Here is the full list of all 18 Ion Assault achievements.
Survive 3 stages in a row without losing a life.
Completed the single player campaign.
Score exceeds 500,000 points (Campaign).
Complete a regular stage without collecting a single Power-Up.
Destroy 50 big asteroids in a single game.
Destroy five asteroids at once.
Destroy seven asteroids at once.
Finished a stage in less than 90 seconds.
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).