Could we use a giant catapult to launch a ship into space?
The cost of launching anything is largely the energy cost, not the equipment. Even if we were to build a giant catapult (not a bad idea, perhaps), we’d still have to store a huge amount of energy in it per kg of mass that we put into orbit. Can’t get around that cost. Then there’s the problem of acceleration. The human body can only stand roughly 4 or 5 g’s for any length of time (4 or 5 times 9.8 m/s/s) before becoming unconscious. Most catapults launch things very quickly. Even if it were a huge catapult that took, say 30 s to launch its object, the payload would be going from 0 to 18,000 mi/h or roughly 6,000 m/s (rounding off and low on purpose), so 6000 m/s divided by 30s is 200 m/s/s or about 20 g’s. No living thing and not many mechanical things could survive such an acceleration. Then there’s the little problem with friction with the air. Anything going escape velocity, roughly 25,000 mi/hr would burn up in the lower atmosphere. That’s why we have to at least now: a) launch it
