Here is the full list of all 8 Astro Tripper achievements.
Destroy the Spider Boss on Arachnophobia, without destroying any of its mini guns.
Destroy 10 mutated pods in any one level of Training Grounds.
Destroy 20 tanks in sequence.
Destroy both generators on Claustrophobia without killing a Tank.
Destroy 3 Flypods within 5 seconds on any level of Insect Infestation.
Destroy 3 Worms in sequence on The Ooze.
Destroy the Boss without opening more than one outer door. Only 1 of the 3 outer doors may be opened to any degree.
Complete level Fizz Wheels without killing a Fizz Wheel, ( the rolling wheels connected by a laser ).