Suborbital Flight

the flight of a spacecraft along a ballistic trajectory at a velocity less than that needed to achieve earth orbit. A suborbital flight consists of three phases: flight during operation of the launch vehicle’s rocket engines, flight along a ballistic trajectory, and reentry with atmospheric braking and descent. US manned suborbital flights were carried out in Mercury spacecraft by A. Shepard on May 5, 1961, and by V. Grissom on July 21, 1961. Grissom’s flight covered 504 km in approximately 16 min, reaching a maximum altitude of 189 km.