Europa is the sixth largest moon in the solar system but smallest, of Jupiter’s four Galilean moons. There’s no proof that life exist on Europa but it’s one of the most likely candidates for potential life. The moon has an ice crust surface and it has been suspected, to have a water ocean underneath. It is thought life similar to Earth’s deep ocean hydrothermal vents might inhabit this underwater world.
Space colony ideas come with a list of problems and this time Jupiter’s radiation belt is one. I don’t think I’ve mentioned radiation belts before. In short it’s a region surrounding a planet where accelerated particles are trapped and produces radiation. Jupiter’s radiation belt is 10 times stronger than Earth’s own. Europa receives 5.4 SV (540 rem) of radiation per day, 500 rem is considered a fatal dose. Within five minutes of being on its surface in a modern spacesuit, the astronaut would have received a deadly dose of radiation.
Europa is thought to have more water, than all of Earth’s ocean combined underneath its ice sheet. It only makes sense that underwater cities have been mentioned. An added bonus is the inhabitants under Europa ice sheet, would be shielded them harmful radiation. We already know humans can survive under water in submarines and that’s an option.
With this moon's distance from the sun, the cold temperature needs mentioning at −170 °C (-275ºF). We’d assume with liquid water under the surface, the temperature might be more suitable under there. Not only might the temperature be ideal but the pressure is thought to be as well. We can see Jupiter’s gravitational pull causing its other moon’s like the volcanic Io, to generate heat from its core. These moons are being deformed by Jupiter’s gravity, pulling them one way while the neighbouring moons gravity is pulling them the other. This friction which causes heat is called tidal heating.
Some more good news is Europa has an atmosphere, composed of oxygen which is created when charged particles hit the cold surface and produce water vapour. The water vapours then splits into oxygen and hydrogen but the hydrogen escapes from the atmosphere. If you’ve read some of my other articles, you’ll know a major problem is getting enough water to these other locations. Europa doesn’t have this problem. The water can be used for drinking or to even create the habitats.
Another big benefit is the amount of astral bodies around Jupiter. It has three other large moons which all have useful resources. One moon that is often not mentioned as much is Callisto which has many of its own colonization values. Both moons benefit from having 67 neighbouring moons as of June 2018 and more could be discovered. Jupiter is like a mini solar system and all together the moons have the resources for life.
Disadvantages
There is evidence to suggest that Europa, has an ocean under its ice sheet but we don’t know how thick it is.
The radiation on the surface of Europa is still a major problem, as any vessel we know still has to land on the surface. The colonist would still have to find a way to get under the surface which might expose them for a short time. It only takes five minutes before the radiation to become lethal.
Europa also has an unstable surface. Scientist have seen over a few years areas the size of Massachusetts moved underneath the crust and disappear
I’ve mentioned low gravity for each location, I don't feel the need to touch on it again as it's mostly the same. Instead I'll touch on alien organisms. If water does lie under the moon’s ice sheet there's a possibility life might. We wouldn’t know if these microbes are harmful to the human body. We could be exposing the colonist to all sort of unknown illnesses.
Source
https://www.nasa.gov/europa
http://www.freerepublic.com/focus/chat/691006/posts
http://asi.org/adb/06/09/03/02/110/europa2-wkshp.html