Why isn't there an elevator to the highest altitude where an elevator could be built, and then spacecraft can propel from there. It should still reduce fuel costs and the cost to construct space craft?
Would powering the cable permanently, with a power station at the bottom and a constant feed of water for super-heated steam thrusters work? Just throwing scifi at it. I'm just curious why it has to be one component or why the weight can't be supported by propulsion. I'm guessing the TL;DR is the numbers just don't work out?