Here is the full list of all 20 Redshirt achievements.
Add Astra as a Spacebook friend
Get a 'like' on a Spacebook status or post
Get hired for a job at least 3 ranks above your Career Rank, without being properly qualified.
Host a Spacebook event for 3 or more people, where everyone turns up.
Maintain a single romantic relationship for 21 days. What commitment!
Get back together with a former romantic partner.
Get at least four likes on any Spacebook post you make.
Your romantic partner was killed on an away mission
Have at least 6 different items from the S.H.O.P. in your inventory
Get into more than 8 different romantic relationships in a single playthrough
Win the game with away missions frequency setting at highest
Win the game with holodoctor intervention setting at highest
Achieve 4 aspirations in a single playthrough
Win the game by getting to the top of the career tree.
Win the game through the 'bribery' route.
Win the game by making friends with the right people.
Win the game by maintaining a romantic relationship with the right person.
Win the game by buying your way off the station.
Win the game through two different routes.
Win the game through all 5 different routes.