1·NASA's shuttle fleet will be retired next year.
明年，NASA的航天飞机即将退役。
2·This flight is one of the last scheduled for the space shuttle fleet.
这次“发现号”飞行是太空梭机群仅剩几次飞行中的一次。
3·It is the oldest and longest-serving vehicle in the U. S. space agency's shuttle fleet.
发现号是美国太空总署航天飞机机队里最老、服役年头最长的一架航天飞机。
4·NASA needs to finish building the station by 2010 when the shuttle fleet is due to be retired.
美国航空航天局计划在2010年航天飞机退役前，完成空间站的建设工作。
5·The Ares I booster is designed to launch NASA's Orion spacecraft slated to replace the shuttle fleet.
战神I号火箭的设计目的是发射预计将取代航天飞机的NASA猎户座宇宙飞船。
6·The original plan called for building a shuttle fleet and an orbiting space station at the same time.
原计划要求建立一航天飞机机群以及同时建一个轨道空间站。
7·The Discovery lift-off is planned to be the penultimate launch before the shuttle fleet retires early next year.
发现号的升空是明年前半年航天飞机机队退役前的倒数第二次发射。
8·The aging shuttle fleet has been fraught with so many problem that it has been difficult to get a successful launch of late.
老化的航天飞机一直存在着许多问题所以最近已经很难成功发射。
9·The space agency is due to retire the shuttle fleet this year to focus on developing a new spacecraft that can go beyond low-Earth-orbit .
由于“奋进号”即将退役，美国宇航局将重点研发能够超出低地球轨道的新的宇宙飞船。
10·After the Challenger and Columbia disasters, America's shuttle fleet was grounded, which explains the big drop in missions immediately after both accidents.
“挑战者”和“哥伦比亚”灾难后，美国航空队禁飞，即难后美国航空任务骤减的原因。