但是最近，公司已经开始计划更便宜的“亚轨道”飞行，在太空无际黑暗的边缘进行更短时间的冒险。
But more recently, companies have begun to plan more affordable "suborbital" flights—briefer ventures just to the edge of space's vast darkness.
最近，一些公司已经开始计划更经济实惠的“亚轨道”飞行——在太空无际黑暗的边缘进行更短时间的冒险。
More recently, companies have begun to plan more affordable "suborbital" flights—briefer ventures just to the edge of space's vast darkness.
今年早些时候，美国国防高级研究计划局宣布将计划出资，请波音公司研究编队飞行，不过该计划尚未启动。
Earlier this year the country's Defense Advanced Research Projects Agency announced plans to pay Boeing to investigate formation flight, though the program has yet to begin.
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