The flight control software is a critical system on the satellite. The flight software runs on the main computer and is central to the operation of the vehicle.
So far I have found two options for free, open source flight software:
- Core Flight System
Kubos runs on Linux and seems to be a reasonably mature product with good documentation.
Core Flight System is published by NASA, it runs on RTEMS real time operating system and is a proven product having been used on numerous missions and also seems to have reasonable documentation.