Development of radiations tolerant Attitude Control Algorithm for small satellites

Small satellites provide flexible and economical cost-effective solutions for research and development in the field of the space industry. It is possible to implement and test various mission algorithms with very few resources available. The stringent requirement of a smaller mass of spacecraft has almost eliminated the use of propulsion systems in small satellites. The smaller mass and size of the spacecraft, on the other hand, make it easier to control and adjust the attitude and orbit of the spacecraft with only magnetic control or inertial control. In this field, there are many attitude and orbit control algorithms and techniques that have already been explored. As compared to the heavier satellites, the smaller satellites are equally exposed to the radiations and experience the same harsh environment in space but due to the low mass budgeting, it is not preferred to use redundant hardware or extra shielding for them. Nowadays there are many circuits available that are made hardened against radiations during manufacturing. Integrated circuits, processors, and micro-controllers during the design phase can also implement hardware-level radiation hardening techniques to tolerate radiation exposure but this solution leads to very expensive and relatively slow hardware, which does not align with the main motivation of small satellites, i.e. small, inexpensive, and efficient. In order to make the satellite to work while exposed to a radiation environment, software methods can be used. Once it is studied that how often and in which manner the radiations can affect the normal operations of spacecraft, a flexible and robust software algorithm can be developed which can tolerate not all, but many radiation events. This can lead to using cheap commercial off-the-shelf devices without using redundant hardware and heavy shielding. This technique may cause the system to use more memory and perform computation slowly, but it will be much faster and effective as compared to the hardware hardening techniques. The work presented in this report comprised of developing a closed-loop Attitude control flight software for small satellites, such as CubeSat, along with spacecraft dynamics, and environmental effects. The flight software that interacts with the sensors and actuators mathematical models, can make the satellite work into any of the predefined mission modes. The flight software is made robust and hardened against space radiations which can alter the normal software operations and can result in malfunctioning. A comparative analysis is also performed to express how a radiation-tolerant flight software performs in presence of radiation effects as compared to non-hardened flight software. The execution time and memory requirements merits are also discussed.