Proposal: Space Exploration
Would questions about the requirements, construction, feasibility and maintenance of habitats/biospheres on the Moon, Mars, Mercury etc be on topic?
I see no reason why not. Manned exploration is a form of exploration, and the idea of "one-way ticket" travel is currently considered quite feasible (even more so than "fly there, then go back"), so building a permanent base at the destination should be well within the scope.
Just to go a bit further with this idea - discussion questions such as "how will a habitat on Ganymede be constructed" may be too broad, but could easily be broken down to the constraints involved, such as dealing with different gravitational forces, how to shield against radiation etc - those aspects could probably be asked separately.