Greenhouse - hydroponics vs soil

RobertDyck · 2012-07-25 10:16:54

An email list had this link to a NASA study of food for a Mars mission. There are a few things I want to comment on.

http://www.npr.org/2012/07/24/157313902 … rs-mission

First, the person says a Mars greenhouse would use hydroponics instead of soil. That's got a problem: the nutrient solutions. Any hydroponic system requires several highly concentrated nutrient solutions, and these bottles of liquid are heavy. The weight of those supplies is extensive, hauling that to Mars is highly questionable. You could try to make them on Mars, but extracting them from Mars soil and purifying and concentrating to what's required for hydroponics? That would take a lot of equipment. Again weight, we need to minimize anything we send from Earth. For reliability we also have to keep it simple; remember the engineering mantra: KISS = Keep It Simply Stupid.

This is why I recommend simple soil. Shovel some Mars soil into a pressurized greenhouse, add water, grow crops. Ok, so what do we have to do soil to make it suitable? Mars Phoenix measured soil pH. What it found is what scientists expected based on mineral composition measured by previous missions. Phoenix measured pH 7.7.

http://www.space.com/12695-mars-soil-li … study.html

Neutral pH is 7, so that's ever so slightly alkaline. Most food crops want slightly acidic soil, but you could grow something like asparagus. But this can be treated with simple means. Simply bubble Mars atmosphere under pressure through water. This will create carbonated water, also known as soda water. Mars atmosphere is 95.32% CO2, 2.7% N2, 1.6% Ar, as measured by Viking 2. Earth's atmosphere is 78% N2, and 0.9% Ar. Carbonated water typically has pH between 3 and 4, making it a mild acid. Actually, CO2 dissolved in water is called carbonic acid. This will help neutralize alkaline soil. In fact, this has already been tried by gardeners. The following link talks about adding carbonated water to plants.

http://www.gardenguides.com/131867-effe … lants.html

The acid will dissolve alkali minerals from soil, this is an acid-alkali reaction. Dissolving them into solution makes them readily available to plants. Although the link suggests you have to be moderate with carbonated water, too much is bad for plants.

If you look at all the nutrients in Mars soil, it has everything needed to grow plants. It is low in carbon, but adding carbonated water will help with that. Soil is also low in nitrogen; in fact Mars rovers have not yet discovered any nitrogen at all within detection limits. The APXS instrument has a threshold of 0.1%, so nitrogen is less than that. Ok, so we need to add nitrogen fertilizer. Can you say "ammonium nitrate"? I knew you could.

Fertilizer used on Earth is normally measured in "K-P-N", that is three numbers representing the concentration of potassium, phosphorus, and nitrogen. Simply by selecting the right patch of Mars soil we can get enough K and P.

I could describe how to make ammonium nitrate, but for obvious reasons I do not want to post that on the internet. Let's just say we can make it.

So let's see, this means a Mars greenhouse requires Mars soil, Mars atmosphere, water, breathable air to fill the greenhouse, and this one single fertilizer. That sounds a lot simpler than trying to make hydroponic solutions.

louis · 2012-07-25 16:15:15

RobertDyck wrote:

