Converting Slabs of ice into seas. Brine Resouces.

Void · 2020-07-08 13:46:40

And then what are the options for aquatic plants?

This is taken from Crops, Aquatic.
http://www.eattheweeds.com/hydrilla/
Quotes:

Hydrilla became the most troublesome aquatic weed in the state. (It can expand 1,000 percent a year grow an inch a day.) Florida currently spends about $30 million annually trying to control it. The strain that was found in Florida was female. Twenty years later male Hydrilla was first reported in Delaware in 1976.
Hydrillas roots, photo by Alison Fox
Hydrillas roots, photo by Alison Fox
Since that introduction some 60 years ago Hydrilla is now found in 19 states and Washington DC, from the endotrophic waters of Maine, west to wet Washington state. Called the perfect aquatic plant it adapts to a wide variety of climates and water conditions. Hydrilla can also reproduce four ways: rhizomes, tubers, turions (buds) and fragmentation. It, and Water Hyacinths, are the two most expensive weeds in the world. Because of the economic impact of the species there is a huge amount of information written about Hydrilla as a problem. Historical use of Hydrilla prior to it becoming a “noxious” weed is scant limited to a few references to how it was named and its use in making white sugar (more on that in a moment.)
A search of Chinese literature, for example, shows Hydrilla being cultivated for crab farming, and certain fish farming as well. They eat it. Duck like it, too, and snails. These are all foods the Chinese eat but no mentioning of eating Hydrilla directly. In the Philippines much is made of its nutritional qualities, but again no references found about eating it directly.

The mild earthy-flavored powder is 13% calcium which some writers call the richest plant source of calcium on the planet. It’s also high in B-12 and iron. Further, Hydrilla has been investigated as possible animal fodder. It has 16 percent more available dry matter for fodder than cattails and no bad chemicals were found in it during the examination for cattle food. In fact in one study when fed Hydrilla cows gave 20% more milk and chickens 14% more eggs, probably related to the calcium content. But what about Hydrilla as food for people?

And this one has an encouraging factor, the tolerance of cool dark waters. But also a warning about being poisoned by blue-green algae:
Quote:

It may simply be that texture kept the plant off the dinner table, that and the fact it can grow with just 1% of sunlight. That allows Hydrilla to inhabit cold dark deep areas of lakes one might not want to bother with if there are other edible plants around.
One tentative down side is when water condition are just right (or wrong depending on perspective) there can be a blue-green algae bloom which can grow on the top leaves of Hydrilla. That cyanobacteria can produce toxic chemicals. And while that is a warning about Hydrilla is should be looked out for on every aquatic plant that one might eat (and that includes seaweed as well.) Always avoid blue-green algae.

So, for this one we don't need an air filled enclosure, or perhaps a concentrating mirror.

So, far I don't know what it's tolerance of salt is. But it can be in a fresh water bag if necessary.

More:
https://www.lakegeorgeassociation.org/e … /hydrilla/

This sort of suggests that salt tolerance may exist:
https://www.sciencedirect.com/science/a … 5200004064

The video here suggests that the plant can grow in all types of water, so, I guess salt water then.
http://plants.ifas.ufl.edu/plant-direct … ticillata/

So, I am thinking that this plant will be ideal.
In fact I think that a open bottom water bag with heated water inside would work ideally, as it is likely that the plants could be continuously extracted down to a diving bell, when the bag is crowded. Thinned out so to speak.

I think the plant could be improved as potential human food by selective breeding, and genetic engineering. Be carful what you let loose from that on Earth.

------

Duck weed would likely grow in a heated open bag, and could be continuously harvested, but of course it needs a air pocket, and perhaps more light.

Done.

Last edited by Void (2020-07-08 14:09:14)

Void · 2020-07-08 14:36:45

Oxygen.

If Hydrilla can grow that fast, how much Oxygen?

And if people don't eat it, do other things with it.

Grow mushrooms? There is a certain potential to perhaps engineer mushrooms to have qualities we like better.

Maybe a bit less cruelty than keeping animals. Um....The mushroom actually lives underground. We only eat its reproductive organs. Same as apples so don't get grossed out.

Ferment the Hydrilla for Methane?

Maybe various things. Feed birds that lay Eggs?

I am wondering how it comes to have Vitamin B12. That's supposed to be from bacteria, I thought.
Nutrition:
http://www.eattheweeds.com/wp-content/u … erview.gif

Done.

Last edited by Void (2020-07-08 14:39:26)

Void · 2020-07-08 16:39:12

(th)

Sorry I missed your post #47 earlier.

Yes I think you are relatively correct about a full barometric airlock. However I hate to squander moisture. And also if you have boiling in a fresh water top, you then probably make ice.

My solution from a "Lake", would be to have a shed over the hole. That shed can be pressurized by Martian air if pumped in at a rate > then leakage rate. And that could work for fresh water. Any evaporation should be relatively slow. The pressure needed should be relatively low. If it is a "Tin Shed" , much of the moisture should condense on it's cold walls. That could be scraped and collected or, just use a heat lamp and melt it and collect the runoff periodically. I do think that where we usually have "Lakes", we will have an abundance of water. But it is OK to think frugal.

