Crate astrodyn_time

Expand description

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

Pure-Rust port of JEOD’s models/environment/time/. The crate models the standard astronomical and engineering time scales (TAI, UTC, UT1, TT, TDB, GPS, GMST), the leap-second table that ties UTC to TAI, and the per-simulation user-defined epoch (UDE) and mission-elapsed time (MET) that mission code typically logs against.

§Public surface

TimeManager and TimeScaleId — the orchestrator that owns the currently registered time scales and answers conversions between them. Mirrors JEOD’s TimeManager.
SimulationTime — the resource the integration loop advances each step; downstream consumers (gravity, ephemeris, atmosphere) read from it rather than tracking their own clocks.
DynamicTime — the dynamics-frame time state passed through the integrator.
LeapSecondTable — parser/lookup for JEOD’s models/environment/time/data/Leap_Second.dat. Required for any simulation that hits a UTC↔TAI conversion.
Calendar / epoch types: CalendarDate and UTC_EPOCH_TAI_TJT from time_utc, UserDefinedEpoch from time_ude, MissionElapsedTime from time_met, GpsTimeComponents and TAI_GPS_OFFSET from time_gps, plus the epoch module.
Per-pair time converters: time_converter_tai_tdb, time_converter_tai_tt, and time_converter_ut1_gmst each port one of JEOD’s TimeConverter_* classes. GMST in particular drives Earth’s body-fixed rotation in astrodyn_frames.

JEOD source: models/environment/time/ (and the models/environment/time/data/ subdirectory for Leap_Second.dat). Pure Rust, zero Bevy dependency.

§Example

Build a calendar date and round-trip it through the truncated Julian representation that the per-scale converters consume internally:

use astrodyn_time::time_utc::{calendar_to_tjt, tjt_to_calendar, CalendarDate};

let cal = CalendarDate::new(2025, 1, 1, 0, 0, 0.0);
let tjt = calendar_to_tjt(&cal);
let back = tjt_to_calendar(tjt);
assert_eq!(back.year, cal.year);
assert_eq!(back.month, cal.month);
assert_eq!(back.day, cal.day);

Re-exports§

pub use leap_second::LeapSecondTable;
pub use simulation_time::SimulationTime;
pub use time_dyn::DynamicTime;
pub use time_gps::GpsTimeComponents;
pub use time_gps::TAI_GPS_OFFSET;
pub use time_manager::TimeManager;
pub use time_manager::TimeScaleId;
pub use time_met::MissionElapsedTime;
pub use time_ude::UserDefinedEpoch;
pub use time_utc::CalendarDate;
pub use time_utc::UTC_EPOCH_TAI_TJT;
pub use epoch::*;

Modules§

epoch: Standard astronomical epochs and JD ↔ MJD ↔ TJT conversions.
leap_second: LeapSecondTable — TAI ↔ UTC leap-second lookup.
simulation_time: SimulationTime — the per-step time-state resource that the integration loop advances each step and that downstream consumers (gravity, ephemeris, atmosphere) read from.
time_converter_tai_tdb: TAI ↔ TDB time-scale conversion.
time_converter_tai_tt: TAI ↔ TT time-scale conversion (constant 32.184 s offset).
time_converter_ut1_gmst: UT1 → GMST conversion (Greenwich Mean Sidereal Time).
time_dyn: DYN — Dynamic Time scale.
time_gps: GPS time scale — constant offset from TAI plus GPS week/day decomposition.
time_manager: Time Manager — dependency-ordered conversion between time scales.
time_met: MET — Mission Elapsed Time.
time_ude: UDE — User-Defined Epoch time scale.
time_utc: UTC time scale — calendar representation and TAI↔UTC conversion.

