ARMSTRONG AND ALDRIN VERIFY EAGLE'S STATUS.
CARRIED TO THE LUNAR SURFACE.
Flown Apollo 11 LM Activation Checklist, page ACT-50/ACT-51, a single sheet printed recto and verso. NASA/MSC, May 26, 1969, updated July 4,1969. 5½ x 8 inches. With a Typed Letter Signed by BUZZ ALDRIN.
During this period of the mission, Armstrong and Aldrin were in the final stages of Lunar Module checks before they separated from Command Module Columbia to begin their descent to the lunar surface. They performed a critical Reaction Control Subsystem (RCS) test. Any problems could potentially scrub the planned lunar landing.
BUZZ ALDRIN'S signed provenance letter reads in part: "Enclosed with this letter is a sheet numbered ACT-50 and Act-51 from the Apollo 11 LM Activation Checklist. The entire checklist was carried to the Moon on the flight of Apollo 11 during July 16 to 24, 1969. Then the checklist, including this sheet, was taken to the surface of the Moon in Lunar Module Eagle during the first lunar landing on July 20, 1969. It lists some critical flight tests performed by Commander Neil Armstrong.
Side ACT-50 has the last two parts in the 'RCS (Reaction Control Subsystem) PRESSURIZATION.' This subsystem used a group of four small rocket engines attached at four equal distant points outside on our Ascent Stage to provide Eagle's attitude control during flight. We recycled the 'SYS A&B ASC(cent) FEED' switches and completed the other three steps of part 5. Neil and I then checked the 'TEMP/PRESS Mon' values in part 6. All pressures and temperatures were as expected. At about 99 hours and 24 minutes into the mission, we started the 'RCS CHECKOUT' by setting the proper circuit breakers 'CB' to either open or closed and configured other switches.
Side ACT-51 has the remaining steps of part 2 and parts 3, 4, and 5 of the RCS checkout. These steps included Neil's check of his 'CDR ACA' or Attitude Controller Assembly. He did a series of checks including roll right and left commands, pitch up and down inputs, then yaw left and right commands. We completed this series of test with less than 3 hours before Eagle landed on the lunar surface. If our RCS rockets failed to perform properly, it could have prevented Neil Armstrong and myself from becoming the first humans to land and walk on the Moon....
This sheet has been in my private collection since 1969. On side ACT-50, I have written: 'Flown to the lunar surface on Apollo XI' and signed it along the right side. I have signed my name on side ACT-51."