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Collision Avoidance

Collision Avoidance (COLA) refers to the process of reducing collision risk by planning and executing maneuvers in response to high-risk conjunctions. Only objects with some form of trajectory control can participate. While traditional COLA involves thrust-based maneuvers, techniques like differential drag have also been used in LEO between non-thrusting spacecraft to reduce collision risk.

COLA decisions require timely, high-confidence inputs, including accurate ephemerides, risk assessments, and coordination between affected operators. The goal is to reduce the probability of collision (Pc) below an acceptable threshold with minimal disruptions to mission plans.

Conjunction Mitigation​

COLA maneuvers typically target the point of closest approach, using trajectory adjustments to reduce risk along an efficient direction. Operators must weigh fuel constraints, mission timing, and maneuver windows against the assessed risk.

Key requirements for effective mitigation:

  • High-accuracy ephemerides for both RSOs
  • Reliable Pc estimates and uncertainty characterization
  • Knowledge of the other operator's intent or maneuver posture
  • Internal authority to make Go / No Go decisions

In Satcat, COLA planning is supported through:

  • Auto-generated maneuver tradespace options
  • Risk metrics and Pc trend visualizations
  • Tools for uploading and validating operational ephemerides
  • Operator-to-operator coordination interfaces

Alignment with SSC Guidelines​

Satcat's maneuver recommendation logic is aligned with the Space Safety Coalition's (SSC) endorsed Best Practices for Space Operations Sustainability, which recommend:

  • Avoiding simultaneous maneuvers without coordination
  • Minimizing risk through cooperation between responsible parties

These guidelines are implemented through the Rules of the Road protocol within Satcat, which assigns maneuver responsibility and broadcasts operator intent.

Autonomous Collision Avoidance​

Some operators employ onboard or ground-based automation to execute COLA maneuvers without bilateral coordination. These systems rely on defined thresholds for Pc or miss distance, and may trigger impulsive or low-thrust maneuvers when criteria are met.

Satcat supports this operational mode by:

  • Allowing operators to pre-declare “Auto-Maneuver” responsibility status
  • Surfacing this designation to all affected parties during coordination
  • Integrated screening with automated-maneuvering constellation APIs

Autonomous COLA workflows must still comply with shared coordination norms to avoid unintentional conflict with other operator plans.

For more detail on maneuver assignment, intent signaling, and operator interaction, see: