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#1 2021-06-21 06:51:19

louis
Member
From: UK
Registered: 2008-03-24
Posts: 6,915

Chinese greenhouses

Could this be the basis for Mars greenhouses?

https://www.youtube.com/watch?v=WNJnwCbnFX4

Apparently with an uninsulated floor, these greenhouses survived a Manitoba winter, never going below freezing inside.

Some adaptations:

This would have to be pressurised. IIRC it has been suggested you could operate on Mars with 20% of Earth atmosphere pressure and near 100% CO2. Not sure how that fits in with using plastic.

The thermal blanket might need to be on the inside, rather than the outside.

You might need to use thermogenic plants to add heat overnight.

Insolation levels might need to be boosted through use of reflectors. Shallow craters might make good locations for using Chinese greenhouses (on south facing terraces) with reflectors placed around the crater.

There might be some need for supplementary heating e.g. running hot water pipes from nearby urban centres - especially making use of waste heat from industrial processes.

Last edited by louis (2021-06-21 06:52:12)


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#2 2021-06-21 07:20:27

tahanson43206
Moderator
Registered: 2018-04-27
Posts: 7,617

Re: Chinese greenhouses

For Louis re new topic ...

Best wishes for success with this new topic!

Thanks for the link to the video!  I was surprised to see that these greenhouse designs have reached the level of development shown, but then remembered that the posts in the archive of NewMars forum include mention of similar concepts going back to World War II times.

For the Mars application, some adjustments would be needed, as you indicated.

The archives of the forum contain extensive exploration of requirements for success growing plants on Mars.

The video with which you opened this new topic shows examples of what might be imagined for Mars.

One adjustment I would recommend is using robots to tend all those plants.  Labor at that level is unlikely to appeal to anyone who would be paying for transportation to Mars.

(th)

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#3 2021-06-21 10:31:57

RobertDyck
Moderator
From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 6,769
Website

Re: Chinese greenhouses

I spoke to an engineer about greenhouse design. The atmosphere of Mars transports so little heat that you really only have to worry about heat loss to the ground, and radiant heat. "The Case for Mars" conferences were before the Mars Society was founded, one paper from those early conferences suggested an aluminized mylar curtain drawn across the ceiling inside the greenhouse. Not a hanging curtain, but flat across the greenhouse transparent ceiling. This would be closed at night to contain radiant heat, opened at dawn.

I have also suggested a spectrally selective coating to block UV, and also control IR. Long-wavelength IR comes from warm objects like the floor, walls, furniture, ground, etc. Short-wavelength IR comes from extremely hot objects like the surface of the Sun. A coating to reflect long-wavelength while transparent to short-wavelength can let heat from the Sun in while trapping heat so it can't get out. Of course this isn't perfect. A coating that reflects 10% of short-wavelength while reflecting 40% of long-wavelength will have a net heating effect. But an aluminized mylar curtain will reflect near 100%.

Ground can be used as a thermal mass. The University of Manitoba is in Winnipeg. Here we don't have permafrost. Ground near the edges of the greenhouse will leak heat, but ground under the majority of the greenhouse will be warmed by the greenhouse itself. On Mars you would want something to insulate your greenhouse from the ground. One option is a styrofoam skirt buried in the ground at the periphery of the greenhouse. The idea is to use the ground as thermal mass, but don't let heat leak out to the extremely cold ground that isn't directly under the greenhouse. If the average temperature outdoors day/night is -60°C then the ground will be that temperature. You don't want to loose heat through the ground. And deep ground will be the average over the entire year: summer/winter. On Mars that can be very cold. For Winnipeg the average temperature is about +7.4°C (45.3°F) so deep soil is that temperature. No need to insulate the greenhouse from deep soil, just from ground that isn't under the heated greenhouse. But Mars is much colder.

