据报道，今年7月，与失事航天飞机同类型的一个飞行器已经完成了大约一半。
In July, a sister craft of the crashed spaceplane was reported to be about half-finished.
体型和质量相当于航天飞机的飞行器制造的两个音爆则非常容易区分，人们经常很容易地听到两次响声。
Sonic booms created by vehicles the size and mass of the space shuttle are very distinguishable and two distinct booms are easily heard.
美国航空航天局已经取消了建造后航天飞机时代太空飞行器的计划。
NASA has cancelled its plans for a post-shuttle space vehicle. Until U.
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