Crops

SpaceNut · 2016-05-19 20:21:39

I look forward to a report since we have put in so much work so far into this topic....

RobertDyck · 2016-05-20 01:12:43

Ok. My recipe:
454g (1 pound) package of medium firm tofu. Sunrise brand. Has Chinese writing on the package, but says "Sunrise Soya Foods, Vancouver BC". Drained (was packed in water), and used half the package.
5 ounces dry split green lentils. Not "French Green Lentils"; they're darker, smaller, and the internet says higher in fibre, lower in protein. Regular green lentils are highest in protein. And I had a mixed bag of yellow and green lentils, separated them one-by-one. 5 ounces is what came out of the bag. Cooked in 15 ounces water, bring to boil and simmer 45 minutes. Then drain.
Add 1 cup rice flour. Purchased rice flour, not home made.
4 tablespoons of hemp oil
1 teaspoon cumin powder
1 teaspoon ground fennel seed powder
2 1/2 teaspoons dark soy sauce
2 teaspoons garlic salt (recipe for "facon" called for 3 cloves garlic, but I ran out)
sprinkled fresh ground black pepper from a pepper mill

Mixed with a spoon, but the lentils wouldn't mash. So used a hand immersion blender. That turned it to mush real quick.
Spooned into a Pyrex cake pan. Sprinkled toasted hemp seeds on half.
Baked @ 325°F for 25 minutes.

Turned out a tan colour, not green. However, tastes pretty good! Heavy, with a meaty texture. Wasn't sure what to think at first, it isn't sweet and doesn't exactly taste like any meat. A second bite tastes good, once you know what to expect. Fudge texture. Hemp seeds add crunch. Gives me a bit of gas like any bean dish. I put most into a container in the fridge. Will take it to the Convention Hospitality suite Friday evening. See what they think.

I was thinking the our one member who's vegan would like it. However, she requires gluten free. Checked the ingredients again; garlic salt is made of salt, garlic, and silicon dioxide so it pours smooth (doesn't clump). That's a fancy way of saying fine white sand. Tofu is made of water, soybeans (non-GMO), calcium sulphate, glucono-delta-lactone. But the soy sauce is "water, extract of soya beans, wheat flour, salt & sugar". There's not much, but the wheat would be an issue for the lady who needs gluten free.

I had purchased a bottle of "Rooster" brand soy sauce from a major grocery store. Ew! Don't ever buy that. Cheap, smells rancid and thin (watery). Poured it down the drain. Instead bought a bottle of "Soy Superior Sauce", brand name "ZU MIAO brand", only $1.99 for a 750ml bottle, imported from China. From "Sun Wah Supermarket" in "China town".

Downtown there's a market called "The Forks", converted from an old obsolete train terminal and train maintenance buildings at the forks of the Red and Assiniboine rivers. This city was founded at those forks, so it's an historic location, but now it's a trendy market and "town square" for events. One store specializes in hemp products: shirts, T-shirts, dresses, clothing of all sorts, soap, and seeds. They had a 1 pound bag of raw, shelled hemp seeds for $15, but I didn't have that much money. They had small bags of toasted hemp seeds still in the shell (husk? bran?) for $2. I bought one of those. Tasty snack.

Last edited by RobertDyck (2016-05-20 01:15:24)

SpaceNut · 2016-05-20 21:21:34

So product quality and brand can be closely linked for some items that we perfer a particular flavor for....

SpaceNut · 2016-06-26 22:33:19

I have seen a couple of simular articles relating to using a simulat to grow food....but this is a twist "NASA and private companies are all vying to send astronauts to Mars, but when they get there, they'll all face the same problem -- growing food"

Inside U.S. scientists' groundbreaking test to grow potatoes on Mars

When CBS News visited a Lima greenhouse last month, potato seeds planted in ideal, earthly soil had already sprouted. But after two weeks, the seeds in the Martian-like dirt failed to break through. The scientists found the seeds didn't have room to breathe and the dirt was too salty.
So they'll give the next batch of seeds more space by loosening up the soil, as well as try other varieties of tubers that don't mind a little extra salt in their diet.

