Agriculture Study Mars Pure CO2 Greenhouse

tahanson43206 · 2019-12-17 08:14:43

Marking These plot registries have been marked
0041 Manufacture of atmosphere for habitats
0042 Manufacture of atmosphere for greenhouses
0043 Manufacture of atmosphere for specialized applications such as mobile transporters

The purpose of this new topic is to provide an anchor point for a large scale Earth based study of growth of plants or other biological entities in an all-CO2 atmosphere maintained at Earth-normal pressure and Earth-normal temperature.

The purpose of the study is to carry out a scientific study, managed by appropriate institutions, to evaluate the potential of various Earth-born entities to survive or even thrive in an all-CO2 atmosphere.

SearchTerm:AgricultureStudy
SearchTerm:MarsAgricultureStudy
SearchTerm:Greenhouse

The reason for a focus on Earth-normal pressure of CO2 and Earth-normal temperature is to facilitate instances of the study articles in thousands of locations around the world. These would include homes of those willing to make the investment of funds and time to participate in the study, as well as schools and other educational institutions, and such other institutions as are willing to participate.

This new topic is offered here in honor of kbd512's creativity. It is to be dedicated to agriculture on Mars using all-CO2 at normal (Earth normal) atmospheric pressure.

All forum members who are already registered are invited to contact local colleges and universities to seek out professors willing to take leadership roles in defining the scientific objectives to be achieved, and requirements for equipment to be deployed.

There is need for a coordinating service, and a government agency would be ideal if one can be found to take on the role. Otherwise, an educational institution with sufficient gravitas may be willing to take on the leadership role for collection of data and organization and publication of results.

This is anticipated to be a global project.

For those who are not currently registered in the NewMars forum, please be aware that even though the process to register normally goes smoothly, occasionally a glitch can occur so that the applicant does not receive the automated email that allows the registration to proceed. In that case, please do not hesitate to take advantage of the email service provided for assistance with registration. On the OTHER hand, please do NOT use the email assistance service unless necessary. This is an all-volunteer operation, and the time of each volunteer is precious.

(th)

Last edited by tahanson43206 (2020-07-07 06:35:52)

GW Johnson · 2019-12-17 09:32:17

I know little of biology, but some on these forums do. I thought I had seen one of them post something about photosynthetic plants as we know them needing oxygen as well as carbon dioxide.

There also has to be moisture in the air as well as in the soil around the roots. Very low air density means low absolute moisture content.

Just things to worry about. Myself, I do not know the right answers.

GW

Last edited by GW Johnson (2019-12-17 09:32:48)

tahanson43206 · 2019-12-17 10:22:14

For GW Johnson re #2

Thank you for your contribution to this new topic!

For readers who may not be familiar with Dr. Johnson in the context of education, the forum archive contains a series entitled "EducationDoneRight"

Use the search window at the top of the main form to find the series.

To refine the search, you can specify Author: GW Johnson

***
Your comments are helpful on several levels.

What I am hoping we (forum members) can accomplish here is to inspire a mass scientific undertaking, with participation by families and institutions world wide.

What I have in mind is a sealed terrarium about the size of the (real) terrarium that sits on top of my microwave. It contains a Christmas Ivy that is at least 25 years old, and which has persisted and grown to fill the volume over that time, given only occasional water in the pebbles bed, and the rare dose of fertilizer.

That package is about 12 inches high, the same wide, and about 20 inches long.

For our Metric using friends, that would be 30 x 30 x 50 cm (close enough)

The package would be prepared and sealed by a contractor under the supervision of a major university, and in an ideal world, the entire undertaking would be supervised by NASA in the United States, and by comparable entities in other nations.

The system would be run by a microcontroller programmed to maintain exactly the conditions desired for a study, and I would envision duration on the order of an Earth year for each package.

Since the system would be designed to accomplish both an educational purpose as well as a scientific investigation, the readouts from the microcontroller would be recorded by students (when available for the purpose) and uploaded each day to a central data collection web site.