The differential pressure inside the shed to the outside could be small enough that you might push your way against it to get outside, or just turn off the fan for a short bit. You might want to cover the hole for that with a relatively light weight door, to prevent boiling.

But yes, a barometric airlock. Doesn't seem that hard to do.

Briny water will be better behaved than fresh water.

Done.

Last edited by Void (2020-07-08 16:39:36)

tahanson43206 · 2020-07-08 18:15:46

For Void re #53

Thank you for your reply ... could you find (or make?) an image of a barometric lock? This is probably a term most people have heard, but I am not one of them << grin >>.

It seems you are not in agreement with those who are imagining a habitat far under water, far away from the surface. It seems you are thinking of a hole in the ice, with a shed over it.

This is another example of how words can lead readers astray, when a simple line drawing could make clear what is intended.

(th)

Calliban · 2020-07-08 18:26:49

Void, interesting discovery with Hydrilla. It does suggest that we could use it as a staple crop, much as Earth farming relies on wheat and maize as staple crops. If it is used to make sugar, maybe we could ferment and distill it into rum as well. That would certainly make those long Martian winters a bit more enjoyable! Texture would not be as much of a problem if we can process the food as an ingredient. We can also add flavourings, like curry or yeast (marmite) that will make the food more palatable, whilst remaining minor ingredients by mass. Blue green algae shouldn't be a problem, so long as we carefully screen the rhizomes imported from Earth.

I did some research on sunlight attenuation in water. I will show detailed workings tomorrow. But a summary of results should be useful in informing discussion. At a depth of 5m, the daily light integral is 66.7% what it would be on the surface. Different wavelengths of visible light (400-700nm) have different attenuation coefficients in water. The attenuation coefficient of the red spectrum, is about an order of magnitude greater than the average of the other parts of the visible spectrum. So DLI drops off most rapidly in the first few metres of water. At 10m depth, DLI declined to 55% by my calculation.

On Earth, DLI at 60 degrees northern ranges from 1-40mols. On Mars, at the same latitude, it would be more like 0.5-20. With the attenuation resulting from 10m of water, this would decline to 0.3-11mols. On Earth, my home country the UK is located about 60 degrees north. Due to its position on the eastern side of the Atlantic, it is one of the cloudiest places on Earth. The average DLI is probably not too different to that found at the same latitude on Mars, given the reduced cloud cover on Mars. And yet, England has one of the world's highest yields of cereal crops per acre. The attenuation resulting from the water would be on top of this, though from the previous discussion it would not appear to be any greater than that resulting from a greenhouse at depths up to 10m. The lower sunlight intensity should be partially compensated by higher CO2 levels.

Last edited by Calliban (2020-07-08 18:29:48)

Void · 2020-07-08 18:27:59

I am not up for pictures yet.

This may come close. Instead of Mercury inside, use water or brine:
https://en.wikipedia.org/wiki/Barometer … ometer.svg
It is from this link:
https://en.wikipedia.org/wiki/Barometer

But for Mars we would change it a bit. At the top where there would be a sealed vacuum pocket, you would have the shed. Martian air pressure + what you apply to the inside of the shed in additional pressure from Martian atmosphere pumped into the shed.
At the bottom, the ice covered lake. However you can get rid of the tube.

Sorry I can try some more if you like.

Actually I do not so much favor above ground habitats except in the case of a observation tower with a small glass room at the top where you could sit in the Martian sunlight. It would be pressurized of course, but in this case all the way down to the lake. With an elevator you could ride up. The tube for that tower must also extend a distance into the ice, and into the water to have sufficient pressurization maintained. One possibility would be to extend it all the way down to the bottom, and have it connect to underground tunnels under the lake.

Boring Company tunnels could be under the lake, diving bells in the lake, and submarines. Also various types of diving gear as options.

Deep down vast vaults in the rock. As I see it one type would be like a pyramid shape hollow, but with a somewhat smaller step pyramid inside of it. That way the ceiling could be accessed without massive scaffolds. And supports for the ceiling could anchor to the pyramid inside. This could be yet another way to have artificial light gardens.

A good thing about that is the eventually the waste heat would be vented into the lake.

It would beat living in a tin can on the surface.

Done.

Last edited by Void (2020-07-08 18:36:44)

SpaceNut · 2020-07-08 18:53:27

barometric lock are the same for space or submarine use in that it is about equalization of pressure and of its removal within the chamber area for the crewmen that are in space suits.

The water level can be reduced to a lessor pressure to save on materials for the structure and for the tank materials.

Glass would be a layered safety like glass to prevent the glass from becoming weak as a laminate of clear materials.

Then we also have the clear ceramics as we would see used for space glass windows as well.

Unless we have tons of people, materials processing and energy we will need to think smaller and gradually build up resource for future use.

Have added the Hydrilla and other stuff to the aquatic crop topic.

Calliban · 2020-07-09 07:04:43

I promised to provide a scientific determination of whether we would have enough light to grow crops on Mars at 60 deg north, under 5-10m of ice and water. Here is the answer.

