With all due apologies to Snow White, the above riddle is among the most debateds question among collectors.

The reason is simple to understand: as supply decreases, demand increases. In the case of autographs, that often translates to desirability and value.

Fortunately, those who focus on the signatures of space explorers rarely need to worry about supply. The majority of astronauts and cosmonauts have offered autographs to collectors and admirers. Some like the incomparable John Glenn, have probably provided their signature many tens of thousands of times over.

That said, there still remains a small group of astronauts' and cosmonauts' autographs, that for various reasons are rarely seen and/or are available to collectors.

This article seeks to rank and offer an illustrated reference guide to those autographs. This is of course, a subjective listing and although attention was made to research the facts (with special care to insure the examples included on the following pages were unquestionably authentic), it is certainly not scientific. Nor will everyone reading agree on the order in which the autographs are offered or even the selections themselves.

We invite readers to share your thoughts through the links populated throughout the following pages.

A note about the ranking

This list was compiled without consideration for demand, desirability or value of the autographs. It focuses solely on the estimated number of signatures in existence at the time this article went to print (mid-2002).

Furthermore, it was decided to restrict the astronauts and cosmonauts eligble for inclusion.

If consideration were given to every person trained to fly, a ranking would be nearly impossible. It would be very hard to classify the rarity among the numerous cosmonaut candidates to have never been granted a flight.

Also omitted for different reasons are the members of the most recent NASA astronaut classes (16, 17, 18), as their signatures' supply is limited as a factor of time: they being among the most recent to be chosen.

Remaining are all individuals, from all nations, to fly in space and all unflown NASA astronauts to be selected in Groups 1 through 15.

So, without any further ado, the rarest of them all...