Is it due to energy demand or acceleration damaging the cargo/humans or something else?
In: 6
some good answers already about the problems of using a mass driver to launch from the surface of the Earth into orbit. there’s a secondary question about the use of mass drivers as propulsion once the vehicle is already in space (microgravity, no atmosphere, etc.).
propulsion in space requires reaction mass because the only way you go forward is by pushing something out of the back of the ship. the forward momentum is a result of Newton’s Third Law. No forward momentum for the ship without backward momentum from the propulsion system expelling reaction mass.
so you have to carry mass on the ship in order to shoot it out the back. that’s mass that the ship has to haul around until it’s used. if you’re using a mass driver and shooting out *inert* mass then you also need some other kind of fuel source to generate the power for the mass driver. so now you’ve got a ship with a really large electrical generator (and it’s own fuel source) as well as some inert mass to shoot out the back with the mass driver. the weight problem is starting to add up here.
chemical fueled rocket engines are more efficient here. they don’t use inert mass as fuel, they use mass that is a very dense store of chemical potential energy. it requires minimal energy to ignite, so the ship won’t need a large power system dedicated to the engines. the engine power is stored in the fuel itself. that’s efficient. the energy density of rocket fuel is really just extremely high. it’s going to be extremely hard to beat with anything like the technology we’ve currently got.
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