X-40A Credit - NASA

Boeing X-40A Experimental Space Maneuver Vehicle was built to test landing technologies for the later X-37.

The X-40A successfully completed a series of seven approach and landing tests at NASA Dryden in 2000 and 2001. About 20 percent smaller than the X-37, the X-40A was released from a helicopter at 4600 m during the series of unpowered glide flights. These flights validated the autonomous flight control system planned for the X-37, thereby reducing the risk of the X-37 program.