Self-replicating colony - a challenge but how difficult?

louis · 2018-07-05 16:23:43

Yes, it's a big job. To feed 100,000 people, you'd maybe need anything between 15 and 25 million tonnes of soil, depending how much natural light farming you have.

But at least with a synthetic soil, you know you have a perfect soil (or series of soils, designed for different crops).

I can't imagine it would be much more difficult than testing Mars regolith suitable for growing (which might not be close to your main base/city) clearing it of contaminants like perchlorate and where necessary conditioning it.

Once you have your soil factory in place, I think you could get production up to 500,000 tonnes an Earth year (processing about about 1400 tonnes per sol) in a highly automated facility.

However, we'd probably mix and match...I was forgetting there's no reason why we can't have hydroponic agriculture under natural light conditions.

And yes, I am sure we can make the required fertilisers on Mars but calcium is not very common on Mars it would appear. Or am I wrong on that?

RobertDyck wrote:

Manufacturing soil "from scratch" is a bigger job than you realize. It requires grinding rock to the consistency of flour; it's called rock flour. Then decompose the rock flour to create clay and release nutrients: sodium, potassium, calcium, magnesium. Nature uses moving water over millions of years, it can be accelerated with acid. Peat is a symbiosis of sphagnum moss with a variety of cyanobacteria. That moss produces acid, specifically designed to decompose rock to release nutrients. However, peat normally takes thousands of years. Grinding to rock flour first would accelerate the process, but I tried it in an aquarium. It released so much calcium and magnesium that it converted the water to alkali, killing the peat. Doing this with peat requires an active means to remove calcium and magnesium. When the peat is finished decomposing rock flour, the calcium and magnesium would have to be added back to neutralize the acid. And plants require those nutrients, for one they use a single atom of magnesium for each molecule of chlorophyll. Humans use both calcium and magnesium for bone, so it has to be in our food.
.

SpaceNut · 2018-07-05 17:17:48

The same machines used for grinding up regolith for iron or other mineral ores is the same equipment that will grind up more of it to be able to make soils as well. The same selected ground up soils will be used to make lot of thinks if it has the right chemical signatures to be used. Some will be desolved into solution while others will be used to make glass, iron, aluminum ect..
Send early machines that make the process path of use of the machines in the most common manner.

louis · 2018-07-05 18:13:19

Yes, I am sure there would be a lot of synergy between mining for industry and mining for synthetic soils, with often the powdery residues being used in synthetic soils.

SpaceNut wrote:

The same machines used for grinding up regolith for iron or other mineral ores is the same equipment that will grind up more of it to be able to make soils as well. The same selected ground up soils will be used to make lot of thinks if it has the right chemical signatures to be used. Some will be desolved into solution while others will be used to make glass, iron, aluminum ect..
Send early machines that make the process path of use of the machines in the most common manner.

kbd512 · 2018-07-05 18:57:44

Obtaining the quantity of mineral enriched regolith required to sustain a significant population is probably impractical in the near term. However, pressurized subterranean tunnels using lightweight aeroponic and hydroponic systems have become much more feasible in recent years as a function of the efficiency of LED lights, light pipes, and diffusion of coherent light from solid state lasers. Apart from experimentation in Russia that claimed to double growth rates for certain food crops exposed to diffuse low wattage laser light, it should come as no surprise that marijuana growers in the US have been using lasers in their grow operations for the same reason. Furthermore, it seems to have prevented a lot of diseases from fungal infections and the insects don't like it, either. There have also been some claims made that the taste of the product improved, but that may just be the difference between a very healthy and pesticide-free plant and one that suffers from diseases or has been drowned with chemicals. Furthermore, there have been experiments with higher energy laser pulses from robots that could differentiate food plants from weeds in order to kill the weeds. It may be possible to use a combination of robotics and optical technologies to improve crop yields in small spaces by optimizing growing conditions and exterminating undesirable plants or pests.

