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SpaceX Mars City Buildings / Plan


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1 hour ago, kerbiloid said:

What about the food? Are they going to deliver it or to grow/herd?
(This depends on the population size. Is it enough large to need the local farming, or they will be happy if throw them a truck of frozen chickens once per year.)

I think we'd need to store the plants where there'd still be some natural lighting... Honestly this is the one where we absolutely need transparent inflatable structures (like greenhouses here on Earth), if you want to grow everything completely underground we'd need more electricity.

That being said given the low light levels could a dedicated grow light be more efficient than natural lighting ? I imagine we need some augmentation anyway even in daytime but if we end up providing as much augmentation as it'd be for complete grow light replacement then we'd better ditch the natural lighting completely.

One thing which just came to my realization is that the plants will process CO2 and return them as O2... so maybe we don't need as much O2 or H2 (for sabatier), we just need N2 and the H2 needed for refueling rockets.

Animal husbandry would need a lot of population to start, and there are ways to mitigate the lack of animal sources of nutrition, but at the very least growable stuff is needed.

Edited by YNM
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38 minutes ago, YNM said:

Honestly this is the one where we absolutely need transparent inflatable structures (like greenhouses here on Earth), if you want to grow everything completely underground we'd need more electricity.

Here on the Earth you need ~1 hectare (10 000 m2) of plowland per human to keep him supplied with all kinds of supplies (don't forget the crop rotation). 
A little much for the inflatables. Also the radiation kills the plants just a little less effectively than animals.
Glass is required. A lot of it. And on the Earth you need glassy greenhouses only for vegetables, not for crops and potatoes.

38 minutes ago, YNM said:

That being said given the low light levels

So, ~2 hectares on Mars.

Edited by kerbiloid
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26 minutes ago, kerbiloid said:

Here on the Earth you need ~1 hectare (10 000 m2) of plowland per human to keep him supplied with all kinds of supplies (don't forget the crop rotation). 
A little much for the inflatables. Also the radiation kills the plants just a little less effectively than animals.
Glass is required. A lot of it. And on the Earth you need glassy greenhouses only for vegetables, not for crops and potatoes.

I've heard that in NL they manage to produce 45 tonnes of potatoes per ha cultivated per year nationally, also 505 tonnes of tomatoes per ha cultivated per year. They extensively use hydroponics and artificial lighting (a fairly extensive article from NatGeo from 2017, figures are taken from that article although it reports in "tons" which I presume is US tons). I think it should be possible to push the size down, we just have to think in 3D and we'd need extensive use of hydroponic.

Although they also sometimes ditch the natural lighting completely so perhaps we could do the same underground.

Edited by YNM
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4 hours ago, kerbiloid said:

Depends on the aim, obviously.

What about the food? Are they going to deliver it or to grow/herd?
(This depends on the population size. Is it enough large to need the local farming, or they will be happy if throw them a truck of frozen chickens once per year.)

Just everything starts from food processing, from its appearing to disappearing. And everything other is bound to that.

I assume early small groups have a stock of food, then they try and figure out at least some sort of farming to supplement it. The goal here (Musk and SpaceX types "talking" here, not ME) is a completely self-reliant human civilization there (hence his calls for a million people). Myself, I think they run out of food and start eating the weak, lol.

So yeah, food is critical.

7 hours ago, YNM said:

The first few habs (apart from the repurposed landers) would have to be inflatable I guess... Bring pressurized/liquefied oxygen and nitrogen for the first few missions, later on use sabatier reaction + electrolysis to provide oxygen although we'd still need regular supply of nitrogen and hydrogen.

Yeah, heck, early habs are prebuilt—live in Starships that are not leaving.

The logistics of this are fascinating (even if incredibly unlikely).