You could dig a hole where the greenhouse will be. Line the bottom and sides with styrofoam. Backfill with dirt you dug out. Then build the pressurized greenhouse on that. It still requires a pressure tight enclosure, but not thermal insulation. Heat would leak from the floor of the greenhouse into the ground, but that ground would act as a thermal mass. With styrofoam acting as thermal insulation between dirt beneath the greenhouse and the rest of Mars, that contains the heat. Note this means the ground doesn't have to be within the pressure envelope.

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#4 2021-06-21 10:52:22

RobertDyck
Moderator
From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 6,769
Website

Re: Chinese greenhouses

A study by Guelph University in Canada found spinach can continue to grow at low pressures, without even slowing growth rate. In terms of carbon fixation, growth rate was not affected by pressure. The catch is plenty of water. At lower pressure, water transpires through leaves at a faster rate. But in a sealed greenhouse, water lost through transpiration will become humidity. That humidity will condense, dripping into a collection trough that will direct water back into soil for the plants. So in a sealed greenhouse, higher transpiration doesn't mean water loss, it just causes water to move in a circle faster. They found spinach can grow in 10 kPa pressure (100 mbar, 1.45 psi). That's lower than humans can tolerate. Below that, the plant wilts and stops growing. They even tried an experiment where the reduced pressure to Mars ambient for 1 hour, then restored pressure. This was to simulate pressure loss on Mars. The plants wilted, but did not die. When pressure was restored, plants perked up and continued to grow.

Yes, the movie "The Martian" showed pressure loss. In the movie, all potato plants died. In real life, if the astronaut could seal the breach and restore pressure quickly enough, the plants would survive.

Adding CO2 does enhance plant growth. However, some plants such as wheat require the same partial pressure O2 as humans. They store energy as carbohydrate producing O2 during the day. At night the plants consume carbohydrate and O2, allowing continued growth even in dark.

I would suggest keeping CO2 levels to something humans can tolerate. This allows workers to enter without a breathing mask. Yes, once we have a large settlement on Mars, much of the work will be done by robots. But some work will always be done by humans. CO2 on Earth today is 0.04%, humans can tolerate upto 2% CO2 with nothing more than a mild headache. More than that produces health problems. 10% CO2 for over a hour can be fatal. The critical measure of oxygen is partial pressure, not percent, so breathing 20.946% oxygen at Boulder Colorado is 2.54 psi partial pressure. Breathing 2.54 psi O2 + 2.54 psi N2 = 5.08 psi total pressure would feel the same. If a Mars greenhouse operates at half Earth sea level (not half Boulder), then you would limit CO2 to 4%. That would still be 50 times partial pressure on Earth at sea level, or 100 times percentage. Sure, plants would grow a little faster in 10% CO2, do you really want to make greenhouse air lethal to humans?

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#5 2021-06-21 12:26:58

RobertDyck
Moderator
From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 6,769
Website

Re: Chinese greenhouses

Many years ago I said we should have a program where students can design a greenhouse. Control heat flow to allow a greenhouse to operate 12 months per year in Winnipeg. And use that to design a greenhouse for Mars. But I had the idea of attaching a greenhouse to a high school. Well, the university did it. Ok.

Interesting design. The Chinese greenhouse has a number of common features with a walipini. That's a sunken greenhouse. The Chinese greenhouse isn't sunken, but both are oriented east-west with a thermal mass north wall. I had expected a walipini to extend growing season in Winnipeg, not achieve 12-month operation. The thermal blanket covering the window at night is a difference. Innnteresting. (spoken like Bugs Bunny in the episode where he gives Gossamer a hairdo)

Should I build a walipini for my house? Two sheets of clear multiwall polycarbonate sheet. I had thought of just an air gap between sheets, but this suggests a quilt drawn between the sheets with a motor to extend/retract. Eavestrough (gutter) to collect rain water, directed to a rain barrel inside the greenhouse. A number of years ago the city increased the cost of water, so watering plants in the greenhouse exclusively with rainwater cuts cost. And run all electrical for the greenhouse from solar, with battery inside the greenhouse for power storage.
lexan-polycarbonate-sheets-15942128-64_400.jpg

