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kslusherplantman t1_j0wcbwx wrote

Reply to comment by ok46reddit in World's first rice seeds harvested in orbit onboard China Space Station return to Earth by Opcn

Rice will take too much water to get any kind of harvest in space… water is heavy and not super dense for the amount it takes for various water needs

and therefore a premium in cost to get it to outer space…

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Kvothere t1_j0xc966 wrote

Rice doesn't need all that water you see in rice patties to grow. Its just a weed control technique - rice grows fine submerged and weeds don't. It can be grown in dry fields - or the space station - too, and weeds aren't really a problem in space.

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kslusherplantman t1_j0xlgkp wrote

http://www.knowledgebank.irri.org/step-by-step-production/growth/water-management

Still over a thousand liters per kg. No way we are farming that in space

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Opcn OP t1_j0xzx95 wrote

Most of that is transpired. In space that water is condensed back out of the air and is available to put back to use drinking, washing, or watering plants. You only need enough water to keep the air appropriately humid, provide the hydrogen fixed into carbohydrates, keep the plant tissue hydrated, and keep the soil appropriately moist. Everything beyond that is just recycled and held in a tank as a buffer.

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kslusherplantman t1_j0zqngl wrote

And yet we still have to carry water to space, even with these “recovery systems” because there is water that can’t be recovered, because not ALL of it is transpired.

I’m just pointing out it’s not feasible to use that much water, even if you are recovering most of it

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Opcn OP t1_j0zwo7r wrote

For now it’s not. If we have a permanent presence around mars or further it may be. In any case it’s probably tens of liters per kg and what gets consumed in the process is released when it’s eaten.

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kslusherplantman t1_j0zy01g wrote

It’s around 1500 gallons per kg even without flooding. It still is not a drought tolerant species

And you are over assuming what can be recaptured also.

Water is physically destroyed to create sugars during photosynthesis. So no, you aren’t getting that part back.

Hahaha

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Opcn OP t1_j0zzov6 wrote

> And you are over assuming what can be recaptured also.

My assumption is near 100% of the water not embodied in the macromolecules that make up the plant body. That assumption is based on historical precedent. The ISS currently recycles 90% of their water, but growing plants would decrease the water lost to the sabatier process and wouldn't increase the amount of water lost in the toilets. Growing food large scale on the ISS is impractical, but on a deep space long duration mission it won't necessarily be impractical.

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kslusherplantman t1_j1005q4 wrote

So you are agreeing with my statement! Cool cool

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Opcn OP t1_j100qo4 wrote

You're being impolite, and you know it. I took a reasonable position and backed it up with evidence. Instead of counterevidence you are just sneering back.

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kslusherplantman t1_j10aq2r wrote

Just because you have counter evidence, which is missing parts as you admitted… well. Not sure what I can say to change your mind anyway.

Yes I fully understand every point you make.

You also say it’s not feasible to grow these crops on the space station, which is literally all I was getting at from the beginning.

So you use a bunch of words, and arguments… to agree with me in the end.

Cool cool

Sorry you feel that I’m being derogatory. But one could say you are doing the same for arguing to make the same point I’m making, and then attacking me for your own short fall in logic.

Cool cool

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Opcn OP t1_j10bm2f wrote

I am not agreeing with you that you need to send thousands of liters of water for every kilogram of rice you intend to grow. The vast majority of the water used in growing rice can be recycled. I backed that up with evidence. If you think I'm agreeing they you haven't bothered to understand the situation.

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kslusherplantman t1_j10csii wrote

No, you showed stuff about transpiration. Which is only part of the story.

You totally ignored the fact that you can’t recapture the water lost to carbohydrate production. You know sugars and cell walls and all that jazz…

Which is not insignificant!!!

And as you showed, water recapture still isn’t perfect in its own right.

It would still take 1.5 thousand gallons to grow a kg of rice, even if it’s recaptured, you are still missing part of the equation lost to carbohydrate production.

I do love how you keep acting like your ideas aren’t missing a section.

