A rare Neil Armstrong autograph from the Gemini space program is currently up for grabs at an online auction.
Signed in black ink by the moon's first visitor, it reads: "To Peter Vorzimmer - Best Wishes From Gemini VIII - Neil Armstrong". The lot, which features a photo of Gemini 8, also bears the signature of fellow Moonwalker and Gemini 8 colleague Dave Scott.
Gemini 8, launched in March 1966, three years before Apollo 11, is famed for the first docking of two orbiting spacecraft. It also saw the first occurrence of a major in-flight system failure, which sparked a swift abort of the mission.
Scott would later command the successful Apollo 15 mission to the Moon.
Arriving with a $2,000 estimate, we believe the final price could be much higher, considering the considerable demand for Armstrong's autograph, a reflection of his prominence in space history, and the rarity of such items - he stopped signing in 1994.
According to the PFC40 Autograph Index, Armstrong's autograph rose in value from £550 ($840) to £5,950 ($9,110) between 2000 and 2011, at a rate of 24.17% pa. He is the world's rarest living signature.
You can own one of these rarities today through Paul Fraser Collectibles: take a look at this Life magazine page featuring the autographs of all three Apollo 11 crewmembers.
The estate of Peter Vorzimmer, the co-author of the 1967 NASA Project Gemini Chronology book, has provided several other superb space autographs for the auction, which ends on July 18.
They include a signed photo courtesy of Gene Cernan, the last man on the Moon, valued at $400, and a photo display autographed by first American in space Alan Shepard and Frank Borman, commander of Apollo 8, which has a $1,000 valuation.