Structs§

BodyAttitude: RootInertial → body attitude of vehicle V, witnessed unit-norm and scalar-first / left-transformation (JEOD canonical).
BodyFrame: Body (CoM-centered) frame of vehicle V. Rotates with the vehicle.
Earth: Planet marker for Earth.
Ecef: Earth-centered Earth-fixed frame (ITRF-like). Rotates with Earth.
FrameTransform: Proper rotation taking vectors expressed in From to the same vectors expressed in To.
GMST: Greenwich Mean Sidereal Time (angle, but seconds-ized by convention).
GPS: GPS Time (TAI − 19 s).
GravParam: Gravitational parameter μ = GM tagged with the source planet P.
HarmonicDegree: Spherical-harmonic degree or order index. Unitless ordinal.
InertiaTensor: Mass moment of inertia tensor (kg·m²) expressed in frame F.
IntegOrigin: The integration-frame origin: position and velocity of the integration-frame origin expressed in root-inertial coordinates.
IntegrationFrame: A body’s integration frame — a non-rotating quasi-inertial frame whose origin generally differs from the root inertial origin.
LeftTransform: r' = q r q⁻¹ — the JEOD convention.
Lvlh: Local Vertical / Local Horizontal frame relative to chief vehicle Chief. Z axis points planet-ward; Y opposes orbital angular momentum; X completes the right-handed triad (approximately along-track in near-circular orbits).
Mars: Planet marker for Mars.
MassNode: Mass-tree wildcard inertial-flavor frame for kinematic-propagation scratch state.
Moon: Planet marker for Moon.
Ned: North-East-Down topocentric frame relative to chief vehicle Chief.
NormalizedQuat: A quaternion witnessed to have unit norm at construction time.
PlanetFixed: Planet-fixed frame for any planet P. Rotates with that planet.
PlanetInertial: A particular planet’s inertial (non-rotating, J2000-aligned) frame, centered at the planet’s CoM.
Qty3: Componentwise 3-vector: each of x, y, z carries the dimension D, and the whole vector carries the frame tag F.
Quat: Quaternion tagged with its storage layout and transformation convention.
RightTransform: r' = q⁻¹ r q — the opposite of JEOD; common in many textbooks.
RootInertial: The simulation’s root inertial frame — the unique inertial node at the top of the frame tree.
ScalarFirst: Storage layout [q0, q1, q2, q3] where q0 is the scalar part (JEOD).
ScalarLast: Storage layout [x, y, z, w] where w is the scalar part (glam).
SecondsSince: Seconds elapsed in the named time scale, measured from that scale’s epoch.
SelfPlanet: Phantom marker for “this entity’s own planet” — used by ECS adapters whose per-entity components carry PlanetFixed<P> phantoms but whose planet identity is determined at runtime by the entity itself.
SelfRef: Phantom marker for “this entity’s own vehicle frame” — used by ECS adapters whose per-entity components carry frame phantoms but whose vehicle identity is determined at runtime by the entity itself.
StructuralFrame: Structural (geometric-origin) frame of vehicle V. Rotates with vehicle.
Sun: Planet marker for Sun.
TAI: International Atomic Time.
TDB: Barycentric Dynamical Time (relativistic correction to TT).
TT: Terrestrial Time (TAI + 32.184 s).
TimeConverter: Explicit converter between two time scales.
UT1: Universal Time 1 (Earth-rotation based).
UTC: Coordinated Universal Time (leap-second stepped).

Traits§

Array3Ext: Extension trait on [f64; 3] (raw component arrays from CSVs or JEOD initial conditions) producing frame-tagged 3-vectors.
F64Ext: Unit-construction extension on f64.
Frame: Compile-time reference frame tag.
Layout: Compile-time quaternion storage layout marker.
Planet: Compile-time planet tag used to parameterize planet-fixed frames.
TimeScale: Compile-time time-scale tag.
Transform: Compile-time quaternion transformation convention marker.
Vec3Ext: Extension trait on glam::DVec3 producing frame-tagged 3-vectors.
Vehicle: Compile-time vehicle tag used to parameterize vehicle-relative frames.

Type Aliases§

Acceleration: Acceleration in frame F. Base SI unit: m/s².
AngularAcceleration: Angular acceleration in frame F. Base SI unit: rad/s².
AngularMomentum: Angular momentum in frame F. Base SI unit: kg·m²/s.
AngularVelocity: Angular velocity in frame F. Base SI unit: rad/s.
Force: Force in frame F. Base SI unit: newtons.
JeodQuat: The JEOD canonical quaternion type: scalar-first, left-transformation.
Jerk: Jerk (time derivative of acceleration) in frame F. Base SI unit: m/s³.
MassFlowRate: Scalar mass-flow rate.
Position: Position in frame F (default: RootInertial). Base SI unit: meters.
SpecificAngMom: Scalar specific angular momentum.
SpecificEnergy: Scalar specific energy.
Torque: Torque in frame F. Base SI unit: N·m.
Velocity: Velocity in frame F. Base SI unit: m/s.