Nicholas.Spies@H.CS.CMU.EDU (12/24/85)
Thanks for the basic physics indicating a surface ballistic launch cannot reach stable orbit. Here are a couple of other suggestions. If the masses lauched were shaped to fly in the air (changing their orbital path) would the same objections still pertain? Or if each projectile had an on-board solid-fuel rocket to boost it out of a simple ballistic orbit at a critical point would the idea seem more practical? Even if rail guns seem practical for moon ore it would seem mandatory to have the means of delivering many thousands of tons of Earth material into orbit before much use might be made of the Moon ore. The other idea, suggested by Hans' orbiting propeller, is whether a solid ring, under gravitational compression, much like a bicycle wheel surrounding the Earth, might in principle be built in geosynchronous orbit as the ultimate way of jacking stuff out of the gravity well. Perhaps it could be built along the lines of Fuller's Tensegrity structures and articulated to bend enough to respond to perturbations caused by Lunar and other gravitational irregularities yet stiff enough to allow elevators... It might take a while to build this 154,000 mile structure but why think small! (And, who knows, perhaps such a structure in much lower orbit, if it were sufficiently stiff, could be slowed to rotate to be geosychronized because, after all, where would it fall?)