The U.S. Air Force's Boeing X-37B, which began as a NASA craft but was transferred to the Pentagon in 2004, is an unmanned space plane that looks like a small space shuttle. Like the shuttle, it returns to Earth and lands on a runway. It has been flying successfully for five years. A scaled-up version with an astronaut crew to work outside the vehicle could reestablish America's ability to build and maintain big structures in Earth orbit.
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