Spacecraft

A spacecraft is a vehicle that travels through space using an external method of propulsion, while a spaceship flies through space by means of an internal engine and propellant fuel. A spacecraft is a Type I technology used for sub-light impulse speeds before the invention of faster-than-light methods of travel. Initially spacecraft are for interplanetary travel but later can be used for close interstellar travel.

Spaceships can launch and land by themselves whereas spacecraft need launch-assist mechanisms like:


 * Skyhook (requires reusable suborbital launch vehicle)
 * Space elevator (tether from planet's surface to geostationary orbit)
 * Launch loop (a very fast enclosed rotating loop about 80 km tall)
 * Space fountain (a very tall building held up by a stream of masses fired from its base)
 * Orbital ring (a ring around a planet or moon with spokes hanging down off bearings)
 * Electromagnetic catapult (railgun, coilgun) (an electric gun)
 * Rocket sled launch
 * Space gun (a chemically powered gun)
 * Beam-powered propulsion rockets and jets powered from the ground via a beam
 * High-altitude platforms

and land-assist mechanisms like:


 * Aerobraking allows a spacecraft to reduce the high point of an elliptical orbit by repeated brushes with the atmosphere at the low point of the orbit.
 * Aerocapture converts an incoming hyperbolic orbit to an elliptical orbit in one pass
 * Parachutes can land a probe on a planet or moon with an atmosphere, after a heat shield entry.
 * Airbags can soften the final landing.

Initial spacecraft used rocket or chemical engines that created a thrust reaction by expelling mass. Then electromagnetic and ion thrusters came along until more advanced propulsion technology was invented.

Spacecraft Propulsion methods: