Arc

This project is no longer maintained.

I used it to learn some of the principles of numerical orbit propagation and I ended up starting from scratch with something else. It is by no means supported or particularly useful in its current state, but it might be helpful to someone. A copy of Niels Lohmann's JSON library is included, which is licensed under MIT. Much of the original structure was inspired by David RC Dayton's Pious Squid, also under MIT. Additionally, the NetBSD version of the strptime function is included, which carries is own license.

Arc is a toolkit aimed at providing high-accuracy numerical propagation and orbit/trajectory analysis on spacecraft. It started as a personal project to learn more about the mathematics used in orbit determination/propagation. I've attempted to keep three development goals in mind:

• Simple, unobscured code with sane variable names and logic
• Adherence to as many international scientific standards as practical
• No external dependencies outside the Standard Template Library

Features

• Coordinate systems
  • International Celestial Reference Frame (ICRF)
  • International Terrestrial Reference Frame (ITRF/ECEF)
  • True Equator Mean Equinox (TEME)
  • Keplerian elements
• Planetary positions
  • Numerical approximation
  • Ephemeris interpolation
  • JPL ephemerides (DE430, etc)
• Planetary orientations
  • Earth (IAU 1980)
  • Earth (IAU 2000/2006)
• Time handling
  • Coordinated Universal Time (UTC)
  • Universal Time (UT1)
  • Terrestrial Time (TT)
  • International Atomic Time (TAI)
  • Barycentric Dynamical Time (TDB)
  • Leap second
• Orbital state propagation
  • Keplerian Approximation
  • Ephemeris Interpolation
    • Keplerian
    • Lagrange
    • Hermite
  • Numerical integration
    • 4th-order Runge-Kutta
    • Dormand-Prince
    • Adams-Bashforth-Moulton
• Perturbing force models
  • Aspherical gravity models
    • J2
    • J3
    • EGM-2008
    • GMM-3
  • Atmospheric Drag
    • U.S. Standard 1976
    • Harris-Priester
    • NASA Earth-GRAM
    • NASA Mars-GRAM
  • Third body gravity
  • Solar Radiation Pressure
  • Spacecraft Maneuvers
  • Tidal variations
  • Relativity
• Data input
  • JSON parsing
  • Python library
  • External library call
• Data output
  • Spacecraft Ephemerides
    • STK format
    • CCSDS OEM format
  • Spacecraft Covariance
    • STK format
    • CCSDS OEM format
  • Two-line element set (TLE)