This is an artist's concept of the X-34 reusable technology testbed demonstrator on-orbit. The X-34 was designed to demonstrate technologies that are essential to lowering the cost of access to space. Powered by a LOX and RP-1 liquid Fastrac engine designed and built by the Marshall Space Flight Center, the X-34 would be capable of speeds up to Mach 8 and altitudes of 250,000-feet. The X-34 program was cancelled in 2001.