"Flown in lunar orbit for 6 days during Apollo 15"—the Guidance and Control checklist for the CSM Endeavour
Dave Scott's ring-bound Command/Service Module Guidance and Control Checklist flown into lunar orbit during the Apollo 15 mission, measuring 6 x 8, containing 144 pages (67 double-sided sheets) inside two heavier cardstock covers, signed and flight-certified in blue felt tip, "Flown in lunar orbit for 6 days during Apollo 15, July 26-Aug 7, 1971, Dave Scott, Apollo 15 CDR." The book is identified on the cover as "Part No. SKB32100115-310, S/N 1001," and contains sections for "CMC General," "Alarm Codes," "EXT Verbs," "G&C Systems Management," "Navigation," "Prethrust (P30's & 70's)," "△V vs △0 Long," "P37 Block Data," "Thrusting (P40's)," "Prop Cons," "SPS vs RCS Criteria," "GIMB ANGS vs WT," "Alignments (P50's)," "Star Charts," "Initialization Procedures," "PTC/ORB Rate," "Planet Vectors," and "Erasable Load Update," with the latter section featuring a few handwritten annotations and corrections. In fine condition, with expected light wear.
The G&C Checklist provides the crew with a quick reference to the actions needed to operate the Command Module Primary Guidance, Navigation and Control System (PGNCS). The PGNCS provides the spacecraft with an onboard means of measuring orientation, position, velocity, and trajectory, in addition to providing automatic control over parts of the spacecraft via the Command Module Computer. The PGNCS is a tightly interwoven system that consists of three main subsystems: the Inertial Subsystem (ISS), the Computer Subsystem (CSS), and the Optics Subsystem (OSS). The ISS measures information on the spacecraft orientation and velocity by providing a stable platform of reference, the Inertial Measuring Unit (IMU). The CSS applies this information to its current knowledge of the spacecraft's position and calculates a new estimate, called the state-vector; the CSS also behaves as an integrated auto-pilot. The OSS consists of a sextant and telescope for crew navigation sightings in aligning the IMU.
Accompanied by a signed letter of provenance from Dave Scott, in part: "I hereby certify that the 'CSM G&C Checklist' book included with this letter was used…throughout the 12-day Apollo 15 mission, including lunar orbit for six days…As the mission commander of Apollo 15, after the mission, I was responsible for handling, use and dissemination of the Flight Data File including this 'CSM G&C Checklist' book which has been in my personal collection since NASA presented it to me upon our return to Earth." A fantastic mission-critical flown checklist that spent six days in lunar orbit aboard Apollo 15's 'Endeavour.'