Conjunction Assessment¶

Pro

ConjunctionAssessment and the types in IO.Astrodynamics.SSA are Pro features.

ConjunctionAssessment is the main SSA facade for screening, analyzing, and evaluating conjunction events between a protected spacecraft and candidate secondary objects.

ConjunctionAssessment Methods¶

Method	Description
`Screen(profile, secondaries, window, options)`	Rank many candidates against one protected spacecraft
`Analyze(profile, secondary, window)`	Return the single best conjunction in a window
`AnalyzeAll(profile, secondary, window)`	Return every detected conjunction in a window
`EvaluateAvoidance(encounter, options)`	Generate impulsive avoidance options for an encounter

Each method has two families of overloads:

ILocalizable overloads for generic participants.
PropagationSolution overloads when both trajectories were already propagated, reusing dense output.

ProtectedSpacecraftProfile¶

Packages the protected Spacecraft with maneuver constraints used by avoidance searches.

Property	Description
`Spacecraft`	The protected spacecraft instance

ScreeningOptions¶

Property	Description
`MaxMissDistanceMeters`	Filter threshold for miss distance
`MaxResults`	Maximum number of ranked results to return

Results are ordered by descending collision probability, then by miss distance.

EncounterCase¶

Top-level conjunction result packaging all assessment products.

Property	Type	Description
`EncounterState`	`EncounterState`	Geometry and covariance at TCA
`CollisionRisk`	`CollisionRisk`	Collision probability products
`ToCdm(CdmExportOptions)`	`Cdm`	Export to CCSDS CDM

EncounterState¶

Property	Type	Description
`Epoch`	`Time`	Time of closest approach
`MissDistance`	`double`	Miss distance (m)
`RelativeState`	`RelativeState`	Relative position and velocity
`CombinedRtnCovariance`	`Matrix`	Combined 6x6 RTN covariance
`QualityFlags`	`EncounterQualityFlags`	Covariance and applicability warnings

RelativeState¶

Property	Description
`RelativePositionInertial`	Relative position in ICRF (m)
`RelativeVelocityInertial`	Relative velocity in ICRF (m/s)
`RelativePositionRTN`	Relative position in protected object's RTN frame (m)
`RelativeVelocityRTN`	Relative velocity in RTN frame (m/s)

CollisionRisk¶

Property	Description
`CombinedHardBodyRadius`	Sum of hard-body radii (m)
`ProbabilityOfCollision`	Pc when covariance is available
`ProjectedCovariance`	2D encounter-plane covariance
`RadialSigma` / `InTrackSigma` / `CrossTrackSigma`	RTN sigmas (m)

Practical Limits¶

Collision probability uses a 2D Foster-style encounter-plane method.
EncounterQualityFlags.LowRelativeVelocityEncounter is an applicability warning that the 2D assumption may be degraded.
Covariance is required for both participants to compute Pc.

Example¶

var encounter = ConjunctionAssessment.Analyze(
    new ProtectedSpacecraftProfile(protectedSpacecraft),
    secondarySpacecraft,
    new Window(epoch, epoch.AddMinutes(10.0)));

Console.WriteLine($"Miss distance: {encounter.EncounterState.MissDistance:F1} m");
Console.WriteLine($"Pc: {encounter.CollisionRisk.ProbabilityOfCollision:E3}");

Conjunction Assessment¶