1978 · Microprocessor in Planetary Probe · Work 908 of 1,871
A clean assembly hall in El Segundo in California, on a low steel test stand a wide cone a hundred and forty centimetres across, its point downward, made of shiny silver-grey metal segments divided by narrow black seams, on top of it a flat brick-orange cap set with many small rivets and two short pipe stubs, beside it on a wheeled cradle a polished titanium sphere seventy centimetres across opened at its equator, in its lower half a compact box of grey metal with bundles of white cables, a technician in a white overall and white cap seen from directly behind, gloved hands at a cable connector, bare white walls, even light.
What it was used for
The Large Probe of the Pioneer Venus mission carried the Large Probe Neutral Mass Spectrometer (LNMS), with which J. H. Hoffman's group at the University of Texas at Dallas was to measure the composition of the Venus atmosphere during descent. The final report of 24 May 1982 describes sampling through microleaks, a magnetic sector mass spectrometer, getter and ion pumps and a variable conductance valve. A microprocessor worked inside the instrument; in a later survey Hoffman himself calls it only "an Intel 4-bit processor", without naming a type.
What was new
Here the priority question is itself the subject. The book "Pioneering Venus" by Fimmel, Colin and Burgess (1995) states: "It also used the first microprocessor to fly in space: an Intel 4004."; NASA SP-461 (1983, p. 23) likewise speaks of "the first microprocessor to be flown in space: an Intel 4004". Hoffman and his co-authors put it more carefully in the IEEE Transactions on Geoscience and Remote Sensing of January 1980, where the processor "is thought to be the first such item to have been flown on a deep space probe". The barb: the further a source stands from the instrument, the firmer the claim becomes - and the people involved name no type at all.
What the sources leave open: These passages were gathered by Herb Johnson (retrotechnology.com, 19 July 2019), who calls his own page a "preliminary stub"; SP-461 was not read in the original; the IEEE paper is reprinted with the 1982 NASA final report and confirms the quote. The report text itself mentions no processor, the attached papers only "a microprocessor", without a type. The 1802 does not belong here: Johnson dates its first flight to MAGSAT in 1979.