Some more detailed discussion of light attenuation properties of water. Photosynthetically available radiation basically corresponds to the visible spectrum 400-700nm. However, the rate of photosynthesis appears to depend more upon the number of photons arriving per second, rather than the total energy. This tends to mean that red light is more significant than blue light in terms of utilisation of energy. Hence, the growth rate and health of plants is a function of Daily Light Integral (DLI). This is measured in mols/m2/day.
https://en.wikipedia.org/wiki/Daily_light_integral

The spectrum of light hitting the Earth's upper atmosphere is provided by the link below.
https://en.wikipedia.org/wiki/File:Sola … rum_en.svg

As you can see, the flux is actually quite flat between 400-700nm, with flux levels between 1.5-2W/m2 per nm. I have chosen a few datum points, to model the attenuation of light by water.
Red (600-700nm): flux ~1.5W/m2/nm
Green (500nm): flux ~1.9W/m2/nm
Blue (450nm): flux ~1.9W/m2/nm
Violet (400nm): flux ~1.7W/m2/nm

Each wavelength has its own attenuation coefficient in water. I used the chart below, to estimate attenuation coefficient in water for the datum points that I selected.
https://en.wikipedia.org/wiki/Electroma … _water.png

Red (600-700nm): 0.1-1.0/m
Green (500nm): 0.03/m
Blue (450nm): 0.02/m
Violet (400nm): 0.04/m

Notice also from the chart, that ultraviolet light has a very strong scattering cross section in water. This starts at about 0.1/m at the very beginning of the UV spectrum (350nm) and reaches about 5.0/m at 200nm and then 1E7/m at 160nm. I would suggest that it is quite unlikely that UV would be a serious problem on Mars at a water depth of 5m or more. I doubt that you would need to apply any UV blockers to the water or ice surface.
Back to the visible or photosynthetically available radiation (PAR). The fraction of light reaching a depth of 5m can be calculated for each wavelength. As you can see, red light is attenuated most strongly; the green and blue parts of the spectrum experience relatively little attenuation.

Red (600-700nm): 0.17
Green (500nm): 0.86
Blue (450nm): 0.9
Violet (400nm): 0.82
UV (350nm): 0.59
UV (300nm): 0.33
UV (250nm): 0.01
UV (200nm): 0.0
UV (160nm): 0.0

To determine the effect that attenuation would have on the DLI, I weighted each light wavelength according to its relative flux at the top of the water and its wavelength. So the fraction of DLI present at a given depth can be estimated using the following equation:

F=∑((CA^d)×q×λ)/∑(q×λ)

Where CA is the attenuation coefficient per m, d is the water depth in m; λ is wavelength, q is the flux in W/m2/nm and F is the ratio of DLI at depth, d, compared to the surface. The fraction of DLI still available at depths of 5m and 10m, are 0.667 and 0.55, respectively.

Now we need to estimate how much DLI reaches the top of the pond at our chosen location on Mars. On Earth, wiki provides the following information:

'Outdoors, DLI values vary depending on latitude, time of year, and cloud cover. Occasionally, values over 70 mol·m−2·d−1 can be reached at bright summer days at some locations. Monthly-averaged DLI values range between 20-40 in the tropics, 15-60 at 30° latitude and 1-40 at 60° latitude.[6] For plants growing in the shade of taller plants, such as on the forest floor, DLI may be less than 1 mol·m−2·d−1, even in summer.
In greenhouses, 30-70% of the outside light will be absorbed or reflected by the glass and other greenhouse structures. DLI levels in greenhouses therefore rarely exceed 30 mol·m−2·d−1. In growth chambers, values between 10 and 30 mol·m−2·d−1 are most common[7].'

On Mars, sunlight intensity is 43% of Earth (I am ignoring atmospheric attenuation for the time being). DLI at the surface at 60 degrees latitude, would be 0.4-17.2. At a water depth of 5m and 10m, this would be reduced to 0.27-11.5 and 0.24-9.46, respectively.

I noted in my previous post, the UK is at 60 degrees latitude on Earth and is heavily cloud covered, meaning that it's DLI is probably at the low end of the range we would expect for this latitude. It is difficult to quantify exactly what the DLI is for the UK at different times of year. But it has one of the highest wheat yields per acre on Earth and most temperate vegetables achieve good yields here. What sort of DLI do we need to cultivate crops in green houses? Some indicative information is given in the links below.
https://www.ledtonic.com/blogs/guides/d … quirements
https://www.greenhousemag.com/article/g … light-dli/
https://www.extension.purdue.edu/extmed … -238-W.pdf

These links suggest that most plants will grow and crop at light levels of 10mols/day, but there may be problems with quality. To produce good quality growth of vegetables we need at least 12mols/day. So our pond habitats may need some artificial lighting on top of what they receive from sunlight. However, we can supply this lighting at the red end of the spectrum, where it is most efficiently utilised for photosynthesis. It is also noteworthy that vegetable growth is influenced by other factors such as water stress, CO2 availability, nutrient availability, heat stress, ambient temperature and so on. If we can optimise these other factors, then relatively little additional light may be needed and that light will produce growth at high efficiency.

