Abstract: This invention is directed toward providing a transatmospheric launch system that is essentially totally reusable, provides wide flexibility in choice of orbit, and may be launched quickly on short notice. The system of the invention is a two-stage horizontal takeoff and landing system. An orbiter vehicle (50) is integrated into the underside of an aircraft (2). Aircraft (2) has a cavity (4) opening aftwardly and downwardly to receive vehicle (50). Vehicle (50) and aircraft (2) are releasably connected by struts (30, 32). Aircraft (2) and vehicle (50) proceed to staging conditions under air breathing and then rocket power. Rocket engine (22) of aircraft (2) is throttled to produce a thrust differential with rocket engine (66) of vehicle (50). This differential causes vehicle (50) to automatically pivot away from aircraft (2) on struts (30, 32). After pivoting out of cavity (4), vehicle (50) is disengaged from struts (30, 32) and proceeds on its own to orbit. Aircraft (2) makes a conventional landing.