 The Omega Speedmaster Professional is probably one of the most recognized watches around the world, and that's because it's the watch that Apollo astronauts wore on the surface of the moon. But for NASA, providing its astronauts with a watch to wear during missions was an afterthought. I'm Amy Shearer, and this is a Vintage Space video. It wasn't until 1964 that NASA thought it ought to give its astronauts space-rated watches, and the agency only thought to do it because the astronauts asked for one. And it was designed as, quite literally, a handy way to help astronauts keep track of all the tasks during a mission, a backup to all the clocks and countdown timers already inside the spacecraft. When it came to space-rating a watch, NASA picked six candidate watches from Rolex, Omega, and Longinus, and the technicians who ran the testing knew that these watches would have to stand up to a lot. A watch certified for spaceflight would have to work perfectly in microgravity, work perfectly in a vacuum, as well as in a pure oxygen environment. It would have to withstand temperatures as hot as 200 degrees Fahrenheit and as low as zero degrees Fahrenheit, and survive a quick change between these two temperature extremes. For good measure, NASA also tested the watches to make sure they could withstand high-pressure environments and sustain a load of G-forces. In the end, only three of the six watches survived the first round of testing, and at the end of the second, more thorough round of testing, only the Omega Speedmaster worked. NASA announced that the Omega Speedmaster would be its watch for spaceflight on March 1st, 1965. For more on testing the Omega Watch for spaceflight, check out the links below.