An email list had this link to a NASA study of food for a Mars mission. There are a few things I want to comment on.
http://www.npr.org/2012/07/24/157313902 … rs-mission
First, the person says a Mars greenhouse would use hydroponics instead of soil. That's got a problem: the nutrient solutions. Any hydroponic system requires several highly concentrated nutrient solutions, and these bottles of liquid are heavy. The weight of those supplies is extensive, hauling that to Mars is highly questionable. You could try to make them on Mars, but extracting them from Mars soil and purifying and concentrating to what's required for hydroponics? That would take a lot of equipment. Again weight, we need to minimize anything we send from Earth. For reliability we also have to keep it simple; remember the engineering mantra: KISS = Keep It Simply Stupid.
This is why I recommend simple soil. Shovel some Mars soil into a pressurized greenhouse, add water, grow crops. Ok, so what do we have to do soil to make it suitable? Mars Phoenix measured soil pH. What it found is what scientists expected based on mineral composition measured by previous missions. Phoenix measured pH 7.7.
http://www.space.com/12695-mars-soil-li … study.html
Neutral pH is 7, so that's ever so slightly alkaline. Most food crops want slightly acidic soil, but you could grow something like asparagus. But this can be treated with simple means. Simply bubble Mars atmosphere under pressure through water. This will create carbonated water, also known as soda water. Mars atmosphere is 95.32% CO2, 2.7% N2, 1.6% Ar, as measured by Viking 2. Earth's atmosphere is 78% N2, and 0.9% Ar. Carbonated water typically has pH between 3 and 4, making it a mild acid. Actually, CO2 dissolved in water is called carbonic acid. This will help neutralize alkaline soil. In fact, this has already been tried by gardeners. The following link talks about adding carbonated water to plants.
http://www.gardenguides.com/131867-effe … lants.html
The acid will dissolve alkali minerals from soil, this is an acid-alkali reaction. Dissolving them into solution makes them readily available to plants. Although the link suggests you have to be moderate with carbonated water, too much is bad for plants.
If you look at all the nutrients in Mars soil, it has everything needed to grow plants. It is low in carbon, but adding carbonated water will help with that. Soil is also low in nitrogen; in fact Mars rovers have not yet discovered any nitrogen at all within detection limits. The APXS instrument has a threshold of 0.1%, so nitrogen is less than that. Ok, so we need to add nitrogen fertilizer. Can you say "ammonium nitrate"? I knew you could.
Fertilizer used on Earth is normally measured in "K-P-N", that is three numbers representing the concentration of potassium, phosphorus, and nitrogen. Simply by selecting the right patch of Mars soil we can get enough K and P.
I could describe how to make ammonium nitrate, but for obvious reasons I do not want to post that on the internet. Let's just say we can make it.
So let's see, this means a Mars greenhouse requires Mars soil, Mars atmosphere, water, breathable air to fill the greenhouse, and this one single fertilizer. That sounds a lot simpler than trying to make hydroponic solutions.

My view is that hydroponics are good for the early decades of the economy, not least because you can stack several growing layers within a habitat - maybe growing four crops in a 2 metre high facility.

But as the colony matures of course we want to use soil. My understanding is that soil is pretty complex business. It's not just the nutrients, you need the organic content as well. There may also be issues over the rock particles on Mars which are different from those on Earth I believe. We might need to ground rocks rather than use existing soil. We'll certainly want to recycle our faeces.

RobertDyck · 2012-07-25 17:23:03

Thank you for replying louis. But I believe hydroponics is complex, because of that solution. You can stack layers with soil trays, so that isn't an issue. Here's an example from the Mars Homestead Project, phase 2.

However, I still argue for ambient light greenhouses. I could go on about life support, but every system has a single point of failure: power. Plants are the only means to recycle air and water without power. But that doesn't work if the greenhouse requires power for artificial light. So for life support backup, I want greenhouses that are long and narrow, long east/west with mirrors on either side to reflect sunlight in through the sides. This will double total illumination, and the mirrors don't have to track the sun. At dawn, sunlight reflects westward by the distance between mirrors and greenhouse. At noon light reflects straight in. When the sun sets in the west, light will reflect eastward, again by the distance between mirror and greenhouse. The only tracking will be for seasons: adjust mirror angle 1/2° every second week to adjust for sun altitude. (The astronomy use of 'altitude', not height.)

The more I read of results from Mars probes (orbiters, landers, and rovers), the more I realize Mars soil is the same as Earth. The only exception is superoxides, and those decompose in seconds upon exposure to liquid water. You know, releasing oxygen by soaking soil is a good thing. It helps inflate the greenhouse.

As for feces, that's more complicated. But that's for a more established settlement. An initial science mission should just use Mars soil alone. Terry Kok has done some work with feces, he found a composting toilet is simpler and more stable than a grey water sewage processing system. Of course the BioMars guys would disagree.

