Rockets work by burning fuel. As fuel burns and swells out behind, the swelling pushes the rocket forward.
Solid-fuel rockets are the oldest of all engines, used by the Chinese a thousand years ago.
Solid-fuel engines are basically rods of solid, rubbery fuel with a tube down the middle.
Solid-fuel rockets are usually only used for model rockets and small booster rockets. But the Space Shuttle has two solid-fuel rocket boosters (SRBs) as well as three main liquid-fuel engines.
Most powerful launch rockets use liquid fuel. The Space Shuttle uses hydrogen. Other fuels include kerosene.
Liquid fuel only burns with oxygen, so rockets must also carry an oxidizer (a substance that gives oxygen) such as liquid oxygen (LOX) or nitrogen tetroxide.
Future rocket drives include nuclear thermal engines that would use a nuclear reactor to heat the gas blasted out.
NASA’s Deep Space-1 project is based on xenon ion engines which thrust electrically charged particles called ions, not hot gases, out of the back of the craft.
Solar thermal engines of the future would collect the Sun’s rays with a large mirror to heat gases.
The Saturn V rocket that launched the Apollo mission to the Moon is the most powerful rocket ever built.
Rockets provide the huge thrust needed to beat the pull of Earth’s gravity and launch a spacecraft into space. Rockets burn propellant (propel means ‘push’), to produce hot gases that drive the rocket upwards. Rocket propellant comes in two parts – a solid or liquid fuel, and an oxidizer.
Solid fuel is a rubbery substance that contains hydrogen, and it is usually used in additional, booster rockets.
Liquid fuel is usually liquid hydrogen, and it is typically used on big rockets.
There is no oxygen in space, and the oxidizer supplies the oxygen needed to burn fuel. It is usually liquid oxygen (called ‘lox’ for short).
The first rockets were made 1000 years ago, in China.
Robert Goddard launched the very first liquid-fuel rocket in 1926.
The German V2 war rocket, designed by Werner von Braun, was the first rocket capable of reaching space.