The situation for wheat is more complex and depends on a large number of factors. It is a long-day plant and the best wheat yields occur in northern latitudes during summer. In the far north on Mars under 5-10m of ice, DLI is only about one quarter what we would expect on Earth on a clear day at the same latitude. Wheat will definitely grow more slowly. It is however noteworthy, that Martian summers are twice as long as those on Earth and we will presumably have better control over other inputs to plant growth and environmental stresses. So it may be that we can achieve good yields of wheat during the Martian summer, especially if we provide modest amounts of supplemental lighting.
http://www.fao.org/3/Y4011E/y4011e06.htm

For most crops we can reliably assert that the growing season (as a proportion of the year) will be shorter on Mars unless we are prepared to apply substantial amounts of artificial light. As void has suggested, there are aquatic plants that do well under low light levels. So we may be able to crop shade loving plants between late autumn and early spring. Time will tell.

Last edited by Calliban (2020-07-09 07:11:35)

tahanson43206 · 2020-07-09 07:43:00

This is for Void, with a quote from one of Calliban's recent posts:

The bottom of a deep ice covered pond, may be a good place to build human habitats on Mars. If a layer of aero gel is placed under the ice sheet, the water can be maintained at room temperature. The colonists could enter the water equipped with an oxygen mask and weighted boots, but would not need counter pressure suits. A colony built at the bottom of the pond would need to counter the effects of buoyancy and would need to be water tight. But the structures would not need to be pressure vessels, because the weight of the water would counterbalance internal pressure. The best option would be concrete structures, since the forces acting on the structures are compressive.

It is ** this ** vision that I was thinking about when I suggested not needing air locks at all. If the base of an underwater shelter is open to the pond, then humans can come and go without using a mechanical air lock of any kind.

For Calliban ... I went looking for a post that I ** think ** you had included mention of pressure inside the habitat, but you've used the word pressure so many times I gave up << sigh >>

What would be the pressure inside a habitat at 5 meters of water on Mars, assuming the bottom is open to the water and air pressure inside the habitat is maintained properly?

SearchTerm:WaterPressureMarsAt5MetersDepth

Thanks!
(th)

Void · 2020-07-09 08:26:11

(th) I appreciate your interest in what people have posted here.

I will take a look from time to time, and try to be useful about your questions.

I may also render opinions, related to what you have asked Calaban.
To quote your quote from Calaban:

The best option would be concrete structures, since the forces acting on the structures are compressive.

Yes concrete is a good option if you have concrete. And that is not to slam what is in the quote.
I guess at this point we really have two near time periods to think about for Mars.
1) Boot up.
2) Running. (Later of course greater expansion).

Without existing infrastructure items like concrete are going to be hard to lay hands on during "Boot Up".

I think for farming in a lake, a diving bell is going to be a really important tool. But we cannot make them out of dirt of course, not yet.
We have SpaceX which I think is the only entity that is seriously interested in "Doing" Mars. They are going with Stainless Steel. For Starship. So, since during "Boot Up" we will not have the ability to manufacture diving bells on Mars, I hope to fly some to Mars, made out of stainless steel.

It is going to be a real grunt to either fly them up to LEO, or assemble them in LEO. It may be possible to fly them up to LEO in pieces, and then weld them to form some place along the way. LEO, or on Mars.

Such an "Early Bell", could resemble a fat Starship. Flying it to orbit would be troublesome to say the least. It may have tankage for propellants. I guess maybe in the pattern of Starship, raptors. So, if you fly this thing to Mars like that it may use Starship landing methods. I would not think that a Hohmann transfer would be the preferred method. Rather a spiral out to Mars, perhaps using solar wind drive, and a possible "Ballistic Capture" method. Unlike for Earth, a Magnetic solar wind drive should allow a spiral down to be within reach of the Martian upper atmosphere.

Then you have to have some method of atmospheric entry and landing. But at least you are not screaming in at interplanetary speed. The rigors are less because of that.

In case you missed it previously, something like this:
https://www.centauri-dreams.org/2017/12 … nd-beyond/
For power one possibility would be fold up solar panels, that will work their passage to Mars, and then be deployed on Mars. Perhaps they will ride down in the "Diving Bell" Starships.

Another feature that may reduce the rigors of landing, is that unlike the generalist Starship. Everything could be balanced out, so that the characteristics of getting to the Martian surface are standardized. This should reduce the size of flaps needed, and should allow the heatshield to be also calculated relatively precisely. I am going to suggest an ablative heat shield. I don't think that this device will need a full compliment of engines to land either. All of the above reduce weight, and make things easier.

So, you land this thing on the lakes surface, and hopefully don't crash through the ice. You get rid of the engines and flaps.

How to get it through the ice? Well it is pretty much a cylinder. If you have a surround tent, which you can bond to the ice at its bottom, and also bond to the cylinder shape, you can pressurize the tent which would the encompass the tail end of the ship. Heat the interior, melt the ice, and down it goes, if you have it ballasted. Ballast could be water from the interior of the lake. Methods would need to be worked out, but the thing has to be held to not tip sideways, and then fill the ship to submerge. I don't think we would want a tent as tall as a Starship however, so we would have to inchworm it's way down, moving the cylinder encompassing band up as we filled the Starship.

