Astronaut Captain Lundvik is the voice of self-interest. She is governed by her fear of the unknown, refusing to acknowledge any other possibility than the rigid course she initially embarked upon. She is the soldier in this weeks episode, the implacable force who cannot deviate from her programming. She is willing to sacrifice herself but does so out of a misguided need for martyrdom rather than any true nobility. Its interesting to contrast this story with The Waters of Mars, a similar base-under-siege script from series four. In that episode Captain Adelaide Brooke commits suicide in order to preserve a timeline that pushes humankind forward into space. Here, Captain Lundvik almost derails that chance by refusing to acknowledge the worth of another beings life as equal to our own. Lundvik must break free from her selfishness before she can see the potential of another path.