References

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.
https://celestrak.org/software/vallado-sw.php

“Satellite Orbits: Models, Methods, Applications”, O. Montenbruck and E. Gill, Springer, 2000.
https://doi.org/10.1007/978-3-642-58351-3

Models

This code makes reference to and relies on models generated by the following:

SGP4 Orbit Propagator - https://celestrak.org/software/tskelso-sw.php
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/
NRL model of air density, including density at high altitudes, used in to compute satellite drag
Gravity Models - http://icgem.gfz-potsdam.de/home
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/
Space weather used to modulate the air density used in drag calculations
Earth Orientation Parameters - https://celestrak.org/SpaceData/
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
International Earth Rotation and Reference Systems Service Technical Note 36 for rotation between inertial and Earth-fixed coordinate systems.

The code includes rust test modules and python test modules for verification of nearly 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⁺⁺ distribution