Last edited by RobertDyck (2012-09-25 03:22:49)

louis · 2012-07-26 16:06:26

RobertDyck wrote:

Thank you for replying louis. But I believe hydroponics is complex, because of that solution. You can stack layers with soil trays, so that isn't an issue. Here's an example from the Mars Homestead Project, phase 2.
http://www.marshome.org/images2/albums/ … cam-2C.jpg
However, I still argue for ambient light greenhouses. I could go only about life support, but every system has a single point of failure: power. Plants are the only means to recycle air and water without power. But that doesn't work if the greenhouse requires power for artificial light. So for life support backup, I want greenhouses that are long and narrow, long east/west with mirrors on either side to reflect sunlight in through the sides. This will double total illumination, and the mirrors don't have to track the sun. At dawn, sunlight reflects westward by the distance between mirrors and greenhouse. At noon light reflects straight in. When the sun sets in the west, light will reflect eastward, again by the distance between mirror and greenhouse. The only tracking will be for seasons: adjust mirror angle 1/2° every second week to adjust for sun altitude. (The astronomy use of 'altitude', not height.)
The more I read of results from Mars probes (orbiters, landers, and rovers), the more I realize Mars soil is the same as Earth. The only exception is superoxides, and those decompose in seconds upon exposure to liquid water. You know, releasing oxygen by soaking soil is a good thing. It helps inflate the greenhouse.
As for feces, that's more complicated. But that's for a more established settlement. An initial science mission should just use Mars soil alone. Terry Kok has done some work with feces, he found a composting toilet is simpler and more stable than a grey water sewage processing system. Of course the BioMars guys would disagree.

Great graphic -though I think the soil trays look possibly too shallow for the plants involved.

I am not dogmatic on this - whichever system is most reliable, let's run with that. I think that reliability does require artificial lighting - which is easy to arrange.

I am not sure why would we ever need farm habs as life support. Seems a rather desperate idea.

RobertDyck · 2012-07-26 19:11:28

Backup. Remember there is no way to evacuate from Mars back to Earth. You're on Mars until the planets align for return. So if life support fails, you're dead. With that in mind, I recommend multiple backups, with components that can be mixed-and-matched for even more configurations. If power fails longer than stored oxygen, plants will be your only supply.

That said, preparing for every emergency and every contingency does require artificial lighting as yet another backup. If a Mars dust storm kicks up and covers the hab for several days/weeks/months, then plants will require artificial light. But again, don't design for it. Power can be directed to materials processing if it isn't used for the greenhouse. And again there's that power failure scenario: either live with plants in ambient light or you're dead.

SpaceNut · 2012-07-27 18:30:57

We have talked about the yields of hydroponics versus soil and it does come down to resources such as
negatives
hydroponic water needs are greater
hydroponics also has a higher energy useage for pumps, circulating of the water
positives
hydroponics have a higher fruit (meaning crop) yield per acreage

SpaceNut · 2012-07-28 16:34:14

Hi RobertDyck has there been any research with regards to timelines and crop availability to provide a menu fit to create recipes from....
Say you want to know when you would be able to have a first meal that was Corn Chowder after starting to plant crops....

RobertDyck · 2012-07-29 00:19:02

Upon landing on Mars, unpack all surface equipment. That includes science instruments, garage tent for the rover, and your inflatable greenhouse. The greenhouse would be held down with large tent pegs. Shovel soil into trays. Inflate the greenhouse with a tank of stored air. Set up the trays, an awning inside the greenhouse to reflect heat at night, open it during the day. Again, not my idea, I got that from Dr. Boston's paper. Hang artificial lights, and wire them up. It may take a day or two to get the greenhouse set up. And the astronauts will be called upon to take science measurements. Use an air pump to pressurize Mars atmosphere, that will take a few hours, but can be done at night while they sleep. Then take a bottle of water and pressurize with this Mars atmosphere. That will create soda water, to soak the soil in the trays. Then plant seeds. All this in the first week after landing.

I have a few packages of seeds for garden vegetables. The package records number of days from planting to harvest:
Carrot - Jumbo (coreless) scarlet nantes: 68 days
green pepper - Early California Wonder: 75 days
Corn - Canadian Early Supersweet Hybrid F1: 65-70 days
Peas - Sugar Snap (Edible Pod): 70-75 days

I looked up the website of this seed company, they have more seeds available. http://www.mckenzieseeds.com
Tomato - Rio Grande: 75-85 days
Lettuce - Summertime: 75 days

louis · 2012-07-29 05:36:41

RobertDyck wrote:

