What was one year in which Doug's father was a boy in Ray Bradbury's short story "The Rocket Man"?

's short story
"The Rocket Man" is one of many in his anthology titled . In this
story, Doug is the son of a man who works as a Rocket Man, traveling through space. Doug's
father, referred to as Dad in the story, is frequently gone for three months at a time, leaving
Doug and his mother to miss him terribly.

Early in the story,
Dad has returned once again from a mission. The first day he is
back, Dad absorbs himself in the earth through...