Reliability through redundant parallelism for micro-satellite computing

Spacecraft typically employ rare and expensive radiation-tolerant, radiation-hardened, or at least military qualified parts for computational and other mission critical subsystems. Reasons include reliability in the harsh environment of space, and systems compatibility or heritage with previous missions. The overriding reliability concern leads most satellite computing systems to be rather conservative in design, avoiding novel or commercial-off-the-shelf components. This article describes an alternative approach: an FPGA-arbitrated parallel architecture that allows unqualified commercial devices to be incorporated into a computational device with aggregate reliability figures similar to those of traditional space-qualified alternatives. Apart from the obvious cost benefits in moving to commercial-off-the-shelf devices, these are attractive in situations where lower power consumption and/or higher processing performance are required. The latter argument is particularly of major importance at a time when the gap between required and available processing capability in satellites is widening. An analysis compares the proposed architecture to typical alternatives, maintaining risk of failure to within required levels, and discusses key applications for the parallel architecture.