美国航天飞机２的改进措施美国目前正处在为航天业未来的发展做重大决策的关键阶段，其中很重要的一项决策便是关于现役航天飞机发射系统的更新换代问题的。来自国外运载系统的竞争和现役航天飞机过高的使用成本迫使美国必须尽早就此做出抉择。美国航宇局的一位宇航技术专... Improvements to U.S. Space Shuttle 2 The United States is currently in the crucial stage of making major decisions on the future development of the aerospace industry. One of the most important decisions is about the upgrading of launch systems for active space shuttles. Competing from foreign delivery systems and the high cost of using space vehicles on active duty have compelled the United States to make a decision as soon as possible. A NASA aerospace technology specialist ...