Overview

OREKIT (ORbits Extrapolation KIT) is a free low level space dynamics library written in Java.

It provides basic elements (orbits, dates, attitude, frames ...) and various algorithms to handle them (conversions, analytical and numerical propagation, pointing ...).

Features

  • Time
    • high accuracy absolute dates
    • time scales (TAI, UTC, GPS, TCG, TT, ...)
    • transparent handling of leap seconds
  • Geometry
    • frames hierarchy supporting fixed and time-dependent (or telemetry-dependent) frames
    • predefined frames (EME2000/J2000, GCRF, ITRF2005 and intermediate frames, Veis, topocentric, tnw and qsw local orbital frames, Moon, Sun, planets, solar system barycenter, Earth-Moon barycenter)
    • user extensible (used operationally in real time with a set of about 60 frames on several spacecrafts)
    • transparent handling of IERS Earth Orientation Parameters
    • transparent handling of JPL DE 405 and DE 406 ephemerides
    • transforms including kinematic combination effects
    • composite transforms reduction and caching for efficiency
    • extensible central body shapes models (with predefined spherical and ellipsoidic shapes)
    • cartesian and geodesic coordinates, kinematics
  • Spacecraft state
    • cartesian, elliptical keplerian, circular and equinoctial parameters
    • Two-Lines Elements
    • transparent conversion between all parameters
    • automatic binding with frames
    • attitude state and derivative
    • mass management
  • Propagation
    • analytical propagation models (Kepler, Eckstein-Heschler, SDP4/SGP4 with 2006 corrections)
    • numerical propagators
      • customizable force models
        • central attraction
        • gravity models (automatic reading of SHM (for Eigen models) and EGM formats potential files, even compressed)
        • atmospheric drag (DTM2000, Jacchia-Bowman 2006 and simple exponential models)
        • third body attraction (with data for Sun, Moon and all solar systems planets)
        • radiation pressure with eclipses
        • multiple maneuvers
      • state of the art ODE integrators (adaptive stepsize with error control, continuous output, switching functions, G-stop, step normalization ...)
      • serialization mechanism to store complete results on persistent storage for later use
    • tabulated ephemerides
      • file based
      • memory based
      • integration based
    • unified interface above analytical/numerical/tabulated propagators for easy switch from coarse analysis to fine simulation with one line change
    • all propagators can be used in several different modes
      • slave mode: propagator is driven by calling application
      • master mode: propagator drives application callback functions
      • ephemeris generation mode: all intermediate results are stored during propagation and provided back to the application which can navigate at will through them, effectively using the propagated orbit as if it was an analytical model, even if it really is a numerically propagated one, which is ideal for search and iterative algorithms
    • handling of discrete events during integration (models changes, G-stop, simple notifications ...)
    • predefined discrete events
      • ascending and descending node crossing
      • apogee and perigee crossing
      • raising/setting with respect to a ground location (with customizable triggering elevation)
      • altitude crossing
      • date
      • impulse maneuvers occurrence
  • Attitude
    • extensible attitude evolution models
    • predefined laws
      • central body related attitude (nadir pointing, center pointing, target pointing, yaw compensation, yaw-steering),
      • orbit referenced attitudes (LOF aligned, offset on all axes),
      • space referenced attitudes (inertial, celestial body pointed, spin stabilized)
  • Localized in several languages
    • english
    • french
    • italian
    • norse
    • spanish

Free software

Orekit is freely available both in source and binary formats, with all related documentation and tests.

It is distributed under the Apache License Version 2.0 . This is a well known business-friendly license. This means anybody can use it to build any application, free or not. There are no strings attached to your own code.

Everybody is encouraged to use Orekit as a common low level layer to help interoperability in space systems.

Maintained library

Orekit has been in development since 2002 inside CS Communication & Systèmes and is still used and maintained by its space dynamics experts. It has already been successfully used during the real time monitoring of the rendez-vous phase between the Automated Transfer Vehicle (ATV) and the International Space Station (ISS) by the Centre National d'Études Spatiales (CNES, the French space agency) and European Space Agency (ESA).