astrodyn_time

Time scales, leap seconds, calendar dates, and the time manager for the astrodyn_bevy workspace.

Ports models/environment/time/ from NASA JEOD v5.4.0, including the Leap_Second.dat table.

Layered architecture

astrodyn_bevy        (Bevy ECS adapter, mission code)
   ↓
astrodyn         (orchestration, recipes, single API surface)
   ↓
astrodyn_time        ←  this crate (pure Rust, zero Bevy)
   ↓
astrodyn_quantities  (typed time scales, SecondsSince<S>)

astrodyn_time is part of the astrodyn_* physics layer — pure Rust with no Bevy dependency.

Public surface

• TimeManager, TimeScaleId — orchestrator for registered scales.
• SimulationTime — per-step time-state resource (gravity, ephemeris, atmosphere read from this).
• DynamicTime — dynamics-frame time passed through the integrator.
• LeapSecondTable — JEOD Leap_Second.dat parser / lookup.
• CalendarDate, UTC_EPOCH_TAI_TJT — Gregorian calendar.
• UserDefinedEpoch, MissionElapsedTime — sim-defined epoch + MET.
• GpsTimeComponents, TAI_GPS_OFFSET — GPS week / time-of-week.
• Per-pair converters: time_converter_tai_tdb, time_converter_tai_tt, time_converter_ut1_gmst. GMST drives Earth body-fixed rotation in astrodyn_frames.

See also

• docs/JEOD_invariants.md — TM.*, LS.* invariants this crate enforces.
• Project README and CLAUDE.md — workspace-level architecture.
• Rendered rustdoc: https://docs.rs/astrodyn_time