Here is the full list of all 12 Eterium achievements.
Start a campaign mission playing on Ace difficulty.
Complete the campaign.
The UEA Sirius must survive the encounter in Procyon.
Score more torpedo hits than required to take out a capship (campaign only).
Eject from your ship and survive to continue to the next mission (campaign only).
Take out the B'tao P'ta Patrol Boats attacking the Canopus in the Eridani system.
Successfully escort the courier pilot, Flash, to the jump point.
Complete the Battle of Vega simulator mission series.
Complete a mission without firing a single missile (campaign only).
The Nozomi Maru must survive until she reaches Lyota Station.
Score the killing shot of a capship (campaign only).
Complete a mission in the simulator.