One for the proposed hard-mode, maybe.
I like this idea, not saying it will be implemented any time soon but it could be for GC4. (There are other things in GC3 we are working on just now.) Personally I am in favour of Galacticraft - at least in hard mode - being a game which reproduces how it might feel for a person to live in space, all the things you have to think about like oxygen, CO2, having enough power, recycling water, what to eat, moving in zero gravity, lack of access to everyday resources on Earth (like wood and stone) etc.
We will of course always shield players from the true harshness of space, which I would say is
* the radiation dose
* the danger of solar flares
* small things which matter if you spend a long time in a sealed environment (closed system), like poisons which are not 100% eliminated from the life support systems
* gradual decay and loss of irreplaceable equipment
* the danger of loss of pressure any time due to micro-meteorites (or bad navigation!)
* lack of doctors (!)
But I am thinking about how we can, for example, force players to be eating the delicious Galacticraft
http://wiki.micdoodle8.com/wiki/Can_of_Food unless they have some big space base with a farm.
The lack of animals in space in Galacticraft - there's no way to get an animal into space unless you cheat or use an OP type of mod item which can pick up animals (for example Safari Net in MFR) - is also intended. Actually you could make a chicken farm, if you took eggs.