Purdue To Create Life-Supporting Ecosystem In Space

This is all very interesting.

But.

It strikes me that these elaborate "closed system" approaches, at least for settlement of the Martian surface, are taking things much further than what is required. Is it really necessary to put in all the hard work and perform all the fine-tuning such complex, artificial systems would require? Are settlers on Mars really going to have the time it will take to continually monitor and adjust and tweak and troubleshoot such systems?

There is clearly a need for some form of waste recycling -- whether it is sewage, "grey water", plant waste, what have you. And there is clearly a need to produce (as opposed to continually transport) food for the settlement. And there is clearly a need to continually freshen the air. However, Mars is not interplanetary space -- there are plentiful resources available on the surface. Do recycling and food and air production systems really have to be closed loop systems, when the materials to replace the losses are more-or-less readily available?

I don't believe so. While these sorts of studies are useful, in terms of pushing the technologies involved to higher levels of efficiency, there is always an element of Zeno's paradox involved. Do we really want to wait until that last n% efficiency in the closed-loop system is achieved? Or will we be satisfied with something less: merely "high-efficiency" systems?

Another point which seems misguided to me is the reliance on existing crops. The closed-loop proponents never seem to take advantage of genetic modification to enhance the efficiency of the organisms they plan to use in their reactors and such. Nor do they seem to understand that manipulation of certain plant traits could offset much of the potential difficulty with using Martian soil as-is. Furthermore, this approach could expand with the settlement (just add another greenhouse), whereas the "brittle", expensive, highly-artificial, and imported closed-loop systems would inevitably turn out to be limiting factors to the settlement's growth.

Perhaps including such possibilities in their studies is beyond what their funding will allow, but if so, it is a line of research one would expect to see pursued elsewhere, and referred to as a potential future enhancement. Instead -- silence.

Which is a shame, really. Modified plants which perform these vital functions while requiring little human attention -- even at the cost of some overall efficiency -- would be far more beneficial to the settlers than the elegant but more-trouble-than-it's-worth closed-loop approach. We are not going to Mars to build "Biospheres" for the sake of building "Biospheres", after all -- we are going there to settle and explore. While making for interesting and possibly useful intellectual exercises, closed-loop research must not be regarded as providing us with enabling technology for Mars settlement, especially when there are simpler and cheaper alternatives.