Here is the full list of all 23 Star Explorers achievements.
You have discovered a world of alien life forms!
You have landed on a planet!
You have reached the mothership!
You have completed the First Mission!
You have Completed the Second Mission!
You have completed the Third Mission!
You have discovered an Earth like planet!
You have unlocked an ancient ruin!
You have successfully crafted an ancient artifact!
You have melted in hot lava!
You have succumbed to the corrosive effects of ammonia!
Toxic mercury has overwhelmed you!
You have frozen to death!
You have died from heat and radioactivity simultaneously!
You have died from suffocation and acid simultaneously!
You have crashed your ship into a hypergiant star!
You have found a cave!
You have discovered five caves!
You have discovered ten caves!
You have discovered twenty five caves!
You have landed on five unique planets
You have landed on ten unique planets
You have landed on twenty five unique planets