In a groundbreaking series, George Emad sheds light on the remarkable utilization of the Linux operating system in spacecraft. From SpaceX's Dragon capsule to the widely adored Martian helicopter, Linux has proven its potential as a reliable and efficient choice for space missions. Interestingly, it is not the latest version of the Linux kernel that takes center stage, but rather the stability it offers to ensure the success of these critical missions.

SpaceX, known for its innovative space endeavors, relies on Linux kernel 3.2 (with real-time patches) for the primary flight computers of both its Dragon spacecraft and rockets (Falcon 9 and Starship). With a focus on redundancy, SpaceX employs a triple redundancy setup, utilizing three independent dual-core processors. Each processor runs the same calculations but with a separate instance of Linux on each core. The results are then compared, and any discrepancies are promptly discarded. This approach, combined with off-the-shelf (OTS) x86 computing hardware and flight software written in C++, has proven to be a winning combination for SpaceX's missions.

Following a similar path, NASA has also embraced the power of Linux in their spacecraft. Notably, the Ingenuity helicopter relies heavily on OTS parts and utilizes NASA's open-source F' (F Prime) framework, which is built upon the C++ language. The Linux kernel, in some version, is employed on a Snapdragon 801 System on a Chip (SoC) for Ingenuity, and it has proven its reliability in all 72 flights. However, it is important to note that using Linux in avionics and critical applications is not a straightforward decision. Customization of the monolithic Linux kernel is often required for specific tasks, especially on resource-constrained platforms. Moreover, Linux is not well-suited for hard real-time applications. Nevertheless, the wealth of software and documentation available on the Linux platform presents a worthwhile trade-off that must be carefully considered for each project's unique needs.

With Linux at the forefront of their operations, both SpaceX and NASA demonstrate the remarkable adaptability and reliability of open-source software in the realm of spacecraft. By prioritizing stability over the latest features, these organizations have harnessed the power of Linux to propel their missions skyward, offering a glimpse into the future of space exploration.