satkit 0.13.0

Satellite Orbital Dynamics Toolkit

satkit

Satellite astrodynamics in Rust, with full Python bindings.

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Satkit is a high-performance orbital mechanics library written in Rust with complete Python bindings via PyO3. It handles coordinate transforms, orbit propagation, time systems, gravity models, atmospheric density, and JPL ephemerides -- everything needed for satellite astrodynamics work.

Documentation and tutorials (Python examples, but the concepts and API apply equally to Rust) | Rust API reference

Installation

Rust:

cargo add satkit

Python:

pip install satkit

Pre-built wheels are available for Linux, macOS, and Windows on Python 3.10--3.14.

After installing, download the required data files (gravity models, ephemerides, Earth orientation parameters):

import satkit as sk
sk.utils.update_datafiles()  # one-time download; re-run periodically for fresh EOP/space weather

Quick Examples

SGP4 propagation (Python)

import satkit as sk

tle = sk.TLE.from_lines([
    "ISS (ZARYA)",
    "1 25544U 98067A   24001.50000000  .00016717  00000-0  10270-3 0  9003",
    "2 25544  51.6432 351.4697 0007417 130.5364 329.6482 15.48915330299357"
])

pos, vel = sk.sgp4(tle, sk.time(2024, 1, 2))

High-precision propagation (Python)

import satkit as sk
import numpy as np

r0 = 6378e3 + 500e3  # 500 km altitude
v0 = np.sqrt(sk.consts.mu_earth / r0)

settings = sk.propsettings(
    gravity_model=sk.gravmodel.jgm3,
    gravity_degree=8,
    integrator=sk.integrator.rkv98,  # default; also rkv87, rkv65, rkts54
)

result = sk.propagate(
    np.array([r0, 0, 0, 0, v0, 0]),
    sk.time(2024, 1, 1),
    end=sk.time(2024, 1, 1) + sk.duration.from_days(1),
    propsettings=settings,
)

state = result.interp(sk.time(2024, 1, 1) + sk.duration.from_hours(6))

Coordinate transforms (Python)

import satkit as sk

time = sk.time(2024, 1, 1, 12, 0, 0)
coord = sk.itrfcoord(latitude_deg=42.0, longitude_deg=-71.0, altitude=100.0)

q = sk.frametransform.qitrf2gcrf(time)
gcrf_pos = q * coord.vector

Planetary ephemerides (Rust)

use satkit::{Instant, SolarSystem, jplephem};

let time = Instant::from_datetime(2024, 1, 1, 0, 0, 0.0)?;
let (pos, vel) = jplephem::geocentric_state(SolarSystem::Moon, &time)?;

Features

Coordinate Frames

Full IAU-2006/2000 reduction with Earth orientation parameters:

Frame	Description
ITRF	International Terrestrial Reference Frame (Earth-fixed)
GCRF	Geocentric Celestial Reference Frame (inertial)
TEME	True Equator Mean Equinox (SGP4 output frame)
CIRS	Celestial Intermediate Reference System
TIRS	Terrestrial Intermediate Reference System
Geodetic	Latitude / longitude / altitude (WGS-84)

Plus ENU, NED, and geodesic distance (Vincenty) utilities.

Orbit Propagation

• Numerical -- Selectable adaptive Runge-Kutta integrators (9(8), 8(7), 6(5), 5(4)) with dense output, state transition matrix, and configurable force models
• SGP4 -- Standard TLE/OMM propagator with TLE fitting from precision states
• Keplerian -- Analytical two-body propagation

Force Models

• Earth gravity: JGM2, JGM3, EGM96, ITU GRACE16 (spherical harmonics up to degree/order 360)
• Third-body gravity: Sun and Moon via JPL DE440/441 ephemerides
• Atmospheric drag: NRLMSISE-00 with automatic space weather data
• Solar radiation pressure: Cannonball model with shadow function

Time Systems

Seamless conversion between UTC, TAI, TT, TDB, UT1, and GPS time scales with full leap-second handling.

Solar System

• JPL DE440/DE441 ephemerides for all planets, Sun, Moon, and barycenters
• Fast analytical Sun/Moon models for lower-precision work
• Sunrise/sunset and Moon phase calculations

Cargo Features

Feature	Default	Description
omm-xml	yes	XML OMM deserialization via quick-xml
chrono	no	TimeLike impl for chrono::DateTime

Data Files

Satkit needs external data for gravity models, ephemerides, and Earth orientation. Call update_datafiles() to download them automatically.

Downloaded once: JPL DE440/441 (~100 MB), gravity model coefficients, IERS nutation tables

Update periodically: Space weather indices (F10.7, Ap) and Earth orientation parameters (polar motion, UT1-UTC) -- both sourced from Celestrak.

Testing and Validation

The library is validated against:

• Vallado test cases for SGP4, coordinate transforms, and Keplerian elements
• JPL test vectors for DE440/441 ephemeris interpolation (10,000+ cases)
• ICGEM reference values for gravity field calculations
• GPS SP3 precise ephemerides for multi-day numerical propagation

106 unit tests and 36 doc-tests run on every commit across Linux, macOS, and Windows.

Documentation

• Rust: docs.rs/satkit
• Python: satkit.dev -- tutorials, Jupyter notebooks, and API reference

References

• D. Vallado, Fundamentals of Astrodynamics and Applications, 4th ed., 2013
• O. Montenbruck & E. Gill, Satellite Orbits: Models, Methods, Applications, 2000
• J. Verner, Runge-Kutta integration coefficients

License

MIT