A single Engine with five gears, or five separate Engines with 'fixed' propulsion's, as opposed to transitional gearings? A rocket leaving Earth has 'boosters', once it is orbiting it uses propulsion systems that are more compact and have a weight-to-ratio output more efficient than Earthbound systems due to the fact that the craft is allready in motion,(my wording here may be technically vague,forgive me). What I want to know is, if a Craft is already in a far-off part of Space, then what 'type' of propulsion system is the most efficient for attaining higher speeds?..I know that gas or aerosols can manouvre crafts for docking etc..but I seen an experiment where a 'Superconducting', Electro-Magnetic ring was propelled to a great height, and this was in a Lab on Earth. Is it feasible that crafts can have Superconducting Propulsion systems, on board to be used as 'boosters'? Basically, if a craft lands on another planet or Moon?..and has a Superconducting plate, (which is obviously situated so that it can be lowered to below the craft, the craft being the 'ring' from the experiment that I had seen), then surely this would produce a really fantastic propulsion system to crafts that need a once-only boost for take off from..say Mars or dare I say it bodies that may have surfaces that already have 'superconducting' surface's? The question again, can Superconduction, Electro-Magnetic systems be used to launch crafts from its surface to Orbit?