Think of a skirt or kilt with an elastic band around the waist. The cylinder could pass down someone of a tool pulling the waistband steady, as the cylinder passed down, as the ship filled with water. Eventually, perhaps you get to the pointy cone. At that point you make sure the ship is ballasted correctly and release it. The water in the hole will boil, but I think the ship will pass down before it freezes shut.

Actually if you were doing this in the ice slab that SpaceX is contemplating, the ship might be so long that even though it dropped to the bottom, the nose would point out of the water. In that case you would keep the skirt pressurized until the ice froze around the ship's perimeter.

So now you have it embedded into the lake. Before you pump out the ballast water, you need to secure it to the bottom, and/or bring rocks into it as ballast.

So the tail end of the ship would then be a diving bell structure, and the nose pointing out of the ice, may allow for electrical services to be connected to the ship.

And yes, once you have a sufficient Martian infrastructure, lets hope "Concrete".

I will be back around to the site a few times, I suspect, today.

Done.

Last edited by Void (2020-07-09 09:06:02)

tahanson43206 · 2020-07-09 09:29:31

For Void ... thank you for repeating the link to the Centauri Dreams site! While this quote has little to do with slabs of ice, I found it encouraging because it shows a strategy for slowing a probe at a distant star.

Until now, proposals I have seen suggest sending tiny probes past distant stars without stopping, so that observations would be brief.

7. Deceleration at target star for interstellar flight
For interstellar flights, deploying the plasma magnet as the craft approaches the target star should be enough to decelerate the craft to allow loitering in the system, rather than a fast flyby. Again, the high performance and modest mass and power requirements might make this a good way to decelerate a fast interstellar craft, like a laser propelled photon sail.[1]

I'll ** really stretch ** to make a connection to the topic ... perhaps the ideas developed here can be used in a distant location.

***

Regarding your post #60

Clearly you and Calliban are far apart in your visions.

The diversity makes the discussion interesting, but it can be confusing at times.

(th)

Void · 2020-07-09 10:12:49

Different mind training. That's good. We have all the time in the world, until we run out of time.

For you (th), when I was young, I read a lot of Sci-Fi books, and although I bet I was not that good at it, they verbally described things that you might visualize. I am guessing that there is less of that with young people now.

I have a suggestion for you. When you read words describing something, close your eyes and with your minds eyes, imagine touching it with our hands.

I do disagree with the notion that the plasma propulsion/braking have nothing to do with ice slab habitation methods. I just described in my last post how to get solar panels and stainless steel shells into association with them.

Procreation for mammals usually involves males who are "Cads". With humans, some male parenting behaviors make them "Dads".
Many birds need both the efforts of both parents in order to send their chicks off to be the next generation.

I have seen much evidence that many who visualize the occupation of Mars to be like a reptile laying and egg, and expecting good results.

For us to actually do Mars right, there should be a period where we send massive amounts of assistive materials. That will accelerate the "Boot-Up" process.

Done.

By the way there is nothing at all wrong with the inputs from the other members. They apply appropriately to certain circumstances.

Last edited by Void (2020-07-09 10:22:25)

Void · 2020-07-09 10:17:21

I really thought I would back away today, but I do have something on my mind. Sometimes, it may be proper to seek the base of a reality.
Sea Ice Algae, sub topic(s) "Bubble Wrap and things like bubble wrap", "Ideal Snow Cover", Ice.

Some visuals available:
https://www.nwf.org/Home/Magazines/Nati … -Ice-Algae
https://en.wikipedia.org/wiki/Ice_algae

So, a very basic ecosystem. For fresh water, probably water and ice surface near 0 degC.

For salty waters, perhaps as far down as -13 degC (Probably low productivity).

So, if we don't want to go all out for a gentile environment, we can perhaps in some locations justify, a basic ecology, such as under ice. The demands are less, and hopefully the rewards justify the effort expended.

I think that at this time I have a general template for lakes and seas on Mars.

-Probably bare ice is not ideal.
-Coverings such as Oil pillows, greenhouses, and snow of an appropriate kind are desired above the ice in most cases.
-Although it seems that ice and perhaps snow have some ability to moderate the U.V. flux of Martian sunshine, it may be useful to have -----Titanium Oxide fine particle shielding incorporated somewhere is not a bad idea to investigate.
-For ice water lakes, algae may be the preferred "Crop".
-Where for some fussy vascular plants we might choose to invest in solar concentrators, and robots, for Algae, and perhaps Hydrilla, we might not mind diffused lighting.

So, if we don't care about diffused light, but want as much light as is practical then what about "Bubble Wrap and things like Bubble Wrap?".

Although this could be involved with other types of coverings over ice, I am going to consider a robotically generated ideal layer of snow over the ice.

For that we might be on the ice slab of Korolev Crater, or eventually actually on the Martian polar ice caps.

There, I think we have two energy budgets.
1) The energy of melting.
2) The spectrum of photons available to life.

It is realistic to suspect that Mars may not be as kind as Antarctica, as to be able to create it's own ice covered lakes useful to life.

