X-38 in hangar

Another recent prototype was the X-38 Crew Return Vehicle design, which NASA says was intended to help develop a spacecraft that could serve as a "lifeboat" for the International Space Station, among other uses. In this 1998 photo, an X-38 sits in a hangar at NASA's Dryden Flight Research Center. The project used off-the-shelf technology in order to keep costs down. For instance, NASA says, the flight computer in the X-38 was commercial equipment that was in use in aircraft at the time, and the flight software operating system also was a commercial system.

Clearly reflecting its lifting-body lineage, the X-38 prototype vehicle (several were made) was 28 feet long and 14 feet wide, and weighed approximately 16,000 pounds. The X-38 was built by Scaled Composites, which more recently has been involved in the SpaceShipOne and SpaceShipTwo projects that are at the forefront of the nascent commercial spaceflight industry.