Upon landing on Mars, unpack all surface equipment. That includes science instruments, garage tent for the rover, and your inflatable greenhouse. The greenhouse would be held down with large tent pegs. Shovel soil into trays. Inflate the greenhouse with a tank of stored air. Set up the trays, an awning inside the greenhouse to reflect heat at night, open it during the day. Again, not my idea, I got that from Dr. Boston's paper. Hang artificial lights, and wire them up. It may take a day or two to get the greenhouse set up. And the astronauts will be called upon to take science measurements. Use an air pump to pressurize Mars atmosphere, that will take a few hours, but can be done at night while they sleep. Then take a bottle of water and pressurize with this Mars atmosphere. That will create soda water, to soak the soil in the trays. Then plant seeds. All this in the first week after landing.
I have a few packages of seeds for garden vegetables. The package records number of days from planting to harvest:
Carrot - Jumbo (coreless) scarlet nantes: 68 days
green pepper - Early California Wonder: 75 days
Corn - Canadian Early Supersweet Hybrid F1: 65-70 days
Peas - Sugar Snap (Edible Pod): 70-75 days
I looked up the website of this seed company, they have more seeds available. http://www.mckenzieseeds.com
Tomato - Rio Grande: 75-85 days
Lettuce - Summertime: 75 days

...then discover there are microbes on Mars and that you have just reactivated them with your heating and feeding regime...and they have now infected all your personnel...who have no immunity against them...all your people are vomiting both ends...

This is why I think we would need to begin with hydroponics.

Of course using Mars water would not be without its risks, but I think they would be far less than using Mars regolith. I think it would be easier to analyse water prior to use and it could be distilled, could it not?

So, for the first few missions I think safety first demands we use hydroponics.

Soil could be introduced gradually, first with artificial lighting and then using ambient light and light from strategically placed reflectors.

In terms of crops dwarf buckwheat is one of my favourites - the quickest way to get a versatile cereal. Takes about 60 days I think, if I recall correctly. Can be used in a number of ways, including of course the making of nutritious pancakes - very easy.

SpaceNut · 2012-07-29 08:18:12

I am sure that there will be many a favorite crop

http://www.hort.purdue.edu/newcrop/crops/Buckwheat.html

Buckwheat is usually seeded only after the ground is thoroughly warm in early summer. Plants will begin blooming in about 40 days from seeding and first seeds mature about 35 days later. Harvesting is done when a substantial part of the seed is ripe. Fields are then mowed and plants are stacked to dry before they can be threshed.

health benifits

http://www.hort.purdue.edu/newcrop/afcm/buckwheat.html
Buckwheat yields in Wisconsin and Minnesota typically range from 500 to 2,000 pounds/acre. With good management and favorable weather, buckwheat should yield 1,200 to 1,600 pounds/acre in a cool, moist climate that is common in northern Wisconsin or Minnesota.

acre is:= 43,560 square feet or A square plot of ground, 208.7 feet on a side

But can we afford the yield to footprint used....

SpaceNut · 2012-07-29 08:23:24

louis wrote:

...then discover there are microbes on Mars and that you have just reactivated them with your heating and feeding regime...and they have now infected all your personnel...who have no immunity against them...all your people are vomiting both ends...

At first the greenhouse will be entered into with space suits where we will be testing for such occurences to safe guard the crew.

RobertDyck · 2012-07-29 08:36:02

louis wrote:

...then discover there are microbes on Mars and that you have just reactivated them with your heating and feeding regime...and they have now infected all your personnel...who have no immunity against them...all your people are vomiting both ends...

Sounds like a science fiction story, to be blunt. I seriously doubt Mars is infected with something just waiting to eat people.

Mars was barely warm long enough for the equivalent of primative cyanobacteria to evolve. It's questionable whether there was even time for that, the most advanced organism most likely was an archaea. It didn't have enough time to evolve eukariotic cells, much less anything significant. Earth has had billions of years of competing organism, each working out a way to out do the others. It would be a miracle to get past our immune system.

And surface soil is bathed in UV-A, -B, and -C; that last one will sterilize. When Mars had a thick atmosphere with water, it had a degree of UV protection. Today it's ozone layer is so thin it doesn't provide any protection at all. Surface soil will be sterile, scientists will have to dig to find evidence of life.

Finding any life would be the greatest discovery of the mission. It isn't something to fear.

