[QUOTE=Lumpy]
Any foreseeable large-scale human presence in space is going to depend on permanent settlers living in closed-cycle habitats, whether sitting on a planet’s surface or floating free as space colonies in high orbit. Launch costs will make a “ship everything in and rotate people regularly” approach unaffordable So why hasn’t something as elementary as a human-algae recycled atmosphere been demonstrated yet?
[/QUOTE]
I posted a link sometime back in MPSIMS about an Aussie who did just that in a shipping container at the bottom of a lake.