Randall Munroe explains this very nicely in his piece on Orbital Speed[1]: > But getting to space is easy. The problem is staying there. > To avoid falling ba

Randall Munroe explains this very nicely in his piece on Orbital Speed[1]: > But getting to space is easy. The problem is staying there. > To avoid falling back into the atmosphere, you have to go sideways really, really fast…The speed you need to stay in orbit is about 8 kilometers per second. Only a fraction of a rocket's energy is used to lift up out of the atmosphere; the vast majority of it is used to gain orbital (sideways) speed. Highly recommended. 1: https://what-if.xkcd.com/58/ https://what-if.xkcd.com/58/