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Collision Avoidance

A collision avoidance project designs and evaluates collision avoidance maneuvers using a selected Conjunction Data Message (CDM). Projects include risk analysis for both the primary conjunction and any impacted tertiary conjunction events.

Creating a Project​

Projects are created from the data contained in Conjunction Event CDMs. Operators can open the Maneuver Designer directly from an event page or create a project manually from the Designer dashboard.

  • If a project already exists for the event, it opens automatically.
  • Otherwise, a new project is created and linked to the selected event.

The linked CDM can also be reassigned from the project settings to reflect revised tracking inputs.

Organizations can also have projects generated automatically when Satcat receives a high-risk CDM for a maneuverable RSO. Autogenerate maneuver trade spaces turns this on and the Mitigation planning threshold sets what counts as high risk, both in Control Center under Organization Settings. It applies only to RSOs marked as maneuverable in RSO Parameters.

Project Stages​

Each project consists of three stages:

  1. Planning - Set maneuver type, timing, direction, and bounds
  2. Tradespace Results - Rapidly generate a tradespace of maneuver options and view risk metrics across the grid
  3. High-Fidelity Propagation - Propagate the maneuver plan at the highest possible fidelity and confirm risk metrics

Planning​

Planning sets the project and variant name, the CDM assignment, which may be reassigned to account for updated CDMs, and the primary and secondary RSO settings: CDM state source and Hard body radius (HBR) selection. HBR values are used in all collision probability calculations and sourced from operator input, authoritative third-party datasets such as NASA CARA, and CDMs. To learn more, see Hard body radius.

Maneuver configuration is covered in Tradespace Settings and on each maneuver type page.

Tradespace Results​

A tradespace plots risk metrics across the maneuver parameter space of the configured maneuver type. Each maneuver in it carries its own maneuver parameters and risk metrics.

Satcat provides maneuver tradespaces for the following risk metrics:

  • Collision Probability (Pc)
  • Miss Distance
  • Mahalanobis Distance

Suggested Maneuvers​

With Generate recommended COLA maneuvers enabled, Satcat selects three plans from the tradespace and propagates them as high-fidelity plans: Suggested - Best Overall, Suggested - Earliest Viable, and Suggested - Best Posigrade. They are marked in the tradespace and listed in High-fidelity maneuver plans. One tradespace maneuver can carry more than one suggestion. Each suggestion reports its delta-V magnitude, burn epoch and offset from TCA, and post-maneuver Pc.

Suggestions are generated for Impulsive tradespaces only.

The setting is off by default and configured in Control Center under Organization Settings.

Tertiary Risk Evaluation​

Satcat assesses tradespace maneuvers for impact on additional conjunction events:

  • Aggregate Pc: 1 - Π(1 - Pc_n)
  • Minimum MD across other CDMs

A conjunction event is included when its CDM shares the primary's data source (for example O/O or HAC), is no more than 2 days old, carries a Pc of at least 1e-8 and a miss distance of 5 km or less, and has a TCA within 7 days of the end of the maneuver window.

High-Fidelity Propagation​

After selecting a maneuver from the tradespace, operators may generate a refined propagation using the High-fidelity Plan system. Refining a solution will:

  • Propagate the chosen maneuver plan with the highest possible fidelity
  • Recalculate post-maneuver risk metrics with the Hall 3D Pc method
  • Create a THEORETICAL CDM output linked to the original event
  • Create a downloadable CCSDS OPM file

Generated plans appear in High-fidelity maneuver plans and on the associated conjunction event page.

Putting a Maneuver into Effect​

A high-fidelity plan is a theoretical result. The maneuver takes effect only once its ephemeris is uploaded with an OPERATIONAL designation and a COLA context, which updates the conjunction event and signals the RSO's intent to mitigate. See Enacting a Mitigation Plan.