A lot of 42's usage comes from it's proximity to NASA Goddard's cFS, the most widely used (and in my opinion, best) open-source flight software framework out th

A lot of 42's usage comes from it's proximity to NASA Goddard's cFS, the most widely used (and in my opinion, best) open-source flight software framework out there. However, many space companies move towards using their own simulation stack, especially when it comes to using the models for driving hardware-in-the-loop (HITL/HIL) simulations with things like fault injection for mission operations drills. Other open-source solutions for this include: * Nyx - https://github.com/nyx-space/nyx https://github.com/nyx-space/nyx * Basilisk - https://github.com/AVSLab/basilisk https://github.com/AVSLab/basilisk