Imagine an earth existing with the human earth, having in it things in common like locations (countries like the United States of America and many known nations existing on the human-known planet earth), people, timelines, economic relations and other interests but only differing in advancement in technology---- the parallel earth being ahead... The parallel earth has the fate of the trio of Kyle, Stanley and Michael, who would become The Three Musketeers, having the ambition since childhood of being the first people to travel the nine planets (planets parallel to the ones the human-earth people know) in nine years only to realize it would take them ninety years, being told.
Life In Space---The Parallel Earth Story tells it all