I like the idea of using autonomous systems to handle most of the drudge work, but the sort of systems required presently work much better with human reasoning in the loop. Lots of things could change in the future, but here in the present some combination of humans and robots working together is required to build a successful Mars colony. SpaceNut also wrote about selecting technology sets with synergistic effects for other parts of the overall survival strategy. I also think that's very important.

RobertDyck · 2018-07-05 19:44:17

Producing gardening soil on Earth starts with animal manure. Primary ingredients are compost and manure. We won't have animals at first, or not many, so that doesn't work. The non-animal method is what I described. Using human manure is tricky, and definitely will be done; others far more qualified than I are already working on it.

Fertilizer on Earth is usually rated in K-P-N: potassium, phosphate, nitrogen. I already described nitrogen fertilizer. Potassium is usually from mined potash. That comes from a deposit where an ancient salt sea completely dried up. The Mediterranean completely dried up millions of years ago, long before humans evolved, when dinosaurs roamed the Earth. Plate tectonics closed the strait of Gibraltar. When a sea that large dries up, it leaves layers of different salt: sodium chloride (table salt), potassium chloride (potash), calcium chloride (road salt). What is now the Great Lakes was a salt sea at one point in the past, and it also dried up. This left layers of salts beneath the lakes, which is now being mined. So the ancient ocean of Mars must have left similar layers of salt. The trick is to find the last part that dried up, and look there. The salt is probably deep below ground, like the Mediterranean and Great Lakes. A good place to start looking would be that underground water ice deposit in Utopia Planetia that SpaceNut posted about in Mining Water Ice on Mars.

louis · 2018-07-06 04:22:52

Not clear if you are suggesting that the amount of energy required for indoor farming lighting could be substantially less than the natural energy resulting from insolation. In just one hectare on Earth in the temperate zone insolation could amount to something like 35,000 Kwhs per day - or nearly 3Mws average in 12 hours of light. It's a lot of energy required just to grow maybe just 3 tonnes of food in one year. A community of 100,000 would need 150 tonnes of food every single sol.

Light pipes should certainly be explored. But I suspect the infrastructure requirement would be more costly in terms of applied resources than even a PV system.

Nuclear power could of course provide the power, but then a big nuclear power station would require a lot of human monitoring and intervention, that would be my understanding, and if something goes wrong, there's not a lot you can do to put things right. But really it's the scale that's the problem. I doubt that anyone could think in terms of building a 55GW network of nuclear power stations. I don't believe that would be feasible for a community of 100,000.

On balance I think natural light with surrounding reflectors is probably the right way to go once you reach a certain population (probably around 1000), although I am sure there also be a substantial amount of indoor farming under artificial light (probably for the fast growing crops which can be grown on trays in tiers and which will provide several crops per "year". Regarding reflectors, the weather on Mars is thankfully benign so your reflectors don't need any major support structure.

Creating the farm habswill be a huge call on resources but is pretty much an upfront investment. I think domes are likely to be an inefficient method of construction. Why not have terraces in south facing hillsides with a single glass frontage? Then place reflectors on opposite slopes...

Of course dust storms will disrupt food production, which is why you would need to have substantial food stocks. To cover 400 sols of extreme dust storm conditions would require a reserve stock of 60,000 tonnes for a community of 100,000. That mass could be reduced if you stored a lot of food as dried food of course.

There don't seem to be any easy solutions regarding farming in a pre-terraformed Mars, and the problem comes down to the amount of energy required for plant growth.

kbd512 wrote:

