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#51 2019-11-30 12:52:20

Oldfart1939
Member
Registered: 2016-11-26
Posts: 1,796

Re: Industrial development on Mars

louis wrote:

4. We could use thermogenic plants (plants that generate and release heat at night) to help keep the domes warm at night.

5. A portion of the crops could be bio-fuel. The bio-fuel could be used with oxygen harvested from the domes to act as boilers to heat water that could be circulated around the domes.

6. The domes could maybe have a light rail system (very narrow gauge) for easy movement of harvested crops and humans.

I say "domes" but it is possible they might be more like the plastic polytunnels used in farming on Earth.#

If we could use this, what I would call, Augmented Heat and Light  system of farming, the need for nuclear power or vast solar arrays would not arise. Also, we would not need to build huge, resource-intensive domes (nice though they look in artist's illustrations).

Louis: Can you give me an example of a thermogenic plant?

Your suggestion flies in the face of the laws of thermodynamics, and is a massive perpetual motion machine concept. Plants do what they do by absorption of energy from the sun. The photochemical "dark reaction" consumes some of the stored energy from the "light reaction" by liberating carbon dioxide as product of metabolism. For such a proponent of solar power on Mars, you should have done more homework before making this proposal about thermogenic plants.

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#52 2019-11-30 12:55:59

louis
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From: UK
Registered: 2008-03-24
Posts: 5,339

Re: Industrial development on Mars

I think you have to distinguish early stage (say up to a population of 1000) and the follow on stage.

In the early stage, labour will be in short supply so it's easier to substitute energy for labour. Rather than focussing on building farm structures, it will likely be easier to use cut and cover construction or inflatable habs. In the early stage, also, you don't want to have to deal with extended dust storms when it comes to farming (which really requires you to have built up a big food store).

Later on, I think we can move to natural light farming. 

Oldfart1939 wrote:

I become very frustrated by those claiming underground farming to be "the answer." I again refer everyone so interested in Robert Zubrin's "Entering Space," and his commentary re: energy requirements to do so. Green and growing crops thrive by capturing and converting energy (photons), into carbohydrates and some proteins. Basing this analysis on thermodynamics is the only conceivable way to do any meaningful calculations. Light is the "driver" of these growing plants, since the entire photosynthetic pathway depends upon solar irradiance. Producing enough photons by artificial methods is a distinctly losing proposition. I'm not going to spout the numbers here, because no one would take them seriously enough to matter. They are all in Zubrin's books; note that that final word is PLURAL! He discusses this problem in excruciating detail.


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#53 2019-11-30 16:49:56

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 17,390

Re: Industrial development on Mars

In the early period of time all of the energy is going into refueling for man to go home, making oxygen to breath, finding water to drink and cook with, exploring plus science, running recycling machines and the one thing man must do is exercise or have all sorts of illnesses due to prolonged low gravity. Man must work to do whats needed but smartly...Not doing the heavy lifting but getting dirty so as to build what is needed. Energy, automation are not saviors to mans ability to survive on mars as if they fail we are going to die.

Natural light is 430 w m^2 but what is the energy needed to grow food when its not just the lights, heat, water as you are still feeding pumps with co2, capturing excess oxygen, mixing nutrients, pumping water to the plants, tilling the soil, harvesting the crop, processing it for storage or for immediate use.....

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#54 2019-11-30 18:52:39

louis
Member
From: UK
Registered: 2008-03-24
Posts: 5,339

Re: Industrial development on Mars

The early stage itself can be broken down into (a)  first missions and (b) later missions.

In the first missions (maybe Missions 1-3), with a tiny population of perhaps 10-50 max, it makes no sense to put any great effort into growing food.  The vast bulk of food will be brought in from Earth. You will likely only grow food for its morale boosting: eating fresh salad vegetables will probably improve psychological well being. So in that period the amount of food you grow on Mars might be 2-5% max. Agriculture on that scale won't be that energy-intensive for a tiny population (could probably be covered by a 100 metre sq. array for 50 people at 5% of food consumption).

For later missions in the early stage, you'll need to start putting a lot more resources into agriculture. But at this point, overall development is still v. intense - there are lots of other demands on labour and so constructing farm habs and monitoring agriculture in real time under natural light conditions cannot be considered a priority. It will be better to look to closed hab farming, with maximum automation.

It is only later on, as the population expands that labour will become available for developing natural light farming with human labour input.



SpaceNut wrote:

In the early period of time all of the energy is going into refueling for man to go home, making oxygen to breath, finding water to drink and cook with, exploring plus science, running recycling machines and the one thing man must do is exercise or have all sorts of illnesses due to prolonged low gravity. Man must work to do whats needed but smartly...Not doing the heavy lifting but getting dirty so as to build what is needed. Energy, automation are not saviors to mans ability to survive on mars as if they fail we are going to die.

Natural light is 430 w m^2 but what is the energy needed to grow food when its not just the lights, heat, water as you are still feeding pumps with co2, capturing excess oxygen, mixing nutrients, pumping water to the plants, tilling the soil, harvesting the crop, processing it for storage or for immediate use.....


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

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#55 2019-11-30 21:23:51

Oldfart1939
Member
Registered: 2016-11-26
Posts: 1,796

Re: Industrial development on Mars

I'm not certain anyone understood my comment earlier in posts #50 & #51 of this thread. Plants don't "just grow,' but need nutrients as reaction starting materials in a photochemical reaction pathway. Without light, they don't really grow. The seeds have some nutrient energy, but once sprouted, the system (the plant), requires input of photons to make the photosynthetic reaction of manufacturing carbohydrates from CO2 and water take place. Forget the fertilizers, and everything else but the light input (photons). That's where carbohydrate production originates; photosynthesis.

The energetic pathway required for artificial light plant growth is astronomical (no pun intended!).

Last edited by Oldfart1939 (2019-11-30 21:24:57)

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#56 2019-11-30 21:37:25

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 17,390

Re: Industrial development on Mars

A good rule of thumb is to use a minimum of 50 watts of light per square foot of course plants thrive in full sun, but can adapt to partial shade Minimum sun – 5 hours.  Low-light plants should receive between 10 and 15 watts. So natural light of 430 w m^2 is plenty for mars to grow food with.
https://www.firsttheseedfoundation.org/ … -Light.pdf
Now a 60w light bulb that is LED for the colors that favor food growth will be about 8 to 10 watts to give the same range of lighting energy.

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