SatKit

Satellite astrodynamics in Rust, with full Python bindings.

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.

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

Quick Start

pip install satkit

The satkit_data package is installed automatically as a dependency and includes gravity models, JPL ephemerides, and Earth orientation parameters -- no extra download step needed. To update space weather and Earth orientation parameters to the latest values, run:

import satkit as sk
sk.utils.update_datafiles()

Quick Examples

SGP4 propagation

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

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,
)

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

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

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 -- 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
• Lambert -- Multi-revolution Lambert targeting for orbit transfer design

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 (pure Rust) 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

Quick Links

Installation	Install from PyPI or build from source
Data Files	Required data files for calculations
Learn	Tutorials and theory — from basics to advanced topics
API Reference	Full Python API documentation
Rust API (docs.rs)	Rust API reference
GitHub	Source code and issue tracker

Author

Steven Michael (ssmichael@gmail.com)

Please reach out if you find errors in code or calculations, are interested in contributing to this repository, or have suggestions for improvements to the API.