Obtaining the quantity of mineral enriched regolith required to sustain a significant population is probably impractical in the near term. However, pressurized subterranean tunnels using lightweight aeroponic and hydroponic systems have become much more feasible in recent years as a function of the efficiency of LED lights, light pipes, and diffusion of coherent light from solid state lasers. Apart from experimentation in Russia that claimed to double growth rates for certain food crops exposed to diffuse low wattage laser light, it should come as no surprise that marijuana growers in the US have been using lasers in their grow operations for the same reason. Furthermore, it seems to have prevented a lot of diseases from fungal infections and the insects don't like it, either. There have also been some claims made that the taste of the product improved, but that may just be the difference between a very healthy and pesticide-free plant and one that suffers from diseases or has been drowned with chemicals. Furthermore, there have been experiments with higher energy laser pulses from robots that could differentiate food plants from weeds in order to kill the weeds. It may be possible to use a combination of robotics and optical technologies to improve crop yields in small spaces by optimizing growing conditions and exterminating undesirable plants or pests.
I like the idea of using autonomous systems to handle most of the drudge work, but the sort of systems required presently work much better with human reasoning in the loop. Lots of things could change in the future, but here in the present some combination of humans and robots working together is required to build a successful Mars colony. SpaceNut also wrote about selecting technology sets with synergistic effects for other parts of the overall survival strategy. I also think that's very important.

Last edited by louis (2018-07-06 04:25:33)

kbd512 · 2018-07-06 07:52:29

Louis,

I'm suggesting that a suite of technologies be employed to improve growing conditions for plants on Mars. All of what goes to Mars is a question of mass and volume. Humans can't live on the surface, and likely many food crop plants can't either, as a function of the constant high energy ion bombardment and SPE's that generally are lethal to both humans and food crops. Whether or not something will be flat-out killed by the surface radiation environment is irrelevant to what optimal conditions are for plant health.

It's been well proven here on Earth that soil is not required for plants to grow well. A series of lightweight plastic tubes with nutrient drips could provide the sustenance required for crops to grow on Mars. A series of light pipes could carry light from the surface to the plants. Solar pumped lasers have been existing technology for some time now. Small robots could tend to the crops, killing weeds or bugs and harvesting the crops when the time comes.

As far as where to farm is concerned, use vertical bore holes. Put a fresnel lens that feeds a solar pumped laser on top and then use light pipes, otherwise known as fiber optics, to distribute light to the plants in the module. A water bag on top will absorb ionizing radiation and feed nutrient rich water to the plants below using a combination of gravity and heat from a molten salt tank.

A laser or direct solar beam power, whichever works best from a mass and volume standpoint, would heat the molten salt tank at the bottom of the module to provide temperature regulation, pumping power, and pressurization. There are lots of ways to use the Sun to provide food for the colonists while we get started there. Heck, there's even a solar cell that directly converts water to O2/H2, so a micro turbine could burn the gases produced during the day to produce steam. The process would repeat in daily cycles. If mass and volume are limited, but electrical power less so, then use solid state lasers and LED lights for 24/7 growth. There are many ways to do this, but your point about how much power is required is valid.

In the end, the kind of power required to support 100K colonists indefinitely on Mars will realistically only come from chemical fuels produced on Mars or nuclear fuels produced on Earth, as a function of mass and volume.

louis · 2018-07-06 18:42:10

I do agree on reflection that hydroponic agriculture makes a lot more sense than manufacturing soil (although you still need to manufacture your nutrient solution). Creating synthetic soils is probably more appropriate for developing Earth-like leisure areas on Mars.

However, I don't think the energy issue will go away because it is just huge, huge, huge. If you were to produce enough food to feed a colony of 100,000 in a year it could take up to 55Gws of power (forgetting about heating), depending on what crops you grow. If you use light pipes effectively you need to cover the same area as the crop - possibly up to 18000 hectares (about 134kms x 134kms) in the case of feeding a colony of 100,000. That is a vast amount of infrastructure that your small colony would need to put in place. BTW 55 Gws is getting close to the whole electricity usage of the UK (around 60 Gwes on average) - serving a population of 65 million plus.

It doesn't seem to me that there are many ways of getting the energy bill down, apart from perhaps favouring low energy crops...probably means moving away from grains.

If radiation is a problem for plants (I thought orbital experiments had suggested plants are far less susceptible to growth damage compared with animals) then we may need to use water or ice (in glass cabinets) to filter out radiation. This, again, suggests that terracing, to reduce the amount of structure involved in creating natural light environments would be best.