The central data collection web site could be programmed to ask the student data contributors to provide additional data points from time to time, to make the experience more interesting, and to insure there is feedback to each contributor.

In the packages, the university level organization would provide seeds of a particular plant to be studied, and the necessary inputs would be listed for the individual supervising the student data contributor.

I am thinking of a package cost to a family of around $500 as a target, with that cost falling over time as volume increases.

The package would ultimately be returned to the university level organization for detailed study.

What I am going for here is identification of plants or other biological systems that would thrive in an all CO2 (or near CO2) environment.

If it were to turn out that particular plants thrive in the unique conditions described, those species would (presumably) find immediate homes on Earth, in commercial enterprises.

There are already reports of greenhouses located near fossil fuel power plants to consume CO2, so this would not be a major change.

Edit#1: Inputs to be supplied by the host family/institution include:

a. Clean fresh water
b. Reliable utility power (or equivalent)
c. Natural lighting (supplemented by LED lighting inside the package)
d. Room temperatures (70 degrees Fahrenheit +/- 10 degrees F) (21 degrees Centigrade +/- 3-5)
e. Freedom from vibration or other physical disturbances
f. Note occasional need to clean output receptacle when filled by microcontroller

Edit#2: Online connection discouraged

I would recommend that the study units NOT be connected to the Internet. The risks of a direction are high.

Furthermore, a direct connection to the Internet would defeat the purpose of engaging students (in particular but not exclusively) in data reporting, and in engaging with the data reporting web site when the software running on the web site asks for additional information or suggests specific action that might be appropriate.

(th)

Last edited by tahanson43206 (2019-12-17 13:05:53)

SpaceNut · 2019-12-17 14:05:50

Also the internal Co2 content to gas mix to start and monitored levels as the plants grow plus measured pressure from sowing of seeds to full plant ready to harvest. Nutrient type used to get plants to grow in a hearty manner.

The data is out there just not in format that we can use without mining it...

https://bmcplantbiol.biomedcentral.com/ … 018-1243-3
The optimal CO2 concentrations for the growth of three perennial grass species at CO2 concentration at 400, 600, 800, 1000, and 1200 ppm.

https://link.springer.com/article/10.1007/BF00346400
Elevated atmospheric partial pressure of CO2 and plant growth
Cotton and maize plants were grown under full sunlight in glass houses containing normal ambient partial pressure of CO2 (330±20 μbar) and enriched partial pressure of CO2 (640 ±15 μbar) with four levels of nitrogen nutrient.

https://link.springer.com/article/10.1007/BF00035008
Cotton plants were grown in late spring under full sunlight in glasshouses containing normal ambient partial pressure of CO2 (32±2Pa) and enriched partial pressure of CO2 (64±1.5Pa) and at four levels of nitrogen nutrition

tahanson43206 · 2019-12-17 14:57:13

For SpaceNut re #4

Thanks for these encouraging links!

What I take from their existence (without having read them) is that there is interest in pursuing this line of investigation.

What I'm going for here is a way to enlist a large population in conducting rigorous study of a great number of species to find the ones that thrive under the anticipated conditions at Mars, AND which would thrive if the same conditions were created on Earth.

Thus. an outcome of the research would be discovery of species which would do well in underground growing rooms such as at the poles of the Earth, or in desert regions where conditions are conditions are otherwise hostile to life.

If humans stay on their current path, underground growing rooms will become the MAIN source of nutrition for the population.

