But while higher is better from a fuel conservation perspective, there is an upper limit on how high it is safe to orbit humans for long periods.
越高耗费的燃料越少，而载人飞船能够长时间安全飞行的轨道高度就有上限。
China will conduct research into the technologies for low-cost launch vehicles, new upper stage and the reusable space transportation system between the earth and low-earth orbit.
开展低成本运载火箭、新型上面级、天地往返可重复使用运输系统等技术研究。
The satellite was released from the launcher upper stage and entered the projected orbit.
卫星同发射装置分离进入指定轨道。
NASA's Upper Atmosphere Research Satellite will fall out of orbit soon, with large pieces perhaps reaching Earth's surface, according to NASA's Nick Johnson at a telephone press conference.
美国国家航空和宇宙航行局发言人尼克·约翰逊在一个电话新闻发布会中表示，美国国家航空和宇宙航行局的高层大气研究卫星即将脱离轨道，大片的残余物可能会落到地球表面。
NASA's Upper Atmosphere Research Satellite will fall out of orbit soon, with large pieces perhaps reaching Earth's surface, according to NASA's Nick Johnson at a telephone press conference.
美国国家航空和宇宙航行局发言人尼克·约翰逊在一个电话新闻发布会中表示，美国国家航空和宇宙航行局的高层大气研究卫星即将脱离轨道，大片的残余物可能会落到地球表面。
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