Extinction Event Avoided

Once the Aurora's drive core goes critical and explodes, you can (and should) go fix the mess. Kit up first: a Radiation Suit is non-negotiable, and bring a Repair Tool, a Laser Cutter for sealed doors, and ideally a Propulsion Cannon for rubble. Enter through the blasted-open bow section, work through the ship to the drive room, and weld every breach on the reactor - the achievement pops when the last one seals. The radiation zone then clears after a few in-game days, opening the wreck up for proper looting (Ordered the Prawn lives in here too).