The Pentagon is unable to explain images of what witnesses took to be a high-altitude rocket launched off the coast of southern California at sunset Monday, officials said.

有官员说，美国五角大楼无法解释星期一傍晚在加州南部出现的类似于高空发射火箭后产生的凝结尾流。

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The low-pollution plane to carry between 50 and 100 passengers will take off using normal engines powered by biofuel made from seaweed before switching on its rocket engines at altitude.

该低污染的飞机可以搭载50到100名乘客，起飞时飞机使用从海藻中提炼的生物燃料驱动的常规引擎，当爬升到特定高度时，飞机会切换到火箭引擎。

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During next week?s launch test, the flight is expected to last just over two minutes and reach an altitude of about 28 miles (45 km) as the Ares I-X rocket launches eastward over the Atlantic Ocean.

在下周的发射测试中，“战神I-X”将向东发射在大西洋上空，高度将达到约28英里（45公里），预计飞行时间将持续约两分多钟。

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Will Whitehorn, Virgin Galactic's president, said that one of the things which attracted Aabar was the fact that White Knight (an aircraft which lifts to high altitude a rocket that can then take either passengers or satellites onwards into space) could be flown from Abu Dhabi.

ECONOMIST: Space

Later this year a rocket incorporating the new motor will make an attempt on the UK rocket altitude record, which stands at 10, 540 m (34, 579 ft) and is held by the Mars group.

BBC: Hybrid success for British rocket

He said the rocket reached an altitude of approximately 200 miles, solidly into space, and just 50 miles below the International Space Station.

NPR: SpaceX Makes Progress with Rocket Test