Crate astrodyn_interactions 

Surface interactions: aerodynamics, radiation pressure, contact, lighting, torques.

Pure-Rust port of JEOD’s models/interactions/ plus the surface-model and shadow geometry that those interactions depend on. Each module produces a force, torque, or environmental scalar at a vehicle position; the orchestration that sums these into a body’s astrodyn_dynamics::TotalForce lives in astrodyn.

Public surface

• Aerodynamic drag: aero_drag (port of JEOD models/interactions/aerodynamics/) provides scalar-Cd drag against a ballistic-coefficient body. flat_plate_aero adds the per-facet panel-method drag/lift used for articulated spacecraft.
• Radiation pressure: radiation_pressure ports JEOD models/interactions/radiation_pressure/ — solar flux against a surface model with absorption / specular / diffuse coefficients, shadow-corrected via the shadow module’s umbra/penumbra geometry and via compute_earth_lighting for Earth-albedo and Earth-IR contributions (EarthLightingState, LightingBody, LightingParams).
• Gravity-gradient torque: compute_gravity_torque and its typed sibling compute_gravity_torque_typed port JEOD models/interactions/gravity_torque/ — the cross product of the inertia tensor and the gravity-gradient tensor projected through the body attitude.
• Surface model: SurfaceFacet, ArticulatedFacet, ArticulationState, SurfaceShape in surface_model are the per-facet geometry inputs that aero, SRP, contact, and thermal share.
• Contact: compute_contact_force, compute_contact_force_from_geometry, compute_contact_geometry, ContactFacet, ContactForce, ContactGeometry, ContactMaterial, ContactShape for collision/contact response.
• Thermal: compute_thermal_power_balance, ThermalEnvironment, ThermalFacet, ThermalPowerBalance — per-facet power balance for thermal-rider models.

JEOD source: models/interactions/ and surrounding utilities. Pure Rust, zero Bevy dependency.

Example

Compute ballistic aerodynamic drag for a 1 m² Cd=2.2 plate moving at 7.5 km/s through a thin LEO atmosphere:

use astrodyn_atmosphere::AtmosphereState;
use astrodyn_interactions::{compute_ballistic_drag, DragConfig};
use astrodyn_quantities::frame::SelfPlanet;
use glam::{DMat3, DVec3};

let cfg = DragConfig { cd: 2.2, area: 1.0, constant_density: None };
// 1e-12 kg/m^3 is roughly 400 km altitude.
let atmos = AtmosphereState::<SelfPlanet>::from_raw(1.0e-12, 0.0, 0.0, DVec3::ZERO);
// Velocity along +X at 7.5 km/s; identity rotation (inertial == body).
let v = DVec3::new(7_500.0, 0.0, 0.0);
let force = compute_ballistic_drag(&cfg, &atmos, v, &DMat3::IDENTITY);

// Drag opposes motion (-X) and is small but non-zero.
assert!(force.force.x < 0.0);
assert!(force.force.length() > 0.0 && force.force.length() < 1.0);

Re-exports

pub use contact::compute_contact_force;

pub use contact::compute_contact_force_from_geometry;

pub use contact::compute_contact_geometry;

pub use contact::compute_ground_contact_geometry;

pub use contact::ContactFacet;

pub use contact::ContactForce;

pub use contact::ContactGeometry;

pub use contact::ContactMaterial;

pub use contact::ContactShape;

pub use contact::GroundFacet;

pub use contact::Phase;

pub use contact::SphericalTerrain;

pub use contact::Terrain;

pub use earth_lighting::compute_earth_lighting;

pub use earth_lighting::compute_earth_lighting_typed;

pub use earth_lighting::EarthLightingState;

pub use earth_lighting::LightingBody;

pub use earth_lighting::LightingParams;

pub use forces::collect_and_resolve_forces;

pub use forces::collect_and_resolve_forces_typed;

pub use gravity_torque::compute_gravity_torque;

pub use gravity_torque::compute_gravity_torque_typed;

pub use surface_model::ArticulatedFacet;

pub use surface_model::ArticulationState;

pub use surface_model::SurfaceFacet;

pub use surface_model::SurfaceShape;

pub use thermal_rider::compute_thermal_power_balance;

pub use thermal_rider::ThermalEnvironment;

pub use thermal_rider::ThermalFacet;

pub use thermal_rider::ThermalPowerBalance;

pub use aero_drag::*;

pub use flat_plate_aero::*;

pub use radiation_pressure::*;

pub use shadow::*;

Modules

aero_drag

Aerodynamic drag computation.

contact

Contact dynamics (spring-damper + Coulomb friction).

earth_lighting

Earth lighting model.

flat_plate_aero

Flat-plate aerodynamic surface model.

forces

Force-collection stage: composes per-body external + interaction + gravity contributions into the integrator’s FrameDerivatives (linear and angular accelerations expressed in the integration frame).

gravity_torque

Gravity gradient torque computation.

radiation_pressure

Solar radiation pressure computation.

shadow

Shadow (eclipse) detection.

surface_model

Generic surface geometry model.

thermal_rider

Thermal-rider model: per-facet environmental heating and Stefan-Boltzmann emission.