Consider a cask filled with a highly compressed gas. If we open one of its taps the gas will escape through it in a continuous flow, the elasticity of the gas pushing its particles into space will continuously push the cask itself. The result will a continuous change in the motion of the cask. Given a sufficient number of taps (say, six), we would be able to regulate the outflow of the gas as we liked and the cask (or sphere) would describe any curved line in accordance with any law of velocities.
Konstantin TsiolkovskyFor me, a rocket is only a means--only a method of reaching the depths of space--and not an end in itself... There's no doubt that it's very important to have rocket ships since they will help mankind to settle elsewhere in the universe. But what I'm working for is this resettling... The whole idea is to move away from the Earth to settlements in space.
Konstantin TsiolkovskyFrom the rocket we can see the huge sphere of the planet in one or another phase of the Moon. We can see how the sphere rotates, and how within a few hours it shows all its sides successively ... and we shall observe various points on the surface of the Earth for several minutes and from different sides very closely. This picture is so majestic, attractive and infinitely varied that I wish with all my soul that you and I could see it.
Konstantin TsiolkovskyThe Earth is the cradle of Humanity. But one doesn't always live in the cradle.
Konstantin TsiolkovskyMen are weak now, and yet they transform the Earth's surface. In millions of years their might will increase to the extent that they will change the surface of the Earth, its oceans, the atmosphere, and themselves. They will control the climate and the Solar System just as they control the Earth. They will travel beyond the limits of our planetary system; they will reach other Suns, and use their fresh energy instead of the energy of their dying luminary.
Konstantin Tsiolkovsky