(th)

SpaceNut · 2019-12-17 15:18:27

Like always the references are all in differing measurement values and they are not what we know we have on mars for a starting point of which is not earths air pressure with the content being the values given.

https://www.ncbi.nlm.nih.gov/pubmed/11538810
Plant responses to reduced air pressure: advanced techniques and results.

https://nph.onlinelibrary.wiley.com/doi … 10.03441.x
Plant responses to low [CO2] of the past

https://www.ars.usda.gov/ARSUserFiles/6 … rs_85a.pdf
METHODS OF EXPOSING PLANTS TO ELEVATED CARBON DIOXIDE

http://bigidea.nianet.org/wp-content/up … -et-al.pdf
Low Pressure Greenhouse Concepts for Mars: Atmospheric Composition

SpaceNut · 2019-12-17 15:40:08

We talked about the nutritional effects of high co2 on plants in another topic...
https://www.sciencedirect.com/science/a … 1916303400
Photosynthesis of C3 and C4 Species in Response to Increased CO2 Concentration and Drought Stress

https://www.tandfonline.com/doi/pdf/10.1626/pps.15.118
Effects of CO2 Increase on Wheat Growth and Yield under Different Atmospheric Pressures and Their Interaction with Temperature

https://www.nature.com/articles/s41598- … collection
Coordination between vapor pressure deficit and CO2 on the regulation of photosynthesis and productivity in greenhouse tomato production

https://www.cedarcreek.umn.edu/biblio/f … /t2357.pdf
Why is plant-growth response to elevated CO2 amplified when water is limiting, but reduced when nitrogen is limiting? A growth-optimisation hypothesis

SpaceNut · 2019-12-17 15:52:36

SpaceNut wrote:

https://news.nationalgeographic.com/new … e-science/
https://newatlas.com/carbon-dioxide-atm … ion/51416/
https://www.scientificamerican.com/arti … n-in-food/
Wheat, rice, barley and certain legumes like soybeans are classified as C3 plants, which corresponds to their ability as plants to convert carbon dioxide into energy. These C3 grasses and legumes have been shown to lose up to 15 percent of zinc and iron, the top two minerals in the human body, in experiments that artificially enhanced the concentration of carbon dioxide. These elements are crucial for a healthy immune system, cell development, hemoglobin production and brain function.
The C4 plant growth is different it seems....

RobertDyck wrote:

C3 vs C4 plants:
The first chemical that plants use to fix CO2 is Ribulose 1,5-bisphosphate (RuBP). An enzyme binds one molecule of CO2 to it, the enzyme is called ribulose bisphosphate carboxylase oxygenase (RuBisCO). If the ratio of O2 to CO2 is too high, it will bind O2 instead. This creates a waste product, RuBP with O2 has to be converted back into RuBP. That takes energy. It appears plants have evolved for an atmosphere with much more CO2. This is the first step of what high school called the dark reaction of photosynthesis. The university name for the same thing is the Calvin-Benson cycle because it was discovered by Mr. Calvin and Mr. Benson. The light reaction of photosynthesis is known by the university name "Photophosphorylation". That is highly optimized, extremely energy efficient. However, the Calvin-Benson cycle appears to be a mess, only efficient in an atmosphere with MUCH more CO2.
Some plants have evolved a way to concentrate CO2 in their tissues. Concentrating CO2 means O2 binding will occur much less. It takes energy to concentrate CO2, but less than recycling RuBP. Plants that do this create a large molecule with 4 carbon atoms, then that is broken down into CO2 near chloroplasts. Because the molecule that does his has 4 carbons, these plants are called C4 plants. RuBP has 3 carbon atoms, so plants that don't make C4 are called C3 plants. RuBP is actually used by both groups of plants, but they needed a name.
C4 plants can fix carbon with less energy in today's atmosphere, consequently they grow faster. These tend to be weeds, so weeds out-compete food crops. There are some exceptions; corn is a C4 plant, which is why it grows so well. However, in a greenhouse with elevated CO2, C3 plants will grow faster because they don't have to waste energy concentrating CO2. This both means food crops grow faster, and dramatically reduces weeds.

SpaceNut · 2019-12-17 20:24:09

Knowing that the design of the grwoth chamber for mars wants is to be able to farm in shirt sleeves while in head gear to provide life support for crew tending them in a near co2 mix gas levels being something less than the earths pressure but greater than mars levels at which we are looking to know when plants do better and at what mix levels of gas to pressure.

I think in this topic we are ignoring the mass of the unit and power requirements in order to find what is the acceptible levels of atmospher that plants will grow in.

tahanson43206 · 2019-12-17 20:41:32

For SpaceNut re #9

Thank you for clarifying the scope of the topic....

