Here is the full list of all 31 Citizens of Space trophies - there are 12 bronze, 13 silver, 5 gold and 1 platinum.
Unlock all Trophies
Beat the game with all citizens recruited
Defeat GalactiCo within the Corporate Dimension
Complete all Extermination quests
Complete all Hide-And-Seek quests
Complete all Wanted Poster quests
Stop the GalactiFactory before it totally recalls Earth
Get all citizens to Talent Lv 3
Use 150 items
Collect 1,000 shiny bits
Foil the President's convoluted plot against his own planet
Receive 10,000 damage in combat
Discover the records of GalactiCo's acquisition of Earth
Recover the pieces of Earth noted in the President's intel
Recruit all 40 Citizens
Swap Citizens in battle 100 times
Find 100 treasures
Defeat 1,000 enemies
Recruit 25 citizens
Spend $10,000
Return Earth's core to its proper place
Summon a citizen in battle 50 times
Implement a policy in battle 20 times
Earn $10,000
Rescue the Astronomer from her lunar bunker
Complete 25 bounty missions for the Sheriff
Collect 300 items
Deal 10,000 damage in combat
Discover 30 locations
Recruit 5 citizens
Leave the Galactic Federation of Planets to find the Earth!