When the seven Mercury astronauts were announced to the world in 1959, they were almost immediately deluged by autograph requests. They received so much fan mail that it became practically — if not actually — impossible to respond to it all. Instead of ignoring the letters, NASA decided to employ the use of a machine that would allow secretaries and mail room assistants to apply pen-drawn autographs to astronaut photos and other mailed-in items.

The "autopen" relied on a pattern, referred to as a matrix, that the machine would trace. These patterns, for which each astronaut may and often did have several different styles, began with an authentic signature. The machine's operator would select the type of pen and manually feed the item to be signed. As this was a mechanical process the results were not as smooth as an authentic signature.

Still, to the untrained eye, autopen autographs appear to be real. As they were based on authentic signatures, the autopen could be passed off easier than an attempt by a secretary to forge the astronaut's handwriting. Rubber ink stamps and photos pre-printed with a signature could be more easily identified as fake.

Because they were machine-drawn, autopen autographs do exhibit common qualities. These can include:

As all autopens are reproductions of a pattern, they are nearly identical to other autopens created with the same matrix. While size, placement, thickness and/or spacing between letters and words may differ, autopens can be identified by comparing them to known patterns. As it is very difficult, if near impossible, for a human to sign the same style every time, that by definition is the autopen.

Fortunately, enthusiasts have collected examples of the astronauts' autopen patterns and have published guides. Roy Gutzke's and Simon Vaughan's Astronaut Autopens was the first dedicated study. Relics of the Space Race by Russell Still included a chapter with many examples.

Online, Stephen Beck created the first website devoted to sharing patterns for the early astronauts. Other websites have expanded upon Beck's efforts with more matrixes. Chris Spain's autopen archive includes early space shuttle era patterns as well as illustrations of autopenned and pre- printed crew portraits. For another guide, including shuttle era astronauts, see Craig Stadler's directory of individual and crew autopens.