Science
How does a rocket engine work?
A rocket engine works by burning propellant to produce a huge volume of fast-moving exhaust gas and throwing it backward out of a nozzle. By Newton's third law, pushing that mass backward thrusts the rocket forward — and because it carries its own oxidizer, it works even in the vacuum of space.
See it in motion.
Watch a 2-minute animated lesson that shows exactly how a rocket engine works.
Step by step
- 1Fuel and an oxidizer are burned in a combustion chamber, producing high-pressure, high-temperature gas.
- 2A shaped nozzle accelerates that gas to very high speed as it escapes.
- 3Throwing exhaust backward pushes the rocket forward — Newton's third law of action and reaction.
- 4Carrying its own oxidizer means a rocket needs no outside air, so it works in space.
Frequently asked questions
- How do rockets work in space with no air to push against?
- They don't push against air. Thrust comes from expelling their own exhaust mass backward; the reaction force drives the rocket forward even in a vacuum.
- What's the difference between a rocket and a jet engine?
- A jet engine breathes outside air to burn its fuel; a rocket carries its own oxidizer, so it can operate where there is no air.
- Why are rockets built in stages?
- Dropping empty fuel tanks mid-flight sheds dead weight, so the remaining engines accelerate a much lighter vehicle toward orbit.