José Rios Gallardo (b. 1932) was a Cuban-born American minor league baseball player. His career appears to have lasted only one season, in 1954, when he played with the Artesia NuMexers. He is probably best remembered for pitching what became Joe Bauman's record-breaking 70th homerun.
Gallardo's role in "The Star and the Rockets" is identical to OTL. Harry Turtledove appears to have mispelled his name as "Galardo" in the story. Given how minor Gallardo was to the history of baseball, the error may not have originated with Turtledove.