Longlife Dependable Computers for Spacecrafts

Computers for spacecraft are being developed utilizing fault-tolerant configurations. To attain high dependability mostly using components available for commercial use, many fault-tolerance concepts are systematically combined. Besides adopting the conventional approaches such as spatial diversity based on the majority voting, the usage of ECC, watch dog timers and current limiter, we introduce some new concepts such as softwarevoting with inter-cell communication, time diversity based on the output feedback and stepwise negotiating voting. Most of the results were implemented on the flight model of On-Board Computer (here in after OBC) to be loaded on MUSES-A (Mu Space Experimental Satellite) which will be launched onto lunar swing-by orbit early in 1990. The design approach to construct a fault-tolerant computer system mostly using components in commercial use will be verified on MUSES-A as one of its mission apparatuses for experiment.