When the step-by-step procedures of the Project Gemini space-walks were first mapped out, NASA realized that they did not have an approved wristwatch for space travel. The normal procedure of soliciting bids for the design, manufacture and testing of special “Space Proof” wristwatches was a time consuming process. To save time, NASA sent two systems engineers into downtown Houston “incognito” to purchase several reputable “off-the-shelf” chronographs to be tested for possible use in space. A manual-winding watch was preferred to an automatic watch, as it was assumed that zero-gravity conditions would render the self-winding mechanism ineffective.
Five different brands of chronographs were purchased and returned to NASA for testing. The Speedmaster passed NASA's numerous tests, which included exposure to extreme temperatures, vacuum, intense humidity, corrosion, shock, acceleration, pressure, vibration and noise, whereas the Rolex, Breitling, Bulova, Longines and TAG Heuer, notably, all failed.