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#6 2021-06-21 13:15:33

louis
Member
From: UK
Registered: 2008-03-24
Posts: 6,915

Re: Chinese greenhouses

Thanks for those comments Robert. Do you think solar reflectors will help on Mars, to boost insolation? I'm thinking craters might be good
locations with terraces on the south facing side, where the greenhouses would be located, and reflectors on the east and west sides reflecting light on to the greenhouses. As the wind force is so low on Mars the structures could be quite lightweight.


RobertDyck wrote:

I spoke to an engineer about greenhouse design. The atmosphere of Mars transports so little heat that you really only have to worry about heat loss to the ground, and radiant heat. "The Case for Mars" conferences were before the Mars Society was founded, one paper from those early conferences suggested an aluminized mylar curtain drawn across the ceiling inside the greenhouse. Not a hanging curtain, but flat across the greenhouse transparent ceiling. This would be closed at night to contain radiant heat, opened at dawn.

I have also suggested a spectrally selective coating to block UV, and also control IR. Long-wavelength IR comes from warm objects like the floor, walls, furniture, ground, etc. Short-wavelength IR comes from extremely hot objects like the surface of the Sun. A coating to reflect long-wavelength while transparent to short-wavelength can let heat from the Sun in while trapping heat so it can't get out. Of course this isn't perfect. A coating that reflects 10% of short-wavelength while reflecting 40% of long-wavelength will have a net heating effect. But an aluminized mylar curtain will reflect near 100%.

Ground can be used as a thermal mass. The University of Manitoba is in Winnipeg. Here we don't have permafrost. Ground near the edges of the greenhouse will leak heat, but ground under the majority of the greenhouse will be warmed by the greenhouse itself. On Mars you would want something to insulate your greenhouse from the ground. One option is a styrofoam skirt buried in the ground at the periphery of the greenhouse. The idea is to use the ground as thermal mass, but don't let heat leak out to the extremely cold ground that isn't directly under the greenhouse. If the average temperature outdoors day/night is -60°C then the ground will be that temperature. You don't want to loose heat through the ground. And deep ground will be the average over the entire year: summer/winter. On Mars that can be very cold. For Winnipeg the average temperature is about +7.4°C (45.3°F) so deep soil is that temperature. No need to insulate the greenhouse from deep soil, just from ground that isn't under the heated greenhouse. But Mars is much colder.

You could dig a hole where the greenhouse will be. Line the bottom and sides with styrofoam. Backfill with dirt you dug out. Then build the pressurized greenhouse on that. It still requires a pressure tight enclosure, but not thermal insulation. Heat would leak from the floor of the greenhouse into the ground, but that ground would act as a thermal mass. With styrofoam acting as thermal insulation between dirt beneath the greenhouse and the rest of Mars, that contains the heat. Note this means the ground doesn't have to be within the pressure envelope.


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#7 2021-06-21 14:12:12

RobertDyck
Moderator
From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 6,769
Website

Re: Chinese greenhouses

louis wrote:

Thanks for those comments Robert. Do you think solar reflectors will help on Mars, to boost insolation? I'm thinking craters might be good
locations with terraces on the south facing side, where the greenhouses would be located, and reflectors on the east and west sides reflecting light on to the greenhouses. As the wind force is so low on Mars the structures could be quite lightweight.

