Low cost fault tolerant techniques for nano/pico-satellite applications

Space is a hazardous environment for electronic equipment due to various high energy particles, also referred to as radiation, which adversely affect electronic components. The most notable of these radiation effects are single event latchups and single event upsets. In large and expensive satellites the use of radiation hardened components and redundancy mitigates the effects of radiation on the satellite. These techniques are not feasible on small satellites, especially in the nano to pico range, due to their limited power, size and financial budgets. However, by using fault tolerant design techniques (watchdogs, anti-latchup circuitry, error correction code) and implementing a robust bootloader for in-flight reprogramming, it is possible to achieve an acceptable fault tolerance level for short duration missions within low earth orbit with minimal overhead on the design. These low cost mitigation techniques have been implemented on a CubeSat onboard computer, to be used in the upcoming ZACube2 mission. The evaluation and implementation of these techniques and their impact on the onboard computer in terms of power, size and cost are discussed in this paper.