# Satellite Toolkit with Rust
An accurate, high-performance satellite orbital kinematics toolkit, written in Rust with a sensible interface.
<br/>
Also includes python bindings for *all* functions via via [pyo3](https://pyo3.rs/)
### Github
### Crates.io
### PyPi
## Language Bindings
- **Native Rust** bindings
- **Python bindings** for compiled rust code ... speed of Rust with convenience of Python<br/>
Install with `pip install satkit`<br/>
PyPi includes binary packages for windows, macos (Intel & ARM), and linux. Python documentation is at: <https://satellite-toolkit.readthedocs.io/latest/>
## Features
- High-precision coordinate transforms between:
- International Terrestrial Reference Frame (ITRF)
- Geocentric Celestial Reference Frame (GCRF) using IAU-2000 reduction
- True-Equinox Mean Equator (TEME) frame used in SGP4 propagation of TLEs
- Celestial Intermediate Reference Frame (CIRF)
- Terrestrial Intermediate Reference Frame (TIRF)
- Terrestrial Geodetic frame (latitude, longitude)
- Geodesic distances
- SGP4, and Keplerian orbit propagation
- JPL high-precision planetary ephemerides
- High-order gravity models
- High-precision, high-speed numerical satellite orbit propagation with high-order efficient Runga-Kutta solvers, ability to solve for state transition matrix, and inclusion following forces:
- High-order Earth gravity with multiple models
- Solar gravity
- Lunar gravity
- Drag: NRL MISE-00 density model
- Radiation pressure
## ODE Solvers
The high-precision numerical satellite orbit propagation makes use of adaptive Runga-Kutta methods for integration of ordinary differential equations. The pure-Rust ODE solver is included as part of the library.
The methods use Runga-Kutta pairs for ODE integration and error estimation generated by Jim Verner: [https://www.sfu.ca/~jverner/](https://www.sfu.ca/~jverner/)
## References, Models, and External Software.
### The equations and many of the unit tests underlying this work are drawn from the following sources:
- **"Fundamentals of Astrodynamics and Applications, Fourth Edition"**, D. Vallado, Microcosm Press and Springer, 2013.<br>
[https://celestrak.org/software/vallado-sw.php](https://celestrak.org/software/vallado-sw.php)
- **"Satellite Orbits: Models, Methods, Applications"**, O. Montenbruck and E. Gill, Springer, 2000.<br>
[https://doi.org/10.1007/978-3-642-58351-3](https://doi.org/10.1007/978-3-642-58351-3)
### Data Dependencies
This code makes reference to and relies on models generated by the following:
- **SGP4 Orbit Propagator** - https://celestrak.org/software/tskelso-sw.php<br/>
NORAD / SGP4 orbit propagator used to generate position and velocity states from orbital ephemerides described by Two-Line Element Sets (TLEs). This code base includes a pure-rust translation of the SGP4 orbit propagator
- **NRL MSISE-00 Density Model** - https://ccmc.gsfc.nasa.gov/models/NRLMSIS~00/<br/>
NRL model of air density, including density at high altitudes, used in to compute satellite drag
- **Gravity Models** - http://icgem.gfz-potsdam.de/home<br/>
International Center for Global Earth Models (ICEGM), collection and archive in a common format of all existing global gravity field models
- **Space Weather** - https://celestrak.org/SpaceData/<br/>
Space weather used to modulate the air density used in drag calculations
- **Earth Orientation Parameters** - https://celestrak.org/SpaceData/<br/>
Time-varying Earth orientation parameters used for time epoch conversions and high-precision rotations between the inertial and Earth-fixed coordinate frames
- **IERS Conventions** - https://www.iers.org/IERS/EN/Publications/TechnicalNotes/tn36.html<br/>
International Earth Rotation and Reference Systems Service Technical Note 36 for rotation between inertial and Earth-fixed coordinate systems.
- **JPL Ephemerides** - https://ssd.jpl.nasa.gov/ephem.html<br/>
High-precision ephemerides for solar system bodies (sun, moon, planets) in frame of solar system barycenter
## Verification
The package includes rust test modules and python test modules for verification of nearly all calculations, including but not limited to:
- **JPL Ephemeris** - Via JPL-provided test vectors for Chebychev polynomial calculation
- **SGP4** - Via SGP4 test vectors provided with original C<sup>++</sup> distribution
## Getting Started
### Rust
Simply include the code in your Cargo.toml file to use. Once installed, make sure you run `utils.update_datafiles` to download the most-recent [data files](#data-dependencies) necessary for many calculations. This only needs to be done once, unless more-recent space weather and Earth orientation parameter data is required (these are updated at least daily).
```rust
satkit.utils.update_datafiles()?;
```
### Python
Satkit is available via pypi.org, and can be installed via the `pip` command:
```bash
python -m pip install satkit
```
Binaries are available for Windows (AMD64), Mac (Intel, Apple Silicon) and Linux (x86_64, aarch64) for python versions 3.8 through 3.14.
Once installed, make sure you download the most-recent [data files](#data-dependencies) necessary for many calculations. This only needs to be done once, unless more-recent space weather and Earth orientation parameter data is required (these are updated at least daily).
```python
import satkit as sk
sk.utils.update_datafiles()
```
## Author
Steven Michael (ssmichael@gmail.com)
Please reach out of you find errors in code or calculations, are interested in contributing to this repository, or have suggestions for improvements to the API.