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While scientists are searching the cause of the Columbia disaster, NASA is moving ahead with plans to develop a new craft that would replace shuttles(航开飞机)on space station missions by 2012 and respond quickly to space station emergencies.
The space agency released the first set of mission needs and requirements several days ago for me orbital space plane(轨道航天飞机), which would be designed to transport a crew of four to and from the International Space Station.
Although it includes few specifics, the plan states the orbiter(轨道航天飞机)will be safer cheaper and require less preparation time than the shuttle. It would be able to transport four crew members by 2012--though it would be available for rescue missions by 2010 NASA says the craft should be able to transport injured or ill space station crew- members to "definitive(决定性的) medical care" within 24 hours.
The release of the requirements showed NASA rema
A. be used to rebuild the International Space Station.
B. B. be awarded to the scientists working at NAS
C. be shared by the two projects under the Space Launch Initiative
D. be spent on the investigation of the Columbia disaster.