US: Ascension

[RetiredGreyFox]

A young woman's murder causes the subjects of a century-long mission to populate a new world to question the true nature of the project as they approach the point of no return.

http://www.imdb.com/title/tt3696720/

And another Sci Fi series

 

[RetiredGreyFox]

It's actually The Truman Show

 

[RetiredGreyFox]

Bad idea, well executed.

I'd guessed the "plot twist" from about 10 mins into the first episode.

Of course you did.
I've just watched the first 15 mins again and absolutely nowhere is there any clues.