You are right about the focus upon trying to find the optimum mix of plants able to grow in a dense CO2 atmosphere.

What I have in mind would take place ENTIRELY on Earth, in small terrarium-like sealed containers that would be distributed to interested families and institutions (such as schools).

The questions to be answered would depend upon the Principle Investigator in each supervising university or other equivalent institution, so it is difficult to predict what those might be, but the overall scope of the investigation would be to find plants best able to grow in an environment as depicted by kbd512 in his vision of an Earth-equivalent pressure chamber/greenhouse with LED lighting, filled with Mars CO2 and such other gases as may be required for optimum plant growth.

An alternative scenario for investigation can (and likely will) be performed ahead of tests on Mars. That alternative would require that test chambers on the Earth be evacuated to Mars level CO2 pressure, but such chambers would be best constructed and operated in high level academic environments or government laboratories.

(th)

SpaceNut · 2019-12-17 21:26:45

Man is able to breath at a level that is in a space suit of near 3 psi and we are not harmed with regards to that low pressure in a space suit to our skin or body parts. That said a target value to look to would be that value inside a chamber equal to the space suit environment.
Our life support value for the man to breath is a seperate issue for working in the chamber for pressure and mixed gasses.

https://www.hydrofarm.com/resources/art … enrichment

Carbon dioxide is an odorless gas and a minor constituent of the air we breathe. It comprises only .03 % (300 parts per million, or PPM) of the atmosphere but is vitally important to all life on this planet!
Plants are made up of about 80-90 % carbon and water with other elements like nitrogen, calcium, magnesium, potassium, phosphorous and trace elements making up only a small percentage. Almost all of the carbon in plants comes from this minor 300 PPM of carbon dioxide in the air.
Oxygen comprises almost 20 % of the earth's atmosphere. Most of it was generated by plant life. The process of photosynthesis combines CO2 and water to form sugars and free oxygen. Simple sugars like C6H12O6 provide plants with energy and are formed into the more complex plant parts such as carbohydrates, amino acids, protein, cellulose, leaves, roots, branches and flowers.
With the advent of home greenhouses and indoor growing under artificial lights and the developments in hydroponics in recent years, the need for CO2 generation has drastically increased. Plants growing in a sealed greenhouse or indoor grow room will often deplete the available CO2 and stop growing. The following graph will show what depletion and enrichment does to plant growth:

Above 2,000 PPM, CO2 starts to become toxic to plants and above 4,000 PPM it becomes toxic to people. 1,000ppm of CO2 means that if you could count a million gas molecules, 1,000 of them would be of carbon dioxide and 999,000 molecules would be some other gases.

https://www.co2meter.com/blogs/news/151 … on-defined

http://www.omafra.gov.on.ca/english/cro … 00-077.htm

For most crops the saturation point will be reached at about 1,000–1,300 ppm under ideal circumstances. A lower level (800–1,000 ppm) is recommended for raising seedlings (tomatoes, cucumbers and peppers) as well as for lettuce production. Even lower levels (500–800 ppm) are recommended for African violets and some Gerbera varieties. Increased CO2 levels will shorten the growing period (5%–10%), improve crop quality and yield, as well as, increase leaf size and leaf thickness. The increase in yield of tomato, cucumber and pepper crops is a result of increased numbers and faster flowering per plant.

https://cdiac.ess-dive.lbl.gov/pns/convert.html

https://principia-scientific.org/human- … r-million/

co2 Amount with a volume
https://www.hydroponics.net/learn/co2_calculator.php

tahanson43206 · 2019-12-18 11:07:37

For SpaceNut re #11

Thank you for this set of helpful links!

I liked the graph (which you reproduced in the post) showing the performance of "plants" as CO2 ppm is increased over a range.

In order for kbd512's concept to succeed, plants would need to be found that thrive in an atmosphere of 999,000 ppm. That would be the Holy Grail for a massive study. This way of selecting for plant traits has been going on for thousands of years.

