Capture Set

Author: CislunarSpace

Website: https://cislunarspace.cn

Definition

The capture set is a concept introduced by Hyeraci and Topputo describing the set of initial conditions that enable ballistic capture in a celestial system. For a spacecraft approaching a planet, the capture set identifies all states from which the spacecraft will naturally enter a bounded orbit around the planet without requiring a braking maneuver. The size and shape of the capture set are influenced by the orbital eccentricity of the planet — larger eccentricity favors the generation of capture orbits. The capture set provides a parameter space analysis tool for low-energy capture orbit design, enabling mission designers to identify feasible approach conditions.

Key Properties

  • Represents initial conditions leading to natural (ballistic) capture without propulsive maneuvers.
  • Set size and geometry depend on the planet's orbital eccentricity and mass ratio.
  • Larger eccentricity generally expands the capture set, creating more capture opportunities.
  • Provides a systematic framework for exploring low-energy transfer design space.

References

  • Hyeraci, N. and Topputo, F. "Method to Design Ballistic Capture Transfers to Inner Planets." Journal of Guidance, Control, and Dynamics, 33(6):1884–1893, 2010.