This is excellent science fiction about the space race in an alternative universe in almost the same timeline as ours -- mid 20th to early 21st century told over 4 seasons so far. Russia, the US, private companies, and other countries make great achievements in space including permanent bases on the moon and Mars. Although achievements in space far surpass our own universe in all other respects the world is a very familiar place even if both world and domestic events are different. This is realistic science fiction based on available or near available technologies. It is not science-fiction in the vein of Star Trek or Star Wars , both of which are very good, but very different.
Conflicts between the nations are similar but are based on different events. Presidential elections may have the same or different people who win or lose as in our universe. Terrorism in this universe does not mirror our own but exists. Events that almost precipitate nuclear war are different. There is intrigue , spying, defection and romance.
We see a young cast of characters at the same NASA agency with a large budget grow older together in the space program as some achieve great things. Some survive and others don't. Some die as heroes, And others live to see their heroism celebrated. Each season also introduces some new characters, and advances the timeline, sometimes substantially.
By the fourth season, without revealing any spoilers, we see an interesting dynamic develop. Characters based on Mars from different countries who plan to stay on Mars form bonds and begin to see Mars as their home and not the countries they came from on earth. Instead, those controlling events on earth are seen by this group as their adversaries. The Mars and Earth based characters begin to work at Cross purposes which leads to an exciting climax in the final episode of the fourth season.