Orbital spaceflight
From Academic Kids
An 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. Template:Aero-stub