SpaceNut · 2012-07-29 08:43:28

http://science.howstuffworks.com/space-food4.htm
NASA plans to grow fruits and vegetables on space farms -- greenhouses that are temperature-controlled, artificially lit and employ a hydroponic system, which uses nutrients instead of typical soil. Crops might include soybeans, peanuts, spinach, cabbage, lettuce and rice. Wheat berries and soybeans can be grown and processed into pasta or bread. The astronauts would then prepare these foods into home-cooked meals in a galley kitchen. According to NASA, a sample Martian dinner menu might include spinach and tomato crouton salad, wheat pasta with tomato sauce and a chocolate peanut butter soymilk shake

http://www.nasa.gov/audience/formedia/p … heets.html

NASA Planning Vegan Menu for Astronauts Heading to Mars

http://discovermagazine.com/2008/feb/ju … space-food

Then there is the ISS food growth experiments.....

NeoSM · 2012-07-30 13:37:48

I'm in agreement with Rob on using soil; the mineral water isn't necessarily reusable; new water would have to replace the old water over time. Seems to require extra resources that you may not have readily available.

On another note:

Quote from the second article down:
"Last year, PETA made headlines with a request to SpaceX to make their planned colonies on Mars all-vegan. Well, here’s a start: NASA is working on a vegan menu for their astronauts’ mission to the red planet in 2030."

All I have to say is... no. PETA should stay out of it. If you want to accelerate bone loss in lesser gravity, and rise the food production cost, just cut out meat.

Last edited by NeoSM (2012-07-30 13:40:31)

GW Johnson · 2012-07-30 13:52:36

Lessee if I am understanding things correctly.

Is not "soil" for growing plants not a mixture of rock dust and organic material, with some of that organic material supplying texture and water absorption properties, and some of it the nutrients?

If I am correct about "soil", then we mix rock dust from Mars with wet sewage from the astronauts, plus a little fibrous cellulosic waste (shredded paper works, but shredded stems and leaves work better, later on). We put this under an appropriate atmosphere at an appropriate pressure, shield it from too much UV and nuclear radiation, and plant crops in it.

As for Martian microbes, the odds are they are either quite closely related to us by the panspermia hypothesis, or else they are utterly alien. In either case, we're likely OK, and so are they. It wouldn't take very long to find out on one of the probes, or from a sample return, but we need to get on with that task.

Some of us have pretty much figured out how to get people there within 5-10 years. So has Spacex.

GW

louis · 2012-07-30 14:20:13

GW Johnson wrote:

Lessee if I am understanding things correctly.
Is not "soil" for growing plants not a mixture of rock dust and organic material, with some of that organic material supplying texture and water absorption properties, and some of it the nutrients?
If I am correct about "soil", then we mix rock dust from Mars with wet sewage from the astronauts, plus a little fibrous cellulosic waste (shredded paper works, but shredded stems and leaves work better, later on). We put this under an appropriate atmosphere at an appropriate pressure, shield it from too much UV and nuclear radiation, and plant crops in it.
As for Martian microbes, the odds are they are either quite closely related to us by the panspermia hypothesis, or else they are utterly alien. In either case, we're likely OK, and so are they. It wouldn't take very long to find out on one of the probes, or from a sample return, but we need to get on with that task.
Some of us have pretty much figured out how to get people there within 5-10 years. So has Spacex.
GW

I don't think the Martian microbe fear can be dismissed with a wave of the hand. We might not have the equipment to readily identify them. Remember on Earth we have prions which cause disease but they are very poorly understood - we now understand that they are replicating proteins but they were not even identified until 1982. There might be some nasty surprise waiting in the soil. It would be crazy I think to opt for soil on mission one.

I think once we are established and sure the soil is safe we can begin manufacturing soil. It does have some advantages.

RobertDyck · 2012-07-30 17:26:20

Hi GW Johnson. You're right to a point. However, since Mars Global Surveyor we have discovered there are a lot of hydrated minerals. These include clay. Scientists had said that you can't call any surface material "soil" if it doesn't include organic material. They had called everything on Mars "regolith". However, after years of studying the surface in all it's detail, they got tired of that. They now called bedrock "bedrock", they call boulders boulders, they call stones stones, they call gravel gravel, they call sand sand, and that loose stuff that looks like dry dirt that covers the surface of the planet they now call "soil". It doesn't have any organic material, but with ground rock with particle size smaller than loess, together with simple clay, they might as well call it "soil".

