Constraints

Constraints define additional rules that must be satisfied for access, visibility, or analysis validity. They are attached to assets and evaluated by analysis services such as the access engine.

Built-in Constraint Types

Constraint	Applies to	Mode	Main parameters
Elevation (Ground)	Facility	Continuous	min_deg, max_deg
Azimuth (Ground)	Facility	Discrete	min_deg, max_deg
Range	Spacecraft, sensor, antenna, facility, vehicle	Continuous	min_km, max_km
Ground Elevation	Spacecraft, sensor, vehicle	Continuous	min_deg
Eclipse State	Spacecraft, sensor, vehicle	Discrete	state
Target Illuminated	Spacecraft, sensor, vehicle	Continuous	None
Ground Sun Zenith Angle	Spacecraft, sensor, vehicle	Continuous	min_deg, max_deg
Altitude	Spacecraft, sensor, vehicle	Continuous	min_km, max_km
Solar Beta Angle	Spacecraft, sensor, vehicle	Discrete	min_deg, max_deg

Continuous vs Discrete Constraints

Continuous constraints can be represented as a margin and may support boundary refinement. Discrete constraints are evaluated as boolean state filters and are not always suitable for continuous bisection.

flowchart TD
    C["Constraint"] --> T{"Mode"}
    T -->|Continuous| M["Margin evaluation"]
    T -->|Discrete| B["Boolean mask"]
    M --> R["Boundary refinement possible"]
    B --> F["Filter sampled timeline"]

Constraint Ownership

ASTROLAB collects constraints from the endpoint hierarchy:

• Asset-level constraints.
• Host-level constraints.
• Sensor-level constraints.

This allows a spacecraft bus, facility, mounted payload, or antenna to impose its own requirements without duplicating analysis logic.

Best Practices

• Put ground station horizon rules on the facility.
• Put payload-specific field or operating limits on the sensor or antenna.
• Use range constraints for engineering or operational distance limits.
• Treat eclipse and beta angle constraints carefully, because they may be discrete and sample-step sensitive.