It's mostly sold as alternate history for the space race, but it's first and foremost a drama.
Drama about people that happen to go to space in an alternate world.
Drama about people having sex with >! their dead children's best friend who they also raised once their parents went to space and died, the repercussions which amazingly happened for multiple seasons, it's kind of weird. !<
The driving force of the show is not the alternate history.