Crate astrodyn_gravity 

Gravity: spherical, spherical harmonics (Gottlieb), tides, and relativistic terms.

Pure-Rust port of JEOD’s models/environment/gravity/. The crate produces gravitational acceleration, the gravity-gradient tensor, and the gravitational potential at a body’s position, given a configured set of gravity sources.

Public surface

• Spherical (point-mass) gravity: calc_spherical, gravitation, and gravitation_with_scratch from compute. Output is a astrodyn_dynamics::GravityAcceleration containing acceleration, gradient, and potential — gradient and potential are filled even for the point- mass case so downstream consumers (gravity-gradient torque, energy diagnostics) have what they need.
• Spherical harmonics: calc_nonspherical, calc_nonspherical_typed, calc_nonspherical_with_scratch, and GottliebScratch from spherical_harmonics_calc_nonspherical. This is the ported Gottlieb algorithm from JEOD models/environment/gravity/src/spherical_harmonics_calc_nonspherical.cc — a numerically stable normalized Legendre recursion that scales to high degree and order without the underflow/overflow problems of the classical formulation.
• Configuration types: GravitySource, GravityModel, gravity-controls re-exports from gravity_controls and spherical_harmonics_gravity_controls, and the SphericalHarmonicsData coefficient container.
• Tides and relativistic corrections: tides and relativistic carry the small post-Newtonian and luni-solar tide terms.

JEOD coefficient data lives in models/environment/gravity/data/include/earth_GGM05C.hh (and similar per-body files); coefficients contains the parsing logic that turns the C++ array headers into Vec<Vec<f64>> C and S coefficient tables. Coefficients are normalized as in JEOD; the recursion expects normalized input. Pure Rust, zero Bevy dependency.

Example

Point-mass gravity at the equator of a body with Earth’s mu should point inward (toward the body’s centre):

use astrodyn_gravity::calc_spherical;
use glam::DVec3;

let mu = 3.986_004_415e14; // Earth GGM05C, m^3/s^2
let r = DVec3::new(6_778_137.0, 0.0, 0.0); // 400 km altitude on +X axis

let g = calc_spherical(mu, r);
// Acceleration points back toward the origin (-X) at ~8.7 m/s^2.
assert!(g.grav_accel.x < 0.0);
assert!((g.grav_accel.length() - mu / r.length().powi(2)).abs() < 1e-6);

Re-exports

pub use accumulate::accumulate_gravity;

pub use accumulate::accumulate_gravity_typed;

pub use accumulate::accumulate_relativistic_corrections;

pub use accumulate::accumulate_relativistic_corrections_typed;

pub use accumulate::evaluate_body_gravity_typed;

pub use accumulate::run_gravity_stage;

pub use accumulate::GravityBodyInputs;

pub use accumulate::ResolvedRelativisticSource;

pub use accumulate::ResolvedSource;

pub use compute::calc_spherical;

pub use compute::gravitation;

pub use compute::gravitation_with_scratch;

pub use spherical_harmonics_calc_nonspherical::calc_nonspherical;

pub use spherical_harmonics_calc_nonspherical::calc_nonspherical_typed;

pub use spherical_harmonics_calc_nonspherical::calc_nonspherical_with_scratch;

pub use spherical_harmonics_calc_nonspherical::GottliebScratch;

pub use spherical_harmonics_gravity_source::SphericalHarmonicsData;

pub use gravity_controls::*;

pub use gravity_source::*;

pub use spherical_harmonics_gravity_controls::*;

Modules

accumulate

Gravity stage: per-body gravity accumulation across multiple sources (point-mass, spherical-harmonics with optional tides, plus optional relativistic post-Newtonian corrections).

coefficients

Compact binary serialization for gravity coefficients.

compute

Top-level gravity-acceleration computation.

data

Embedded planetary gravity-coefficient blobs.

fixtures

Committed planetary gravity-coefficient fixtures.

gravity_controls

Per-source gravity-control configuration (GravityControl + typed sibling GravityControlTyped).

gravity_source

GravitySource / GravityModel — the per-body μ + model payload that gravity-control evaluation runs against.

jeod_cc

JEOD C++ source file parsers for gravity coefficient files.

relativistic

Post-Newtonian (PPN) relativistic gravity correction.

spherical_harmonics_calc_nonspherical

Gottlieb (1993) spherical harmonics gravity computation.

spherical_harmonics_gravity_controls

Multi-source GravityControls aggregator — the per-vehicle list of GravityControl entries the gravity pipeline iterates each step.

spherical_harmonics_gravity_source

SphericalHarmonicsData — coefficient table and precomputed Gottlieb helper arrays for spherical-harmonics gravity.

tides

Solid body tidal delta coefficients.

verif

Parser for JEOD’s static gravity-verification reference data.