" if humans start spending serious amounts of time off Earth, they will have to take to using their own excrement for this purpose"
Or pigs in spaaaace, and use their fertiliser. Then they can have space bacon butties.
Three fresh 'nauts have arrived at the International Space Station, bringing it up to its regular complement of six - and clearing the way for the first off-Earth farming. The arriving 'nauts are NASA astronaut Kjell Lindgren, Russian cosmonaut Oleg Kononenko and Japanese astronaut Kimiya Yui. The trio took off from Baikonur …
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You'd need a serious set of bioreactors to process faeces ( and non-edible parts of plants, and...) to plant food. The equipment simply isn't present on the station, and given the cost of launching stuff it's probably more efficient to simply lift a suitable nitrate mix to where it's needed than a load of tanks and piping.
Farming in space ( and the associated problem of closed ecosystems) is a terribly complicated and technically challenging issue, and indeed well worth researching.
It would be better to reclaim the water from the faeces, otherwise you're gradually losing water from the system. For a closed system, or at least one with minimal input required, this would be pretty important.
Also it seems that bacteria are pretty hard to kill so the combination of UV and vacuum may not make it safe for use:
Looks like they need to develop a compact sewage plant after all.
I believe that is one of the "accidental" things they discovered from the Apollo missions. Bacteria survived on some of the cameras they had use on the moon (and were brought back to Earth).
In my own experiments, E.coli can survive in glucose and the high vacuum and radiation of an electron microscope.....though it does tend to get chunks blown out of its membrane.
Have you ever heard of composting? Takes complex organics and breaks them down into soil. The Chinese and Japanese have used "Nightsoil" for centuries to supplement poor soils and add organic fertilizer. No reason that couldn't happen on the ISS if properly accommodated. The only issues are the personal taboo's of the astronauts. If they drink recycled urine, there shouldn't be many left. Speaking of which, the leftover minerals from distilling the urine would be a good addition to the hydroponic fluid.
I'm quite aware of composting, yes. A compost heap is, in fact, a bioreactor. It does not, however, present nitrogen and to a lesser extent potassium, sodium, sulfur and magnesium ( your ultimate goal, after all.. ) in a way plants can actually use. The same goes for the urea left over from the urine distillation: plants cannot metabolise it directly. For hydroponic fluid you ideally want the pure salts as an addition. Soil is a very complex ecosystem, which major output is "plant food" in the form of those salts, but if it was easy to duplicate every greenhouse would have a bloody big reactor, sorry, "compost heap", next to it already..
Incidentally, not using human faeces for human food production is not a taboo, but rock-hard science. Something to do with the nastier shades of pathogenic colon bacteria being spore-formers and the inevitable end result of bouts of explosive diarhhea, or worse. Which you most definitely do not want to happen in a space station.
Versitile Ecology Grows Giant In Exo-farm.
I think we need some sort of test to make that any returning astronauts are actually the same ones we sent up there.
"Look, you fools, you're in danger! Can't you see?! They're after you! They're after all of us! Our wives, our children, everyone! THEY'RE HERE, ALREADY! YOU'RE NEXT!"
Romain lettuce is probably the least useful food source unless you have the gut bacteria to digest cellulose.. Of the mass of leaf, less than 2% is usable carbs and about the same amount of protein. Better would be perhaps algae. Sugarcane or potatoes probably even better but less practical. But more significantly, these plants presumably are not exposed to sunlight...instead one imagines solar power is used to charge batteries and then this is used to power lights shining on the plants...a terrific waste of energy to produce nearly no energy. If the earth's ecosystem is a good example...then one should be trying to cultivate phytoplankton and krill in fermentation chambers exposed to filtered sunlight.
Red romaine lettuce was used in the previous Veg-01 experiment. The current Veg-03 experiment (http://www.nasa.gov/mission_pages/station/research/experiments/1294.html) will use Tokyo Bekana cabbage. Looks like lettuce but is a brassica.
And apparently VEGGIE part of the ISS recreation programme: "Through numerous tests the VEG-03 science team has refined the pillow concept and selected growth media and fertilizers, plant species, materials, and protocols for using the pillow concept in Veggie to grow healthy plants that can provide crew with food and recreation."
Interesting research, but I am certainly glad I don't need to worry about the microbes on my garden produce -- a simple rinse is generally sufficient.
I think it strange they'll let the 'nauts eat some of the lettuce but will only check it after ity comes back to earth. What about DNA mutation and such like, it could evolve into a brain-controlling parasite which would then infect planet earth.
This insanity must stop now.
Paris, brain = a natural togetherness !!
Not the first time they've grown it according to another poster here, so they're pretty certain its safe...
The risk is they are not sure what will happen with different plants, consider that tomatoes are a member of the deadly nightshade, family, so you really want to make sure the zero-g doesn't end up making them a poison for the crew!