Het Astronomie Topic #5

quote:

Op vrijdag 1 april 2011 09:03 schreef ExperimentalFrentalMental het volgende:
31-03-2011

Zwaartekrachtsveld aarde in kaart gebracht

[ afbeelding ]

Na meer dan twaalf maanden meten heeft de Europese GOCE-satelliet genoeg gegevens verzameld om het zwaartekrachtsveld van de aarde nauwkeuriger dan ooit in kaart te brengen. Het resultaat, een driedimensionaal model dat een geoïde wordt genoemd, werd donderdag in München gepresenteerd.

De geoïde is het oppervlak van een denkbeeldige, wereldomvattende oceaan waarin geen getijden en stromingen optreden. De vorm ervan wordt uitsluitend bepaald door het feit dat de aantrekkingskracht aan het oppervlak van onze planeet niet overal even groot is. Het model wordt onder meer gebruikt om oceaanstromingen en veranderingen van de zeespiegel te leren begrijpen.

De GOCE-gegevens geven ook meer inzicht in het ontstaan van grote aardbevingen. Deze worden immers veroorzaakt door plotselinge bewegingen van de tektonische platen van onze planeet, die niet rechtstreeks waarneembaar zijn. Die bewegingen leiden echter ook tot veranderingen in de zwaartekrachtsaantrekking ter plaatse.

© Eddy Echternach (www.astronieuws.nl)

(allesoversterrenkunde)

Radio communications between Yuri Gagarin, Sergei Korolev and Ground Control

YURI GAGARIN DEATH SONG MUSIC VIDEO SUNG BY ELLA GONCHAROVA-BODER

quote:

Cause of jet crash
The cause of the crash that killed Gagarin is not entirely certain, and has been subject to speculation and conspiracy theories over the ensuing decades.

Russian documents declassified in March 2003 showed that the KGB had conducted their own investigation of the accident, in addition to one government and two military investigations. The KGB's report dismissed various conspiracy theories, instead indicating that the actions of air base personnel contributed to the crash. The report states that an air traffic controller provided Gagarin with outdated weather information, and that by the time of his flight, conditions had deteriorated significantly. Ground crew also left external fuel tanks attached to the aircraft. Gagarin's planned flight activities needed clear weather and no outboard tanks. The investigation concluded that Gagarin's aircraft entered a spin, either due to a bird strike or because of a sudden move to avoid another aircraft. Because of the out-of-date weather report, the crew believed their altitude to be higher than it actually was, and could not properly react to bring the MiG-15 out of its spin.[21]

In his 2004 book Two Sides of the Moon, Alexey Leonov recounts that he was flying a helicopter in the same area that day when he heard "two loud booms in the distance." Corroborating other theories, his conclusion is that a Sukhoi jet (which he identifies as a Su-15 'Flagon') was flying below its minimum allowed altitude, and "without realizing it because of the terrible weather conditions, he passed within 10 or 20 meters of Yuri and Seregin's plane while breaking the sound barrier." The resulting turbulence would have sent the MiG into an uncontrolled spin. Leonov believes the first boom he heard was that of the jet breaking the sound barrier, and the second was Gagarin's plane crashing.[22]

Another theory, advanced by the original crash investigator in 2005, hypothesizes that a cabin air vent was accidentally left open by the crew or the previous pilot, leading to oxygen deprivation and leaving the crew incapable of controlling the aircraft.[23] A similar theory, published in Air & Space magazine, is that the crew detected the open vent and followed procedure by executing a rapid dive to a lower altitude. This dive caused them to lose consciousness and crash.[24]

On 12 April 2007, the Kremlin vetoed a new investigation into the death of Gagarin. Government officials said that they saw no reason to begin a new investigation.[25]

In April 2011, documents from a 1968 commission setup by the Central Committee of the Communist Party to investigate the accident were declassified. Those documents revealed that the commission's original conclsuion was that either Gagarin or Seryogin had manoeuvred sharply, likely to avoid a weather balloon, leading the jet into a "supercritical flight regime and to its stalling in complex meteorological conditions". The report also suggested the jet may have been manoeuvring sharply to avoid "entry into the upper limit of the first layer of cloud cover".

quote:

Op woensdag 17 november 2010 08:26 schreef ExperimentalFrentalMental het volgende:
16-11-2010

Compacte dubbelsterren staan op ploffen

[ afbeelding ]

Astronomen hebben in ons Melkwegstelsel een tiental bijzondere dubbelstersystemen ontdekt. Elk van de sterparen bestaat uit twee witte dwergsterren en de helft ervan zal binnen (astronomisch) afzienbare tijd tot ontploffing komen.

Een witte dwerg is het hete, uitgeputte restant van een zonachtige ster die zijn buitenlagen heeft afgestoten. Zo'n dwergster is niet veel groter dan de aarde, maar kan de massa van de zon benaderen. De nu ontdekte witte dwergen zijn met éénvijfde zonsmassa overigens aan de lichte kant.

