Space travel means exploring places in space. People travel in a rocket—a special vehicle that is able to move in the rarefied environment of empty space. Rockets are launched from Earth, travel to space and land on another place like the moon. To send something into space, a lot of energy is needed to break through Earth's gravity. When it's in space, it still needs energy to move forward. Space crafts use fuel to do this. They also use thrusters—special engines that point in different directions to control the speed and direction of the rocket.