Crew Member
Crew Members are hired by the player via Trade, and perform tasks on the ship. The crew has the same survival requirements as civilians, except for being able to wear spacesuits in the absence of an oxygen atmosphere.
Crew members come in different varieties, with each performing certain jobs:

Basic
Basic crew install and dismantle equipment, and move all items (including loading/unloading containers). The also operate most crew stations.

Scientist
Scientists operate Science Stations.

Weapons Officer
Weapons officers operate Weapons Control Centres.