In order to have sufficient melting, we may not be able to rely on melting from photons passing through the ice. So, auxiliary heating needed, I think. Nuclear or solar electric perhaps. Possibly solar thermal as well could be used.

We want the ice sheet to be protective, but not excessively photon blocking.

While with strong addition of energy to the lake waters to melt, I think that we can look at heat losses, and see if we can inhibit them and still have protection for the waters and lifeforms, and sufficient photons, even if they are diffused and hard to focus with a concentrating mirror under water.

So "Bubble Wrap" and things like it.
https://en.wikipedia.org/wiki/Bubble_wrap

OK, so if you have a melting tool, and can melt to an optimum thickness under a layer of ice, with fair precision, you may float a "Tile" of bubble wrap under the ice. The result should be that the ice above will freeze to it. If there is still enough heat loss, then the freezing should proceed downwards, so that ice forms under the bubble wrap as well.

Repeat this as often as you like. End up with an icy surface for the algae to grow on , or I suppose it might be possible to have so much insulation that ice finally does not form under the last layer of bubble wrap.

Remember that the conditions within the bubbles of the bubble wrap will be a "Greater Partial Vacuum", than our sea level air, therefore, you are working with something like a thermos effect, for thermal insulation.

I do believe that this will supply more, but diffused types of useful photons to the lake waters. Suitable perhaps to Algae which may not mind the cold.

For Hydrilla, make bubbles of bubble wrap.

Something like "Nemo's Gardens, but with bubble wrap, or something like bubble wrap.
https://www.bing.com/images/search?q=ne … BasicHover

Open bottom or closed.

Keep in mind that the interior would mostly be filled with water a bit warmer than what is outside, so the floatation problems will be greatly reduced. Less need to struggle to hold it down to the bottom.

Don't you think that we should consider growing Hydrilla on Earth this way? It might not even need anchorage. Perhaps a massive submarine made of "Bubble Wrap, or Something Like Bubble Wrap". With controlled buoyancy and propulsion. Able to rise to the sun when convenient, and able to dive below storms.

I think so.

Done.

Last edited by Void (2020-07-09 10:50:43)

tahanson43206 · 2020-07-09 11:24:28

For Void re closing paragraph in #63

food-growing-underwater-sea-pods-nemos-garden-italy and underwater greenhouse

Since the link attempted above does not work, it is of an image collected by Google for: underwater greenhouse Dubai

There are a number of locations on Earth where underwater greenhouse experiments are underway. Dubai is well known because of their investment in innovative living situations.

I find Calliban's vision of underwater habitats on Mars quite interesting.

Humans able to experience life on Mars in one of the habitats Calliban's words create in the imagination would enjoy a level of exercise denied to citizens who are living in underground habitats. Depending upon success in managing the water body, it might be possible to share the volume with selected fish and perhaps other creatures. These embellishments are in line with similar ideas already recorded in this topic and elsewhere in the NewMars forum archives.

Edit #1: This is an appreciation for the very ** nice ** video of underwater greenhouse design in practice, which Void found after this post.

(th)

Last edited by tahanson43206 (2020-07-09 11:38:19)

Void · 2020-07-09 11:34:54

Curious thing (th), it works for me.

Try this instead:
https://www.bing.com/videos/search?q=ne … &FORM=VIRE

The important thing is they are trying and having some success.

I think doing it with Hydrilla, using a mostly water filled "VOID", will be easier. Open bottom or closed bottom.

Done.

Last edited by Void (2020-07-09 11:37:19)

Calliban · 2020-07-09 19:56:11

Interesting answer on Quora, regarding the frequency of light most suitable for plant growth.
https://www.quora.com/Can-I-use-normal- … s=68223420

Plants benefit from a certain amount of ultraviolet light. Blue light triggers root development. Red light is most important for driving photosynthesis and is the most efficiently absorbed light. Green light is almost useless to plants. Artificial light sources optimised for plant growth are LED bulbs that contain blue and red emitters, that produce a purple light as interpreted by human eyes.

Water and ice strongly absorb light from the red end of the spectrum. Plenty of blue and green and some ultraviolet make it through. This suggests to me that supplemental light provided for crop growth under the ice should focus on red light in summer. This is in many ways economically convenient, as red LEDs are highly efficient and the light is absorbed and used efficiently. If we wish to grow during winter, we would need to add supplemental blue light as well. It is interesting that the optimal blend of frequencies for plant growth appears to change at different stages in plant development. But the red and blue parts of the spectrum are the staples for plants.

It also occurs to me that water is very effective at attenuating short wave UV light. It would also appear to be undesirable to remove UV entirely. So you would probably want to forego spraying the ice with titanium oxide or other sunscreens.

Last edited by Calliban (2020-07-09 20:02:30)

Calliban · 2020-07-09 21:26:48

Plants that grow well in shaded areas, I.e. low light levels.
https://www.gardenbetty.com/shade-vegetables/

Basically, leafy vegetables do better under these conditions than fruiting vegetables. In Northern England and Scotland, kale has traditionally been grown as a winter crop. The northern half of the UK has very low light levels in winter. In addition to being 50-60 degrees north, it is very cloudy a receives very little direct sunlight.