This is the best representation of the "terraces under glass" concept I can find on Earth:

http://www.momtastic.com/webecoist/2013 … ormations/

kbd512 wrote:

Louis,
I'm suggesting that a suite of technologies be employed to improve growing conditions for plants on Mars. All of what goes to Mars is a question of mass and volume. Humans can't live on the surface, and likely many food crop plants can't either, as a function of the constant high energy ion bombardment and SPE's that generally are lethal to both humans and food crops. Whether or not something will be flat-out killed by the surface radiation environment is irrelevant to what optimal conditions are for plant health.
It's been well proven here on Earth that soil is not required for plants to grow well. A series of lightweight plastic tubes with nutrient drips could provide the sustenance required for crops to grow on Mars. A series of light pipes could carry light from the surface to the plants. Solar pumped lasers have been existing technology for some time now. Small robots could tend to the crops, killing weeds or bugs and harvesting the crops when the time comes.
As far as where to farm is concerned, use vertical bore holes. Put a fresnel lens that feeds a solar pumped laser on top and then use light pipes, otherwise known as fiber optics, to distribute light to the plants in the module. A water bag on top will absorb ionizing radiation and feed nutrient rich water to the plants below using a combination of gravity and heat from a molten salt tank.
A laser or direct solar beam power, whichever works best from a mass and volume standpoint, would heat the molten salt tank at the bottom of the module to provide temperature regulation, pumping power, and pressurization. There are lots of ways to use the Sun to provide food for the colonists while we get started there. Heck, there's even a solar cell that directly converts water to O2/H2, so a micro turbine could burn the gases produced during the day to produce steam. The process would repeat in daily cycles. If mass and volume are limited, but electrical power less so, then use solid state lasers and LED lights for 24/7 growth. There are many ways to do this, but your point about how much power is required is valid.
In the end, the kind of power required to support 100K colonists indefinitely on Mars will realistically only come from chemical fuels produced on Mars or nuclear fuels produced on Earth, as a function of mass and volume.

SpaceNut · 2018-07-06 19:25:38

Well we have ground up the soils, selected the minerals to make glass and other stuff needed for a greenhouse to viable on the surface. We have made a thick walled clear glass for making so that light will shine through so long as the rocks/small pepples are not whipped around by the martian winds causing it to break. So what is the floor made of to complete the greenhouse, how will we build the air lock for a crewman to be able to go inside....?
So a little glass with reflective aluminum vapor coating the glass to make it into the mirrors can be done as well as making thin metal mirrors but what about the sand blasting that mars will have for months at a time and its effects on what man wants to do?

RobertDyck · 2018-07-07 06:02:14

louis wrote:

Not clear if you are suggesting that the amount of energy required for indoor farming lighting could be substantially less than the natural energy resulting from insolation.
kbd512 wrote:
...

You two are debating this. I have pointed out that all other life support systems have a single point of failure: power. The only life support system capable of recycling oxygen without any power what so ever is an ambient light greenhouse. On a planet without a breathable atmosphere, that's very important. A greenhouse is far too bulky for an interplanetary spacecraft, but perfect for the surface of Mars. No fancy technology, just tempered glass roof and tempered glass walls. "Tempered" to make the glass harder than sand and dust grains blown in a dust storm, so it doesn't scratch. If the glass is not harder, a dust storm will "sand blast" the windows, crazing them. Most vegetables don't need anything more than that, but grain crops including wheat require full sun, so mirrors to double illumination. Again I argue for long narrow greenhouses oriented perfectly east-west with flat mirrors along the sides. This means mirrors do not have to track the sun. When the sun rises in the east, light would reflect westward, but with a long greenhouse that just shines the light into a different part of the greenhouse. At high noon light would reflect perfectly perpendicular into the greenhouse. When the sun sets in the west, light would reflect eastward, again shining into a different part of the greenhouse. Mirror angle would have to be adjusted for season, but that requires 1° change of mirror angle every 14 Mars solar days (sols). So every second week. If power completely failed, an astronaut could go outside in a spacesuit to adjust mirror angle by hand.