I envisioned greenhouses on flat ground. With habitat built into a hillside. Two styles of greenhouse. Most vegetables thrive in shade; crops that do grow in shade you can build a dome greenhouse. Maximum growing area for minimum enclosure surface. Mars orbit gets 47% as much sunlight as Earth orbit, but we really need to compare surface. Earth has a lot of atmosphere; oxygen and humidity absorb significant light. Mars surface gets 53% as much light as Earth surface.
solar_radiation_spectrum.jpg

Some crops require full sun, such as grain, corn, etc. For crops that do, I have suggested a long-narrow greenhouse. Twice as wide as high, and much longer than wide. The long end oriented perfectly east-west. With flat mirrors outside the greenhouse, full length along both long sides. Mirror height the same as top of greenhouse. This does not have to track the Sun. At noon sunlight reflects from mirrors directly into sides of the greenhouse, so as much light from mirrors as directly from the Sun. That doubles insolation. At dawn light shines from east to west, reflecting off the mirror westward into the greenhouse, but still into the greenhouse. At dusk light shines west to east, reflecting eastward into the greenhouse. Mirror angle will have to adjust for season, but only 1° every 14 Mars solar days (sols). That's every second week. That could be done with automation, or simply an astronaut in a spacesuit adjusting a support rod to the next notch.

Some crops that require full sun:

  • Tomatoes

  • Eggplant

  • Corn

  • Squash

  • Peppers

  • Cucumbers

  • Melons

Some crops that grow well in shade:

  • kale

  • lettuce

  • green onion (scallions)

  • spinach

  • Fiddleheads

Some crops that tolerate partial shade: (grow faster in full sun, but grow well in 4-5 hours direct sun per day)

  • Beans

  • Peas

  • root veggies (carrots, potatoes, etc)

  • Brussels sprouts

  • squash

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#8 2021-06-21 14:18:19

Void
Member
Registered: 2011-12-29
Posts: 3,923

Re: Chinese greenhouses

-----------------------------------------------------------------------------------

Robert, I see you have made yet another post, I hope my post does not go to far afield, and anoy you.

I have become very interested in your topic of the Chinese greehnouse.

I like your work.  Robert often has good things to provide in many topics.

I am most interested in the thermal blanket.  I think, that due to gravity and low wind damage potential, that could of course be automated, to rise above the greenhouse during sunlight,
and so also have a reflective coating, and with that, perhaps bring the light levels in the greenhouse significantly higher.  Maybe ~75% of Earth luminosity?

Of course the transparancy will have to be enduring by methods suggested in prior postsof this topic.

I do remember that you Robert have knowledge about what the limits of garden crops may be per air pressure, and mixture of the air solution.

I support what has been presented as is for the most part, very inovative.

However, I always want to utilize ice and water.  So, I will attempt to make a mutated version to put on an covered body of water.  This is related to connecting a greenhouse to a
permafrost situation, which I recall Robert mentioned.

-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

The water version:

So, then this "Chinese greenhouse" might be used to melt a lake or sea, where there is sufficient ground ice.  Where the Chinese rover is, may be such a place.

It is considered that there are slabs of ice the size of States or perhaps even provences on Mars, with significant ice thickness.

To adapt an aquatic "Skylight" version, of course the "North Wall would only be insulated, and not much of a heat sink.  But of course the heat sink can be in the water, by various means.

I do like the UV protection of the glaze that Robert has suggested, but a thin layer of ice could help filter the sunlight of UV if needed.

I would use tricks I have mentioned in prior posts, such as pressurized bags under water, under ice.  Some of the pressurization would be
by pumping Martian air into the greenhouse to stabalize the ice if possible, so that would be a partial pressure perhaps 10 mBar and up.

Since the blanket would also be a reflector of sunlight into the "Portal", going down as deep as 5-10 feet would add about 50 to 100 mBar
additional pressure.  And then the "Bags" that you grew the crops in could hold additional pressure. In this way it is likely that sufficient
pressure could be provided with sufficient light.   

Another benefit would be that if you got a short dust storm, a more minor one, your crops might endure a lack of the needed light for a number
of days without complete damage to the crops.

For planting and harvesting of course you bring the "Planters/Bags" down deeper and perhaps even into a diving bell at the bottom of the body
of liquid water, where humans can work with the materials as might be practicle.

It can be noted that this is also a solution that can greatly reduce radiation problems, as water and probably ice can moderate those problems
very well.

