Pegasus is an air-launched launch vehicle developed by Orbital Sciences Corporation (OSC) and now built and launched by Northrop Grumman. Capable of carrying small payloads of up to into low Earth orbit, Pegasus first flew in 1990 and remains active . The vehicle consists of three solid propellant stages and an optional monopropellant fourth stage. Pegasus is released from its carrier aircraft at approximately , and its first stage has a wing and a tail to provide lift and attitude control while in the atmosphere. Notably, the first stage does not have a thrust vector control (TVC) system. History Pegasus was designed by a team led by Antonio Elias. The Pegasus's three Orion solid motors were developed by Hercules Aerospace (later Alliant Techsystems) specifically for the Pegasus launcher but using advanced carbon fiber, propellant formulation and case insulation technologies originally developed for the terminated USAF Small ICBM program. The wing and fins' structures were designed by Burt Rutan and his company, Scaled Composites, which manufactured them for Orbital. Mass: 18,500 kg (Pegasus), 23,130 kg (Pegasus XL) Length: 16.9 m (Pegasus), 17.6 m (Pegasus XL) Diameter: 1.27 m Wing span: 6.7 m Payload: 443 kg (1.18 m diameter, 2.13 m length) Started in the spring of 1987, the development project was funded by Orbital Sciences Corporation and Hercules Aerospace, and did not receive any government funding. Government funding was received to support operational testing. NASA did provide the use of the B-52 carrier aircraft on a cost-reimbursable basis during the development (captive carry tests) and the first few flights. Two Orbital internal projects, the Orbcomm communications constellation and the OrbView observation satellites, served as anchor customers to help justify the private funding. There were no Pegasus test launches prior to the first operational launch on 5 April 1990 with NASA test pilot and former astronaut Gordon Fullerton in command of the carrier aircraft. Initially, a NASA-owned B-52 Stratofortress NB-008 served as the carrier aircraft. By 1994, Orbital had transitioned to their "Stargazer" L-1011, a converted airliner which was formerly owned by Air Canada. The name "Stargazer" is an homage to the television series Star Trek: The Next Generation: the character Jean-Luc Picard was captain of a ship named Stargazer prior to the events of the series, and his first officer William Riker once served aboard a ship named Pegasus. During its 45-launch history, the Pegasus program had three mission failures (STEP-1,