Johnny Mars Bar
Well-Known Member
No idea why Seiko are putting that on their site because mechanical watches of course work in zero gravity, they are powered by the potential energy of the wound main spring.
Perhaps they are alluding to automatic movements - the rotor will be affected by gravity in some circumstances but the vast majority of its power comes from the momentum of you swinging your arm about, not gravity pulling on the rotor.
Either way mechanical watches have been worn in space many times, most famously the Speedy Professional which is a mechanical wind, and many Breitlings, lots of others too.
'Watches worn in space' is big topic of interest and in Omega's case, a marketing opportunity they've been milking for half a century.