IanM · 2016-07-04 18:59:30

I've noticed that Martian dirt is known as salty. Is it known what exactly type of salt or salts are in the soil? If it's ideally Sodium Chloride, or even another useful salt such as Magnesium Chloride, it could theoretically be extracted from the soil and put to use on its own in addition to making the soil more friendly to these various crops. Of course, I'd have to know more about the composition of Martian regolith in order to assess it.

RobertDyck · 2016-07-04 19:41:38

Mars Phoenix, published in Science
Detection of Perchlorate and the Soluble Chemistry of Martian Soil at the Phoenix Lander Site
F2.large.jpg?width=800&height=600&carousel=1

Fig. 2
Sensor response for the analysis of a 1-cc sample (Rosy Red on sol 30) after delivery to 25 ml of solution in the WCL. The responses of the sensors are shown after filtering, determination of activity from the calibration, and conversion to solution concentration with the Debye-Hückel formula. The first vertical dashed line marks delivery of a crucible containing calibration salts; the second dashed line marks the sample addition. Red circles are chloride measurements using chronopotentiometry. The time axis is labeled by sol and local mean solar time. The small error bar is typical for monovalent ions, and the larger error bar is for divalent ions (relative errors are smaller). The slow increase in Cl– is attributed to a source within the WCL assembly, not the martian soil. For ClO4, a small contribution due to interference from NO3 in the leaching and calibration solutions has been subtracted.

Table 1 (formatted better in the paper, follow the link above)

				      Rosy Red	Sorce1	Sorce2	Average
Na+ (mM)				1.4	1.10	1.4	1.4
K+ (mM)					0.36	0.17	0.39	0.38
Ca²+ (mM)				0.55	0.42	0.6	0.58
Mg²+ (mM)				2.9	2.20	3.7	3.3
Cl– (mM)				0.6	0.24	0.47	0.54
ClO4– (mM)				2.6	2.10	2.2	2.4
Conductivity (μS/cm)			NA	1000	1400	1400
pH					7.7	7.6	—	7.7
Equivalent conductivity at 25°C (μS/cm)	NA	1370	1900	1900
ClO4– mass (mg)				6.50	5.25	5.50	6.00
Conductivity at 25°C (calculated, μS/cm) 815	636	918	866
Total cation charge (mM)		9.66	7.51	11.39	10.53
Total anion charge (mM)			4.30	3.44	3.77	4.04
Anion deficit, if monovalent (mM)	5.36	4.07	7.62	6.49
Anion deficit, if divalent (mM)		2.68	2.04	3.81	3.25

Last edited by RobertDyck (2016-07-04 19:44:23)

IanM · 2016-07-04 20:05:34

A lot of the ions could be extracted and combined for different uses, though it might get a bit complicated, especially as water soluble perchlorate is. Perhaps an organic solvent such as acetone may be used to collect perchlorate ions instead.

In any case, it is desirable to have salt-resistant varieties of different crops.

RobertDyck · 2016-07-05 01:41:22

Wikipedia: Perchlorate Treatment ex situ and in situ

Several technologies can remove perchlorate, via treatments ex situ and in situ. Ex situ treatments include ion exchange using perchlorate-selective or nitrite-specific resins, bioremediation using packed-bed or fluidized-bed bioreactors, and membrane technologies via electrodialysis and reverse osmosis. In ex situ treatment via ion exchange, contaminants are attracted and adhere to the ion exchange resin because such resins and ions of contaminants have opposite charge. As the ion of the contaminant adheres to the resin, another charged ion is expelled into the water being treated, in which then ion is exchanged for the contaminant. Ion exchange technology has advantages of being well-suitable for perchlorate treatment and high volume throughput but has a downside that it does not treat chlorinated solvents. In addition, ex situ technology of liquid phase carbon adsorption is employed, where granular activated carbon (GAC) is used to eliminate low levels of perchlorate and pretreatment may be required in arranging GAC for perchlorate elimination. Furthermore, in situ treatments, such as bioremediation via perchlorate-selective microbes and permeable reactive barrier, are also being used to treat perchlorate. In situ bioremediation has advantages of minimal above-ground infrastructure and its ability to treat chlorinated solvents, perchlorate, nitrate, and RDX simultaneously. However, it has a downside that it may negatively affect secondary water quality. In situ technology of phytoremediation could also be utilized, even though perchlorate phytoremediation mechanism is not fully founded yet.

