliche Raumrichtungen. Aus diesem Grund könnte ein Pulsar für den Beobachter entweder als Gamma- oder als Radiopulsar erscheinen.
Quelle: MAX-PLANCK-GESELLSCHAFT, MÜNCHEN

Tags: Astronomie 

1596 Views

Sonntag, 2. August 2015 - 09:45 Uhr

Astronomie - Sterne in unserer Galaxie bewegen sich weit von zu Hause

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Stars in Our Galaxy Move Far From Home
When it comes to our galaxy, home is where the star is.
Scientists with the Sloan Digital Sky Survey (SDSS) have created a new map of the Milky Way and determined that 30 percent of stars have dramatically changed their orbits. This discovery, published in yesterday's issue of The Astrophysical Journal, brings a new understanding of how stars are formed, and how they travel throughout our galaxy.
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A single frame from an animation shows how stellar orbits in the Milky Way can change. + MORE +
Credit: Dana Berry / SkyWorks Digital, Inc.; SDSS collaboration
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"In our modern world, many people move far away from their birthplaces, sometimes halfway around the world," says Michael Hayden of New Mexico State University (NMSU), the lead author of the new study. "Now we're finding the same is true of stars in our galaxy — about 30 percent of the stars in our Galaxy have traveled a long way from the orbits in which they were born."
To build a map of the Milky Way, the scientists used the SDSS Apache Point Observatory Galactic Evolution Explorer (APOGEE) spectrograph to observe 100,000 stars during a 4-year campaign.
The key to creating and interpreting this map is measuring the elements in the atmosphere of each star. "From the chemical composition of a star, we can learn its ancestry and life history," Hayden says.
The chemical information comes from spectra, which are detailed measurements of how much light the star gives off at different wavelengths. Spectra show prominent lines that correspond to elements and molecules present. Reading the spectral lines of a star can tell astronomers what the star is made of.
"Stellar spectra show us that the chemical makeup of our galaxy is constantly changing," says Jon Holtzman, an astronomer at NMSU who was involved in the study. "Stars create heavier elements in their cores, and when the stars die, those heavier elements go back into the gas from which the next stars form."
As a result of this process of "chemical enrichment," each generation of stars has a higher percentage of heavier elements than the previous generation did. In some regions of the Galaxy, star formation has proceeded more vigorously than in other regions -- and in these more vigorous regions, more generations of stars have formed. Thus, the average amount of heavier elements in stars varies across different parts of the Galaxy. Astronomers can use the amount of heavy elements in a star to determine what part of the Galaxy the star was born in.
Hayden and colleagues used APOGEE data to map the relative amounts of 15 separate elements, including carbon, silicon, and iron, for stars all over the Galaxy.
What they found surprised them — up to 30 percent of stars had compositions indicating that they were formed in parts of the Galaxy far from their current positions.
"While on average the stars in the outer disk of the Milky Way have less heavy element enrichment, there is a fraction of stars in the outer disk that have heavier element abundances that are more typical of stars in the inner disk," says Jo Bovy of the Institute for Advanced Study and the University of Toronto, another key member of the research team.
When the team looked at the pattern of element abundances in detail, they found that much of the data could be explained by a model in which stars migrate into new orbits around the Galactic Center, moving nearer or farther with time. These random in-and-out motions are referred to as "migration," and are likely caused by irregularities in the Galactic disk, such as the Milky Way's famous spiral arms. Evidence of stellar migration had previously been seen in stars near the Sun, but the new study is the first clear evidence that migration occurs for stars throughout the Galaxy.
Future studies by astronomers using data from SDSS promise even more new discoveries. "These latest results take advantage of only a small fraction of the available APOGEE data," says Steven Majewski, the Principal Investigator of APOGEE. "Once we unlock the full information content of APOGEE, we will understand the chemistry and shape of our galaxy much more clearly."
 
About SDSS-III
Funding for SDSS-III has been provided by the Alfred P. Sloan Foundation, the Participating Institutions, the National Science Foundation, and the U.S. Department of Energy Office of Science.
SDSS-III is managed by the Astrophysical Research Consortium for the Participating Institutions of the SDSS-III Collaboration including the University of Arizona, the Brazilian Participation Group, Brookhaven National Laboratory, Carnegie Mellon University, University of Florida, the French Participation Group, the German Participation Group, Harvard University, the Instituto de Astrofisica de Canarias, the Michigan State/Notre Dame/JINA Participation Group, Johns Hopkins University, Lawrence Berkeley National Laboratory, Max Planck Institute for Astrophysics, Max Planck Institute for Extraterrestrial Physics, New Mexico State University, New York University, The Ohio State University, Pennsylvania State University, University of Portsmouth, Princeton University, the Spanish Participation Group, University of Tokyo, University of Utah, Vanderbilt University, University of Virginia, University of Washington, and Yale University.
Quelle: SDSS-III

