Hello,

I am excited by the information provided by a Reference Services
Archivist at the National Air and Space Museum:

"Although many calculations during the Apollo era could now be made with
computers, slide rules were still used by astronauts in space and
mission control on the ground. Many of the mission transcripts are
available online and provide brief moments of insight into this question.

"For example, in Apollo 8, a reference is made to using a slide rule to
calculate orbit distance from earth
(http://history.nasa.gov/ap08fj/04day1_maroon.htm) and to calculate fuel
burned during a Trans-Earth injection (TEI)
(http://history.nasa.gov/ap08fj/20day5-6_black.htm). Again, in the
Apollo 8 transcripts, a slide rule is used
(http://history.nasa.gov/ap08fj/16day4_final_orbit_tei.htm). The Apollo
11 transcripts note that Aldrin asked Armstrong if he thought they would
need a slide rule in the lunar module and Armstrong replies that he
doesn't think they'd need two
(http://history.nasa.gov/ap11fj/13day4-eagle-checkout.htm). In the
Apollo 15 mission, a slide rule was used to calculate drips and leakage
(http://history.nasa.gov/ap15fj/08day3_leak_hilltop.htm). A side note
in the Apollo 15 mission transcripts notes that a crucial scene in the
movie Apollo 13 where slide rules were shown would actually have not
featured a slide rule
(http://history.nasa.gov/ap15fj/12day5_landing_prep.htm).

"If you are interested in other examples of slide rule use in the
mission transcripts, you can visit NASA.gov and run a search for Apollo
+ "slide rule." "

The preceding is in contrast to the write-up in this image which says
that slide-rules were carried _only_ as a back-up to computers for use
"in the event of a computer malfunction"
http://sliderulemuseum.com/Pickett/Pickett_N600ES_Buzz_Aldrin_SlideRuleAuctionLetter.jpg
The transcripts cited by the Reference Services Archivist show the
slide rule being used on-flight even when there was no computer
malfunction.

Note also the transcript that points out the mus-representation in the
movie Apollo 13.

--Suresh