The org.orekit.propagation.analytical.tle package provides classes to read, and extrapolate from, orbital elements in Two-Line Elements (TLE) format.
TLE orbits are supplied in two-line element format, then converted into an internal format for easier retrieval and future extrapolation. All the values provided by a TLE only make sense when translated by the corresponding propagator. Even when no extrapolation in time is needed, state information (position and velocity coordinates) can only be computed through the propagator. Untreated values like inclination, RAAN, mean Motion, etc. can’t be used by themselves without loss of precision.
The implemented TLE model conforms to new 2006 corrected model. More information on the TLE format can be found on the CelesTrak website.
The TLE orbit representation is de-correlated from other orbit representations provided by Orbits package. It is due to the fact that TLE representation depends on a very specific dynamic model, which is not compatible with Orbits models in present architecture.
It is considered to be closer to a propagation model than to an orbit representation and has been moved within the org.orekit.propagation package since 6.0. This move allowed the rich features from the global propagation framework (master/slave/ephemeris mode, events handling) to be used with TLE.