Orbit Propagation
Propagators (SGP4 and Orekit numerical), supported element formats (TLE, OMM, classical Keplerian), and how to choose between them.
Orbit propagation computes a satellite’s position and velocity over time. SMD offers two propagators and three input formats.
Propagators
SGP4
The standard analytical propagator for TLE/OMM-based satellites. Fast and appropriate for catalog objects and quick trade studies.
Numerical propagator (Orekit)
High-fidelity numerical integration powered by Orekit, including perturbations such as J2 (Earth oblateness), atmospheric drag, and third-body effects. Best for design studies where accuracy matters. Available on the Pro plan.
Input formats
| Format | Description | Use case |
|---|---|---|
| TLE | Two-Line Element set, legacy NORAD format | Catalog satellites from Space-Track and similar sources |
| OMM | CCSDS Orbit Mean-elements Message, modern standard | Catalog data without the TLE 5-digit NORAD ID limitation |
| Classical elements | Keplerian elements you define directly | Designing your own mission orbit |
SMD handles TLE and OMM seamlessly: when OMM is available, elements are converted internally without lossy TLE string synthesis.
Which should I use?
- Importing a real satellite that already has a TLE/OMM → SGP4.
- Designing a new mission and studying perturbation effects → numerical propagator.
- Quick visibility or coverage estimate → SGP4 is usually sufficient and cheaper in credits.
Viewing results
Propagated data renders on the 3D globe and as time series: position, velocity, ground track, and classical elements along the trajectory.