The vast majority of plants would expire in the test conditions proposed. A tiny few would last longer than the others, and the offspring of those would be selected for the next trial.

Ultimately varieties that would do well on Mars without needing lots of imported Nitrogen would emerge from the process.

Thank you again for the links you've provided showing the state-of-the-art in plant physiology research with respect to CO2.

For the biochemists to ponder: What is the mechanism in existing plants that requires metering of accessibility of CO2 molecules to plant structures?

Clearly existing plants NEED to experience 998,000 collisions with neutral molecules to facilitate admission of 2,000 ppm of CO2 into the structures.

Is that just the result of conditions that existed during the evolution of plants, or is there something more fundamental at work?

Edit: Low greenhouse pressure might substitute for the presence of neutral gas molecules, if the rate of collision with plant surfaces is the issue.

(th)

Last edited by tahanson43206 (2019-12-18 11:09:24)

tahanson43206 · 2019-12-18 11:25:04

For SpaceNut re topic in general ...

In order to try to move the topic along, I've written to a local Land Grant university, to see if someone might be interested in the topic, and willing to contribute to its development:

Hello,
Thank you for reviewing this inquiry!
Please forward to someone who might be interested in the question under discussion.
***
The NewMars.com/forum is an activity of the Mars Society. It has been active since (about) 2001, and remains active today.
I am participating in a discussion about greenhouse design for Mars.
Since Mars has an atmosphere consisting almost entirely of Carbon Dioxide, it would be advantageous to provide a greenhouse with an atmosphere consisting of planetary atmosphere increased to Earth-normal pressure.
This design would facilitate access to plants by human workers, who would wear oxygen/air masks but would otherwise enjoy "normal" temperatures and pressure while tending the plants.
The issue at hand is that (according to research discovered by a member of the forum) plants as a group appear to have evolved to function best at a PPM of (about) 2000 of CO2. On Mars, that ratio would require import of 998,000 PPM of neutral gas, such as Nitrogen.
There is a need for Nitrogen for growth of plants, but I suspect the actual amount needed is far less than 998,000 PPM.
It is proposed that a massive study on Earth, of a great variety of plants to be tested in sealed terrariums, would discover varieties which can be bred toward greater and greater tolerance of CO2, until the objective of 998,000 PPM is achieved.
If there is someone in the department interested in considering this question in conversation with members of the NewMars.com/forum, registration is free and open to the public.
If someone decides to pursue this, I post in the forum as tahanson43206.
Thank you again for considering this inquiry!

(th)

RobertDyck · 2019-12-18 13:35:52

The chart by SpaceNut in post #11 shows growth vs CO2. I don't dispute that, but do dispute the word "normal" for 300 ppm CO2. As the Canadian federal government imposes carbon tax, this is has become a sensitive issue. Past interglacial periods have shown CO2 rise from 200 ppm during an ice age, and the end of an ice age, to 300 ppm at the height of an interglacial period. The chart below shows CO2 at 344.3 ppm in 1984, rising to 405.5 ppm in 2017. It was ~280 ppm in 1855, beginning of the Industrial Revolution. So yes, humans increased CO2 from 280 to 405, but nature would have increased it to 300 anyway. Back to the topic, current "normal air" is about 400 ppm.

SpaceNut · 2019-12-18 18:07:28

Mars first crew greenhouse

Nutrient Management in Closed system for Martian Greenhouse

Automating a Mars Garden

https://notrickszone.com/2019/12/02/sci … he-planet/

Earth’s atmosphere contains 400 ppm CO2 (0.04%). Mars has a 950,000 ppm (95%) CO2 atmosphere.

lowest point of Hellas Planitia it can get as high as 1,155 pascals (0.1675 psi).

