Flown Apollo 11 checklist sheet taken to the lunar surface

FLOWN Apollo 11 LM G and N Dictionary, page PGNS-1/PGNS-2, a single sheet printed recto and verso. NASA/MSC, May 29, 1969. 5½ by 8 inches, having a tab extension that reads: “STARS, PROGRAMS, VERBS.” With a Typed Letter Signed by BUZZ ALDRIN.

'Stars, Programs, Verbs' tab slightly bent, possibly due to crew usage. Inscribed using ball point pen.
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Almost immediately after the first lunar landing, Neil Armstrong and Buzz Aldrin performed the complex task of realigning their onboard navigation equipment. This required taking star sightings though an onboard telescope. Their computer would recognize a number code for individual stars and the crew used this sheet as a reference guide to verify each star correctly. This realignment told the computer where they were, relative to select star measurements and readied Lunar Module Eagle for an emergency lift-off or an early return from the lunar surface.

The reverse side lists computer programs for flight operations. Neil Armstrong had just successfully guided Eagle to the lunar landing using programs 64, 65, and 66. That final program, “66 Landing Phase (ROD),” allowed Armstrong to manually guide Eagle to a desired landing point while the computer controlled engine thrust. He manually made small changes in descent thrust with commands via the Rate of Descent (ROD) switch. Several other programs including 32, 33, 72, 73, 75, and 76 enabled Armstrong and Aldrin to leave the Moon and return to Michael Collins in CSM Columbia.

Accompanied by BUZZ ALDRIN’S signed provenance letter on his personal stationery which reads: “Accompanying this letter is sheet labeled PGNS-1 and PGNS-2 from the Apollo 11 LM G and N Dictionary, Part No. SKB32100074-361, S/N 101. The dictionary was carried to the Moon on the flight of Apollo 11 during July 16 to 24, 1969. Then the entire Guidance and Navigation (G and N) Dictionary, including this page, was taken to the surface of the Moon in lunar module Eagle during the first lunar landing on July 20, 1969. PGNS stands for Primary Guidance and Navigation Section. Each side of this sheet has a tab that reads: “STARS, PROGRAMS, VERBS.”

This sheet was one of the few celestial aids we had on the lunar surface. PGNS-1 has four columns of information, the first two being a listing in octal or base 8 format with its associated star name. Our guidance and navigation computer used octal numbers to recognize stars. For our convenience, the next two columns list the stars alphabetically with their octal code number.

Side PGNS-2 list the actual computer program numbers and their associated name which incidentally fairly well described what the program was designed to perform.

The complete dictionary was a vital document to the success of our mission. It not only provided definitions of computer codes, but contained detailed information on steps required to operate flight equipment associated with the first lunar landing.

The sheet has been in my private collection since 1969. I have written on side PGNS-1: “Carried to the Moon on Apollo XI,” and signed it along the left margin. In addition I wrote: “Down to the lunar surface in LM 5” and signed again along the center margin. I have also enclosed a copy of the cover of this dictionary.”

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