NASA Operational Simulator for Space Systems (NOS3)
A NASA open-source digital-twin and software-simulation environment for spacecraft integration and test.
NASA Trick Simulation Environment
NASA’s open simulation environment for model integration, execution control, data recording, and analysis.
Skyfield
A production-stable MIT-licensed Python library for precise positions of planets, stars, and Earth satellites.
FreeFlyer
Commercial astrodynamics software for space mission design, analysis, and operations across the mission lifecycle.
Basilisk
An open-source astrodynamics and spacecraft simulation framework for research, GNC, and hardware-in-the-loop work.
TudatPy
TU Delft’s open-source Python interface for numerical astrodynamics, propagation, estimation, and space research.