SpaceNut · 2019-12-23 20:08:46

Scrubbing carbon dioxide from smokestacks for cleaner industrial emissions

CO2 has increased 40 percent since the dawn of the industrial age, contributing heavily to a warming planet.
atmospheric carbon dioxide concentration in 2018 was 407.4 parts per million

The atmosphere of Mars is the layer of gases surrounding Mars. The atmospheric pressure on the Martian surface averages 600 pascals (0.087 psi), about 0.6% of Earth's mean sea level pressure of 101.3 kilopascals (14.69 psi)...

tahanson43206 · 2019-12-31 19:25:02

In another topic, SpaceNut renewed the topic of balloon flight on Mars.

By a chain of links, I arrived at a realization that a problem reported earlier in THIS topic may NOT be a problem on Mars!

The problem reported earlier appeared in a paper at a link which (I suspect) was probably found by SpaceNut.

The paper reported that plants on Earth which were exposed to increased amounts of CO2 responded favorably as ppm increased to a value above 400 PPM, reached a point of maximum performance, and then fell off as PPM increased.

I've forgotten the details but they are available for anyone to check, earlier in this topic.

What SpaceNut's reminder about balloons on Mars allowed me to realize on this occasion, that the reduced pressure of Mars WAS NOT TESTED in the papers which were cited earlier.

This brings me back to the entire purpose of this topic, which was to actually STUDY the performance of plants in an atmosphere equivalent to that of Mars.

I asked Mr. Google for help with this, and MAY have discovered a blind spot in research done to date. All the citations which appeared in the top page or so of results confirmed my suspicion that researchers have been concentrating on soil. There exists a small possibility that NO research has been done at Mars equivalent atmosphere, which would require a (near) vacuum chamber.

In the absence of knowledge on this point, I eagerly await the efforts of someone in the forum community who can investigate this question further.

The OPTIMUM result would be to discover that the Mars atmosphere JUST HAPPENS to provide the exact amount of CO2 PPM that Earth plants need for optimum growth.

I realize that this happy outcome is highly unlikely, but in the absence of knowledge, it is possible to hope.

(th)

Last edited by tahanson43206 (2019-12-31 19:25:17)

tahanson43206 · 2019-12-31 19:33:05

As a caveat to the original premise of this topic ....

kbd512 had introduced the idea of growing plants in the native Mars atmosphere, and I allowed myself to imagine a scenario in which a human gardener would enter a greenhouse maintained at Mars normal pressure wearing only an oxygen mask.

The citations found in SpaceNut's balloon topic included a caution that the Mars atmosphere is above the Armstrong limit, so humans could not move about in the Mars atmosphere without a protective garment. I would appreciate a forum member investigating to see what kind of garment would be required to permit a human to safely work in a Mars normal greenhouse.

Hopefully a simple pressure fabric garment would be sufficient to hold human body parts together, but at this point, I have no idea what is possible beyond the default of wearing a space suit with full pressurization, or partial pressurization as we have done in the American space program.

(th)

Last edited by tahanson43206 (2019-12-31 19:33:33)

SpaceNut · 2019-12-31 19:40:26

The mechanical pressure suit is in with the other topics for space suits, think spandex extra strength...

The pressure drop on mars for an open green house cause the plants to transpire, dry up and die in the experiments.

Like you noted the suit would need a breathing aperatus simular to a scaba tank with full mask plus head gear to protect. A tank that is pressurize air of 5000 psi is already possible. with composites and even weighs less than 20 lbs full for 2 tanks on like a back pack harness.. .

Spacesuits - personal spaceship
Spacesuits - Its about time we came back to them
New idea for Mechanical CounterPressure suit

tahanson43206 · 2019-12-31 21:02:24

For SpaceNut re #19

Thank you for the recollection that pressure in a Mars greenhouse affects transpiration ...

I asked Mr. Google: The pressure drop on mars for an open green house cause the plants to transpire, dry up and die in the experiments.

And the top citation was the kind of study (I suspect) you were remembering:
https://www.researchgate.net/publicatio … nvironment

This publication clearly shows that plants will grow in an atmosphere with pressure well below that of Earth normal (sea level) provided that partial pressures of carbon dioxide, water vapor and oxygen are within the optimum range. A neutral gas is needed to make up the difference.

