Rocket engines are powerful machines that propel rockets into space. They work by burning fuel and creating hot gases that shoot out of the back, pushing the rocket forward. This process is based on Newton's third law of motion, which states that for every action, there is an equal and opposite reaction. There are different types of rocket engines, including liquid rocket engines and solid rocket boosters. Liquid engines use liquid fuel and oxidizer, while solid boosters contain a solid mixture. Both types are essential for missions, such as those conducted by NASA or SpaceX, to explore space and send satellites into orbit.