摘要
Abstract
After canceling Constellation program,to transport crew and cargo to International Space Station（ISS） after the shuttle＇s retirement,America will depend on commercial transport system to transport crew and cargo to ISS.The papar describes the situation and development of American human spaceflight commercial transportation program.The purpose of the program is to reduce cost and shorten the gap,and the program includes commercial cargo tranpotation service,commercial resupply service and commercial crew development programs.The predominance of commercial vehicles is low-cost,and some spacecraft are reusable.To ensure the safety of commercial transportation system,NASA will strictly monitor and manage the program.The prospect of commercial transportation system is optimistic,and it will become the important transportation vehicles to ISS in the future.关键词
载人航天/“国际空间站”/商业乘员和货物运输/商业轨道运输服务/商业乘员开发Key words
hunman spaceflight/International Space Station/commercial crew and cargo transportation/commercial orbit transportation service/commercial crew development分类
航空航天
