Here is the full list of all 18 Starscape achievements.
For rescuing 5 missing crew members
Ion weapons
Particle lasers
Zone 1 complete
Game completed on hard difficulty
For rescuing 10 missing crew members
For rescuing 15 missing crew members
For rescuing 20 missing crew members
For rescuing 25 missing crew members
Drone weapons
Defensive shields
Nova bomb
Zone 2 complete
Zone 3 complete
Zone 4 complete
Zone 5 complete
Game completed on easy difficulty
Game completed on normal difficulty