Asked by Dylan Moran
Since their invention by the Chinese in the 13th Century, rockets have seen a substantial amount of development, although they still work on the same principle. Modern rockets come in two main categories, solid fuel and liquid fuel.
Liquid-fuel rockets most commonly use liquid oxygen and either kerosene or liquid hydrogen. These combinations work well in space and down closer to the ground, resulting in a multitude of uses from the first stages of the Saturn V and Falcon rockets to the Space Shuttle’s main engines used to get the orbiter in position in space.
Solid-rocket fuel is easier and cheaper to handle and make as you don’t have to cool materials to cryogenic temperatures. This means solid fuel is quite prevalent in military applications and also the first stages of space rockets. Made from powdered aluminium and an oxidiser, this fuel is often used in booster rockets to give ’craft that extra kick needed to lift off and make their way into space.
Answered by Josh Barker, Education Team Presenter for the National Space Centre.
Image courtesy of NASA