The Hellenic Navy (HN) (Greek: Πολεμικό Ναυτικό, Polemikó Naftikó, abbreviated ΠΝ) is the naval force of Greece, part of the Greek Armed Forces. The modern Greek navy has its roots in the naval forces of various Aegean Islands, which fought in the Greek War of Independence. During the periods of monarchy (1833–1924 and 1936–1973) it was known as the Royal Navy (Βασιλικόν Ναυτικόν, Vasilikón Naftikón, abbreviated ΒΝ).The total displacement of all the navy's vessels is approximately 150,000 tons.The motto of the Hellenic Navy is "Μέγα το της Θαλάσσης Κράτος" from Thucydides' account of Pericles' oration on the eve of the Peloponnesian War. This has been roughly translated as "Great is the country that controls the sea". The Hellenic Navy's emblem consists of an anchor in front of a crossed Christian cross and trident, with the cross symbolizing Greek Orthodoxy, and the trident symbolizing Poseidon, the god of the sea in Greek mythology. Pericles' words are written across the top of the emblem. "The navy, as it represents a necessary weapon for Greece, should only be created for war and aim to victory."...............The Hellenic Merchant Marine refers to the Merchant Marine of Greece, engaged in commerce and transportation of goods and services universally. It consists of the merchant vessels owned by Greek civilians, flying either the Greek flag or a flag of convenience. Greece is a maritime nation by tradition, as shipping is arguably the oldest form of occupation of the Greeks and a key element of Greek economic activity since the ancient times. Nowadays, Greece has the largest merchant fleet in the world, which is the second largest contributor to the national economy after tourism and forms the backbone of world shipping. The Greek fleet flies a variety of flags, however some Greek shipowners gradually return to Greece following the changes to the legislative framework governing their operations and the improvement of infrastructure.Blogger Tips and Tricks
This is a bilingual blog in English and / or Greek and you can translate any post to any language by pressing on the appropriate flag....Note that there is provided below a scrolling text with the 30 recent posts...Αυτό είναι ένα δίγλωσσο blog στα Αγγλικά η/και στα Ελληνικά και μπορείτε να μεταφράσετε οποιοδήποτε ποστ σε οποιαδήποτε γλώσσα κάνοντας κλικ στη σχετική σημαία. Σημειωτέον ότι παρακάτω παρέχεται και ένα κινούμενο κείμενο με τα 30 πρόσφατα ποστς....This is a bilingual blog in English and / or Greek and you can translate any post to any language by pressing on the appropriate flag....Note that there is provided below a scrolling text with the 30 recent posts...Αυτό είναι ένα δίγλωσσο blog στα Αγγλικά η/και στα Ελληνικά και μπορείτε να μεταφράσετε οποιοδήποτε ποστ σε οποιαδήποτε γλώσσα κάνοντας κλικ στη σχετική σημαία. Σημειωτέον ότι παρακάτω παρέχεται και ένα κινούμενο κείμενο με τα 30 πρόσφατα ποστς.........

Wednesday, February 9, 2011

New rocket ....[2085 ]

New rocket could lift astronauts

Liberty concept (ATK) Liberty would launch from the Kennedy Space Center using existing infrastructure
Two of the world's leading rocket companies are joining forces to develop a new vehicle to launch astronauts into orbit.
The bottom part of the proposed Liberty rocket would be based on the solid-fuelled boosters that help get the shuttle off the ground.
The top half would use the liquid-fuelled core-stage technology and engine that powers the Ariane 5.
The concept has been put forward by ATK from the US and Astrium from Europe.
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Their idea is being submitted to the US space agency (Nasa), which is seeking commercial solutions to take astronauts to and from the space station following the retirement of the shuttles later this year.
There has been deep concern in the US Congress about the length of time it might take to provide commercial alternatives, leaving America reliant on Russian Soyuz vehicles until perhaps the latter part of this decade.
But ATK and Astrium believe their experience means they could have the 90m-high (300ft) Liberty rocket ready to fly by 2013, and operational with astronauts on board by 2015. 
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Liberty concept (ATK)
ATK's boosters are already rated to carry humans into space, and the Ariane 5 was originally conceived as an astronaut launcher.
"This team represents the true sense of international partnership in that we looked across borders to find the best for our customers," said Blake Larson, the president of ATK Aerospace Systems Group.
Ares-1 (USA)  
ATK produced the first-stage of a test version of the proposed Ares-1 crew-launch rocket
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"Together we combine unique flight-proven systems and commercial experience that allows us to offer the market's most capable launch vehicle along with flexibility to meet a wide variety of emerging needs. Liberty provides greater performance at less cost than any other comparable launch vehicle."
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Silvio Sandrone, Astrium's vice-president of launcher sales and business development, told BBC News: "It's a very cool idea; it's got the potential to be a fast development, building on existing experience and existing teams. Certainly it would be cheaper and faster than starting from scratch.
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"For Astrium, also, it means accessing a market which has been barred to us up until now."
ATK and Astrium say Liberty's ability to put about 20 tonnes in low-Earth orbit, the altitude occupied by the International Space Station, means it could loft any of the astronaut capsules currently in development. Some of these craft are also chasing financial support from Nasa's Commercial Crew Development (CCDev) Program.
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The space shuttle uses ATK's four-segment solid rocket boosters (SRBs) to do the major part of lifting the shuttle stack off the Earth. Liberty would use a first-stage that incorporated a larger, five-segment booster - a technology ATK has already been testing. 
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Dream Chaser  
Nasa is assisting a number of companies in the development of commercial crew systems
A five-segment booster would have formed the first stage of Nasa's Ares-1 crew launcher before it was abandoned as a concept. Indeed, in shape the Ares and Liberty designs look very similar.
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Europe's Ariane 5 was initially conceived as the launcher that would put a mini-shuttle, called Hermes, in orbit. When European Space Agency (Esa) member states decided to cancel this shuttle project on the grounds of cost, the Ariane 5 was turned into a commercial satellite launcher.
Today, this 50m-high rocket puts just over half of all the large telecommunications satellites in orbit each year.
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The Ariane's core stage, which is prepared in northern France, uses liquid hydrogen and liquid oxygen as its propellants. With its Vulcain-2 engine, this core stage has now powered Ariane on more than 40 consecutive successful missions over the past eight years. It is considered highly reliable.
"Obviously, there are modifications we will need to make. The Vulcain engine as you know is ignited on the ground, but on Liberty it would need to ignite in the vacuum of space. This is something Europe can do. Ariane's upper-stage has a cryogenic engine that can ignite in a vacuum," Mr Sandrone told BBC News.

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