Rockets can work in space because they don’t need anything to push against an they have their own supply of oxygen. Tnside the combustion chamber of a rocket, propellant burns to create hot gases that push in all directions. The pressure on the topof the chamber is not balanced by a pressure on the bottom.
This unbalanced upward force thrusts the rocket in the sky, the shuttle shown here uses five main rockets-two solid-fuel boosters, and three liquid- fuel rockets.