How do rockets work?

Rockets, unlike aeroplane jet engines, are designed to operate in space. [iStockphoto] 

Rockets have allowed us to launch robots, animals, and people into orbits around the Earth — and even beyond. They do not work by "pushing against the air," instead, rockets use momentum or the amount of power a moving object has.

Rockets work by ejecting hot exhaust that functions similarly to a basketball. The gas molecules in the exhaust do not weigh much, but they escape the rocket's nozzle quickly, giving them a lot of velocity. As a result, with the same overall oomph, the rocket moves in the opposite direction of the exhaust.

The combustion of fuel in a rocket engine produces exhaust. Rockets, unlike airplane jet engines, are designed to operate in space: they lack air intakes and carry their own oxidizers, compounds that act as oxygen in the combustion of fuel.

The fuel and oxidizer in a rocket, known as propellants, can be solid or liquid. Solid propellants were utilised in the side boosters of the space shuttle, although liquid propellants are employed in many modern rockets.

Where are rockets launched?

There are many launch sites around the world, each with different pros and cons. In general, the closer a launch site is to the Equator, the more efficient it is.

That is because the Equator moves faster than Earth's poles as the planet rotates, like the outer edge of a spinning record.

Launch sites at higher latitudes more easily place satellites into orbits that pass over the poles.