Here is the full list of all 20 Sublunar achievements.
Accept a mission.
Recruit a crew member.
Buy a gear.
Buy a weapon.
Complete a mission.
Complete a region.
Complete all regions.
Complete a region with every faction.
Subside a revolt.
Fend off a bandit attack.
Upgrade a settlement.
Have three settlements upgraded, with the same upgrade, at the same time.
Complete a job.
Reach level 5.
Reach level 10.
Reach level 15.
Play a game in sandbox mode.
Travel many orbits.
Travel many more orbits.
Travel the most orbits.