FSX SpacePort is an add-on for Microsoft's Flight Simulator X (FSX) that enables a high-fidelity simulation of spaceflight using the visual environment, assets and the ecosystem of Microsoft's Flight Simulator X.

FSX SpacePort does not rely on FSX's flight model - instead, it completely replaces it with its own physics engine which implements a sophisticated deterministic physics solver to precisely simulate spaceflight in real time.

This physics engine is applied only to the objects that were designed to be used as spacecraft, meaning - the default aircraft fly as normal, and the spacecraft objects behave under ballistic astrodynamic rules of motion.

Along with the physics engine comes a sophisticated, high-fidelity collision engine, completely user-definable through FSX's SimObject container expanded with spacecraft-specific functionality.