This does not require light pipes or anything fancy. Remember overall radiation on Mars is half that of ISS, and astronauts survive there just fine. A permanent settlement would want radiation shielding for habitats, but plants are much more hardy vs radiation. Greenhouse windows would have a spectrally selective coating to filter out UV B and C, and most of UV A. The coating NASA used for spacecraft windows for years is a very thin coating of metal, vacuum deposited: gold, nickel, and silver oxide. There are other chemical coatings now, but the metal has the additional effect of blocking X-rays. There isn't much X-rays in space, but the metal coating would shield what little there is. At a low altitude location like Elysium Planetia or Utopia Planetia, the atmosphere of Mars blocks 98% of heavy ion galactic cosmic rays. Greenhouse windows would block all beta radiation, and the metal coating would block all alpha radiation. So you don't need and don't want to bury a greenhouse.

In case of long duration dust storms, artificial light would be necessary. But don't design the greenhouse to require it for normal operation. That's just for emergency use. Again, one purpose of the greenhouse is life support in case of total power failure. And you want to reserve power for industrial uses. During a dust storm, all industry would shut down, power would be used for life support.

kbd512 · 2018-07-07 06:55:35

Rob,

The overall radiation on Mars is half that on ISS when there are no severe SPE's to contend with. Unfortunately, there are severe SPE's to contend with. The radiation measurements from Curiosity proved that. The data is freely available to anyone who wants to look at it and it's already been posted in another thread. I can't recall which of us did that right now and I'm too lazy to hunt it down for you, but at least one of us already did (maybe you?). If the greenhouse glass is thick enough, as in thick enough to hold in an Earth sea level atmosphere, then it's also thick enough to attenuate most of the radiation events to survivable levels. For what should be obvious reasons, that's never going to be sent to Mars. If concrete and glass can be made on Mars, then there's no practical reason why a greenhouse can't be built that uses mass of materials to both contain an Earth-like atmosphere and attenuate SPE's. However, the glass won't attenuate GCR's. The effect may be less than aboard ISS, but it's still there. I'm not concerned about the heavy GCR's. That's rarefied stuff compared to Hydrogen ions.

So far as I'm aware, the only two truly closed loop life support experiments conducted on Earth in Biosphere 2 to sustain human life have failed. It's not that it can't work or won't ever work, but substantially more experimentation is required. I do not look with favor upon the idea that an absolutely inhospitable planet be used as a testing ground with human guinea pigs. I'm trying to first create the technosphere from the biosphere experiments.

Fast forward to about the 13 minute mark and listen to what the man has to say:
Inside Biosphere 2: The World's Largest Earth Science Experiment

That's what I've been trying to explain to Louis, with respect to what needs to be done on Mars, during initial experimentation. Until we can prove that the biosphere works, the colonists can't rely upon science experiments for food, water, or air. Our technological capabilities and understanding of basic biology are at least two generations from being able to sustain 100K people on Mars.

Terraformer · 2018-07-07 06:58:59

Biosphere 2 attempted to be completely closed loop, though? On Mars, water and CO2 can be added to make up losses (as I remember, losing CO2 was one of the problems they had, since the concrete was absorbing it). We can also use artificial buffering.

SpaceNut · 2018-07-07 09:03:19

So we will need to replicate vapor depositing of coatings on glass as well as figuring out how to temper the glass but what about the floor?
https://en.wikipedia.org/wiki/Physical_vapor_deposition
This also opens up making solar cells as well.

https://www.corning.com/worldwide/en/in … ition.html

I can see that there are many ways to do this..

