Refuge-Planet

Definition
A Refuge-Planet, or Shelter-Planet, is a place in the universe where you and your people can find a new home after running away (or, in that context, flying away) from your home planet, after a disaster, an invasion or maybe too much pollution in the air that is not anymore breathable plus a catastrophic temperature rise that causes horribly important collateral damages (cough cough humans cough). Non exhaustive list.

Number
We don't know the exact number of Shelter-Planets in activity at this moment, but there are certainly more than 20 of them in the known universe. A dedicated team of scientists from various species is currently trying to inventory all of them, but there is still a lot of work.

How it works
When a people (in one or more spaceships) reaches a Refuge-Planet, negotiations with all the species' representatives and scientists begin. They decide, regarding its past history and the reason they quit their home planet, if the new people deserve a second chance, and if so they decide where in the planet they could live.

They also talk about what the newbies can add to the current functioning of the Planet. If the agreements are violated, the people is kicked out without delay and has to find a new Shelter-Planet, but with "Planet Killer" on a resume, it's difficult to find a new Shelter-Planet willing to let you stay.

Experiments then begin: the newbies'metabolism is almost 100% of the time not adapted to the atmosphere or temperature, so they need to modify it before settling down.

After the new refugees' metabolism is correctly modified, they can begin their installation.

All the spaceships are then kept in a huge shed made for that use only, and all the informations on the new species are collected and preciously kept in an enormous library that contains all the intelligence, history, stories and discoveries of all the people who ever stepped (or flew, or swam, it depends) on that Shelter-Planet.