The X-34 technology demonstrator was a NASA-funded program to demonstrate low-cost reusable launch technologies in an autonomous rocket-powered space plane. While not meant to reach orbit, X-34 was designed to reach a speed of Mach 8, fly to 250,000 feet and autonomously return to Earth for a runway landing to mimic the characteristics of the first stage of a reusable launcher. Powered by an oxygen-kerosene powered rocket engine, X-34 was designed to be air-launched from the belly of Orbital’s Stargazer L-1011 carrier aircraft, much like our Pegasus® space launch vehicle.
Between 1998 and 1999 Orbital delivered two X-34 vehicles and conducted captive carry flights of the first airframe mated to the L-1011 in April 1999. Unfortunately, X-34 was not destined to fly under its own power. The program was cancelled in early 2001.