User blog comment:Mattd43/Public Domain Space Heroes./@comment-1212133-20100608180747

Buck Rogers originally appeared as Anthony Rogers in Amazing Stories which was not renewed. The film serial is also public domain to my knowledge. His radio serials are public domain but the scripts as unpublished works are still under copyright for 95 years. The re-prints of the strips in Famous Funnies and the Buck Rogers series by Toby were not renewed but the I do not know the copyright status of the original comic strips published between 1929-1963.

Flash Gordon originally debut in a comic strip in January 7, 1934. I am not sure where to find the renewal information for comic strips. Flash Gordon Conquers the Universe film serial is public domain.

Tom Corbett's comic appearances at Prize or Dell were not renewed.But he first appeared on TV so you would need to see if the episodes were renewed to discover if he was in the public domain.