 

7 hours ago, YNM said:

Building the habs from scratch, I'm tempted to see more of a concrete/adobe thing rather than more inflatables or tin cans. Inflatables usually mean hydrocarbon which we don't have a lot of at hand. Blast furnaces (and later oxygen blowing for steelmaking) requires oxygen to work so I think that's a lot of oxygen used up just to refine iron/steel. I'm imagining more of reinforced earth structure with the reinforcement made out of sintered rock, back on Earth we have basalt rebars but idk what rock/mineral would be suitable on Mars. This is why I think underground is the way to go, you only need the "concrete" with reinforcement for lining the tunnels rather than building everything out of it. Either that or a massive inflatable dome where the inside would look like those villages from ancient times made out of mud.

Yeah, agreed.

The space civil engineering guys have been talking about this stuff for decades (I used to go to their conference here annually in the early 1990s).

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2 hours ago, YNM said:

I've heard that in NL they manage to produce 45 tonnes of potatoes per ha cultivated per year nationally

A monoculture potato is good, of course, but that's exactly how the Irish population of the USA had grown.

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1 hour ago, kerbiloid said:

A monoculture potato is good, of course, but that's exactly how the Irish population of the USA had grown.

There're a lot more things that you can grow hydroponically... If anything the only one you can't are the potatoes. The most impressive numbers coming from them are for vegetables like tomatoes, carrots, chili and pepper, and probably leaf-based stuff like spinach or lettuce. We practically already try the same on the ISS, albeit obviously on a much smaller scale.

2 hours ago, tater said:

... live in Starships that are not leaving.

The logistics of this are fascinating (even if incredibly unlikely).

I actually have questions too, does Musk want to leave starships over on Mars or something ? If they abandon all the starships on Mars then we'd have a steady supply of starship-habs.

Edited by YNM
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https://ttu-ir.tdl.org/bitstream/handle/2346/73105/ICES_2017_347.pdf?sequence=1&isAllowed=y

220 m3 per person for food, completely closed cycle. If the ceiling is 6m tall in a space growing food for 100 people, the floor area is ~3666 m2.

Surprisingly reasonable. If you allowed for some less efficient use of space, make it bigger, and with some crops, even fruit trees, bushes, etc, grown on the ground, in soil. Assuming northern hemisphere Mars, make the north wall habitation or public space that views the garden. You make the garden space long and skinny so that each apartment has one end open to the agro area. Each apartment could be 10m wide, and you could have 50 apartments and the greenhouse is ~15m wide (by 250m long).

Looks like you could house 100 people in pretty good style (~100m2 per apartment) in less area than 5 houses use up along my street (including land, not just houses), all with an "outside view" into the area that grows their food. Obviously the agro area could be larger and include public spaces that are also green. Light could be via normal windows, but it could also be using light pipes and heliostats on the roof (with the real windows reserved for the views outside on the far side from the apartments.

Sleeping areas would be at the rear of the apartments, completely covered with regolith (100% GCR protection).

The engineering/design goal here is the need for growing food, supplemental O2 production, CO2 mitigation, waste processing, etc, combined with the human space requirements for wellbeing (residential and public).

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1 hour ago, tater said:

https://ttu-ir.tdl.org/bitstream/handle/2346/73105/ICES_2017_347.pdf?sequence=1&isAllowed=y

220 m3 per person for food, completely closed cycle. If the ceiling is 6m tall in a space growing food for 100 people, the floor area is ~3666 m2.

I presume this is completely artificial-light only ?

If that's the case I think we might as well build them completely underground...

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8 minutes ago, YNM said:

I presume this is completely artificial-light only ?

If that's the case I think we might as well build them completely underground...

They have to do that for the Moon, as days are a month long (so 2 weeks day, 2 weeks night).

Using solar seems dumb if you have a 25 hour day. Why take ~20% of less insolation instead of 100%? Solar radiation is ~590 W/m2 at Mars (vs ~1000 W/m2 here). PVs will get you 20%? So at Mars PVs get you ~118W/m2. LEDs are 40-50% efficient. Call it 50%. So we're at ~55W/m2 of light for every m2 of PV on the surface. So for the "price" of the same surface covered with glass on a greenhouse, you need roughly 10X that area covered with glass that happens to be PVs. My PVs are ~3-4mm of glass, so the glass use is almost a wash if the windows are strong enough for people to walk on them on Earth (~30mm thick, laminated). But high end glass is still far cheaper than PVs.

