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Constraints

Asset reference

Concept

Constraints are rule filters attached to platforms (spacecraft, vehicle, facility). They answer: under what geometric or lighting conditions may this asset participate in access?

They are first-class mission data. Engines that evaluate line-of-sight, coverage samples, or contacts consult applicable constraints. Misconfigured constraints are a common reason for “empty” access or coverage.

See also Flight dynamics — Access.

When to use

Constraint Typical intent
Range Keep relative distance inside a band (e.g. max ISL range)
Ground elevation Facility only counts inside a min/max elevation band
Eclipse Require sunlight or eclipse for the platform
Target illuminated Optical collect only when the target is lit
Sun zenith angle Limit by ground lighting geometry
Altitude Gate by platform height
Solar beta angle Gate by orbit–Sun geometry

Constraint types

Type key Label Default parameters
range Range min_km: 0, max_km: 2000
ground_elevation Ground elevation min_deg: 10, max_deg: 90
eclipse Eclipse state state: not_in (not_in / in)
target_illuminated Target illuminated (none)
sun_zenith_angle Ground sun zenith angle min_deg: 0, max_deg: 80
altitude Altitude min_km: 0, max_km: 2000
solar_beta_angle Solar beta angle min_deg: -90, max_deg: 90

How engines apply them

At each sample time the access kernel evaluates geometry (LOS, FOV, elevation, …) and enabled constraints on the participating platforms. If any required constraint fails, the sample is not an access / coverage hit.

flowchart LR
  Geo["Geometry tests"] --> C["Enabled constraints"]
  C --> Ok{"All pass?"}
  Ok -->|yes| Acc["Access / sample valid"]
  Ok -->|no| No["Rejected"]

UI pattern

On spacecraft (Constraints tab) and vehicle:

  1. Choose constraint type → Add constraint.
  2. Toggle Enabled.
  3. Edit numeric parameters.
  4. Remove when obsolete.

On facility (Web): Add constraint seeds Range 0–2000 km; you can change type and Remove. Enabled and numeric fields are not shown on that editor.

Platform constraints

Spacecraft Constraints tab — elevation (or other) mask with Enabled.

Design tips

  • Start with ground elevation on facilities before blaming the propagator.
  • Pair eclipse / illumination with optical sensors deliberately — they silently zero night collects.
  • Wide range caps are safer while debugging; tighten later for operational realism.
  • Disabled constraints remain in the document but are ignored by engines.