Liquid Fueled rockets that are used today are inefficient and ineffective, therefore they will eventually have to be phased out. They are not very effective way to transport in space because they require there own supply of oxygen that is required for the propellant to burn.
A rocket is essentially a chamber, from one end of which gases are expelled at a great speed, thereby driving the chamber in the opposite direction by the recoil, (Golden 47). Rockets are able to go forward through space because of Newton's "Third Law of Motion": For every action there is an equal and opposite reaction.".
Rockets have been around for a long time. Ever since the ancient Chinese invented gunpowder, man has been experimenting with rockets. They used them as weapons in war and as fireworks (Bryan 349). Then in 1903, Konstatin Tsiolkovsky, a Russian schoolteacher, did some studies on theoretical space travel, and showed why rockets would be necessary for space travel. He concluded that because a rocket is a reaction-propelled device that carries both its own supply of fuel and the oxygen that is necessary to support combustion in space, where no oxygen is available. This conclusion showed that a rocket is the only vehicle currently capable of carrying man beyond the Earth's atmosphere. This also proved that only rockets can travel in the near vacuum of space, while the air-breathing engines of jets would sputter out if they tried to climb beyond the lower atmosphere (Bryan 352).
A fuel must have oxygen to burn in a rocket engine. When fuels burn on Earth, they use the oxygen in the air. Since rockets go where there is no oxygen, they must take their own supply of oxygen with them in the form of a chemical. This chemical is called an oxidizer. Tsiolkovsky also proposed liquid hydrogen and liquid oxygen as the most efficient propellants for rocket engines. He knew that solid-fuel rockets were easy to make, but the fuel did not always burn evenly.