TechnicalCDM
Conjunction Data Message
A standardized message format providing detailed information about a predicted close approach between two space objects.
Conjunction Data Messages (CDMs) are the standard format for communicating collision risk information between space operators and conjunction service providers.
Message Contents
- Object identifications (both objects)
- Time of closest approach (TCA)
- Miss distance vector
- Relative velocity
- State vectors with covariance
- Collision probability
- Screening volume details
CCSDS Standard CDMs follow the Consultative Committee for Space Data Systems (CCSDS) standard, ensuring interoperability between different systems and organizations.
CDM Workflow
- Initial CDM: Several days before TCA
- Updates: As tracking data improves
- Final CDM: ~24-48 hours before TCA
- Post-event: Confirmation of safe passage
Response Actions Upon receiving a CDM, operators should:
- Assess collision probability
- Evaluate maneuver options
- Coordinate with other operator if possible
- Execute avoidance if warranted
- Report actions to regulatory authorities
Quality Metrics CDM quality depends on:
- Tracking data accuracy
- Covariance realism
- Update frequency