Processing sewage to be suitable for growing plants is tricky. You have to break down feces into something plants can use. That means some sort of microbe, either a soggy pile of solid material (composting) or shredding the "logs" to be suspended in water as a brown liquid (digester). Either way the microbes can be finicky. Contamination of food crops with fecal coliform is another danger. I'm trying to avoid that by just using Mars "soil" with carbonated water and ammonium nitrate fertilizer. Once you have crops, then use shredded stems and leaves from the previous crop.

Last edited by RobertDyck (2012-09-25 03:37:55)

RobertDyck · 2012-07-30 17:32:26

NeoSM, yea I read that PETA thing. I'm trying to ignore it. I have one member of the local Mars Society chapter who's a wanna-be vegan. He still eats meat, but talks about being vegan. I mentioned in a talk that a permanent Mars settlement would be vegan at first, just because it's practical. Keeping livestock is energy and resource intensive, read "expensive". And getting livestock there is difficult. This wanna-be vegan really liked that. Then I said once the settlement is rich they could transport livestock; he didn't like that. So now PETA is jumping on the bandwagon. Well, at least that means they're reading my stuff.

louis · 2012-07-30 18:30:03

RobertDyck wrote:

Hi GW Johnson. You're right to a point. However, since Mars Global Surveyor we have discovered there are a log of hydrated minerals. These include clay. Scientists had said that you can't call any surface material "soil" if it doesn't include organic material. They had called everything on Mars "regolith". However, after years of studying the surface in all it's detail, they got tired of that. They now called bedrock "bedrock", they call boulders boulders, they call stones stones, they call gravel gravel, they call sand sand, and that loose stuff that looks like dry dirt that covers the surface of the planet they now call "soil". It doesn't have any organic material, but with ground rock with particle size smaller than loess, together with simple clay, they might as well call it "soil".
Processing sewage to be suitable for growing plants is tricky. You have to break down feces into something plants can use. That means some sort of microbe, either a soggy pile of solid material (composting) or shredding the "logs" to be suspended in water as a brown liquid (digester). Either way the microbes can be finicky. Contamination of food crops with fecal coliform is another danger. I'm trying to avoid that by just using Mars "soil" with carbonated water and ammonium nitrate fertilizer. Once you have crops, then use shredded stems and leaves from the previous crop.

I've kept a plant alive in the office for several years with no biofeed - purely, just feeding it back its own leaves!

NeoSM · 2012-07-30 20:34:27

RobertDyck wrote:

Then I said once the settlement is rich they could transport livestock; he didn't like that.

Win

Also, has there been any research done on Aquaponics systems for Mars? To over simplify it - it's like a hydroponics system, however under the plants (in the water) are fish (usually fast breeding fish like Tilapia). The fish waste serves as food for the plants while the plants generate oxygen and filter the water for the fish to survive and breathe. The fish just keep breeding, and once they "over populate" you just take the extra and eat them. Atleast then we wouldnt be stuck with just plants.

SpaceNut · 2012-07-30 21:10:21

What Do I Need to Know About Recycling Sewage for a Vegetable Garden?

Using Sewage Sludge as Fertilizer

http://www.rid-x.com/faq.shtml

Q: How does RID-X® work?
A: RID-X® Septic Tank System Treatment contains billions of 100% natural active bacteria and enzymes to break down household waste. By adding RID-X®, you restore the delicate balance of beneficial bacterial and enzymes needed to help keep your system operating at full efficiency. Each box and bottle of RID-X® contains the following ingredients scientifically proven to break down household waste:
Cellulase breaks down toilet paper, vegetable matter and some foods
Lipase breaks down fats, oils and grease
Protease breaks down proteins
Amylase breaks down starches
Q: How soon does RID-X® begin work?
A: The enzymes in RID-X® begin working as soon as they come in contact with water. The bacteria take 2-4 hours to germinate and then begin to break down solid waste. If the temperature and conditions are favorable, then the bacteria will multiply to the maximum level that the environment will allow in about 2-4 days. Since septic systems vary, the speed at which the bacteria and enzymes break down waste varies.

Homemade Rid-X

Create a solution of 1 qt. warm water, 2 cups packed brown sugar and 1 package of active dry yeast.

RobertDyck · 2012-07-30 21:24:38

NeoSM wrote:

has there been any research done on Aquaponics systems for Mars?

