02-18-2018, 06:21 PM
HOTPE - you get it. I'm going to reverse your question, but the answer applies both ways.
If you have a space elevator and want to launch something into low earth orbit (LEO), then you have the choice of launching it from the elevator in LEO or moving it higher and then manoeuvring into LEO. Both require some method of propulsion. Simply moving something up the elevator to LEO will result in the object falling straight back to Earth as it won't have the velocity to remain in LEO. Launching it from higher up requires the same thing. I'll do the math if you want, but you still need some sort propulsion to either speed the satellite up or slow it down, and then adjust its actual orbit.
Flinging something into LEO with just the right velocity to get into that orbit is a way to get around that. The satellite will still need some sort of propulsion to adjust its orbit by small amounts, basically thrusters, but won't need rocket engines to do so.
I don't know if you ever watched the movie "Gravity". The CGI effects were great and the premise of the "Kessler effect" is real, i.e., a collision between satellites could cascade as debris is thrown into all sorts of orbits colliding with other satellites, but the rest of the movie with an astronaut moving between orbits was nonsense. You need a lot of energy to do that plus the space around the Earth is larger than most people realize. You need an awful lot of energy to move between geosynchronous orbit and LEO, and vice versa - even for a microwave oven!
If you have a space elevator and want to launch something into low earth orbit (LEO), then you have the choice of launching it from the elevator in LEO or moving it higher and then manoeuvring into LEO. Both require some method of propulsion. Simply moving something up the elevator to LEO will result in the object falling straight back to Earth as it won't have the velocity to remain in LEO. Launching it from higher up requires the same thing. I'll do the math if you want, but you still need some sort propulsion to either speed the satellite up or slow it down, and then adjust its actual orbit.
Flinging something into LEO with just the right velocity to get into that orbit is a way to get around that. The satellite will still need some sort of propulsion to adjust its orbit by small amounts, basically thrusters, but won't need rocket engines to do so.
I don't know if you ever watched the movie "Gravity". The CGI effects were great and the premise of the "Kessler effect" is real, i.e., a collision between satellites could cascade as debris is thrown into all sorts of orbits colliding with other satellites, but the rest of the movie with an astronaut moving between orbits was nonsense. You need a lot of energy to do that plus the space around the Earth is larger than most people realize. You need an awful lot of energy to move between geosynchronous orbit and LEO, and vice versa - even for a microwave oven!