"Activated carbon" is used to remove bad smells from spacecraft cabin air. It's just carbon foam, usually made from charcoal. Organics stick to carbon, so foam maximizes surface area. I believe the reverse water-gas shift (RWGS) can be run to completion under the right conditions. That extracts all oxygen from CO2, leaving carbon soot. The carbon soot can the be compressed under high pressure and heat to form poor quality graphite. That graphite can then be processed to foam, creating activated carbon for filtration. For cabin air, that activated carbon can be recycled by baking-out bad smells. I think perchlorate breaks down at high temperatures, becoming O2 and chlorine. Would have to be careful not to release chlorine gas into cabin air. Chlorine will burn with hydrogen, the product can be dissolved in water to form hydrochloric acid. That reacts with sodium hydroxide to form water and salt (sodium chloride).

The wikipedia article mentioned bioremediation. What microogranisms break down perchlorate? Can we add that to soil? The first step is to just soak soil with water. That will break down some perchlorate into normal chlorine ions and oxygen. That will off-gas O2. Chlorine in solution with sodium or potassium or calcium is salt. This also emphasizes that Mars ice has to be reverse osmosis filtered before it's drinking water. Greenhouse methods of recycling water uses grey water (processed sewage) to water crops, which transpire through leaves to produce humidity. That humidity condenses on cold windows, collected in troughs. That's the cleanest, sweetest drinking water you could hope for. Obviously no perchlorate since it's condensed humidity. But soil perchlorate could get into root crops, like carrots. Ideal is a catalyst that will break down perchlorate to form chlorine and oxygen. Is there such a catalyst?

elderflower · 2016-07-05 05:21:01

There will need to be a system for recycling organic waste. This might include anaerobic digestion which would generate methane. There would then need to be some aerobic treatment of sludge and liquids, after which they could be diluted and transferred to aquaculture ponds which would also need addition of Oxygen. In these ponds Settlers might grow shellfish, crustaceans, marine snails and even fish which would clean the water ready for reuse and the settled mud could be added to rinsed regolith to make soil. At some point there must be a discard percentage to avoid build up of unwanted substances (heavy metals from regolith, for example).

GW Johnson · 2016-07-05 09:57:34

My background isn't chemistry. I would like to understand better what is being discussed here.

What I see above in the post 306 data looks like some metal ions and both chlorine and chlorate ions. Would it be fair to say that either of the chlorine or chlorate ions would "fit" on any of the metal ions? These positive metal + negative ions undissociated in the dry soil I presume are the "salts", only one of which is sodium chloride.

The order of magnitude of the ion concentrations in the test solution seems to be 10^-3 "M", by which "M" I am guessing means molarity, in turn defined as moles of the whatever per liter of solution, if memory serves? Are these numbers considered to be high or low? What do the test solutions mean with regard to how much of these "salt" minerals are actually in the dry Martian dirt?

I noticed in the table of results a pH number of about 7.6, which is actually fairly neutral, as I recall. I thought I had read that some locations tested acidic, and some other locations tested alkaline. I don't recall any pH numbers to specify how acidic or how alkaline. But if memory serves, 7.0 is defined as neutral. 5 to 9 are certainly quite tolerable, as I recall.

