About two years ago I obtained this 'NASA names 35 New Space Shuttle Astronauts' mail cover postmarked January 16, 1978 Houston TX. This group of 35 included America's first six female astronauts! When I first obtained this cover it had already been signed by five of the six. The only signature it did not have was Rhea Seddons'. As you can see, it now has the signatures of all six of NASA's first female astronauts: Kathryn D. Sullivan, Sally Ride, Anna Lee Fisher, Judith A. Resnik, Shannon Lucid, and last, but not least, Rhea Seddon!
Thanks to the efforts of a fellow collector, Seddon signed the item at the Astronaut Scholarship Foundation's 'Astronaut Autograph and Memorabilia Show' November 2014. The below picture shows her holding the item after signing!
According to the collector who obtained Seddons' signature for me, she was excited to see this item and immediately recognized the significance of the postmark date on the cover!