Today’s guest blogger is Matthew Haley, Specialist in Fine Books and Manuscripts at the auction house Bonhams.

An autograph of the first man who walked on the Moon is a must-have for space-history collectors. But an astronomical number of forgeries of Neil Armstrong’s signature fly around in the market place, so buyers are understandably nervous.

The so-called “insurance” postal covers from Apollo 11 are a safe way of acquiring the crew’s autographs. As Buzz Aldrin has explained, “Since we were unable to obtain adequate life insurance due to the high risk nature of being an astronaut, we signed this group of covers and evenly distributed them to our families for safe keeping while we performed our mission. If an unfortunate event prevented our safe return, the covers would have provided a limited financial means of support to our families.”

An insurance cover with the right postmarks (the launch date of July 16 or the lunar landing date of July 20, 1969), the right cachets (printed images of the Apollo 11 crew emblem or the lunar surface), and a letter of authenticity from one of the astronauts gives you a gilt-edged piece featuring the autographs of Neil Armstrong, Buzz Aldrin, and Michael Collins. Expect to pay upwards of $5,000 in auction.