The Apollo stowage lists show that each mission had exactly one slide rule "on crew" (i.e. in somebody's spacesuit) at launch. Who carried the slide rule? Was it always the same role (CDR, CMP, LMP), or did the crew decide among themselves who would carry it?

Here is a snippet of Apollo 11's stowage manifest:

sliderule in Apollo 11 stowage

This answer claims that both Armstrong and Aldrin had slide rules, but that does not fit the official stowage manifest. Any such claim of more than one slide rule per mission should be supported by proper sources.

Update: I'm principally interested in the government-furnished sliderules. It's possible that some astronauts brought their own model as a personal preference item; such answers are acceptable, but if possible should indicate that they were personal items.

  • $\begingroup$ There's a discussion here that appears to predate A16 and mostly fussing over what model of slide rule was taken; doesn't have any hard info. $\endgroup$ Jul 1, 2020 at 1:07

1 Answer 1


Heritage Auctions auctioned a slide rule purported to be Aldrin's for almost \$78,000. Given Aldrin's nickname of "Dr. Rendezvous" for his PhD thesis in orbital mechanics, he would seem the most likely candidate to carry the slide rule on the mission.

However, there's a small hint that two slide rules might have been carried on the flight. 84 hours into Apollo 11, Armstrong and Aldrin are checking out the LM and getting things stowed where they want them, and there's this exchange:

084:11:08 Aldrin (onboard): Can you think of any use for a slide rule in the LM, Neil?

084:11:19 Aldrin (onboard): Huh?

084:11:27 Armstrong (onboard): I can't think of any use for two of them.

084:11:31 Aldrin (onboard): Okay.

084:15:24 Aldrin (onboard): That comm was so good I don't think I'd need those damn things [garble].

"Can't think of any use for two of them" might just be an oddball joke (i.e. "one is useless, two are still useless") but it might possible indicate that Armstrong knew one had already been placed in the LM when Aldrin presented his on-crew rule.

I didn't find any mention of slide rules in the other Apollo flight journals.

  • $\begingroup$ Yes, I knew that his PhD at MIT was on that topic. But it would also be helpful to know about the other missions as well. $\endgroup$
    – DrSheldon
    Jul 1, 2020 at 1:02
  • $\begingroup$ Ah, sorry, I thought you were only asking about A11. $\endgroup$ Jul 1, 2020 at 1:04

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