The space agency is also working on a Crew Exploration Vehicle - or CEV - which would ferry crews of up to six astronauts and their cargo into space.

• 最近几年，对美国宇航局来说可谓是步履维艰。由于哥伦比亚号航天飞机在2003年重返地面的时候在德克萨斯州上空解体，美国的载人宇宙飞行停顿了两年多。