This game is still a ways from being released, but at the heart of this game is the Unreal Engine 3 -- the same engine that powers Unreal Tournament 3, America's Army 3, and dozens of other titles. Unreal Engine 3 is a multi-platform engine that has an OpenGL renderer and is compatible with Mac OS X and Linux even though we haven't seen any titles be released yet for Linux.
Will Astronaut: Moon, Mars and Beyond have a native Linux port? We have been tipped off that it is indeed being considered. Though this shouldn't be much of a surprise considering NASA extensively uses Linux in its operations (including Fedora). If a native Linux port of this NASA MMO will indeed come, we can only hope that it will be developed in lockstep with the Windows client and will be released around the same time, compared to the waiting game that there has been for Unreal Tournament 3, Shadowgrounds: Survivor, and so many other titles.
A space game won't appeal to all Linux gamers, but at least it's not yet another first-person shooter and it will be a modern-day game.