I do know that soil and groundwaters around here where I live usually fall in the pH 8.5 to 9.5 range (limestone underlying black clay, former ocean bottom country), and the groundwaters tend to be a bit high in mineral content (a bunch of different species), and sometimes a tad salty (meaning sodium chloride). Yet, they serve fine for both agricultural and human purposes. Most of the minerals are metal chlorides and carbonates, I believe. Perchlorates is something we don't see much of here.

So I guess my final question is: are these numbers for Martian soil really indicative of problems, or are they actually rather similar to what we live on here? Is this question being blown out of proportion because the numbers are technically off of neutral? Do the perchlorates vs carbonates really matter?

Final comment: I bet these results vary quite drastically from site to site on Mars, just like they do here.

GW

Last edited by GW Johnson (2016-07-05 10:07:36)

RobertDyck · 2016-07-05 11:44:56

GW: you're right. The description says they dumped a 1cc sample into the instrument. Most people here should be familiar with metric, but just to belabour the obvious: 1cc = 1 cubic centimetre = 1 millilitre = 1ml. The instrument contains 25ml of solution (probably water). When salts dissolve in water, they are a mixture of positive and negative ions. It doesn't matter which solid salt the ions came from, they freely mix in water. All that matters is that charge is balanced. If it isn't balanced, then you have acid or alkali. Yes, pH of 7.0 is neutral, low is acid and high is alkali. Soil pH in the range you gave is quite tolerable, but some crops prefer (grow better) in mildly acidic soil, others in mildly alkali soil. Many food crops prefer mildly acid.

Winnipeg and the surrounding area is very flat. It's black clay, sometimes called Manitoba Gumbo. This is the bottom of a dried-up glacial lake known as Lake Agassiz. Soil is slightly acid here. Although Winnipeg has black clay that is very deep, the underlying bedrock is Canadian Shield. Places in Manitoba where bedrock is close to the surface, we get peat bogs. Sphagnum moss predominates, which deliberately creates strong acid to dissolve rock. The moss acts like a sponge to soak up rain water. A peat bog has cyanobacteria growing in symbiosis, which fixes nitrogen from air. Together these plants can get everything they need from rock, air, rain, and sunlight. Canadian Shield is basalt, very old igneous rock like Mars. Peat grows very slowly, but creates soil from bedrock. It's one of the reasons soil here is slightly acid.

Mars surface soil is wind mixed across the entire planet. It tends to be one of two types: rust red, or black. That's it. But as Curiosity demonstrated, that surface soil can be very thin. Beneath that homogeneous surface, it's as varied as Earth. Phoenix sampled soil very far north. It's where the polar ice cap extends during winter, but melts during spring for summer. Scientists suspected there was underlying ice beneath the soil, permafrost that never melts. They dug with Phoenix shovel right after it landed. The first scoop had a problem, it hit solid ice. They couldn't get a single full scoop because they scraped a thin layer of soil away from solid ice. Well, they dug to find ice, just weren't expecting to find it that close to the surface. So that location is not the same as other locations, but the wind-blown surface is actually the same.

Spirit found soil where it first sampled to be generic Mars surface. They were disappointed at first; Opportunity provided such beautiful results with the very first image it sent back. But in the end they did get valuable science from Spirit, they just had to drive a lot to get it. Spirit landed in Elysium Planetia, a couple hundred km from the frozen pack ice where many people want to build a human base. Surface soil is fairly consistent between Phoenix and Spirit. However, Opportunity landed in a highly unusual location. It's an evaporite plain, probably fed by a hot spring. All dried up and inactive now. Rock at Meridiani Planum where Opportunity landed includes jarosite, a sedimentary mineral that only forms in mildly acidic water. It doesn't form in strong acid or neutral pH. What's interesting is the wind-blown soil that dominates the surface of most of Mars contains fines from ground-up rock. Minerals in that include plagioclase feldspar and alkali feldspar. That wind-blown soil is alkali, because it comes from alkali igneous rock.

