How much extra speed after a planet's pull, and how are nudges kept small?
Research question: How much speed does a probe need to add on its own after a planet's pull, and how do teams keep the engine nudges small?
The records do not give a specific speed a probe must add on its own after a planet's pull. They show that an Earth gravity assist lets a spacecraft return with a higher hyperbolic excess velocity relative to the starting planet, which is how it gains speed from the planet's pull 5. To cut the engine burns needed, one approach is a single lunar gravity assist, which significantly reduces the total velocity-change requirement but lengthens the flight 1. Electric propulsion offers continuous steering, which can be used to approach a planet with extra hyperbolic excess velocity to enhance the assist 3. Aerogravity assists add aerodynamic forces to bend the velocity vector further and increase momentum exchange 6. The newest fact is from 2025, roughly a year and a half before October 2026 1.
Sources
"Single LGA transfer trajectory significantly reduce"Database Driven Design Method for LEO-DRO Lunar Gravity Assist Transfer Trajectory (2025)
"Propellantless propulsive systems such as Electric Solar Wind Sails are capable of accelerating a deep-space probe, only requiring a small amount of propellant for attitude and spin-rate control."Optimal Earth Gravity-Assist Maneuvers with an Electric Solar Wind Sail (2022)
"Electric propulsion provides a spacecraft with continuous steering capabilities, which can be used to approach a planet with hyperbolic excess velocity that enhances the gravity assist."Optimal Low-Thrust Escape Trajectories Using Gravity Assist (1999)
"The momentum exchange that can be achieved during a so-called gravity assist is limited by the mass of the planetary body."Aerogravity assists: Hypersonic maneuvering to improve planetary gravity assists (2016)
"in which a spacecraft departs from the Earth’s sphere of influence, moves in the interplanetary space, and then re-encounters the Earth with an increased hyperbolic excess velocity with respect to the starting planet."Optimal Earth Gravity-Assist Maneuvers with an Electric Solar Wind Sail (2022)
"an aerogravity assist was proposed, a maneuver where, in addition to the gravitational forces, use is made of aerodynamic forces to increase the bending angle of the velocity, hence increasing the momentum exchange."Aerogravity assists: Hypersonic maneuvering to improve planetary gravity assists (2016)
"taking advantage of an augmented thrust magnitude in the vicinity of the Sun due to the increased solar wind ion density."Optimal Earth Gravity-Assist Maneuvers with an Electric Solar Wind Sail (2022)
"It was determined that the reduction in velocity could be increased by 167% with respect to a gravity assist: from 2.3 km/s for a gravity assist to 6.2 km/s for an aerogravity assist."Aerogravity assists: Hypersonic maneuvering to improve planetary gravity assists (2016)