Boy howdy do I love this show. First of all it's my most famous premise in science fiction - strand a group of humans light years from home with virtually no hope of ever returning to Earth.
Create conflict by giving the main characters different ideas about how things should be run on the ship and let them go at each other. The civilian scientist clashes with the military commander.
Add the crisis of limited resources constantly hanging over their heads and - best yet - place them on a derelict alien craft that they neither fully understand or can fully operate effectively. (mysterious aliens who want the ship for themselves is also a nice touch)
Everyday is a struggle to survive not just physically but mentally too and that creates the best drama around. This show is very smartly written and cast and uses a plot devices called the 'stones' that allows them to communicate with earth and swap their 'essence' with another person on Earth.
You can visit family and loved ones but you don't look like the person they remember. Just another way to torture these people by giving them only the illusion of home without all the benefits of love and companionship because it is hard to accept that the person the families knew is now in another person's body.
