Chris tries to figure out what exactly he heard in the Habitat, and Sophia tries to keep herself focused on the tasks at hand.

Christopher and Sophia step into unusual roles, including that of parent and child.

We learn why someone would fight and die for supplies from the Mission Control storage rooms. And we learn a good reason why nobody who's left the Earth would be in a hurry to go back.

Two voices reach out across the void, but are either of them heard? One faces impending death, the other faces abundant life.

The mystery of the Captain's suicide deepens. Sophia has advice on how Chris can reconnect with the shipmates but he's afraid to put the plan into action.

The atmosphere of the ship changes, both literally and metaphorically -- and Dr. Mason's life monitors suggest a chilling possibility.

Chris pushes Sophia past her breaking point, forcing him to see her in a new light. Speaking of light, there's one still burning inside the airlock.

Chris and Sophia struggle to understand each other's predicaments.

Here is where it all begins — with howling alarms and the desperate plea: Konyechny, do you read?