Kale is a perennial that is hardy and can resist frost. It also grows well in low light levels, so is well suited to these locations as a winter food source. It is basically a wild cabbage.

On Mars under the Korolov ice lake, kale may turn out to be an important staple food. We can feed it small amount of artificial light if necessary. But what we really need is plants that minimise the requirement to do that, as it is expensive.

Last edited by Calliban (2020-07-09 21:31:22)

Calliban · 2020-07-09 21:50:54

Miscanthus is a C4 crop with unusually high growth rate and highly efficient utilisation of photosynthetically available radiation. It appears to grow at a rate that is proportional to light level. It is perennial, with the rhizomes laying dormant in the soil during winter.
https://onlinelibrary.wiley.com/doi/10. … 12.02579.x

It has been tested as an animal feed, but is less efficiently broken down in the rumen than corn straw. The leaves die off in late summer, leaving woody stems. These may be used as fuel, raw material or could be used as a substrate for mushroom growth as Void has previously suggested.

Switch grass also grows rapidly and will grow year round up to 55 degrees north on the American continent. It is used as animal foda.
https://wimastergardener.org/article/sw … -virgatum/

Last edited by Calliban (2020-07-09 21:53:12)

Calliban · 2020-07-10 04:22:26

Not an aquatic crop, but the traditional answer for feeding lots of people with limited land and resources is: potatoes. In the UK, annual yields are about 40 tonnes per hectare (4kg/m2/year). Annual insolation in the southern UK is about 1000kWh/m2/year. The energy content of potatoes is about 1000 kilo calorie per kg. So 2kg of potatoes per day is enough for basic energy requirements, though not full nutritional requirements. To feed one person on potatoes, would require a minimum land budget of 183m2 in the UK.

It is the red portion of the sunlight spectrum that drives photosynthesis, which appears to be about 10% of total solar flux reaching ground level. So to achieve UK potato yields, we would need to provide LED lighting of about 100kWh per square metre per year. The best red LEDs are about 30% efficient, so we would need 333kWh of electrical energy per square metre per year. To feed one person with potatoes, that equates to 61,000kWh of electric power per year. If that electric power costs $0.1/kWh, say, total energy expenditure per person would be $6100 per year for basic food needs. Expensive, but doable.

It would be somewhat more expensive if we had to provide the other parts of photosynthetically available spectrum as well. But it does appear that blue and violet light penetrates far enough into water that we should be able to rely on nature for those parts of the spectrum.

Of course, in the UK, most farmers will not crop potatoes all year round. That suggests to me that in an optimised system, our energy bill will be lower. And with plenty of nuclear waste heat, our plants will not be inhibited by cold in Martian farming areas, so we could probably fit in an extra crop of potatoes that grows slowly between autumn and spring. An optimised farming strategy can probably achieve some significant savings over what I have identified.

I have hope that some low light plants like kale will be able to survive in our underwater Martian greenhouses all year round with no supplemental lighting. But there will be minimal growth for 50% of the year on Mars, because light levels are just too low. But there should be good growth in the summer where plants should receive DLI of 10mols/m2/day. That is enough for good growth in leafy plants, though it will retard the growth of non-leafy vegetables. We would harvest kale throughout the summer and let it recover over autumn and winter.

Hydrilla appears to be a rich source of vitamin A and B vitamins. These are components that a potato diet lacks. Hydrilla should grow without supplemental lighting in Martian ponds, though the growth rate will be low for half of the year. Unless we find a way to remove excess vitamin A, it cannot be more than a small contributor to human diet. We could use it for other purposes, like animal fodder, mushroom production and of course, booze.

Micro algae do well under low light levels and in fact, tend to saturate under heavy light levels. This is something we could grow all year round in our Martian ice lakes, presumably without supplementary lighting, provided we do provide enough heat, CO2 and trace elements.

Can we produce sufficient human diets in which 90% of human needs are met from these sources? I do not know. It is very different to what most of us would be accustomed to. But provided we can blend these components and process them into palatable foods, I think it could work.

Last edited by Calliban (2020-07-10 04:50:34)

tahanson43206 · 2020-07-10 07:02:18

For Calliban and Void re topic ...

The article at the link below describes work in China to purify water using highly efficient processes that work at the nano scale, and rely largely on natural components. Since the water on Mars (as reflected in the title of this topic) will contain suspended matter, this non-mechanical, highly efficient system may be applicable there.

https://www.popularmechanics.com/scienc … bes-water/

However, when I went back to check the URL just now it didn't work.

Search Results
Web results
Clean Water & Solar-Powered Nanotubes - Popular Mechanics www.popularmechanics.com › science › solar-powered...
1 day ago - Researchers in China have developed a prototype they say improves the concept of a solar steam generator, making it more efficient and feasible ...

If someone can find an post an alternate link to the story I'd appreciate it.

What I remember is that the Chinese researchers created a multi-layered system of wood fiber and a variety of other components that pulls water from below and liberates the water molecules at the surface for collection, while leaving the water borne substances behind. The system works by harnessing solar energy, which (as I remember the article) allows for accumulation of enough energy in one of the layers to liberate water molecules from the adhesive bonds they form with other molecules while acting as a solvent.

