It posits a world where the Soviets won the race to the moon and reaped enough cultural and economic benefits to stay together, and the space race never ended. Various political events play out differently, and somewhat different things happen culturally and very different things happen technologically. It does a season per decade, and from the thumbnail it's no secret that humans make it to Mars.

Imagine if you began with "The Right Stuff" and started down a path towards Star Trek a decade at a time. It's far from perfect, but it's a fun ride and has a lot of "smart people solve hard problems" scenes.

It's an alternate-history telling of the space race. In its version the USSR makes it to the moon first, so the US doubles-down on their space program and continues beyond Apollo.