* Astronomy

Aviation Week & Space Technology is reported that the "highly classified" project funded by the U.S. military for the development and testing of a small orbital space plane in the 1990s. The project involved a large carrier aircraft called the SR-3, modelled on the XB-70 Valkyrie supersonic bomber of the 1960s, as well as a small space plane called the XOV (for "experimental orbital vehicle").
The mothership would carry the XOV under its fuselage, rise to high altitude, then release the space plane at supersonic speeds. After the release, the XOV would fire its rocket engines to rise into orbit, and the mothership would return to base.

At the end of its mission, the the two-person XOV space vehicle which may have made more than one orbital mission, would return to Earth along a flight profile much like that of the space shuttle.

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