SpaceNut · 2018-07-07 13:01:10

Here's what future Mars and lunar space colonies could look like

AAzHryh.img?h=416&w=799&m=6&q=60&u=t&o=f&l=f

Looks more like a dump with all the busted parts....

https://www.nasa.gov/directorates/space … about.html

RobertDyck · 2018-07-07 14:12:40

kbd512 wrote:

The overall radiation on Mars is half that on ISS when there are no severe SPE's to contend with. Unfortunately, there are severe SPE's to contend with.

And the Nile river has periodic floods. You can't grow crops on land that's flooded. That doesn't stop them from growing crops anyway; they just replant. In fact, floods bring fresh silt that enrich the soil. Severe solar radiation events will likely kill crops. Fine, replant. Keep a bank of seeds in a radiation shielded bunker.

kbd512 wrote:

The radiation measurements from Curiosity proved that.

I would like to see data, how often do radiation events happen. I posted data from Mars Odyssey, it has overall radiation with calculated estimates of surface radiation.

kbd512 wrote:

If concrete and glass can be made on Mars, then there's no practical reason why a greenhouse can't be built that uses mass of materials to both contain an Earth-like atmosphere and attenuate SPE's. However, the glass won't attenuate GCR's. The effect may be less than aboard ISS, but it's still there. I'm not concerned about the heavy GCR's. That's rarefied stuff compared to Hydrogen ions.

Yes, most radiation on the surface is proton. And most of that is solar, so lower energy. GCR includes light ions, which get through the atmosphere. About half of GCR medium ions are blocked by the atmosphere. I'm thinking that Mars permanent settlement habitat windows would have two panes, with mineral oil between. That's what radiation work cells used in the 1950s, and the NERVA test stand in the 1970s used. I have fantasies of building a villa on Mars, with a dome built on the peak of a hill overlooking the surrounding area. A single piece of ALON (Aluminum oxynitride), strong enough to stop substantial meteorites. A double wall dome with mineral oil between, each dome a single cast. With the natural bedrock of the hill as floor of this room, and a big round bed in the centre of the room. Obviously the dome would require strong anchors into the bedrock to hold it down due to pressure. The rest of the habitat would have 2.4 to 3 metre thick regolith over concrete, with a metal pressure vessel inner wall. Meteorites could strike the regolith on the roof all they want. And windows in walls would have a roof overhang to shade them from radiation, as well as protection from meteorites. That overhang would also be built of reinforced concrete with regolith piled on top. The special round bedroom on the hilltop would have a stairway leading into the floor from the rest of the habitat. The stairway would require a trap door that could close pressure tight, and at the bottom a door in a wall that could also seal pressure right. In case of pressure leak, the stairway could act as an airlock. With something like 2" thick ALON and 4" to 6" of mineral oil between, that room would be perfectly safe most of the time. During an SPE just evacuate that room. Visualize lying on the bed with a beautiful woman, watching the sunset with salmon pink sky and baby blue sunset. Yes, the sky straight up would most likely be dark blue and the brightest stars visible even during the day. With natural bedrock floor and 360° view to the horizon in all directions, it would be the closest to being outdoors without a spacesuit.

kbd512 wrote:

So far as I'm aware, the only two truly closed loop life support experiments conducted on Earth in Biosphere 2 to sustain human life have failed. It's not that it can't work or won't ever work, but substantially more experimentation is required. I do not look with favor upon the idea that an absolutely inhospitable planet be used as a testing ground with human guinea pigs. I'm trying to first create the technosphere from the biosphere experiments.

Johnson Space Centre tried a smaller closed-loop experiment. They had a single man live in a sealed habitat with a small greenhouse and exercycle. When he exercised, plants grew faster. They measured and documented it. That was because he exhaled more CO2 while exercising, elevated CO2 caused accelerated plant growth. But the greenhouse was enough to recycle oxygen, not enough to grow food. He lasted several months.

Biosphere 2 had a few problems. One was they used twigs to add organic matter to poor soil for at least one of their biomes. They forgot to take into account O2 consumed by bacteria that decayed those twigs.

kbd512 wrote:

Until we can prove that the biosphere works, the colonists can't rely upon science experiments for food, water, or air.

