Orbital Sciences X-34
 The Orbital Sciences X-34 was intended as a low-cost testbed to demonstrate key technologies integratable to the Reusable Launch Vehicle program. It was intended to be an autonomous pilotless craft powered by a 'Fastrac' liquid rocket engine capable of reaching Mach 8 and performing 25 test flights per year. The X-34 began as a program for a suborbital reusable-rocket technology demonstrator.