In 1998 HBO pulled a viewership for a Tom Hanks produced miniseries about the Apollo program that even exceeded the audience numbers for Game of Thrones.
https://www.multichannel.com/news/hb...s-earth-140394
https://www.nytimes.com/2019/04/30/a...e-ratings.html
I doubt a series like that would get half those numbers nowadays.
Why were TV viewers more interested in space in the 90s? Both realistic and sci fi?