Orbital Sciences' Stargazer L-1011 carrier aircraft with X-34 attached beneath.
Another artist's conception of the X-33, this time after engine shutdown.
X-34 Technology Testbed Demonstrator.
The unique XV-15 Tiltrotor aircraft is seen in vertical flight at the NASA Dryden Flight Research Center.
This is an artist's conception of the NASA/Lockheed Martin X-33 on the back of a modified 747 airliner.
Orbital Sciences' Stargazer L-1011 carrier aircraft with X-34 attached.
An overall view of the launch pad built for the X-33.
The XV-15 Tiltrotor aircraft undergoing tests on the VTOL stand.
X-34 technology testbed demonstrator.
An artist's conception of the X-33 in flight, with the aerospike engine firing.