Even though I review hundreds of space and aviation autographs every month, I always enjoy looking at cool items. Every once-in-a-while something comes along that really knocks me out of my chair... and this X-15 multi-signed photo is one of them.
To my knowledge, no single item exists that was signed by all twelve X-15 pilots due to the untimely death of Mike Adams. So, eleven of the twelve is probably the best you will ever do. In speaking with other seasoned collectors, I am aware of only one other item signed by eleven.
As of this writing, the photo is at $1,612 with over two weeks until it closes. Where it ends will be anyone's guess, but I suspect some deep-pocketed collectors will be battling it out.