An FPGA running a soft core was out of the question? There are plenty of rad-hard FPGAs out there. Combine it with some rad-hard flash or eeprom and you've got

An FPGA running a soft core was out of the question? There are plenty of rad-hard FPGAs out there. Combine it with some rad-hard flash or eeprom and you've got what's flying in a lot of satellites these days.