This is my ideas page. If I feel that it isn’t too spoilery to reveal something, it will show up below.
Selection of the Orion’s crew
They had to compete with other crews to get the honour. It may be an old ship, but it’s one of a kind. It does create a pressure to live up to expectations, especially on Caroline, the commander of the expedition.
Those you leave behind
That we know of, Caroline and Rhona had to leave family and loved ones behind, so one of the things they have to deal with is isolation, which only increases as they get further from home.
Tegan has difficulty forming friendships because she has a secret she doesn’t want to share, and is befriended by Erica, who is socially awkward for the usual reasons.
No Way Home
Morale suffers later on when the ship is cut off from the only known way home, and someone is incapacitated in a battle with the Siphen.