Here is the full list of all 12 Eterium achievements.
Score the killing shot of a capship (campaign only).
Complete a mission in the simulator.
Eject from your ship and survive to continue to the next mission (campaign only).
Start a campaign mission playing on Ace difficulty.
Complete a mission without firing a single missile (campaign only).
Complete the Battle of Vega simulator mission series.
Score more torpedo hits than required to take out a capship (campaign only).
Complete the campaign.
The Nozomi Maru must survive until she reaches Lyota Station.
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.
The UEA Sirius must survive the encounter in Procyon.