We've already reported on two of the highlights of Regency Superior's space sale, which is coming up on October 14: a St Gaudens gold coin carried alongside Apollo 11 moonwalker Neil Armstrong on Gemini 8 and a Russian Orlan-D spacesuit.
Both are extraordinary pieces of space memorabilia, but neither is the lot which Regency picked out as their favourite in the sale.
Instead, Vice President Penney Kols commented, "The highlight of this sale has got to be a gorgeous NASA photo of 'Earth above Moon' signed by all twelve Moon Walkers.
"To have all Moon Walkers sign on one piece is just a spectacular achievement, and considered the Holy Grail of space autograph collecting."
That's right, it's a one-of-a-kind colour 8"x10" photo of Earth above Moon autographed by all twelve men who walked on the moon.
The piece is clearly signed in black by Neil Armstrong, Buzz Aldrin, Charles Conrad, Alan Bean, Alan Shepard, Ed Mitchell, Dave Scott, Jim Irwin, John Young, Charlie Duke, Gene Cernan and Harrison Schmitt.
Such a photo is 'Holy Grail' of space autograph collecting since they are extremely rare and almost never available. Neil Armstrong never signs any more, and some of the other signatories have now died.
The photograph is in outstanding condition with only a couple of fingerprints or smudges in the black area, making it a conditional rarity as well as an outright one.
Expected to sell for $20,000-$30,000, the photo is going under the hammer in California and online.