Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. The Boeing X-37, also known as the X-37 Orbital Test Vehicle, is a reusable unmanned spacecraft, operated by the United States Air Force for orbital spaceflight missions intended to demonstrate reusable space technologies. Boosted into space by a rocket, then re-entering Earth's atmosphere and landing as a spaceplane having spent 469 days in space, the X-37 successfully completed its mission, though most of the mission parameters for the first flight have not been disclosed, as it still remains a a classified project. Learn more about what is known about the mysterious robotic vertical-takeoff, horizontal-landing spaceplane in the following pages.