The largest problems with Biosphere 2 were O2 recycling, and the fact their bean crop failed. Every time they tried to clean the plant infection plaguing the beans, it came back. My argument has been a Mars habitat should use greenhouses for primary life support, but have chemical/mechanical as a backup. On a planet without a breathable atmosphere, you absolutely require multiple backups. So if you have a lack of O2 like Biosphere 2, then turn on the water electrolysis tank. Or direct CO2 electrolysis. Again, multiple backups that use different principles: belt, suspenders, and a couple other things too.

Last edited by RobertDyck (2018-07-07 18:36:24)

louis · 2018-07-07 14:40:47

I think that is a very important point. A lot of their problems came from inability to resupply or vent. I think there was also a build up of humidity - leading to mould formation.

Terraformer wrote:

Biosphere 2 attempted to be completely closed loop, though? On Mars, water and CO2 can be added to make up losses (as I remember, losing CO2 was one of the problems they had, since the concrete was absorbing it). We can also use artificial buffering.

louis · 2018-07-07 14:50:32

Very interesting! Mr Musk might follow your plan when he moves to Mars.

RobertDyck wrote:

Yes, most radiation on the surface is proton. And most of that is solar, so lower energy. GCR includes light ions, which get through the atmosphere. About half of GCR medium ions are blocked by the atmosphere. I'm thinking that Mars permanent settlement habitat windows would have two panes, with mineral oil between. That's what radiation work cells used in the 1950s, and the NERVA test stand in the 1970s used. I have fantasies of building a villa on Mars, with a dome built on the peak of a hill overlooking the surrounding area. A single piece of ALON (Aluminum oxynitride), strong enough to stop substantial meteorites. A double wall dome with mineral oil between, each done a single cast. With the natural bedrock of the hill as floor of this room, and a big round bed in the centre of the room. Obviously the dome would require strong anchors into the bedrock to hold it down due to pressure. The rest of the habitat would have 2.4 to 3 metre thick regolith over concrete, with a metal pressure vessel inner wall. Meteorites could strike the regolith on the roof all they want. And windows in walls would have a roof overhang to shade them from radiation, as well as protection from meteorites. That overhang would also be built of reinforced concrete with regolith piled on top. The special round bedroom on the hilltop would have a stairway leading into the floor from the rest of the habitat. The stairway would require a trap door that could close pressure tight, and at the bottom a door in a wall that could also seal pressure right. In case of pressure leak, the stairway could act as an airlock. With something like 2" thick ALON and 4" to 6" of mineral oil between, that room would be perfectly safe most of the time. During an SPE just evacuate that room. Visual lying on the bed with a beautiful woman, watching the sunset with salmon pink sky and baby blue sunset. Yes, the sky straight up would most likely be dark blue and the brightest stars visible even during the day. With natural bedrock floor and 360° view to the horizon in all directions, it would be the closest to being outdoors without a spacesuit.

SpaceNut · 2018-07-07 15:02:13

I agree think the windows in the ISS for the ability to shield man from the effects of damaging dust/rocks that would hit any glass and of course if the materials selected are correct any SPE events are mitigated before we have to figure out the amount or coincidences of how often they occur.

louis · 2018-07-07 17:17:55

Presumably any floor would have an aerogel or equivalent layer. Over the insulating layer, I favour basalt tiles being laid. Another option might be bamboo wood floors. You can get a very nice finish:

https://en.wikipedia.org/wiki/Bamboo_floor

But making and installing bamboo flooring might be quite labour intensive, whereas basalt tiles could be pretty straightforward.

SpaceNut wrote:

So we will need to replicate vapor depositing of coatings on glass as well as figuring out how to temper the glass but what about the floor?
https://en.wikipedia.org/wiki/Physical_vapor_deposition
This also opens up making solar cells as well.
https://www.corning.com/worldwide/en/in … ition.html
I can see that there are many ways to do this..

