Escape velocity

Escape velocity is the minimum initial speed needed for an object to reach infinite distance from a gravitating body with zero residual speed, without further propulsion.

Gravitational potential energy: Energy associated with the positions of masses in a gravitational field. The launch speed must supply enough energy to overcome the body's gravitational potential.
Kinetic energy: Energy an object has because of its motion. The launch object's kinetic energy pays the energetic cost of climbing out of the gravitational well.
Rocket equation: An equation relating a rocket's change in velocity to exhaust speed and the ratio of its initial and final mass. A rocket must build enough velocity change to reach escape speed, while gravity and drag add losses.
Orbital velocity: The speed required for an object to follow a particular orbit around a gravitating body. A bound orbit needs less speed than escape at the same distance.
Earth: The third planet from the Sun and the only known world with abundant surface liquid water. Its surface escape speed is about 11.2 kilometers per second, ignoring atmospheric drag and rotation.
Specific orbital energy: Orbital mechanical energy per unit mass, combining kinetic and gravitational potential energy. Escape occurs when the object's specific orbital energy reaches zero or greater.
Gravitational field: A physical field that describes the gravitational force experienced per unit mass at each point in space. Escape speed is defined relative to the extent and strength of this field.
Atmospheric escape: The loss of gas from an atmosphere into space through thermal or nonthermal processes. A planet's escape speed helps determine whether atmospheric particles can remain gravitationally bound.
Terminal velocity: The steady speed reached when drag balances the driving force on a moving object. Unlike escape velocity, it depends on resistance from a medium rather than gravitational binding alone.
Moon: Earth's only natural satellite, a rocky body with a diameter about one-quarter of Earth's. Its much smaller mass and radius give a surface escape speed of about 2.38 kilometers per second.

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