So remind me, vast majority… is that all? Nope…

So since you are so smart, please link where you talked about loss to carb production. Oh, you didn’t.. hmmm

Stop being a little piss baby and admit you forgot a massive part of where water goes, carb production.

So vast majority can be recaptured FROM TRANSPIRATION.

What about the rest of the water a plant needs that isn’t lost to transpiration??? Hmm…

And all this for you to agree with me that it can’t feasibly be grown on a space station

Hahhahahaaaaaaaaaaaaa

Carbon dioxide + Water + Sunlight = Sugar + Oxygen or 6 CO2 + 6 H20 + Energy => C6H1206 + 6 02

Every single simple sugar takes 6 water molecules to produce 1 simple sugar.

So… what you have to say about that? Hmm… not lost to transpiration. Hmm…

Edit: and depending on the plant, it’s only something like 40% of the water intake is lost to transpiration.

So 60% still goes solely to the plant.

60% of water use, is the majority of water use not lost to transpiration.

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Opcn OP t1_j10gf46 wrote

>You totally ignored the fact that you can’t recapture the water lost to carbohydrate production. You know sugars and cell walls and all that jazz…

No, I didn't ignore that. Each kilogram of carbohydrate takes ~600 grams of water. Guess how much water is released by the body when that carbohydrate is consumed and metabolized? 600 grams. So lets say you have 30cm of soil and a yield of 2kg per square meter maintained at 33% moisture by volume (a reasonable number and round to make the math easier) let's say 2 to 1 crop residue to yield (which is an overestimate but that more than makes up for the fact that a tiny percentage is going to be oils which take more water for a kilo of product) so that's 100 liters in the soil, 3.6 liters in dry matter and because the plant is living at some point say 2.5* the dry weight of yield and residues so 15liters. Add all that together and you've got 118.6 liters of water not counting the 25 ml of water per cubic meter that you can potentially have as humidity.

The 100 liters of water cycles through the air which is nearly 100% recycled. The crop residues are composted releasing the water, the food is eaten, releasing the water.

The two ways that the ISS loses most of its water are through air cycling (which the plants decrease the need for) and through disposal of poop (some of which may be composted with crop residue). At no point are thousands of liters of water going into every kilo. At no point do you need thousands of liters of water for every kilo that you want. Also, there is water in space, in comets, in lunar craters, buried in the martian regolith and frozen in the martian icecaps. There isn't a whole lot of food out there.

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kslusherplantman t1_j10scf5 wrote

You are again ignoring that not all the carbs a plant produces goes into what we eat……………

All this for you to say, like I was saying, it’s not feasible to use rice to produce food on a space station.

You are dense aren’t you?!?

I’m done with this since you are clearly being willfully obtuse of my stance and your stance LEADING TO THE SAME CONCLUSION

Or do you disagree we cannot feasibly with current technology grow rice for consumption on a space station?

Do you need me to copy and paste where you said that?

I’m done

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Opcn OP t1_j10szqs wrote

> You are again ignoring that not all the carbs a plant produces goes into what we eat……………

"Each kilogram of carbohydrate takes ~600 grams of water. Guess how much water is released by the body when that carbohydrate is consumed and metabolized? 600 grams."

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kslusherplantman t1_j11beio wrote

Oh, so you eat the whole plant?

Or are you just eating the “seeds” and leaving the rest of the plant?

You do realize there is more plant left behind the when you harvest rice?

Oh, that’s right, you are only eating a tiny section of the plant itself………..

Yes you are ignoring the whole weight of the plant that is still carbohydrates, but we can’t digest.

Or can you, amongst all humans, break down cellulose??? Oh you can’t…. Cool cool cool cool

Yes, still being willfully obtuse. And being quite dumb about it also

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Opcn OP t1_j11el0t wrote

> Oh, so you eat the whole plant?

>Or are you just eating the “seeds” and leaving the rest of the plant?

>You do realize there is more plant left behind the when you harvest rice?

>Oh, that’s right, you are only eating a tiny section of the plant itself………..