I have argued that wind-blown alkali dust could blow into the mildly acid water at Meridiani Planum causing change of pH. Some reactions necessary for genesis of RNA require alkali conditions, others require acid, others require neutral. But I've argued an evaporite plain of mildly acid water surrounded by alkali dust? That'll do it. One scientist with a Ph.D. in biology didn't want to listen. She has the degree, I don't. I was giving her information based on geochemistry. I've found if I prepare, I can look up what a scientist is currently researching. That by looking for information outside that scientist's field of study, can find something that impacts that current research but the scientist has not heard of. My attempt to be relevant, and demonstrate I know what I'm talking about. I found those with a Ph.D. are usually surprised that I can do this, sometimes threatened that a guy with a lowly undergraduate education in computer science can hold a discussion as a pier with someone who has a Ph.D.!

This is a long-winded way of saying I believe results are consistent with wind-blown red surface soil. It's the only wet chemistry lab sent to Mars, so the only data we have. The rovers get data from many more locations, but they don't have a wet chemistry lab.

Last edited by RobertDyck (2016-07-05 22:03:35)

RobertDyck · 2016-07-05 12:15:04

Agriculture Manitoba: Soil Management Guide
Table 5.5 on that page has numbers for Electrical Conductivity (EC). It's calibrated in dS/m (deci-seconds per metre) while numbers from Mars Phoenix are calibrated in μS/cm (micro-seconds per centimetre). 1 Second = 10 dS = 1,000,000 μS. 1 Metre = 100 centimetres. So to convert the numbers from Mars Phoenix to units on the Agriculture Manitoba page, divide by 1,000. And use the adjusted numbers for 25°C. Those numbers correspond to marginal to poor for soybean.

The primary concern is chlorate. That's toxic to humans, and plants. Just soaking in water will cause some chlorate to decompose to O2 and chlorine, converting chlorate salts to normal salts. But getting rid of the last of the chlorate will be an issue. And we really need to reduce total soil salinity. One option is to wash the soil, run water from soil through a reverse osmosis filter, then return clean water to soil. I'm concerned that may remove micronutrients. For one, plants need magnesium. Every molecule of chlorophyll has one atom of magnesium. But "washing" may be the best means to deal with chlorate.

Last edited by RobertDyck (2016-07-05 12:16:28)

GW Johnson · 2016-07-05 13:38:20

Thanks, RobertDyck. I understand better what these results might mean.

Apparently the dessication process Mars underwent long ago resulted in some poor chemistry (creation of chlorates) as the surface water disappeared. But it sounds like the re-introduction of plain fresh water neutralizes a big chunk of that effect.

My guess is that any sort of agriculture we might want to establish on Mars will depend upon creating a fresh water supply to "wash" the dirt "clean". And maybe some trace elements in fertilizers initially brought from Earth. But this ought to be locally replicable once started, given sewage reprocessing as fertilizer, with appropriate microbes.

GW

Last edited by GW Johnson (2016-07-05 13:41:37)

RobertDyck · 2016-07-05 22:19:15

I've given a long-winded description a few times how to extract nitrogen from Mars atmosphere, and process it to form ammonium nitrate fertilizer. That's the white granules, traditional nitrogen fertilizer. And there should be salt peter somewhere in the dried-up ocean basin. When a salt water ocean or sea evaporates completely away, salt precipitates out. A body of water that large precipitates salt in layers: first one kind of salt, then another. Under and near the great lakes are vast salt deposits, one layer sodium chloride, one potassium chloride, one calcium chloride. What is now the great lakes was once a much larger salt water sea. Then it completely dried up. Then it partially flooded again, creating the lakes we know today. The salt from that ancient sea is what we mine for salt today. Calcium chloride is used for road salt. Potassium chloride is potash, great potassium fertilizer. We haven't found any yet, but it has to be there somewhere. Probably buried, just like salts are on Earth.

GW Johnson · 2016-07-07 12:14:10

Well, buried useful salt deposits just goes to prove that prospecting will be very important. That's not something that can be done with remote sensing, nor just shuffling around on the surface. Takes at the very least a drill rig. Perhaps real mining equipment.