And a great number of such "Portal, Chinese Greenhouses" could be linked by way of the water.  Even the size of states of provences.

-------------------------------------------------------------------------------------------------------------------------------------------------

My apologies for my bad temperament some time back, I guess I needed some quiet time.  No fault of the membership.

Done.


I like people who criticize angels dancing on a pinhead.  I also like it when angels dance on my pinhead.

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#9 2021-06-21 15:16:18

louis
Member
From: UK
Registered: 2008-03-24
Posts: 6,915

Re: Chinese greenhouses

I guess a couple of other relevant factors are that with a greenhouse in an area of maximum insolation on Mars  we might be approach Earth-based temperate light levels, especially if we then factor in the longer period of higher insolation in Mars's nearly two years long orbit around the Sun.

RobertDyck wrote:
louis wrote:

Thanks for those comments Robert. Do you think solar reflectors will help on Mars, to boost insolation? I'm thinking craters might be good
locations with terraces on the south facing side, where the greenhouses would be located, and reflectors on the east and west sides reflecting light on to the greenhouses. As the wind force is so low on Mars the structures could be quite lightweight.

I envisioned greenhouses on flat ground. With habitat built into a hillside. Two styles of greenhouse. Most vegetables thrive in shade; crops that do grow in shade you can build a dome greenhouse. Maximum growing area for minimum enclosure surface. Mars orbit gets 47% as much sunlight as Earth orbit, but we really need to compare surface. Earth has a lot of atmosphere; oxygen and humidity absorb significant light. Mars surface gets 53% as much light as Earth surface.
https://greensarawak.com/wp-content/upl … ectrum.jpg

Some crops require full sun, such as grain, corn, etc. For crops that do, I have suggested a long-narrow greenhouse. Twice as wide as high, and much longer than wide. The long end oriented perfectly east-west. With flat mirrors outside the greenhouse, full length along both long sides. Mirror height the same as top of greenhouse. This does not have to track the Sun. At noon sunlight reflects from mirrors directly into sides of the greenhouse, so as much light from mirrors as directly from the Sun. That doubles insolation. At dawn light shines from east to west, reflecting off the mirror westward into the greenhouse, but still into the greenhouse. At dusk light shines west to east, reflecting eastward into the greenhouse. Mirror angle will have to adjust for season, but only 1° every 14 Mars solar days (sols). That's every second week. That could be done with automation, or simply an astronaut in a spacesuit adjusting a support rod to the next notch.

Some crops that require full sun:

  • Tomatoes

  • Eggplant

  • Corn

  • Squash

  • Peppers

  • Cucumbers

  • Melons

Some crops that grow well in shade:

  • kale

  • lettuce

  • green onion (scallions)

  • spinach

  • Fiddleheads

Some crops that tolerate partial shade: (grow faster in full sun, but grow well in 4-5 hours direct sun per day)

  • Beans

  • Peas

  • root veggies (carrots, potatoes, etc)

  • Brussels sprouts

  • squash


Let's Go to Mars...Google on: Fast Track to Mars blogspot.com

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#10 2021-06-21 15:31:34

RobertDyck
Moderator
From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 6,769
Website

Re: Chinese greenhouses

Void, welcome. Glad you're back.

One of the things with agriculture is many different configurations are possible. And they all work.

You mentioned transparency. An inflatable greenhouse is great for a science mission, but don't expect it to last long-term. I suggest PCTFE film for a science mission, with spectrally selective coating. But after a major dust storm, the film greenhouse would be scratched. For long-term using in-situ materials, I suggest tempered glass. That's just normal glass that's been given a heat treatment.

Scientific American: How is tempered glass made?

Tempered glass is stronger than normal glass. But the important feature for Mars is that it's harder than minerals on Mars surface. That means harder than dust and sand. Sand cannot scratch anything harder than itself. So this means dust / sand storms will not scratch or craze windows.