" let's say 2 to 1 crop residue to yield (which is an overestimate but that more than makes up for the fact that a tiny percentage is going to be oils which take more water for a kilo of product) so that's 100 liters in the soil, 3.6 liters in dry matter"

>Yes you are ignoring the whole weight of the plant that is still carbohydrates, but we can’t digest.

>Or can you, amongst all humans, break down cellulose??? Oh you can’t…. Cool cool cool cool

"The crop residues are composted releasing the water, the food is eaten, releasing the water."

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[deleted] t1_j11fy65 wrote

[removed]

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Opcn OP t1_j11gter wrote

Composting the residues and eating the yields uses exactly as much oxygen as growing releases. And it releases exactly as much H20 and CO2 as growing consumed.

I'm not an idiot, and I've looked into this extensively. Stop treating me so poorly. Did you not notice that your last two abusive responses were over how I missed something that I clearly addressed in a previous comment?

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kslusherplantman t1_j11i0t4 wrote

In a perfect system, yes. Which also doesn’t exist

But you already admitted their capture of vaporous water wasn’t 100%

And composting would also not be 100% efficient either.

Willfully obtuse…

And this is so odd, considering you agree with me that growing them in space isn’t feasible…

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Opcn OP t1_j11n3wg wrote

It's functionally 100%. It's not perfect, because every system leaks, but we are talking 2.5 milliliters per day loss from the ISS as unrecovered humidity.

Composting wouldn't be 100% efficient, but you go through 10-20 crop cycles and the amount of hydrogen locked into the recalcitrant residues is going to be measured in milligrams per kilogram of crop yield.

You keep declaring me stupid but NASA, ESA, CSA, ISRO, and CNSA are all still looking at this process and they absolutely aren't treating it as forgone stupid conclusion like you are. There are a lot of really brilliant and really well educated people who are looking really carefully at this, and building test systems on earth and in space.

What's the better explanation? That extremely well educated people from many different academic and industrial disciplines are all failing to notice the very basic considerations that you would expect an elementary school class to think of in a guided exercise, or that you haven't thought it through?

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kslusherplantman t1_j149dns wrote

So what’s a 1% loss on 1500 gallons per system? Per kg… so even 2% loss of 1500 gallons per kg.

60 gallon x 8 lbs per gallon.

Remember 1500 is per kg WITHOUT FLOODING.

1 kg of rice feeds 6-8 people ONE TIME.

So that would feed the space station for two days, and you still have to add additional nutrients.

So let’s say they only eat a half portion per day.

That 1 kg of rice doesn’t even last a week…

Yeah, they aren’t going to be growing it for consumption for a while. Why?

It’s cheaper to move the bloody dry rice than the water for the rice….

It’s all good, you still agreed LONG ago in this thread it’s not going to happen for a while.

Again I’m just being practical on the matter.

Now, do I say it won’t ever happen. Nope…

I said as of now it’s not feasible, especially considering it’s cheaper and more effective to take a kg of rice to space, than to take the water to make the rice.

I notice you aren’t offering any math to the solution, so I’ll put it this way.

I’m being pragmatic about the situation, you just seem to want it to be a reality even if the logic of the situation deems otherwise.

Do we need to be able to do it? Yes

Are we there yet, and still a while in the future? absolutely

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kslusherplantman t1_j0zy5kr wrote

It’s around 1500 gallons per kg even without flooding. It still is not a drought tolerant species

And you are over assuming what can be recaptured also.

Water is physically destroyed to create sugars during photosynthesis. So no, you aren’t getting that part back.

Hahaha

If that was the case, we could eat nothing but carbs and get much water back… but we don’t. So…

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sotpmoke t1_j0ze77m wrote

There is no air in space…

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Opcn OP t1_j0ztnco wrote

Tell that to the astronauts on the space station

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sotpmoke t1_j0zuhos wrote

Ok thats inside a space station with compression. Theres no air in space.

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Opcn OP t1_j0zx90t wrote

Inside the chinese space station is where the rice was grown. No one is talking about growing anything out in the vacuum of space.

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carebeartears t1_j0xbvip wrote

rice doesn't have to grow in water, it is grown in water because the competition ( weeds etc) can't.

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