Rocket propellant is a special type of fuel used to power rockets and spacecraft. It consists of two main components: a fuel and an oxidizer. The fuel provides the energy, while the oxidizer helps the fuel burn in space, where there is no air. Common examples of rocket propellants include liquid hydrogen and liquid oxygen, which are often used in large rockets like the Space Shuttle. When the propellant is ignited, it creates a high-pressure gas that expands rapidly. This gas is expelled out of the rocket's engine, producing thrust that propels the rocket upward. The efficiency and power of the propellant are crucial for missions to reach destinations like the Moon or Mars.