Rockets11.28 - Understand that a space probe must reach the Earth’s escape velocity, the energy requirements of which can be met only by the use of rockets
9.4 - Understand that a spacecraft traveling to the Moon must reach the Earth’s escape velocity, the energy requirements of which can be met only by the use of rockets
A rocket needs to reach a certain speed to break free of Earth’s gravity. This amount is 11.2 km per second (7 miles a second) and is known as Earth’s Escape Velocity. If it fails to reach this speed the rocket will stay well within Earth’s gravity and probably crash.
It takes an enormous force for a rocket to achieve this speed. To do it rerquires a controlled explosion where the rocket is filled with liquid propellant usually Liquid Oxygen or Nitrogen. It is easier to control liquid propellant rather than solid propellant. A rocket also consists of smaller rockets that are called stages. The Space Shuttle uses three rockets to get into space. To reach the Moon NASA used the Saturn V rockets which were the largest built.