Here is the full list of all 18 Ion Assault achievements.
Completed the single player campaign.
Score exceeds 500,000 points (Campaign).
Destroy 50 big asteroids in a single game.
Survive 3 stages in a row without losing a life.
Destroy five asteroids at once.
Finished a stage in less than 90 seconds.
Destroy seven asteroids at once.
Complete a regular stage without collecting a single Power-Up.
Complete a whole sector without dying once.
Score exceeds 1,500,000 points (Campaign).
Get two extra-lives with a single score upload.
Score exceeds 500,000 points (Survival).
Score exceeds 1,000,000 points (Survival).
Score exceeds 2,500,000 points (Survival).
Score exceeds 5,000,000 points (Survival).
Score exceeds 10,000,000 points (Survival).
Score exceeds 3,000,000 points (Campaign).
Score exceeds 5,000,000 points (Campaign).