Which just goes to prove that "exploration" in the sense that I use that word is not as simple and easy as it sounds. There are two questions to ask, but answering them is not easy. (1) What all is there? (2) Where exactly is it? Answering those two questions properly underlies the most successful colony establishments from 300-500 years ago.

I wonder if the perchlorates have something to do with harsh UV shining on very salty water as the planet dried up. We don't seem to have much of that stuff here, but then we are still mostly wet.

GW

SpaceNut · 2016-07-09 11:50:13

We know so much about mars and yet these simple questions still pervail without sending the right types of missions being designed to gain the knowledge needed for a manned mission. It appears Mars is not on the mission design path for nasa as its derailed by SLS.....

GW Johnson · 2016-07-09 14:24:35

We don't have to know everything in advance to send crews to Mars. Just send them with enough stuff to live and to return, no matter what they do actually find there. It's suspenders, belt, and armored codpiece. It's heavier and more expensive, but it works, and can be done sooner. The choice depends upon what tradeoffs you make.

GW

SpaceNut · 2016-07-09 20:46:14

Here is some on going work that would relate to not only deep space but for how to grow once we get to mars.
Mass. base working on gardens aboard subs

When a Navy submarine goes to sea on a monthslong voyage, the lettuce, tomatoes and other fresh fruits and vegetables on board run out in a week or two, forcing the crew to rely on canned, frozen or dehydrated products. After about a week, the lettuce in the salad bar becomes slightly translucent, then runs out, and the fresh tomatoes, carrots and celery are gone, too. Thawed fruit, bean or pasta salad, and soups take their place at the salad bar. Pudding occasionally shows up when the fruit is gone.
But what if subs had their own gardens where food could be grown under lights?
The U.S. military is testing out the idea by growing plants hydroponically - that is, with nutrient solution instead of soil - inside a 40-foot shipping container on dry land at a laboratory in Natick.
This is the second phase of the testing. Holman first tried to grow 83 varieties of fruits and vegetables to see which ones did best. The leafy greens and green onions thrived. Root vegetables did fairly well. Strawberries and rhubarb grew but probably wouldn't produce enough to make it worthwhile, Holman said.
The cucumbers, on the other hand, were a mess. The vines climbed everywhere. And the large leaves on the zucchini plants blocked the lights.
The tomato plants grew but didn't produce fruit because the lighting wasn't bright enough and the temperature was too low.
"I doubt that every meal could have fresh fruits and vegetables," Steed said, "but if you could do it from time to time, it takes something that's really essential to crew morale and makes it better."

SpaceNut · 2016-07-12 20:36:33

'Mars tomato': Scientists announce edible 'space' harvest

1467134555461.jpg?ve=1&tl=1

project announced a harvest of four foods: radish, pea, rye and tomatoes. The bounty was tested for metals including iron, cadmium, chrome and lead, and the plants were deemed safe to eat because they did not contain harmful amounts of these metals.
Of the four crops harvested and tested, the radish was found to have the highest metal content.

Terraformer · 2016-07-13 16:02:47

That's good to know.

I hope they do the research with potatoes as well.

We really could do with a minimalist set of plants for food, that are versatile enough to produce variety in meals and provide everything we need. I think potato will be a major plant,

SpaceNut · 2016-07-13 17:08:10

Potatoes can be brown, tan, yellow, red, and purple. Potatoes grow best where nights are cool. Potato varieties are often classified according to the number of days they require to come to harvest: “early” season (75-90 days), “midseason” (90-135 days), and “late-season” (135-160 days).

Yield. Each plant will produce about 5 to 10 potatoes.