Tags: Astronomie 

1619 Views

Sonntag, 2. August 2015 - 08:30 Uhr

Raumfahrt-History - 1972: Venus-Sonde Venera 8

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Aus dem CENAP-Archiv:

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Quelle: Flug-Revue, CENAP-Archiv


Tags: Raumfahrt 

1448 Views

Samstag, 1. August 2015 - 23:00 Uhr

Raumfahrt-History - 1972: Wernher von Braun: Krieg im Kosmos gibt es nicht

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Aus dem CENAP-Archiv:

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Quelle: HöRZU, CENAP-Archiv


Tags: Raumfahrt 

1362 Views

Samstag, 1. August 2015 - 18:00 Uhr

Raumfahrt - Boeing´s XS-1 Experimenteller Raumgleiter

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Pentagon satellite-launching UAV development enters new phase ahead of 2016 competition
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Key Points
DARPA has awarded Boeing USD6.6 million to continue work on the XS-1 Experimental Spaceplane
The agency plans to hold a Phase II competition among the three teams working on the project next year for the follow-on production order
The Pentagon's Defense Advanced Research Projects Agency (DARPA) has awarded Boeing a contract modification worth USD6.6 million to continue work on the XS-1 Experimental Spaceplane, according to a 28 July announcement to Congress.
The programme is developing a reusable, unmanned booster with costs, operation, and reliability similar to modern aircraft that will launch small-payload satellites of 3,000 to 5,000 lb into low-Earth orbit. XS-1 would employ a reusable first stage to fly to hypersonic speeds at a suborbital altitude. Then, one or more expendable upper stages would separate and deploy a satellite into Low Earth Orbit. The reusable first stage would then return to earth and be prepared for the next flight.
Under Phase 1B, Boeing is responsible for developing a demonstration concept and core technologies for XS-1, DARPA said in a statement. The award of Phase 1B brings the total value of the Boeing team's work to date from USD10 million to USD16.6 million, according to the statement. Boeing is providing USD6 million of the costs, while DARPA is funding the remainder. Work on this phase is expected to be completed by August 2016.
DARPA wants XS-1 to fly as often as daily in a 10-day period at a cost of less than USD5 million per flight. It wants a vehicle that can reach speeds in excess of Mach 10, according to the agency.
Boeing and partner Blue Origin was one of three company teams chosen by DARPA in 2014 to begin designing the XS-1. The other teams were Northrop Grumman with Virgin Galactic, and Masten Space Systems with XCOR.
DARPA plans to hold a Phase II competition next year for the follow-on production order to build the vehicle and conduct demonstration flights, according to the statement.
Quelle: IHS JANE

Tags: Raumfahrt 

1428 Views

Samstag, 1. August 2015 - 15:39 Uhr

Astronomie - Radarbilder von Asteroid 1999 JD6 vom 25. Juli 2015

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Radar images of asteroid 1999 JD6 were obtained on July 25, 2015. The asteroid is between 660 - 980 feet (200 - 300 meters) in diameter. Image credit: NASA/JPL-Caltech/GSSR

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Earth Flyby of 'Space Peanut' Captured in New Video

NASA scientists have used two giant, Earth-based radio telescopes to bounce radar signals off a passing asteroid and produce images of the peanut-shaped body as it approached close to Earth this past weekend.
The asteroid appears to be a contact binary -- an asteroid with two lobes that are stuck together.
The images show the rotation of the asteroid, named 1999 JD6, which made its closest approach on July 24 at 9:55 p.m. PDT (12:55 a.m. EDT on July 25) at a distance of about 4.5 million miles (7.2 million kilometers, or about 19 times the distance from Earth to the moon).
"Radar imaging has shown that about 15 percent of near-Earth asteroids larger than 600 feet [about 180 meters], including 1999 JD6, have this sort of lobed, peanut shape," said Lance Benner of NASA's Jet Propulsion Laboratory in Pasadena, California, who leads NASA's asteroid radar research program.
To obtain the views, researchers paired NASA's 230-foot-wide (70-meter) Deep Space Network antenna at Goldstone, California, with the 330-foot (100-meter) National Science Foundation Green Bank Telescope in West Virginia. Using this approach, the Goldstone antenna beams a radar signal at an asteroid and Green Bank receives the reflections. The technique, referred to as a bistatic observation, dramatically improves the amount of detail that can be seen in radar images. The new views obtained with the technique show features as small as about 25 feet (7.5 meters) wide.
The individual images used in the movie were generated from data collected on July 25. They show the asteroid is highly elongated, with a length of approximately 1.2 miles (2 kilometers) on its long axis. The movie spans a period of about seven hours, 40 minutes.
This week's flyby was the closest approach the asteroid will make to Earth for about the next 40 years. The next time it will approach Earth this closely is in 2054, at approximately the same distance of this week's flyby.
Data from the new observations will be particularly useful to Sean Marshall, a graduate student at Cornell University in Ithaca, New York, whose doctoral research on 1999 JD6 is funded by NASA's Near-Earth Object Program. "I'm interested in this particular asteroid because estimates of its size from previous observations, at infrared wavelengths, have not agreed. The radar data will allow us to conclusively resolve the mystery of its size to better understand this interesting little world," he said.
Despite the uncertainty about its size, asteroid 1999 JD6 has been studied extensively and many of its physical properties, as well as its trajectory, are well known. It rotates in just over seven-and-a-half hours and is thought to be a relatively dark object. Asteroid 1999 JD6 was discovered on May 12, 1999, by the Lowell Observatory Near-Earth-Object Search, located in Flagstaff, Arizona.
Radar is a powerful technique for studying an asteroid's size, shape, rotation, surface features and surface roughness, and for improving the calculation of asteroid orbits. Radar measurements of asteroid distances and velocities often enable computation of asteroid orbits much further into the future than would be possible otherwise.
NASA places a high priority on tracking asteroids and protecting our home planet from them. In fact, the U.S. has the most robust and productive survey and detection program for discovering near-Earth objects (NEOs). To date, U.S. assets have discovered over 98 percent of the known NEOs.
In addition to the resources NASA puts into understanding asteroids, it also partners with other U.S. government agencies, university-based astronomers, and space science institutes across the country, often with grants, interagency transfers and other contracts from NASA, and also with international space agencies and institutions that are working to track and better understand these objects.
NASA's Near-Earth Object Program at NASA Headquarters, Washington, manages and funds the search, study and monitoring of asteroids and comets whose orbits periodically bring them close to Earth. JPL manages the Near-Earth Object Program Office for NASA's Science Mission Directorate in Washington. JPL is a division of the California Institute of Technology in Pasadena.
Quelle: NASA

