Space Data Network advanced propagator
SDN-AP
Free, open-source software that predicts where satellites and other tracked objects in orbit will be, for a whole catalog at once, in a web browser or on a server.
Overview
Knowing Where Everything In Orbit Will Be
Satellites and debris travel at several kilometers per second. Operators, researchers and the public need to know where each object will be hours and days from now: to steer clear of close approaches, to point telescopes and antennas, and to plan missions.
A whole catalog at once
One call predicts the positions of thousands of objects. The same module runs in a web browser and on a server and gives the same bytes in both.
Every kind of orbit
Low orbits that skim the atmosphere, navigation satellites, geostationary orbits, long elliptical orbits, and paths to the Moon and between the planets.
The forces that matter
Earth's uneven gravity, the drag of the upper atmosphere, the push of sunlight and the pull of the Sun and Moon, averaged over each orbit so the work stays fast.
Open and free
Apache-2.0. Anyone may read the code, run it, check its results and build on it, with no fee and no login.
How it works
Standard Messages In, Positions Out
SDN-AP speaks Space Data Standards, the open message formats of the Space Data Network, so any software in any major language can feed it and read its results.
Orbits in
Each object arrives as a standard element set: a compact description of its orbit at one moment.
One configuration
A single configuration message picks the theory, the forces and the output. Anything it asks for that cannot be done is refused by name, never dropped.
Positions out
SDN-AP returns positions and velocities for every object at the times requested, as a standard ephemeris message.
Explore
Go Deeper
The theory behind the predictions, the full configuration reference, the module itself, and a live run in your browser.
Theory
Mean elements, the three theories in the module, and how each orbit regime is handled.
Read the theory →Whitepaper
One semi-analytic theory family with calibrated drag, tesseral gravity, maneuvers, reentry and launch, in a single WebAssembly module
Read the whitepaper →Configuration
Every table and field of the configuration message, generated from the Space Data Standards schema.
Open the reference →Demo
Propagate a synthetic catalog with the real module, running on your own machine.
Run the demo →Downloads
The module, version 0.1.0, with its SHA-256 and its license files.
Get the module →