FLOWN LM Crewman Optical Alignment Sight (COAS)

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  • Apollo Lunar Module Crewman Optical Alignment Sight (COAS) for aiding the astronaut in rendezvous, docking, and navigation.
  • Flown to earth orbit as part of the Apollo 9 Lunar Module (LM-3) in the first manned flight of the LM, March 3-13, 1969.
  • Displays a graduated circle reticle on the combiner (angled glass plate) that appears to be at infinite distance, superimposed over the target in view.
  • Could be mounted and set for use at the left window (“LW”), overhead window (“OW”), and right window (“RW”).
  • Large knob controls the reticle light intensity; small knob is pulled to rotate the barrel to set the window position.
  • A similar unit was used in the Apollo Command Module, and a follow-on design has been used in the Space Shuttle.
  • This version (-0009) included a built-in neutral density (dimming) filter that reduced the maximum lamp brightness, to accommodate star sightings. During docking operations on the Apollo 9 flight, the reticle image viewed through this artifact was not visible for a time because of the bright sunlit Command Module. The lamp brightness was increased on later versions (-0021, -0025), used on Apollo 10 and later, with the removal of the built-in filter in favor of an external detachable filter.
  • Utilized during the Apollo 9 mission in demonstrations of normal and contingency flight operations.
  • Flown status confirmed through comparison with NASA photos (see detailed comparison and discussion).

1.55 lbs. (0.71 kg)

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This LM COAS artifact is shown mounted in launch position above the left window (with reflective cover) in the Apollo 9 Lunar Module (LM-3). (NASA photo)

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