Dictionary of Meaning
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Orbital spaceflight
*** Shopping-Tip: Orbital spaceflight
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
outer space space but does not go fast enough to complete a single orbit. Note too that the
edge of space (100
kilometre 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 at least 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.
Orbital spaceflight from Earth is normally achieved by large rockets that are capable of a
delta-v between 9.3 and 10 km/s. The only proven technique involves launching nearly vertically for a few kilometers and then progressively flattening the trajectory at roughly 100-200 km and accelerating on a horizontal trajectory (with the rocket angled to fight gravity and maintain altitude) for a 5-8 minute burn until orbital velocity is achieved. Frequently 2-3 stages are employed.
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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Category:spaceflight
