An orbital mechanics maneuver where a spacecraft arrives on a hyperbolic trajectory and dives deep into a planet's atmosphere to kill enough velocity to be captured into a closed orbit. Unlike gradual aerobraking, this is a one-shot, high-heat event. It requires a robust heat shield and precise navigation, as entering too shallow results in flying off into deep space, and too deep results in burning up or impacting the surface.
Heard on the job
The thermal protection system is sized for aerocapture at Mars, not just a gradual step-down.