An expansionist is someone who wants to increase the size of the country or the number of people who live there. They believe that by doing this, the country will be better off.
Unfeasible means that something is impossible or unlikely to happen. Trying to do something that is unfeasible is pointless.
An airlock is a device that is used to protect astronauts from the environment. The airlock is a small room that is sealed off from the outside environment.
A magnetosphere is a layer of the Earth's atmosphere that is filled with magnetic fields. These fields interact with the solar wind, and they influence the way that the Earth's radiation is distributed.
A windowless room is a room that doesn't have any windows. This means that the room is very dark and difficult to see in.
A survivable situation is one in which you can survive and live to see another day. A survivable situation is not always easy, but it is possible.
To decontaminate something is to clean it or to make it safe so that it can be used again. Sometimes decontaminating something means eliminating the agents that cause the damage.
Terraforming is the process of modifying a planet or planet-like body so that it can be inhabited by human beings. This can involve things like changing the climate, changing the environment, and adding new plants and animals.