The US Air Force's X-37B space plane is circling Earth and, although it is on a classified mission with an officially unpublished orbit, sky watchers have spotted it.

美国空军的 X-37B太空船当时正在环绕地球，在某个官方未公开的轨道执行秘密任务。 天空观察者发现了它。

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The plane was flown by NASA for 19 years as a "flying test bed, " according to the Smithsonian National Air and Space Museum, as well as a chase plane.

这架飞机是飞往美国航天局19为“飞行试验台年，”根据史密森国家航空航天博物馆，以及一个追逐飞机。

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The enemy plane was shot down the moment (that) it intruded into our air space.

这架敌机一侵入我国领空就被击落。

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This appears to be the mindset of the Air Force regarding its experimental X-37B space plane, the billion-dollar robotic vehicle's orbital flight being extended beyond the 270 days it was initially designed for.

ENGADGET: Air Force X-37B space plane books additional time on orbital cruise, orders another margarita