What I take from this is confirmation that a greenhouse can perform well WITHOUT needing an Earth-normal pressure.

The biggest challenge for the design of a deployable Martian greenhouse is to achieve maximum light transmittance while keeping heat loss to acceptable levels. Radiation heat transfer will dominate for Martian conditions. The low density atmosphere will reduce conductive and convective heat transfer through the atmosphere outside the greenhouse. Operating greenhouses at internal pressures as low as 0.1 Earth atmosphere has been discussed, but it appears that plants may not be productive at pressures below 0.2 or 0.3 Earth atmospheric. Conduction and natural convection inside the structure will be greatly reduced at 0.1 Earth atmosphere and hence a higher pressure may be required to maintain a good thermal and mass transfer balance.

The paper cited is primarily concerned with design of a greenhouse that can be deployed on the surface of Mars.

I am NOT interested in that particular problem. Fortunately there are individuals and groups that are.

I AM interested in the option of placing a greenhouse well underground for radiation protection of the workers.

The citation quoted above suggests a practical lower limit for pressure in an off-Earth greenhouse may be on the order of .3 Earth normal pressure.

Returning to Google for the Armstrong Limit:

Image result for armstrong limit percent of earth normal pressure
On Earth, the limit is around 18–19 km (11–12 mi; 59,000–62,000 ft) above sea level, above which atmospheric air pressure drops below 0.0618 atm (6.3 kPa, 47 mmHg, or about 1 psi).

This quotation confirms that the .3 atm cited above for minimum pressure for plant growth is well above the Armstrong limit, and the worker can wear street clothing supplemented by an air supply.

Another Google search found this paper summarizing air pressure vs altitude:
https://www.avs.org/AVS/files/c7/c7edae … f87b9e.pdf

This table shows that .3 atmosphere is (about) 5.46 psi, and that corresponds to an altitude of 25,000 feet.

The height of Mount Everest is given (by Google) as: 29,029 feet

The practical experience of (by now) hundreds if not thousands of visitors to the top of Mount Everest show that humans can tolerate .3 atmosphere without a pressure suit, but (in most cases, WITH air breathing equipment).

In summary, as of this point in the development of the topic, I think it is reasonable to suppose that it is NOT necessary to pressurize a greenhouse on Mars to more than about .3 atmosphere, so the costs associated with equipment and seals can be reduced from that required for the human habitation spaces.

(th)

Last edited by tahanson43206 (2019-12-31 21:03:47)

SpaceNut · 2019-12-31 22:04:03

The soils of mars are porous just as they are here on earth until you get down in the bedrock and then you need drilling and explosive equipment to dig into it. Cracks in the rock with any pressure will in time leak out. So we are then looking to have or make a sealed chamber with air lock to be able to rise the co2 content in the partial air pressure.

Since we are looking at energy used to pressurize then we are looking at the low energy construction techniques as well. We also know that plants have a higher tolerance to the space radiation that we are harmed by. That said under ground means energy to heat, circulate the air moisture, lighting....

http://dl.icdst.org/pdfs/files/04cc9251 … 03abcd.pdf
HEAT AND MASS TRANSFER OF A LOW PRESSURE MARS GREENHOUSE:
SIMULATION AND EXPERIMENTAL ANALYSIS

Digging in and taking cover
Lunar and Martian dirt could provide radiation shielding for crews on future missions.

Oddly, one of the better ways to stop radiation is with lightweight materials - hydrogen, boron, and lithium. The nuclei of heavy elements in cosmic rays can be shattered by lightweight atoms without producing additional hazardous recoil products like neutrons.