Several people have talked about that. They usually mention tilapia, a breed of fish often used in aquaculture.
Wikipedia: Tilapia

Last edited by RobertDyck (2012-07-30 21:26:12)

Glandu · 2012-07-31 02:17:06

Tilapia is poor in terms of nutrients. It's far from being as healthy as other fishes. Yet, if it's doable & other fishes are not.....

louis · 2012-07-31 05:58:49

GW Johnson wrote:

Lessee if I am understanding things correctly.
Is not "soil" for growing plants not a mixture of rock dust and organic material, with some of that organic material supplying texture and water absorption properties, and some of it the nutrients?
If I am correct about "soil", then we mix rock dust from Mars with wet sewage from the astronauts, plus a little fibrous cellulosic waste (shredded paper works, but shredded stems and leaves work better, later on). We put this under an appropriate atmosphere at an appropriate pressure, shield it from too much UV and nuclear radiation, and plant crops in it.
As for Martian microbes, the odds are they are either quite closely related to us by the panspermia hypothesis, or else they are utterly alien. In either case, we're likely OK, and so are they. It wouldn't take very long to find out on one of the probes, or from a sample return, but we need to get on with that task.
Some of us have pretty much figured out how to get people there within 5-10 years. So has Spacex.
GW

One issue I am not sure has been bottomed out is I have read the dust on Mars like that on the Moon is potentially very dangerous to inhale. That could be an issue re tending of plants by humans. Does anyone have any information on that?

RobertDyck · 2012-07-31 10:08:57

louis wrote:

One issue I am not sure has been bottomed out is I have read the dust on Mars like that on the Moon is potentially very dangerous to inhale. That could be an issue re tending of plants by humans. Does anyone have any information on that?

Get it wet. Then it isn't dust, it's soil. At least in a greenhouse.

Outside on the surface, astronauts will wear a space suit. When they come in, just ensure the EVA prep room has air filtration. And this is a reason some engineers argue for an MCP spacesuit: it's machine washable.

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#1 2012-07-25 10:16:54

Greenhouse - hydroponics vs soil

#2 2012-07-25 16:15:15

Re: Greenhouse - hydroponics vs soil

#3 2012-07-25 17:23:03

Re: Greenhouse - hydroponics vs soil

#4 2012-07-26 16:06:26

Re: Greenhouse - hydroponics vs soil

#5 2012-07-26 19:11:28

Re: Greenhouse - hydroponics vs soil

#6 2012-07-27 18:30:57

Re: Greenhouse - hydroponics vs soil

#7 2012-07-28 16:34:14

Re: Greenhouse - hydroponics vs soil

#8 2012-07-29 00:19:02

Re: Greenhouse - hydroponics vs soil

#9 2012-07-29 05:36:41

Re: Greenhouse - hydroponics vs soil

#10 2012-07-29 08:18:12

Re: Greenhouse - hydroponics vs soil

#11 2012-07-29 08:23:24

Re: Greenhouse - hydroponics vs soil

#12 2012-07-29 08:36:02

Re: Greenhouse - hydroponics vs soil

#13 2012-07-29 08:43:28

Re: Greenhouse - hydroponics vs soil

#14 2012-07-30 13:37:48

Re: Greenhouse - hydroponics vs soil

#15 2012-07-30 13:52:36

Re: Greenhouse - hydroponics vs soil

#16 2012-07-30 14:20:13

Re: Greenhouse - hydroponics vs soil

#17 2012-07-30 17:26:20

Re: Greenhouse - hydroponics vs soil

#18 2012-07-30 17:32:26

Re: Greenhouse - hydroponics vs soil

#19 2012-07-30 18:30:03

Re: Greenhouse - hydroponics vs soil

#20 2012-07-30 20:34:27

Re: Greenhouse - hydroponics vs soil

#21 2012-07-30 21:10:21

Re: Greenhouse - hydroponics vs soil

#22 2012-07-30 21:24:38

Re: Greenhouse - hydroponics vs soil

#23 2012-07-31 02:17:06

Re: Greenhouse - hydroponics vs soil

#24 2012-07-31 05:58:49

Re: Greenhouse - hydroponics vs soil

#25 2012-07-31 10:08:57

Re: Greenhouse - hydroponics vs soil

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