Flight is the process by which an object moves through an atmosphere (or beyond it, as in spaceflight) without contact with the surface. This can be achieved by generating aerodynamic lift associated with propulsive thrust, aerostatically using buoyancy, or by ballistic movement. Many things can fly, from natural aviators such as birds, bats, and insects, to human inventions like : aircraft, including airplanes, helicopters, balloons, and rockets which may carry spacecraft. The engineering aspects of flight are the purview of aerospace engineering which is subdivided into Aeronautics, The study of vehicles that travel through the air Astronautics, the study of vehicles that travel through space And ballistics, the study of the flight of projectiles.