{
  "id": "concepts",
  "title": "Concept map",
  "summary": "The concepts of the ApsisRS kernels and the relationships between them. Each node opens the document that explains it.",
  "nodes": [
    {
      "id": "overview",
      "label": "Concept overview",
      "kind": "concept",
      "group": "overview",
      "summary": "Scope and reading order of the concept set.",
      "document": "overview"
    },
    {
      "id": "architecture-apsis-rs",
      "label": "Workspace architecture",
      "kind": "concept",
      "group": "overview",
      "summary": "The layer order and the crates in each layer.",
      "document": "architecture-apsis-rs"
    },
    {
      "id": "standards-and-provenance",
      "label": "Standards and provenance",
      "kind": "concept",
      "group": "overview",
      "summary": "The public sources each algorithm follows.",
      "document": "standards-and-provenance"
    },
    {
      "id": "time-scales",
      "label": "Time scales",
      "kind": "concept",
      "group": "time",
      "summary": "UTC, TAI, TT, and GPS, and the storage convention.",
      "document": "time-scales"
    },
    {
      "id": "leap-seconds",
      "label": "Leap seconds",
      "kind": "concept",
      "group": "time",
      "summary": "The step discontinuities in UTC and the embedded table.",
      "document": "leap-seconds"
    },
    {
      "id": "calendar-and-mjd",
      "label": "Calendars and MJD",
      "kind": "concept",
      "group": "time",
      "summary": "Day numbering and the proleptic Gregorian calendar.",
      "document": "calendar-and-mjd"
    },
    {
      "id": "reference-frames",
      "label": "Reference frames",
      "kind": "concept",
      "group": "geometry",
      "summary": "Inertial, Earth-fixed, and geodetic frames.",
      "document": "reference-frames"
    },
    {
      "id": "earth-rotation-angle",
      "label": "Earth Rotation Angle",
      "kind": "concept",
      "group": "geometry",
      "summary": "The angle that relates the two Cartesian frames.",
      "document": "earth-rotation-angle"
    },
    {
      "id": "geodesy-wgs84",
      "label": "WGS 84 and geodetic coordinates",
      "kind": "concept",
      "group": "geometry",
      "summary": "Latitude, longitude, height, and the Cartesian conversion.",
      "document": "geodesy-wgs84"
    },
    {
      "id": "tle-format",
      "label": "Two-line element format",
      "kind": "data",
      "group": "elements",
      "summary": "The fixed width element record and its checksum.",
      "document": "tle-format"
    },
    {
      "id": "keplerian-elements",
      "label": "Keplerian elements",
      "kind": "concept",
      "group": "elements",
      "summary": "The six classical elements and the two-body solution.",
      "document": "keplerian-elements"
    },
    {
      "id": "sgp4",
      "label": "SGP4 and SDP4",
      "kind": "concept",
      "group": "propagation",
      "summary": "The analytical propagator the element sets are fitted to.",
      "document": "sgp4"
    },
    {
      "id": "perturbations",
      "label": "Orbital perturbations",
      "kind": "concept",
      "group": "propagation",
      "summary": "The forces that make an orbit deviate from an ellipse.",
      "document": "perturbations"
    },
    {
      "id": "propagator-comparison",
      "label": "Choosing a propagator",
      "kind": "concept",
      "group": "propagation",
      "summary": "The propagation methods compared by accuracy and cost.",
      "document": "propagator-comparison"
    },
    {
      "id": "ephemeris-interpolation",
      "label": "Ephemeris interpolation",
      "kind": "concept",
      "group": "propagation",
      "summary": "Sampling a track once and querying it by interpolation.",
      "document": "ephemeris-interpolation"
    },
    {
      "id": "method-hpop",
      "label": "HPOP",
      "kind": "concept",
      "group": "methods",
      "summary": "Numerical integration of a high order force model. Not implemented in apsis-rs.",
      "document": "propagator-comparison"
    },
    {
      "id": "method-numerical",
      "label": "Numerical integration",
      "kind": "concept",
      "group": "methods",
      "summary": "Integrating the equations of motion from a force model. Not implemented in apsis-rs.",
      "document": "propagator-comparison"
    },
    {
      "id": "method-two-body",
      "label": "Two-body propagation",
      "kind": "concept",
      "group": "methods",
      "summary": "The closed form Keplerian solution. Implemented as apsis-kepler.",
      "document": "keplerian-elements"
    },
    {
      "id": "crate-apsis-time",
      "label": "apsis-time",
      "kind": "crate",
      "group": "time",
      "summary": "Time scales, epochs, and calendar conversions.",
