It may be one of the lesser-known space watches, but the Sinn 140 gives the Omega Speedmaster Moonwatch a run for its money

Manufacturers work hard to make sure that new watches adhere to design expectations when producing a model specific to a genre. If you are considering the purchase of a serious dive watch, you may have certain expectations in your mind; what the exterior of the watch will look like and what complications it may have. Love them or loath them the image of a Rolex Submariner will probably have popped into your mind. Equally, when planning a new field watch you may have pictured a classic Hamilton Khaki and even subconsciously assessed your choices against that impression.

One of the most exclusive and elite genres is watches that have been blasted from the Earth strapped to the wrist of an astronaut. Everything in this club tends to be judged against one giant - the Omega Speedmaster Moonwatch. It was after all, as the case back says, the first watch worn on the Moon.

As living in space evolved from the cramped conditions of Apollo to the relative luxury of the Space Shuttle and International Space Station so too did the eclectic collection of watches which orbited the Earth. Unusual spatial timekeepers include the divisive Omega X-33, a Timex Ironman Data Link, a Seiko A829-6029 (now known as “The Astronaut”) and the humble Timex Expedition to name but a few.

One of the lesser knows models, but certainly the most technically impressive, should be at the forefront of the history of watches yet it is not often the first choice of someone on a quest to buy a space watch. It is the Sinn 140 ST Space Chronograph.

The 140 (and the very similar 142) is one of Sinn's flagship models and with good reason. It was first worn in space in 1985 as part of the personal equipment belonging to German astronaut Reinhard Furrer when he was a payload specialist aboard the Challenger Shuttle flight STS-61A. The watch flew again on several flights in the 1990s.

The current evolution of the 140 boasts the superior technology we would expect from Sinn. The 44mm steel case has been additionally hardened with Sinn's TEGIMENT Technology, first showcased on the 756 Duochronograph at Baselworld 2003. This is not a coating like PVD. The TEGIMENT process physically alters metal to be harder and more scratch-resistant.

The 140 is also equipped with dehumidifying technology which is designed to address a basic issue with mechanical watches: the ageing of oils due to moisture in the air contained inside or passing into the watch. The Sinn 140 movement is consequently mounted in a virtually moisture-free atmosphere thanks to the three technical elements. A proprietary Ar-Dehumidifying Technology drying capsule, EDR seals and protective gas filling. The combination prevents any chance of fogging due to sudden cold – an extremely useful feature when you consider that the temperatures outside the ISS range from +121C to -157C.

So how do each of these clever elements work?

The drying capsule is filled with copper sulphate which absorbs moisture. This substance turns blue as water saturation rises and the system features a small reference viewing window of sapphire crystal glass built into the case lug.

The Sinn 140 only uses Extreme Diffusion-Reducing (EDR) seals. These seals allow the passage of only 25% of the moisture normally permitted to enter a superior manufacture chronograph.

Finally, the 140 is gas-filled which produces both a barrier to ingress and a perfect environment for the dehumidifying mechanism to operate optimally.

The watch is powered by the in-house Sinn SZ01 movement. This is based on the bulletproof Valjoux 7750 and boasts 25-jewels and a 42-hour power reserve. The biggest change to the standard 7750 is that the SZ01 has a 60-minute register on the chronograph that's tracked from a hand at the centre of the dial. This makes it much easier to see elapsed minutes than in a traditional small sub-dial.

Build quality is outstanding with the watch feeling suitable robust on the wrist. This sensation is backed up with the 140 offering shock resistance compliant with DIN ISO 1413 and anti-magnetic capability in conformity to DIN 8309.

There is no doubt that the Sinn 140 is a highly complex machine yet the dial belays this with a beautifully clear and logical layout. Legibility is outstanding and operational use is enhanced by critical tools being coated in bold red and the entire dial having a generous application of Super-LumiNova. Given the requirement for a watch in space to deliver accurate information immediately, without any misinterpretation, the Sinn totally delivers as a standout watch in this genre.

Sinn 140 St Space Chronograph Watch

Close up dial shot of the Sinn 140 St Space Chronograph Watch - Image credit WatchGecko.

Final thoughts

At £4225 the 140 is by no means a cheap watch. However, when you consider its technical prowess and the fact that a new Omega Speedmaster Professional Moonwatch will cost you £5710, the Sinn presents a compelling case.

When we think of watches in space, we naturally drift towards one, perhaps two, brands which have been photographed many times on spacewalks. However, it is important to appreciate that many other hugely capable watches have proven themselves in zero-G and indeed are technically much more impressive than the old die-hards. The Sinn 140 St Space Chronograph definitely falls into that category and if you are minded to expanding your space collection, this unique watch demands serious consideration.