Keith wrote: > >>> There is plenty of energy around if we can figure out how to get >>> it. For example, a solar power satellite repays the energy needed >>> to lift it to GEO in about a day (at 100% efficiency). Five percent >>> efficient rockets would replay the lift energy in 3 weeks. >> >> This is almost surely wrong. Did you do the math? > > Yes. > > Specific orbital energy is u/2r, (398,600/42,000)/2 or -4.75Mj/kg > Ok > Potential is -9.5Mk/kg and kinetic is 4.75Mj/kg > > Potential at the earth's surface is -62.6 MJ/kg; the > difference is 53.1Mj/kg. > Ok.
> Using a space elevator, > I didn't know you were invoking Magic. "If I had magical fairy godparents I would make 2 + 2 = fish". Try to do the same exercise using chemical rockets :-) Alberto Monteiro _______________________________________________ http://www.mccmedia.com/mailman/listinfo/brin-l
