Pioneer Venus Orbiter (1978)
Uses an Intel 4004, which is the first microprocessor to go to space^[http://www.retrotechnology.com/restore/pioneer_4004.html]!
Galileo Orbiter (1989)
Uses six RCA 1802/CDP1802 microprocessors in a complex, redundant arrangement as illustrated below in its Command Data System^[https://ntrs.nasa.gov/api/citations/19810003136/downloads/19810003136.pdf]. The CDP1802s run virtual machines, can be reprogrammed in-flight. The Galileo Orbiter uses 11 more CDP1802s in its instruments^[https://www.retrotechnology.com/memship/1802_landmark.html]. It’s relevant, however, that NASA acknowledges the inadequacy of the CDP1802 and chose it due to decrease in R&D funds and a necessity for cheap components. In its altitude control system, Galileo uses an ATAC-16 computer which has four Am2901 4-bit bit-slice processors^[doi:10.1109/ISSCC.1991.689047].
MAGSAT (1979)
Uses two RCA 1802/CDP1802 microprocessors in a redundant arrangement^[http://www.retrotechnology.com/memship/magsat_command.pdf].
Hubble Space Telescope (1990)
Uses an RCA 1801 microprocessor^[https://web.archive.org/web/20161006205644/http://trs-new.jpl.nasa.gov/dspace/bitstream/2014/35164/1/93-0731.pdf].
Magellan Spacecraft (1989)
Uses four RCA 1802/CDP1802 microprocessors in combination with two ATAC-16 computers which have four Am2901 4-bit bit-slice processors each^[https://ntrs.nasa.gov/api/citations/19900019276/downloads/19900019276.pdf] ^[https://www2.jpl.nasa.gov/galileo/aacscomputer.html].
Mars Observer (1992)
Uses a Marconi MAS1750 chip set (no details of this can be found) as the main processor and an SA3300B microprocessor for the camera^[doi:10.1109/ISSCC.1991.689047]. The SA3300B is a radiation-hardened variant of the National Semiconductor NS32016 16/32-bit microprocessor^[https://www.osti.gov/servlets/purl/6081851], which is a fascinating microprocessor family which failed commercially, yet found its uses in many strange places.
