The Pegasus rocket is a winged space launch vehicle capable of carrying small, unmanned satellites (443 kilograms) into low Earth orbit. It is air-launched, as part of an expendable launch system developed by Orbital Sciences Corporation (Orbital). Three main stages burning solid propellant provide the thrust. It flies as a rocket-powered aircraft before leaving the atmosphere.
The Pegasus is carried aloft below a carrier aircraft and launched at approximately 40,000 ft (12,000 m). The carrier aircraft provides flexibility to launch the rocket from anywhere rather than just a fixed pad. A high-altitude, winged flight launch also allows the rocket to avoid flight in the densest part of the atmosphere where a larger launch vehicle, carrying much more fuel, would be needed to overcome air friction and gravity.