SpaceNut · 2018-07-08 07:26:02

Still looking at how the glass ties into the flooring to complete the sealing of the chamber.

talking about what will be grown in the older topics.

This concrete (yes, concrete) is going high-tech

Concrete has an emissions problem. Its essential ingredient, cement, has a huge carbon footprint.
Cement is the glue that makes concrete strong, but the process of making cement requires superheating calcium carbonate, or limestone, and releases massive amounts of carbon dioxide into the atmosphere.
Cement is responsible for 7% of global man-made greenhouse emissions, making it the world's second largest industrial source of carbon dioxide, according to the International Energy Agency.
CarbonCure's system takes captured CO2 and injects it into concrete as it's being mixed. Once the concrete hardens, that carbon is sequestered forever. Even if the building is torn down, the carbon stays put. That's because it reacts with the concrete and becomes a mineral.

https://www.carboncure.com/

RobertDyck · 2018-07-08 12:54:35

SpaceNut wrote:

Cement is responsible for 7% of global man-made greenhouse emissions, making it the world's second largest industrial source of carbon dioxide, according to the International Energy Agency.
CarbonCure's system takes captured CO2 and injects it into concrete as it's being mixed. Once the concrete hardens, that carbon is sequestered forever. Even if the building is torn down, the carbon stays put. That's because it reacts with the concrete and becomes a mineral.

This is really isn't a solution. People and companies won't do it because this costs money to do, but doesn't significantly increase strength of the concrete. A better solution is to recycle concrete. But companies just want to buy stuff, they don't understand where cement comes from. I found most companies don't understand recycling.

Making cement from rock:
CaCO3 → CaO + CO2
SiO2 + CaO → Ca3SiO5 or 3CaO.SiO2

Setting cement:
2 Ca3SiO5 + 7 H2O ---> 3 CaO.2SiO2.4H2O + 3 Ca(OH)2 + 173.6kJ

The obvious solution is bake old concrete in the same kiln used to make Portland cement. Sand and gravel used as aggregate in concrete will throw the balance off. The solution is to add more limestone. It has become common practice to use old concrete as aggregate, so that means the chemical balance won't be thrown off as much, so baking that to cement won't require as much limestone. Recycling concrete to cement will require far less limestone than making cement from new rock. That means less old concrete to dispose of, and less CO2 released in the process of making cement.

I tried to recommend this to one engineer who worked for Manitoba Hydro. She and other engineers complained about the condition of the old dam; it was over 100 years old. Rather than try to fix cracks in the concrete, they wanted to build a new dam. It's a remote site, a custom rail line to access it. She wanted to build a road to the site, so cement trucks to build a new dam. I pointed out recycling old concrete on-site would dramatically cut down on transportation cost, and reduce cost of cement and aggregate to make concrete. She didn't want to do that, she wanted to buy new stuff. She didn't even know how cement is made, she just knew how to order it from a catalogue.

Terraformer · 2018-07-08 16:21:31

From watching Rocket City Rednecks, that does seem to be an issue with a lot of engineers, probably the worse the younger they are. They're intelligent and knowledgeable about a lot of stuff, but lack hands on experience in actually making things, so they'll propose things which work in theory but can't be implemented in practice. But I'm not an engineer, so I don't have first hand experience of this. GW Johnson will know more about that.

SpaceNut · 2018-07-08 17:45:16

On mars it will take many building cycles before we will be looking at the agregate reuse for marscrete from taring down an old building or expanding an existing shape of one. The again we can use broken glass spheres in the marscrete as well.

Mark Friedenbach · 2018-07-09 15:24:53

I’m very surprised this hasn’t been mentioned yet in the thread, the definitive resource on self-replicating machinery:

http://www.molecularassembler.com/KSRM.htm

And the NASA study:

https://ntrs.nasa.gov/archive/nasa/casi … 007077.pdf

SpaceNut · 2018-07-09 19:41:04

Nano and molecular machines will require quite a bit of energy to make them make anything useful so we could just bring a batch of different bacteria to do the work for use....

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