It is the first watch worn on the Moon to come to auction. It's why David Scott's Bulova has a $50,000 starting bid ahead of RR Auction's October 22 sale.

The Apollo 15 commander wore the back-up watch on his third and final extravehicular activity (EVA) on the Moon's surface, after his NASA-regulation Omega chronometer had broken.

Scott used the Bulova when his NASA-issue Rolex broke

Scott explains his decision to carry an unofficial back-up was down to the vital need to track the use of oxygen, water and battery while on the Moon's surface.

"Under certain anticipated operational conditions, the only method of monitoring these vital systems was with a wrist chronograph," Scott said.

"I only had the NASA-provided Omega Speedmaster, which was a single point failure under these conditions.

"As a matter of prudence, I then decided that I would also carry the Bulova as a backup."

With the third EVA complete, Scott wore the watch during the rest of the mission, including splashdown.

Apollo 15 memorabilia rarely comes out of the large shadow cast by collectibles from the more famous Apollo 11 and 13 missions.

Yet this watch's unique status could see the balance redressed.

Click here to view this unusual David Scott signature we have for sale.

You can view all our space autographs for sale here.

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