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