The world's first privately developed spacecraft-launch vehicle and the first winged vehicle to accelerate to eight times the speed of sound. Pegasus carried out its first mission in 1990 and had conducted a total of 35 by 2004. The three-stage, delta-wing rocket is first carried to about 12 200 m by aeroplane, and then released with its payload to free-fall for five seconds before its motor is fired. The satellites, which each weigh up to 450 kg, are placed into a low orbit. Of the more than 43 launches conducted by 2017, there have been 29 consecutive fully successful missions and only three failures. Satellite launches include NASA's Reuven Ramaty High-Energy Solar Spectroscopic Imager (RHESSI) on 5 February 2002, the Canadian Space Agency's Science Satellite (SCISAT-1) on 12 August 2003, and NASA’s Cyclone Global Navigation Satellite System (CYGNSS) in 2016.

The launcher was created and built by Orbital ATK; Orbital's Stargazer L-1011 aircraft carries Pegasus. Orbital's Hyper-X launch vehicle was flight-proven on a Pegasus rocket before it launched NASA's X-43A hypersonic research aircraft which set the aeronautical speed record on 27 March 2004.