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Orbital SpaceflightAn orbital spaceflight (or orbital flight) in the general sense is a spaceflight where the trajectory of a spacecraft reaches the height of, and through having an appropriate velocity enters into, orbit around an astronomical body. Most commonly the term is applied specifically to Earth orbit: reaching Earth orbit from the Earth's surface. In this latter sense, the expression "orbital spaceflight" is mostly used to distinguish from sub-orbital spaceflights, which are flights where the spacecraft reaches space but does not go fast enough to complete a single orbit. Note too that the edge of space (100 km) is much lower than the altitude where a vehicle can circle the earth even once without reentering due to atmospheric drag. Also note that the required speed to "go orbital" (to achieve orbit with known methods) requires atleast 9 km/s (18,000 mph) delta-v, while sub-orbital spacecraft may only fly at about 1.1 km/s to 1.3 km/s (2,500 mph to 3,000 mph). Refer to the article Difference between sub-orbital and orbital spaceflights for further information. There are three main 'bands' of orbit: low Earth orbit, intermediate circular orbit and geostationary orbit. Project HARP was a failed attempt, and a ram accelerator is another design, to launch an object into orbit with a gun, possibly with additional propulsion by a rocket.
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