Aground

This achievement is unlocked upon completion of the quest "Launch Virus" given by CaptAIn.

Although missable if you're doing strictly the magic path, it's pretty straight forward if you're progressing by doing science quests.

Summary:

• Quest: Launch Virus
• Quest giver: CaptAIn
• Location: Colony Ship (space ship in Colony Orbit, CaptAIn's Planet, Unoiks 213 System)
• Requirements: Destroy or disable an enemy cruiser

To fulfill the requirements you're supposed to return to Enemy HQ and deal with a cruiser in it's orbit. A cruiser can be dealt with either by destroying it (fire your ship weapons) or by entering it and killing enemies inside (position your ship over enemy's and press ).