Tags: Astronomie 

1382 Views

Samstag, 1. August 2015 - 12:30 Uhr

Raumfahrt-History - 1961: Venera-1 Flug zur Venus

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Venera 1 startete am 12. Februar 1961 und verließ die Erdumlaufbahn. Allerdings brach der Kontakt zu der Sonde bereits am 19. Februar 1961 in 2 Millionen Kilometern Entfernung zur Erde ab. Die stumme Sonde flog am 20. Mai 1961 in 100.000 km Entfernung an der Venus vorbei, womit sie das erste vom Menschen erzeugte Objekt war, das in die Nähe der Venus kam. Die Sonde wog 643,5 kg.

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Venera 1 (Automatic Interplanetary Station) was the first spacecraft to fly by Venus. The probe consisted of a cylindrical body topped by a dome, totaling 2.035 meters in height, 1.050 meters in diameter, with a fueled mass of 643.5 kg. Two solar panels, with a total area of 2 square meters, extended radially from the cylinder. A large (over 2 meter diameter) high-gain net antenna was planned to transmit signals from Venus at 8 cm and 32 cm wavelengths. This antenna was attached to the cylinder. A 2.4 meter long omni-directional antenna arm was designed for 1.6 m wavelength transmissions, and a T-shaped antenna was used to transmit signals to Earth at 922.8 MHz at 1 bit/sec. Uplink commands were sent ot the spacecraft at 770 MHz at 1.6 bit/sec. The probe was equipped with scientific instruments including a magnetometer attached to the end of a 2 meter boom, ion traps, micrometeorite detectors, and cosmic radiation counters. The dome contained a sphere pressurized at 1.2 atm., which carried a Soviet pennant and was designed to float on the putative Venus oceans after the intended Venus impact. Venera 1 had an on-board mid-course correction engine (although this was not labelled in diagrams of the spacecraft). Temperature control, nominally 30 C, was achieved with thermal shutters. Attitude control was achieved through the use of Sun and star sensors, gyroscopes, and nitrogen gas jets.
Venera 1 was launched on 12 February 1961 along with an Earth orbiting launch platform (Tyazheliy Sputnik 5 (61-003C)) with a SL-6/A-2-e launcher. From a 229 x 282 km, 65.7 degree inclination orbit, the Venera 1 automatic interplanetary station was launched from the platform towards Venus with the fourth stage Zond rocket. Two communications sessions were achieved in the days right after launch, one on 12 February at a distance of 126,300 km, and one on 13 February at 488,900 km. The station was scheduled to transmit nominally every 5 days. On 17 February, a communication session took place from 1.89 million km, showing normal operations with temperature of 29 C and pressure of 900 mm inside the dome. The scientific instruments also returned data. On 22 February a command session was held at 3.2 million km, according to the OKB-1 Design Bureau the commands were acknowledged, but this has also been reported as a failure and the last successful communications may have been on 17 February. On 27 February "fadeouts" were reported, there is no record of successful communication. On 4 March, at a distance of 7.5 million km, communications failed, and no further contact was made with Venera 1. The mid-course correction motors could not be fired, and on May 19 and 20, 1961, Venera 1 passed within 100,000 km of Venus and entered a heliocentric orbit.
Quelle: NASA
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Quelle: CENAP-Archiv

Tags: Raumfahrt 

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