An aerogravity assist, or AGA, is a theoretical spacecraft maneuver designed to change velocity when arriving at a body with an atmosphere.
An aerogravity assist uses a closer approach to the planet, dipping into the atmosphere, so the spacecraft can also use aerodynamic lift with upside-down wings to augment gravity and further curve the trajectory.
This enables the spacecraft to deflect through a larger angle, resulting in a higher delta-v (change in velocity).
In an aerogravity assist, however, the goal is not to use the atmosphere to slow the spacecraft down, but instead use it to achieve a larger change in direction.
While the use of an aerogravity assist has been proposed for a variety of missions, including the capture of a spacecraft into orbit about Saturn,[1] the technique has not yet been used in practice.