Here is the full list of all 15 Astronimo achievements.
Equip a new helmet
Punch a crewmate into a grinder
Fight another crewmate... a lot
Collect all musical taunts
Play and complete a community world
Submit your first world
Achieve levitation
Complete a challenge with another Local Player
Place and build with all the workshop parts at least once (excluding stickers and cosmetics)
Build your first rocket ship
Stack three Crowns of Glory
Land on all planets and moons
Attempted to land on the Sun
Complete the game in under 5 hours
Collect 5000 Ore