In de onderzochte dubbelstersystemen spiralen de beide dwergsterren geleidelijk naar elkaar toe. In de helft van de gevallen zal dat er uiteindelijk toe leiden dat de ene ster de andere opslokt. In één geval zal dat 'al' binnen honderd miljoen jaar gebeuren.

Wanneer twee van deze dwergsterren zich met elkaar verenigen, kan hun gezamenlijke massa een kritieke waarde overschrijden. Het resultaat is dan een supernova-explosie, maar waarschijnlijk wel een relatief zwakke variant.

© Eddy Echternach (www.astronieuws.nl)

(allesoversterrenkunde)

quote:

Op zondag 10 april 2011 21:42 schreef Schonedal het volgende:

[..]

Dit soort artist impressions van dubbelsterren hebben naar mijn idee een specifieke fout.
Als twee hemellichamen om elkaar heen draaien zoals het stelsel aarde maan zullen er twee vloedbergen ontstaan.
De grote gasvormige ster zal dat dus ook hebben alleen aan een kant wordt het gas door de witte dwerg opgeslokt aan de andere zijde wordt het gas de ruimte ingeslingerd.
Het uitstromende gas krijgt bovendien door de rotatie een S vorm.
Dit wordt meestal vergeten.

SPOILER

Om spoilers te kunnen lezen moet je zijn ingelogd. Je moet je daarvoor eerst gratis Registreren. Ook kun je spoilers niet lezen als je een ban hebt.

quote:

Dutch initiative SpaceLinq announces that it will operate as Europe's first spaceflight operator from within Holland's territory. Lelystad Airport is the proposed home base for the future EU Spaceport Lelystad, as long as all regulation and approval from the government and Airport partners will be granted. It also requires investigating planning, environmental and safety issues.
"Nonetheless, we are very excited about the opportunities to service the EU spaceflight market from Lelystad", says Chuck Lauer, US co-founder of SpaceLinq.

"We choose Lelystad for its location next to the sea and close proximity to the North Sea military reserve airspace. Besides, the open space and available land, plus the desire of the community to encourage new technology and industry are other reasons to choose Lelystad as SpaceLinq`s domicile.

"Also important to choose Holland is the fact that the European spaceflight market may be the largest in the world, and the Amsterdam region is already one of the greatest tourist destinations on the planet."

Flights can be expected to take place as soon as June, 2015.

Space: the next commercial frontier
The changing landscape of the space arena is giving birth to privately funded initiatives around the globe. SpaceLinq NV, Europe's first spaceliner to propose operating spaceflights from within European airspace, has chosen the Lelystad Airport as its future base for flight operations. With a unique mission profile and vehicle architecture, SpaceLinq is able to launch and re-enter the atmosphere from almost every standard, commercial airport.

The privatization trend in the US is catching on in Europe and other regions. With new government cutbacks being announced daily, the focus and demand of spaceflight services has shifted to the private sector market. SpaceLinq will provide short and long-term benefits to the scientific community as well as the tourist and payload markets.

By selling flights to the nearby Dutch and German space organizations, SpaceLinq will capture the market demand for less expensive and more frequent opportunities for microgravity research, astronomy, climate research, and small satellite launch.

The European Space Agency is also interested in the potential use for commercial suborbital vehicles for microgravity research, Earth observation and remote sensing applications, astronomy, and small satellite launch. SpaceLinq submitted its plans for suborbital flight services to ESA under its Request for Information solicitation in February.

The SpaceLinq spaceliner vehicle will seat one pilot plus five customers when flying space tourism flights. For research purposes the four rear seats are removed and replaced with experiment racks or other payloads, while leaving the front right seat in place for payload operators or researchers to fly and operate their experiments.

The spaceplane will use turbojet engines for takeoff and landing and a liquid oxygen / kerosene main rocket engine to power the ascent to space and over three minutes of weightlessness as the vehicle coasts up to the 100 km+ peak altitude and back. Its technical development has brought the design to a level of maturity that reassures investor confidence to see the vehicle through, all the way to the final testing stage.

"We are very excited about the opportunities to service the EU spaceflight market from Lelystad" says Chuck Lauer, the US co-founder of SpaceLinq.

"We choose Lelystad for its location next to the sea and close proximity to the North Sea military reserve airspace. Besides, the open space and available land, plus the desire of the community to encourage new technology and industry are other reasons to choose Lelystad as SpaceLinq`s domicile.

"Also important to choose Holland is the fact that the European spaceflight market may be the largest in the world, and the Amsterdam region is already one of the greatest tourist destinations on the planet, with great hotels, museums, fine dining and numerous cultural events and attractions. Combining this incredible base of existing Five Star tourism infrastructure with the new opportunities for exciting and breathtakingly beautiful commercial spaceflight will be a winning formula."