Editing Delta-v (section)

===Oberth effect===
{{main article|Oberth effect}}
{{see also|Gravitational slingshot#Powered slingshots}}
From power considerations, it turns out that when applying delta-''v'' in the direction of the velocity the [[specific orbital energy]] gained per unit delta-''v'' is equal to the instantaneous speed. This is called the Oberth effect.

For example, a satellite in an elliptical orbit is boosted more efficiently at high speed (that is, small altitude) than at low speed (that is, high altitude).

Another example is that when a vehicle is making a pass of a planet, burning the propellant at closest approach rather than further out gives significantly higher final speed, and this is even more so when the planet is a large one with a deep gravity field, such as Jupiter.