CONTIGO: satellite-derived atmospheric density from orbits

Precise orbit data from LEO satellites (including whole constellations) carries a signature of atmospheric drag. CONTIGO extracts it: it computes the energy dissipation rate (EDR) of each spacecraft and converts it into an effective density that can be used to validate or drive density models.

Highlights

• Plug-in physics. Every force (gravity field, third-body, solar radiation pressure, …) implements a common ForceModel protocol, so new forces drop into the core EDRDensity calculation without touching it.
• Flexible data layer. Spacecraft and Constellation classes load HDF, CSV, and SP3 orbit files (zipped or not) and normalize them into one internal state.
• Fast ephemerides. Choice of SPICE or Orekit, plus a quantized, lazily loaded ephemeris cache shared across a constellation and a small Java helper that batches Orekit calls.
• Validated. Energy terms agree with Orekit’s independent computation (figure above).

GitHub