The RCA CDP1802 microprocessor was used in the Galileo spacecraft

The RCA CDP1802 microprocessor was used in the Galileo spacecraft

The RCA CDP1802 microprocessor was not used in the Viking (or Voyager) spacecraft/landers. This is a common misconception that has been spread around the Internet and World Wide Web. The Galileo spacecraft and some satellites used the RCA CDP1802 microprocessor.

For some years up to Dec 2009, it was a common error on the Web, to attribute the COSMAC 1802 as in use in the Viking or Voyager planetary spacecrafts of the 1970's. In the cosmacelf discussion group at that time, there was interest in recovering the "Viking 1802 code". At that time, I researched primary information sources for Viking, Voyager and Galileo hardware features. I found at that time that among those crafts, only the Galileo used the 1802 microprocessor. Galileo was among the first spacecraft (apparently, but see below) to use a microprocessor, in fact Galileo used multiple 1802 processors. Concurrently, others in cosmacelf found and reported similar information about Viking and Voyager. I discussed this error in cosmacelf and provided references there and on this Web page as below. Subsequently, many Web sites (including Wikipedia) have corrected their information. Further discussion led to a review of amateur satellites and their use of the 1802, which is noted here and detailed on another Web page. - Herb Johnson, Aug 2011

It is debatable as to which spacecraft was "first" to "use" the 1802. Either way, Galileo or MAGSAT or AMSAT Phase III, the 1802 appears to be the first microprocessor in an operational orbiting spacecraft. The earliest into space was the MAGSAT in Oct 1979, for certain. The hardware choices for MAGSAT and Galileo, and for AMSAT Phase III amateur satellites, occurred during the same 1976-78 time frame. As the Galileo was far more complex, it took longer to design and construct; and it borrowed "architecture" and design tools from the earlier Voyager program. Additionally, the Galileo mission requirements, funding, retesting, repairs, lanuch windows and vehicles - all were in flux through the days before final, delayed launch in 1989. Establishing specific dates for Galileo's specific design or construction events is a It is daunting task. It's also difficult for the AMSAT Phase III program. - Herb Johnson, August 2011

We are grateful to William Donnelly for updating our previous details. Further details and references can be found at

Further interesting sites related to the project are as follows:


Source of Information : William Donnelly email





The RCA CDP1802 microprocessor was used in the Galileo spacecraft

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