Here is the full list of all 47 Titan Attacks achievements.
Perfect Challenge Level 91
100 aliens escape capture
Perfect Challenge Level 98
50 aliens escape capture
Used 25 smartbombs
Destroyed 100 saucers
Completed the Titan levels
Killed 100 parachuting aliens
Captured 100 live aliens
Everything maxed out
Upgraded addons to maximum rate
Guns and addons maxed
Maxed gun power
Captured 50 live aliens
Added all addons to ship
Completed the Earth Levels
Completed the Moon levels
Completed the Mars levels
Completed the Saturn levels
Perfect Challenge Level 84
Perfect Challenge Level 63
Perfect Challenge Level 77
Perfect Challenge Level 70
Perfect Challenge Level 49
Perfect Challenge Level 56
Perfect Challenge Level 42
Destroyed 50 saucers
Killed 50 parachuting aliens
Got 100 skill shots
Maxed gun bullets
Killed 25 parachuting aliens
25 aliens escape capture
10 aliens escape capture
Captured 25 live aliens
Perfect Challenge Level 35
Perfect Challenge Level 14
Perfect Challenge Level 28
Got 50 skill shots
Perfect Challenge Level 21
Killed 10 parachuting aliens
Destroyed 25 saucers
Captured 10 live aliens
Perfect Challenge Level 7
Got 25 skill shots
Got the x9 multiplier
Got 10 skill shots
Destroyed 10 saucers