Class GroundAtNightDetector

  • All Implemented Interfaces:
    EventDetector

    public class GroundAtNightDetector
    extends AbstractDetector<GroundAtNightDetector>
    Detector for ground location being at night.

    This detector is mainly useful for scheduling optical measurements (either passive telescope observation of satellites against the stars background or active satellite laser ranging).

    The g function of this detector is positive when ground is at night (i.e. Sun is below dawn/dusk elevation angle).

    Since:
    9.3
    Author:
    Luc Maisonobe
    • Field Detail

      • CIVIL_DAWN_DUSK_ELEVATION

        public static final double CIVIL_DAWN_DUSK_ELEVATION
        Sun elevation at civil dawn/dusk (6° below horizon).
      • NAUTICAL_DAWN_DUSK_ELEVATION

        public static final double NAUTICAL_DAWN_DUSK_ELEVATION
        Sun elevation at nautical dawn/dusk (12° below horizon).
      • ASTRONOMICAL_DAWN_DUSK_ELEVATION

        public static final double ASTRONOMICAL_DAWN_DUSK_ELEVATION
        Sun elevation at astronomical dawn/dusk (18° below horizon).
    • Method Detail

      • g

        public double g​(SpacecraftState state)
        Compute the value of the switching function. This function must be continuous (at least in its roots neighborhood), as the integrator will need to find its roots to locate the events.

        The g function of this detector is positive when ground is at night (i.e. Sun is below dawn/dusk elevation angle).

        This function only depends on date, not on the actual position of the spacecraft.

        Parameters:
        state - the current state information: date, kinematics, attitude
        Returns:
        value of the switching function