Quadibloc wrote:
Mars is indeed an attractive place to consider building a space
colony. Its thin - but not virtually nonexistent - atmosphere, though,
complicates landing on it. And while it has most of the elements
needed for permanent habitation, nitrogen is in very short supply.


You do realize that nitrogen makes up 2.7 % of the Martian atmosphere?
You could just chill the atmosphere till the CO2 becomes liquid or dry
ice (depending on the pressure you do this at) and the argon goes
liquid, then separate the nitrogen gas out.
It will stay gaseous at a higher temperature than CO2 or argon will.
You will have to go through a lot of atmosphere to get a significant
amount of nitrogen, but that's a lot easier than dragging it all the way
back from Pluto.


Pat