Blastoff for the spacecraft which could one day take humans to Mars is set for the final countdown as Nasa begins assembling the giant rockets that will propel it into orbit. The huge Delta IV Heavy rocket has been put together for the first time at Cape Canaveral Air Force Station in Florida ahead of a first test flight of the Orion capsule in December. It will blast the experimental  capsule in orbit - although the rockets are then expected to be replaced by Nasa's even bigger Space Launch system. Scroll down for video The huge Delta IV Heavy rocket has been put together for the first time at Cape Canaveral Air Force Station in Florida ahead of a first test flight of the Orion capsule in December, a mission known as Exploration Flight Test-1.
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Three Delta IV boosters collectively generate 1.96 million pounds of thrust
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Orion capsule will undergo first test flight in December
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Comes as Nasa bosses reveal private contracts for shuttle replacement so they can concentrate on the project
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