As mentioned before, this movie's special effects were implemented by one of the very best, and that is reflected in the sound scientific background as well.  The Valley Forge looks, feels, and moves like a huge, hulking starship not meant for nimble maneuvering or combat like Star Trek's Enterprise or Battlestar Galactica's Vipers.  Lowell has to contend with course corrections that mean travelling thousands or even millions of kilometers of course with the change of a single degree.  If this all sounds like background noise, consider the implications of making mistakes when you are completely cut off from everyone and everything.  It's that consistent reminder that makes these very basic problems suddenly monumental.  The stakes are high.  When the Valley Forge crashes through Saturn's rings, we feel the impact of the tiniest of rocks, the pull of gravity, the turning of the ship.

From here, it would be easy and tempting for this movie to degenerate into an Avatar-like series of cliches about how hurting nature is bad, but Dern's presence guides the movie to a more compelling place.  Key to this is that Lowell does not take perverse satisfaction in killing his crew mates.  There are scenes which show that his actions haunt him consistently throughout the journey, with flashbacks and a very haunting sequence where he has the ship's drones bury the one crew member he had to personally (and brutally) dispatch hand-to-hand.

Lowell also realizes at many points just how despairing his actions are, given how alone they have made him.  When he renames the ship's three drones Huey, Dewey and Louie after the infamous Disney characters, we can't help but think of how he is trying to desperately replace the people he's killed.  He treats the drones like people from that moment on; teaching them to play cards, talking to them, and even caring for them when he accidentally crashes into one with a buggy.