Astronaut William E. Thornton used at least one autopen example during his career as a space hero.  These autopen autographs are still floating around and some may find their way onto eBay.  Collectors should be aware of the risk with William Thornton signatures, especially with STS-8 and STS-51B items.

This Guide will reproduce the known example of his autopen autograph.  This comes from the archives of Space Autograph News, an underground and out-of-print newsletter published in the 1990s.

William Thornton was born April 14, 1929.  He flew into space on STS-8 in 1983 and STS-51B in 1985.

An autopen is a machine-generated signature used widely by celebrities and politicians in the previous century.  These fake autographs were sent by the thousands in response to fan mail.  Early NASA astronauts were known to use autopens, so cautious collectors always watch out.

Fortunately, if you can identify autopens, you'll eliminate a lot of risky material from your portfolio.  I've prepared an index of 104 early astronauts who have used autopens in my Guide "Fake Autopen Directory of NASA Astronaut Autographs".

http://reviews.ebay.com/Fake-Autopen-Directory-of-NASA-Astronaut-Autographs_W0QQugidZ10000000001388198

I have also prepared 104 different Guides, one for each early astronaut, to document their known examples of autopen signatures.  Use these individual guides to check your own space autographs for autopens.

Let me know if you have any updates to this Guide, and I'll keep adding to it.  If this Guide is helpful, please take a moment to leave feedback.  That would make me happy!