航天飞机是美国航宇局为廉价开发宇宙空间而研制的轨道输送空间飞机。与过去发射的仅飞行一次就抛弃的火箭相比,航天飞机则是具有发射100次寿命的历史上首次反复使用的空间飞机,能大幅度地降低发射费用。不过,最近的空间计划费用中的80%被消耗在航天飞机上,发射费用只占20%。但是, The space shuttle is a spacecraft that is being developed by NASA for the cheap development of space. Compared with the rocket launched in the past, which was abandoned only once, the space shuttle has the first time in history that the launch of a space shuttle launchers 100 life cycles, and the launch cost can be greatly reduced. However, 80% of the most recent space program costs are spent on space shuttles, with launch costs accounting for only 20%. but,