The separation of water molecules from dissolved materials is one of the greatest needs of humans anywhere on Earth. That will certainly be the case on Mars as well.

(th)

Last edited by tahanson43206 (2020-07-10 07:02:49)

Void · 2020-07-10 08:19:55

Large supplies of clean water have always been a major requirement for a "Civilization".

Void · 2020-07-10 08:21:05

Large supplies of clean water have always been a major requirement for a "Civilization".

Perhaps the quality of this output can be better than for distilled water. Distilled water probably needs things added back to it.

Last edited by Void (2020-07-10 08:22:14)

Void · 2020-07-10 08:23:43

I have had a very stimulating morning. Various people here suggest stuff, and I draw a hesitation or even blank, but given time, I see that some method may exist, to incorporate it into a larger weave of things. I must have done right yesterday and slept well last night.

Previously I mentioned Diving Bells in the lakes/seas. I start with stainless steel ones and we hope to get to concrete ones per Calaban.

It seems likely that the Mars solar flux by itself through ice is not going to be enough to melt a lake/sea. But that is OK. We can use nuclear of some kind as per Dr. Zubrins apparent thinking.

We may also use auxiliary solar, and so by one or both these families of means have auxiliary electric power. One could have underwater lights, to stimulate plant growth, and to add heat to the lake/sea, but it they are directly in the water, that is somewhat incompatible as per electric short circuits and safety.

So, first I thought, lets put Calibans plants in pockets hung to the inside wall of a diving bell. This then leaves the floors, (And I would expect many floors), clear for other activities. Then I thought of the Nemo's Gardens people and their spiral water gutter which is an innovation of theirs. So, here that is:
https://www.bing.com/videos/search?q=ne … &FORM=VIRE

And so your LED's shinning on those plants then warms up your diving bell above the ambient of the water outside. The heat flow out of the diving bell supplies the extra heat for the lake/sea to maintain a liquid state.

So for the lake/sea, you have a partially ice cover with some photons getting in when the sunlight is available. This will allow for life compatible with living under ice in a cold sea water condition.

But I might want to grow hydrilla. So, I have a robot keep the bottom of the ice relatively clean by removing/harvesting algae.

So, I want to put a bubble wrap enclosure up near this ice, with the desire to grow Hydrilla in it. This will be a water filled bag. It can either have an open or closed bottom. We are wanting solar light to heat up the water temperature in the bag sufficiently to encourage Hydrilla growth.

Then I thought that the water on the outside of the diving bell would be warmed up, so why not collect that and pump it into the grow bags for Hydrilla?

Then I started thinking about some other ideas from members, such as an aquarium above a garden. That aquarium would have a plastic lid, and a transparent bottom. That is from Spacenut.

From that I transitioned to putting Nemo's garden over our diving bell. Technically, NEMO's garden structures are transparent diving bells.

So, we put a transparent diving bell over our opaque diving bell, and anchor the stuff. Fill the gap with air. Now you have thermal insulation for the diving bell. You also have a place to put a water spiral for growing plants. They will get some light from through the ice.
But as you need to add heat to the lake/sea, for it to remain liquid, you use LED's to supplement that, particularly deeper down.

So, to manipulate this "Air-gap garden", you need to get to the plants. So, you have a hoist that can bring you and perhaps more than one person to virtually every point on the outside of the opaque shell. You may have plants also inside the ship hung on the walls, or on the floors.

And excess heat can be conducted to growth bags for Hydrilla.

Not bad I think.

Done.

Last edited by Void (2020-07-10 08:49:28)

tahanson43206 · 2020-07-10 09:35:02

For Void re #72

It is helpful (to me at least) to be reminded from time to time that humans need minerals added to pure water if the use is for drinking.

That rule-of-thumb is probably true for other activities as well, but it appears to ** definitely ** be true for drinking ...

Here is an earlier post in which I reported observations by a friend on the subject. I was unable to find another post I offered. It contained a link to an exhaustive study of minerals found (and NOT found) in very highly regarded spring water supplies on Earth.

http://newmars.com/forums/viewtopic.php … 57#p152057

A biologist friend reminded me that humans and other creatures have evolved to depend upon the mixture of elements and compounds that are collected by rain water as it percolates through rock and soil. The resulting mixture contains elements and compounds that are beneficial for good health. The subject came up when I pointed out that the output of a fuel cell power system is pure water (plus any contaminants from air taken in to supply oxygen) which can be consumed safely. The biologist pointed out that such pure water is a capable solvent, which will leach minerals out of the body. For this reason he suggested using the example of spring water, for which detailed chemical analysis is available on the Internet and in hard copy references.

For SpaceNut ... if you have a couple of minutes, I'd appreciate your looking for the post I put up, containing a link to a study of the analysis of spring water in a US location. I'm surprised not to be able to find it, after trying a number of search methods.

(th)

Void · 2020-07-10 11:03:15

Yes (th), and water is vastly important for a civilization. While it is conceivable that we could mix lake water with distilled, for Mars, at least in the beginning we have to worry about toxins. Later on it could be that we spill a chemical into our lake and then need your device for that.

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