Monster Encounter

A monster encounter is something that can happen to any spacecraft that have an online avatar on board. When triggered a number of big animals will spawn somewhere on the spacecraft.

These animals are dangerous and can easily lead to the death of multiple crewmen. Any non-stationed troops will generally rush to attempted and eliminate the animals.

Worst case scenario is that a ship's officer is killed, since this would result in lost long distance contact with the vessel and vulnerability to dark matter collisions.

The resulting deaths from a monster encounter generally lead to a rat problem because of the carcasses that will end up on the floor.

Encounter Trigger Conditions

Monster encounters are rare and most of their trigger conditions are secret. It has however been mentioned that heavy trading with cities is what will ultimately cause the monster encounter.

Quotes from patch notes

Related patch notes
Update 2016-01-21 and 2016-01-22: Monster Encounters People seem to have fun with occasional monster encounters on their ship. Done. Don't ask for details. ;^)