      "document": "time-scales",
      "api": "Epoch"
    },
    {
      "id": "crate-apsis-coord",
      "label": "apsis-coord",
      "kind": "crate",
      "group": "geometry",
      "summary": "Positions that carry their reference frame in the type.",
      "document": "reference-frames",
      "api": "Eci"
    },
    {
      "id": "crate-apsis-sgp4",
      "label": "apsis-sgp4",
      "kind": "crate",
      "group": "propagation",
      "summary": "The SGP4 and SDP4 analytical orbit propagator.",
      "document": "sgp4",
      "api": "Satellite"
    }
  ],
  "edges": [
    {
      "source": "overview",
      "target": "architecture-apsis-rs",
      "kind": "explains",
      "label": "structure"
    },
    {
      "source": "overview",
      "target": "standards-and-provenance",
      "kind": "explains",
      "label": "sources"
    },
    {
      "source": "time-scales",
      "target": "leap-seconds",
      "kind": "uses",
      "label": "UTC offset"
    },
    {
      "source": "time-scales",
      "target": "calendar-and-mjd",
      "kind": "uses",
      "label": "date display"
    },
    {
      "source": "leap-seconds",
      "target": "calendar-and-mjd",
      "kind": "relates",
      "label": "inserted seconds"
    },
    {
      "source": "reference-frames",
      "target": "earth-rotation-angle",
      "kind": "uses",
      "label": "rotation"
    },
    {
      "source": "reference-frames",
      "target": "geodesy-wgs84",
      "kind": "uses",
      "label": "ellipsoid"
    },
    {
      "source": "earth-rotation-angle",
      "target": "calendar-and-mjd",
      "kind": "uses",
      "label": "days since J2000"
    },
    {
      "source": "earth-rotation-angle",
      "target": "time-scales",
      "kind": "uses",
      "label": "UT1"
    },
    {
      "source": "tle-format",
      "target": "sgp4",
      "kind": "feeds",
      "label": "mean elements"
    },
    {
      "source": "sgp4",
      "target": "tle-format",
      "kind": "consumes",
      "label": "input"
    },
    {
      "source": "sgp4",
      "target": "keplerian-elements",
      "kind": "compares",
      "label": "osculating conversion"
    },
    {
      "source": "sgp4",
      "target": "perturbations",
      "kind": "models",
      "label": "J2 and drag"
    },
    {
      "source": "sgp4",
      "target": "reference-frames",
      "kind": "outputs",
      "label": "TEME"
    },
    {
      "source": "sgp4",
      "target": "time-scales",
      "kind": "uses",
      "label": "epoch"
    },
    {
      "source": "keplerian-elements",
      "target": "perturbations",
      "kind": "contrasts",
      "label": "no perturbations"
    },
    {
      "source": "ephemeris-interpolation",
      "target": "sgp4",
      "kind": "uses",
      "label": "samples"
    },
    {
      "source": "propagator-comparison",
      "target": "sgp4",
      "kind": "compares",
      "label": "accuracy and cost"
    },
    {
      "source": "propagator-comparison",
      "target": "method-hpop",
      "kind": "compares",
      "label": "accuracy and cost"
    },
    {
      "source": "propagator-comparison",
      "target": "method-numerical",
      "kind": "compares",
      "label": "accuracy and cost"
    },
    {
      "source": "propagator-comparison",
      "target": "method-two-body",
      "kind": "compares",
      "label": "accuracy and cost"
    },
    {
      "source": "propagator-comparison",
      "target": "ephemeris-interpolation",
      "kind": "recommends",
      "label": "many queries"
    },
    {
      "source": "method-two-body",
      "target": "keplerian-elements",
      "kind": "defines",
      "label": "solution"
    },
    {
      "source": "method-hpop",
      "target": "perturbations",
      "kind": "models",
      "label": "full force model"
    },
    {
      "source": "method-numerical",
      "target": "perturbations",
      "kind": "models",
      "label": "selected forces"
    },
    {
      "source": "crate-apsis-time",
      "target": "time-scales",
      "kind": "implements",
      "label": "Epoch"
    },
    {
      "source": "crate-apsis-coord",
      "target": "reference-frames",
      "kind": "implements",
      "label": "Eci, Ecef, Geodetic"
    },
    {
      "source": "crate-apsis-sgp4",
      "target": "sgp4",
      "kind": "implements",
      "label": "Satellite"
    },
    {
      "source": "standards-and-provenance",
      "target": "sgp4",
      "kind": "cites",
      "label": "Vallado 2006"
    },
    {
      "source": "standards-and-provenance",
      "target": "geodesy-wgs84",
      "kind": "cites",
      "label": "NIMA TR8350.2"
    },
    {
      "source": "standards-and-provenance",
      "target": "earth-rotation-angle",
      "kind": "cites",
      "label": "IERS 2010"
    }
  ]
}