Suborbital Spaceflight

Suborbital spaceflight is a spaceflight in which the vehicle reaches outer space but its trajectory returns to the surface of the body it launched from without completing a full orbit, so the vehicle does not become an artificial satellite and does not reach the velocity needed to escape the planet's gravity. The internationally recognized boundary of space for this purpose is the Karman line, 100 kilometers above sea level, though the United States military and NASA have historically awarded astronaut wings for flights reaching a lower threshold of 50 miles (80 kilometers). Crewed suborbital vehicles include the rocket-powered X-15 research aircraft of the 1960s and, in the twenty-first century commercial spaceflight era, Virgin Galactic's SpaceShipTwo; uncrewed suborbital flight is also the basic trajectory of intercontinental ballistic missiles and scientific sounding rockets.