Aerobraking

An artist's conception of aerobraking with the Mars Reconnaissance Orbiter
An example of Aerobraking
   Mars Reconnaissance Orbiter ·   Mars

Aerobraking is a spaceflight maneuver that reduces the high point of an elliptical orbit (apoapsis) by flying the vehicle through the atmosphere at the low point of the orbit (periapsis). The resulting drag slows the spacecraft. Aerobraking is used when a spacecraft requires a low orbit after arriving at a body with an atmosphere, as it requires less fuel than using propulsion to slow down.