LUNAR MODULE-FLOWN ALIGNMENT SIGHT BULB.
Flown on Apollo 15, a Crewman Optical Alignment Sight (COAS) space light bulb assembly, being a ½-inch diameter filament bulb protected by sprung plastic sheath, mounted on a knurled gray metal circular knob. Approximately 2 inches high x 1½ inches in diameter. Manufactured by Jay-El Products of Gardena, CA, with part number "850258-1" and lot number "04950L 643A01 131."
AN OPTICAL COMPONENT FLOWN TO THE LUNAR SURFACE on board the Apollo 15 Command Module Falcon. With DAVE SCOTT'S SIGNED provenance note, stating that "this light bulb assembly consists of a light bulb mounted inside a housing that is inserted into the COAS to illuminate the optical reticle used for docking alignment.
The Crewman Optical Alignment Sight (COAS) is an alignment aid that provides fixed line-of-sight attitude reference between the Lunar Module and the Command Module as well as the horizon (Earth and Moon) and stars ... An essential element of the COAS is the reticle lighting and intensity control. The COAS is used during both daylight and darkness operations, including a broad range of illumined backgrounds. To ensure this capability during a mission, a spare bulb assembly was carried aboard the spacecraft." One function of the COAS was to enable the Lunar Module to redock with the Command Module after leaving the lunar surface. Scott's letter illustrates the position of the present assembly in a series of photographs and diagrams.