We know all about the Omega Speedmaster ‘Moonwatch’, as the first wristwatch on the Moon, which cemented its place in the history when the Apollo 11 mission successfully landed on the Lunar surface on the wrist of Buzz Aldrin. But there’s a little-known Heuer stopwatch that played a small but very important role when Neil Armstrong was piloting the lunar module “Eagle” to land on the Moon.
Since the initial landing site was too cavernous and rocky, Armstrong had to manoeuvre the Eagle to a different location. This, in return, caused extra fuel to be used and it had reached critical levels. In the event of all fuel being used without a safe landing, an abort would have been necessary and thus no landing on the Moon would have been possible.
For the Apollo 11 mission, Bob Carlton was the flight controller in charge of the lunar module and its control, guidance and navigation systems.
The stopwatch he used was a Heuer and most likely a variation of the reference 332.401 split seconds model. Vintage Heuer guru, Jeff Stein of OnTheDash, has identified the model previously here, on Chronocentric.
As you can see on the stopwatch used by Carlton, there are pieces of sticky tape at certain positions. In the documentary Mission Control: The Unsung Heroes of Apollo (2017, by David Fairhead), Bob Carlton explains he placed the tape at various spots to indicate time remaining at intervals. You can see some extracts of this movie (which we highly recommend) below, the watch being visible and its role explained.
Gene Kranz, the flight director issued an order that the only radio communication to Armstrong while trying to guide the Eagle down, would be Carlton giving timing warnings. You can hear Carlton on the official audio from the mission saying 60 seconds, then 30 seconds. He says in the documentary that when Armstrong had landed the Eagle, he stopped the stopwatch and indicated that 18 seconds worth of fuel remained.
In 1978 NASA transferred the stopwatch to the National Air and Space Museum of the Smithsonian. The Heuer stopwatch is currently on display in the Human Spaceflight exhibition at the Steven F. Udvar-Hazy Center in Chantilly, Virginia.
It may have only been a stopwatch, but it helped mankind to land on the Moon and, because of that, it also is very special.