Plant potatoes in full sun. Potatoes require a cool but frost-free growing season of 75 to 135 or more days. The ideal potato growing temperature is 45° to 80°F. Hot weather will reduce the number of tubers per plant. Potatoes prefer well-drained fertile soil high in organic matter with pH of 5.0 to 5.5.

http://www.motherearthnews.com/organic- … jzgoe.aspx

http://www.harvesttotable.com/category/recipes/

elderflower · 2016-07-14 06:38:08

There is one imported resource that hasn't been considered yet. Parachute "silk". This could easily withstand the pressure needed inside a greenhouse and if proofed or lined with film, would enable a very low leakage rate. Processing it into a translucent skirt for an agriculture enclosure should need only sticky tape, thread and a sewing machine. You would need a double wall, I should think, for safety and reduction of heat loss. Mirror film deployed on light frames could reflect sunlight through the translucent wall into a regolith covered masonry structure

GW Johnson · 2016-07-15 09:04:39

I'm not familiar with what you seem to mean by "parachute 'silk' ". Most of the chutes I have seen are a fine-woven synthetic fiber resembling nylon and dacron.

I like the idea of a fabric-reinforced flexible composite as a pressure-retaining balloon. I'm a little worried by cold embrittlement at Mars temperatures with nearly all our polymers, though.

Not sure you will get any effective translucence, though, especially with the polymer added to seal between the fibers. I like bouncing light off a mirror into the greenhouse, but I think your transmissibility factors will be closer to 1% than 10%, when you really need 90% +.

On the other hand, the vegetable-growing experiments with simulated soils are encouraging. One must ask how "close" the simulation really is with the simulated soils: what properties did they match? The salt chemistry is of concern, although some have suggested simple water-washing with fresh water takes care of enough of that problem. Not sure from what I read above what sort of organic matter they used. Plain rock dust is pretty much barren.

GW

Last edited by GW Johnson (2016-07-15 09:08:35)

RobertDyck · 2016-07-15 10:30:54

The Mars soil simulant that NASA uses is "JSC Mars 1", which is volcanic soil from Hawaii. I had a look at the element concentrations from an APXS instrument compared to results from the APXS instrument on Sojourner. They weren't as close as I would like. And no perchlorates at all.

I think he's talking of using landing parachutes. But I would be concerned that isn't pressure tight. Making it pressure tight would be more work than just sending a dedicated inflatable.

I have suggested using PCTFE with a fibreglass shim. That's loose weave fibreglass fibre, the shim is thermally bonded to the polymer film. PCTFE is the most impermeable to water of any polymer known to man, and more impermeable to oxygen than any polymer rated for temperatures below -80°C. Service temperature for this material is +132°C...-240°C. And the second most transparent polymer, the only one more transparent is too rigid to form a film. And highly resistant to UV, primarily because UV shines right through. I favour fibreglass because it's transparent, and the manufacturer of the polymer film already supports fibreglass.

SpaceNut · 2016-07-26 18:43:32

There is now whereon earth that we can create a mars environment , gravity, temperature conditions but we can come to one or the other extremes of no gravity and of all but what can we learn from being inside a submarine.

Veggie subs? Army researcher studies submarine agriculture for Navy

Holman, an engineering technician with the Joint Foodservice and Engineering Team at the Army Natick Soldier Research, Development and Engineering Center, has spent the past year testing the feasibility of growing fruits and vegetables on U.S. warships. His "hydroponic farm," which uses nutrient enriched water, and no soil, resides in a 40-by-8-foot repurposed refrigerated shipping container behind Combat Feeding.
The climate-controlled space is illuminated with LED lights to make it a 24-hour operation that simulates daytime and nighttime conditions and accelerates plant growth. In the first phase of testing, Holman grew dozens of different plants.
"We tested 83 different varieties of plants, including vegetables and fruits -- everything from strawberries to zucchini, beans and rhubarb -- a little bit of everything," Holman said. "About 51 of those 83 that we tried grew well in hydroponic conditions. The whole concept was to grow a salad for the submariners."
Leafy green vegetables did particularly well, but plants requiring more sun and heat, such as tomatoes, struggled.
"It does grow root vegetables pretty well, other than they come out a little bit smaller, shorter, because of the way that they grow," said Holman, referring to carrots and radishes.

As the article put it "No. 1 hurdle that they're going to have is space to grow it"....which is the same hurdle that we will have for mars.....

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