Gravity-Assisted maneuvers have been used as a technique to reduce fuel
consumption in deep space missions for several decades now. It opened the doors
of the exterior solar system. The literature shows those results, as well as
new versions of this maneuver, which includes: the use of propulsion combined
with the close approach, both high or low thrust; the passage by the atmosphere
of a planet to help to change the trajectory of the spacecraft; the use of
tethers to increase the changes in the velocity of the spacecraft. All those
new versions have the goal of increasing the variations of energy given by the
maneuver, making possible missions that would not be possible without this
technique