Crate use_orbit 

use-orbit

Orbital mechanics helpers for RustUse.

Install

[dependencies]
use-orbit = "0.0.1"

Foundation

use-orbit provides small f64-first helpers for circular and elliptical two-body orbital mechanics.

It focuses on scalar orbital relations such as gravitational parameter, orbital speed, orbital period, semi-major axis, apoapsis and periapsis relations, vis-viva speed, escape relations, and simple orbital state summaries.

Inputs are expected to be SI-style numeric values:

• kilograms for mass
• meters for radius, altitude, apsides, and semi-major axis
• cubic meters per second squared for gravitational parameter
• meters per second for speed and delta-v
• seconds for orbital period and transfer time
• joules per kilogram for specific orbital energy

The crate does not define a full unit system.

General gravity helpers belong in use-gravity. General constants belong in the top-level use-constants set. Unit abstractions belong in the top-level use-units set. Simulation and numerical propagation belong in the top-level use-simulation set or a future specialized crate.

Example

use use_orbit::{CentralBody, EllipticalOrbit, hohmann_total_delta_v};

let earth = CentralBody::with_radius(5.972e24, 6.371e6);
let low_orbit_radius = earth.and_then(|body| body.orbital_radius_from_altitude(400_000.0));
let low_orbit_speed = earth.and_then(|body| {
	low_orbit_radius.and_then(|radius| body.circular_orbital_speed_at_radius(radius))
});
let transfer = hohmann_total_delta_v(398_600_441_800_000.0, 6_771_000.0, 42_164_000.0);

assert_eq!(low_orbit_radius, Some(6_771_000.0));
assert!(low_orbit_speed.is_some_and(|speed| speed > 7_600.0));
assert!(transfer.is_some_and(|delta_v| delta_v > 0.0));
assert!(EllipticalOrbit::new(100.0, 10.0, 20.0)
	.and_then(|orbit| orbit.period())
	.is_some_and(|period| period > 0.0));

When to use directly

Choose use-orbit when you need small reusable orbit formulas without a larger astrodynamics stack.

Scope

• APIs stay f64-first and dependency-free.
• The crate focuses on two-body scalar orbital helpers, not n-body simulation or ephemeris modeling.
• The crate keeps only a couple of convenience constants locally.
• Broader constants and units belong in the top-level use-constants and use-units sets.

Status

use-orbit is a pre-1.0 crate with a deliberately small API. Orbital mechanics helpers.

Modules

prelude

Structs

CentralBody

Mass and optional radius for a central body used in orbital calculations.

EllipticalOrbit

Elliptical orbit state described by a gravitational parameter and apsides.

Constants

GRAVITATIONAL_CONSTANT

Newtonian constant of gravitation, in cubic meters per kilogram second squared.

STANDARD_GRAVITY

Conventional standard gravity, in meters per second squared.

Functions

altitude_from_orbital_radius

Computes altitude from body radius and orbital radius.

apoapsis_from_semi_major_axis_eccentricity

Computes apoapsis radius from semi-major axis and eccentricity.

apoapsis_speed

Computes speed at apoapsis using the vis-viva equation.

circular_orbital_period

Computes the orbital period for a circular orbit.

circular_orbital_speed

Computes the speed for a circular orbit at a radius around a body with gravitational parameter.

eccentricity_from_apsides

Computes eccentricity from periapsis and apoapsis radii.

elliptical_orbital_period

Computes the orbital period for an elliptical orbit.

escape_speed

Computes escape speed from a distance around a body with gravitational parameter.

gravitational_parameter

Computes the standard gravitational parameter from a source mass.

hohmann_delta_v_1

Computes the first burn for a Hohmann transfer.

hohmann_delta_v_2

Computes the second burn for a Hohmann transfer.

hohmann_total_delta_v

Computes the total scalar delta-v magnitude for a Hohmann transfer.

hohmann_transfer_semi_major_axis

Computes the semi-major axis of a Hohmann transfer ellipse.

hohmann_transfer_time

Computes the transfer time for a Hohmann transfer.

orbital_radius_from_altitude

Computes orbital radius from body radius and altitude.

orbital_radius_from_circular_speed

Computes the circular orbital radius from circular speed.

orbital_radius_from_period

Computes the circular orbital radius from an orbital period.

periapsis_from_semi_major_axis_eccentricity

Computes periapsis radius from semi-major axis and eccentricity.

periapsis_speed

Computes speed at periapsis using the vis-viva equation.

semi_major_axis_from_apsides

Computes the semi-major axis from periapsis and apoapsis radii.

semi_major_axis_from_specific_energy

Computes the semi-major axis for a bound orbit from specific orbital energy.

source_mass_from_gravitational_parameter

Computes the source mass from a standard gravitational parameter.

specific_orbital_energy

Computes specific orbital energy.

vis_viva_speed

Computes orbital speed from the vis-viva equation.