For mars taking the time to pick the perfect sample of those is not happening for selecting the regolith density of 1.5 g/cm3 mix of elements.

http://www.marsjournal.org/contents/200 … 6_0004.pdf
Radiation Effects and Shielding Requirements in Human Missions to the Moon and Mars

seems that water content and thickness of 50 cm upward are part of the definition of lowering the dosage.

https://ttu-ir.tdl.org/bitstream/handle … sequence=1
Radiation Protection Strategy Development for Mars …

We also know that high content hydrogen plastics as polyethylene shielding of 5, 10, and 15 g/cm2 are another good mediator of risk but thats not happening either unless we are bringing it from earth.

https://authors.library.caltech.edu/426 … _FINAL.pdf
Mars’ Surface Radiation Environment Measured with the instruments on Curiosity

https://spaceradiation.larc.nasa.gov/na … 217983.pdf
https://mepag.jpl.nasa.gov/reports/Mars … _Study.pdf
https://ntrs.nasa.gov/archive/nasa/casi … 002067.pdf

tahanson43206 · 2020-01-01 21:06:15

For SpaceNut re this topic ...

The paper you found and showed in another topic is appropriate for this topic.

This is a PhD level paper, reporting on extensive investigation of growing plants (lettuce) in a simulated Mars greenhouse.

http://dl.icdst.org/pdfs/files/04cc9251 … 03abcd.pdf

Thank you for finding this paper!

(th)

SpaceNut · 2020-01-01 21:34:08

Its in the above post as heat and mass transfer but the document covers more than reduced pressure and co2 content as it looks at surface solar lighting and covering to keep heat in for the night.

I got thinking about the crew entering a day time greenhouse one could fill a water blatter on a platform or clear tank so as to see the water as the means to reduce radiation exposure. Move the water to heat concentrating tanks that are better insulated when crews are not present in the greenhouse. This loop of heating are solar thermal concentrating collector boxes.
one could use the water to obsorb heat during the day to aid in controlling the temperature once the curtains are drawn for the night to slow radiant heat loss.

Found another topic that we have here
A Mars Hab with Radiation Shielding
Space Radiation + counter measures
Radiation amount type risk mitigation

Of course what is going to grow that we want is the issue.
Food for Thought, what does a garden need to grow

Of course we have individual topics as well for each food type.

SpaceNut · 2020-01-08 21:05:58

Lots of good information in this Farming and the geography of nutrient production for human use: a transdisciplinary analysis

The variety of crops and of livestock as well as fish biomes but not how much land or energy for each are required. Lest we forget we have hugh biomes of forest and oceans with which we would not live with as well.

So data from FOOD, LAND, POPULATION and the U.S. ECONOMY

At least 1.2 acres per person is required in order to maintain current American plus Currently the 400 gallons of oil equivalents expended to feed each American ...

Its actually more when we include the other resources which make these other food possible along with the breathable air and materials we take for granted.

Lets call it 2 acres and that converts to 8093.71 m^2 for just 1 person....or 90 meters on a side...
https://www.metric-conversions.org/area … meters.htm

So now what is the energy that we need for solar light...
Goggling mars greenhouse floor thermal insulation for heat lose calculations reference materials
Will read more tomorrow for these links

https://www.greenhousemag.com/article/t … heat-loss/

Conductive heat loss = SA x U x TD
Infiltration heat loss = 0.02 x V x C x TD

http://www.marshome.org/files2/Hublitz2.pdf
ENGINEERING CONCEPTS FOR INFLATABLE MARS SURFACE GREENHOUSES

https://farm-energy.extension.org/wp-co … tation.pdf
Greenhouse Energy Efficiency (Heating)

Terraformer · 2020-01-09 02:59:22

Martians, of course, will not be eating the typical American diet, and their farms will not lie fallow over winter.

The bare minimum to sustain a human being on a calorie basis, in a temperate Terran climate, comes to around 250 m^2. That's for growing potatoes. If you have milk too, you'll have an almost complete diet, but then you need to produce the grass to feed the goats or cows. Cows get a feed conversion ratio of ~10 after accounting for water content, so they're maybe 12.5% efficient (given the fat content) at converting calories in the form of cellulose to calories humans can digest? Given that corn produces 8 tonnes of food per hectare versus the 25 tonnes of cellulose produced by certain grasses, it seems that pastoralism requires three times the land area to produce the same calories as corn...

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