the original NASA testing, which resulted in the Speedmaster being selected for use on space flights, commenced in 1962 and was completed by 1965. I believe that there were only five watches in this competition.

There may have been a second round of testing, some years later, and the Hamilton Count-Down could have been included in that test. I will do some further research and let you know what I learn (or perhaps Mr. Maddox can provide this information).

Jeff