High reliability in spacecraft computer systems

One approach to high reliability in spacecraft computer subsystems is to provide layers of redundancy, fault tolerance through detection and recovery circuitry, coupled with radiation hardening. The additional circuitry required for high reliability can significantly increase the size, weight and power consumption of the subsystem. Today´s spacecraft are smaller and cannot afford the added power and weight or cost of traditional redundant computer subsystems. The high reliability systems that depend on 38510 grade 1 electrical parts are often too expensive. To keep the computer subsystem power, weight and cost to a minimum, the computer could be based on an application specific integrated circuit (ASIC) intensive architecture. With internally redundant ASICs, the computer subsystem can be kept to a minimum size, weight, power while still achieving low cost. Additional features, such as error detection and correction (EDAC) on both the address and data busses, and triply redundant voted control lines add significantly to the reliability of the computer subsystem. Often the computer can easily meet the mission reliability requirements using either all 38510 grade 2 electrical parts or a mix of grade 1 and 2 parts, which greatly reduces system cost