Here is the full list of all 12 Eterium achievements.
Complete a mission without firing a single missile (campaign only).
Eject from your ship and survive to continue to the next mission (campaign only).
Start a campaign mission playing on Ace difficulty.
Complete the Battle of Vega simulator mission series.
Complete a mission in the simulator.
Score the killing shot of a capship (campaign only).
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.