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#11 2021-06-21 18:48:33

louis
Member
From: UK
Registered: 2008-03-24
Posts: 6,915

Re: Chinese greenhouses

Well why not have a really thin outer layer of plastic that can be removed after a dust storm and then replaced by another.

RobertDyck wrote:

Void, welcome. Glad you're back.

One of the things with agriculture is many different configurations are possible. And they all work.

You mentioned transparency. An inflatable greenhouse is great for a science mission, but don't expect it to last long-term. I suggest PCTFE film for a science mission, with spectrally selective coating. But after a major dust storm, the film greenhouse would be scratched. For long-term using in-situ materials, I suggest tempered glass. That's just normal glass that's been given a heat treatment.

Scientific American: How is tempered glass made?

Tempered glass is stronger than normal glass. But the important feature for Mars is that it's harder than minerals on Mars surface. That means harder than dust and sand. Sand cannot scratch anything harder than itself. So this means dust / sand storms will not scratch or craze windows.


Let's Go to Mars...Google on: Fast Track to Mars blogspot.com

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#12 2021-06-21 21:00:43

Void
Member
Registered: 2011-12-29
Posts: 3,923

Re: Chinese greenhouses

-----------------------------------------------------------------------------------
Thank You...

A good topic from Louis, wonderful content added.  Life is good.

Yes Robert in the past I have bee a bit whimpy about the notion of making glass.  Howewver you have shown methods, and it seems that
if humans could travel to Mars by the Million, and if humans could in some cases build aquatic under ice reservoirs, it seems that we
should think to have the attitude to conquer other chanenges such as making glass.  Perhaps even eventually transparent Aluminum.

Your concerns about abrasion from a dust storm are to be taken seriously.

I do visualize the blanket as having a shiny underside, and a outside that can resist abrasion.  And when practicle, during a dust storm
I anticipate keeping the covers down.  But at some point, if the crops are dying from a lack of light, it may be necessary to try to raise
the blankets even during a partiallly light blocking dust storm.  Fluorine will be hard to get and hard to handle, so yes, glass makes lots
of sense, and will likely put up with the abrasive environment better.

Where I have mentioned that on Mars we have the advantage of .38 g, and low wind force, in raising the blanket up during the day, we also
have the reality that at night, when the blanket is down, it will insulate rather better than on Earth, as it's "Dead Air" spaces will be
of a higher partial vacuum.

I am also quite interested in a situation where indeed some of these greenhouses would be pressurized as you have worked on.  This again is
another situation where I guess we should dare to make it work.  I like domes even less, but still I think that Martians shold seek to
master that craft.

For some of your greenhouses, even though they would not be for aquaculture, it might be possible to access them by having an appropriate
PPE, and swiming up through a hole in an ice covered reservoir.  I know that you know what an ice fishing house is like.  A bit like that.
Then if your PPE malfunctions, and you are wearing weights, you might jump in the hole, and drop down through the water to backup life
support.  Likely people would travel in pairs, per a "Buddy System" to lend assistance to each other.

I am very encouraced.  I think that great things can be made to happen.

Done


I like people who criticize angels dancing on a pinhead.  I also like it when angels dance on my pinhead.

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#13 2021-06-23 06:05:37

Calliban
Member
From: Northern England, UK
Registered: 2019-08-18
Posts: 1,197

Re: Chinese greenhouses

A good idea, that will help to shield plants from day-night temperature cycles.  At relatively low pressures, a poly-tunnel type arrangement could use material excavated from trenches to counterbalance internal pressure.


Interested in space science, engineering and technology.

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#14 2021-06-28 13:06:01

louis
Member
From: UK
Registered: 2008-03-24
Posts: 6,915

Re: Chinese greenhouses

Video about various greenhouse material used on Earth:

https://www.youtube.com/watch?v=G2Y3tWmdcMc

Any thoughts in relation to Mars? I would have thought a UV blocking coating would be required.


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