Halyard Flight Software Framework

Halyard is the foundation of Halcyon's flight software. It provides a component model, message bus, scheduler and fault-protection engine on which ship-specific applications are built. The same core runs on a 4 Mc Sparrow Trainer and a high-performance Aurora Mk II courier.

Jonas Lindqvist's flight software team released Halyard as open source in 2183, arguing that safety-critical code benefits from more eyes. Today it has more than 300 external contributors and runs aboard spacecraft from a dozen organisations.

Partners adopt Halyard to cut development time on their own vehicles and to make their software easier to certify. The fault-protection engine, which automatically safes a ship when sensors disagree, is its most-used component.

Halyard is Apache-2.0 licensed. Contribution guidelines require full test coverage and a hardware-in-the-loop run before merge. The full set of outputs (flight software framework, hardware abstraction layer and fault-protection engine) is licensed Apache-2.0, with source and documentation at https://git.halcyon.example/halyard. Halcyon commits to keeping it available for at least twenty years, with older versions preserved in the open data archive. Feedback from partners shapes the roadmap; most new features over the past two years began as a request on the public tracker.