Over-the-Air Firmware Update for an Educational CubeSat Project

Abstract

The CubeSat standard has been envisioned to teach students about satellites from the initial conceptualization to the in-orbit operation. Educational satellite projects have contributed to the creation of skilled workforce and have also advanced spacecraft technology. Unfortunately, educational satellites are not always successful. Design defects in the hardware can be isolated and addressed by running functional checks before launch. On the other hand, software bugs are difficult to identify and may go unidentified months into in-orbit operation. Due to the limited time available for software testing, students cannot spend sufficient time running the satellite software in an operational scenario. While in-orbit software patching is quite a simple and routine task for traditional commercial and government satellite operators, they are uncommon in the CubeSat domain. In this paper, the question of why satellite firmware updates are not very common for educational satellites is addressed. Technical necessities for an upgradable CubeSat are examined for both microcontroller and system-on-a-chip based CubeSats. After comparing both systems, a hybrid system is proposed as a solution for educational CubeSats. A system capable of upgrading the satellite firmware in a single satellite pass is synthesized. It is found out that a roadblock to over-the-air software updates for CubeSats is created not only by the technical aspect, but also by the students’ habit of skipping some engineering practices in their design process. Although their actions may not be critical to the mission success, they are much more important when a maintainable satellite firmware is desired. This paper explores the challenges in upgrading CubeSat flight software in orbit, some possible ways to implement this functionality, demonstration of a method that will allow in-orbit software updates despite having low resources, and a few recommendations for a maintainable satellite software.