I would expect greenhouses to be just that on Mars, greenhouses, glass to the sky.

There was that interesting talk about 2 sided PVs for satellite power generation (and it had an integrated antenna array to broadcast the power). Wonder if such a clear PV could work as a greenhouse roof? The PVs take whatever % they grab, and the rest lights the crops?

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2 hours ago, tater said:

 

Using solar seems dumb if you have a 25 hour day. Why take ~20% of less insolation instead of 100%? Solar radiation is ~590 W/m2 at Mars (vs ~1000 W/m2 here). PVs will get you 20%? So at Mars PVs get you ~118W/m2. LEDs are 40-50% efficient. Call it 50%. So we're at ~55W/m2 of light for every m2 of PV on the surface. So for the "price" of the same surface covered with glass on a greenhouse, you need roughly 10X that area covered with glass that happens to be PVs. My PVs are ~3-4mm of glass, so the glass use is almost a wash if the windows are strong enough for people to walk on them on Earth (~30mm thick, laminated). But high end glass is still far cheaper than PVs.

I would expect greenhouses to be just that on Mars, greenhouses, glass to the sky.

There was that interesting talk about 2 sided PVs for satellite power generation (and it had an integrated antenna array to broadcast the power). Wonder if such a clear PV could work as a greenhouse roof? The PVs take whatever % they grab, and the rest lights the crops?

I see a design tradeoff between a massive, 2-dimensional pressurized farming area constructed with fragile transparent material, vs a larger, but unpressurized outdoor solar array that pipes electricity into a smaller, more structurally efficient opaque pressure vessel. With artificial lighting, the grow beds can be oriented 3 dimensionally around the light source to optimize the use of interior space, not to mention increased biomass productivity from the availability of higher intensity, around -the-clock lighting if energy storage or a secondary power source is available.

Please note this farming stuff is beyond subject areas with which I am familiar, so any corrections or links to further info/research/sources/numbers would be appreciated. 

Edited by mrfox
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Just now, mrfox said:

I see a design tradeoff between a massive, 2-dimensional pressurized farming area constructed with fragile transparent material, vs a larger, but unpressurized outdoor solar array that pipes electricity into an smaller, more structurally efficient opaque pressure vessel. With artificial lighting, the grow beds can be oriented 3 dimensionally around the light source to optimize the use of interior space, not to mention increased biomass productivity from the availability of higher intensity, 24 hr lighting.

Please note this is not a subject area with which I am familiar, so any corrections or links to further info/research/sources/numbers would be appreciated. 

Yeah, assuming 24 hour growing is desirable (I have no idea about plants and any day/night cycle benefits for their health).

Calling glass fragile... why? 30mm, laminated glass is fine for crowds to walk on. There are glass-bottomed swimming pools that hold vastly more than 1 atm (I want to say a household fish tank is substantially higher than 1 atm on the side walls).

The 24/7 (25/7? What does Mars do for months?) light means that the space is not ideal for dual use (I was also considering the space as someplace people might like to be around, vertical hydroponics along the glass walls, and the center with more tradition spaces that can grow things, and humans can walk among.

The critical difference is what can be manufactured locally, and what has to be delivered.

Early on, everything complex has to be shipped. So small window openings like the hab concepts linked above since the windows are sent there complete (as are all penetrations). Early farm units might even be inflatable.

Solar panels likely get shipped for a long time before there is a semiconductor industry there to mfg PVs locally. (lol, it's funny to talk about martian industry since I'm not really in the "Occupy Mars!" camp, I'm more in the Bezos camp of Gerry O'Neill fans). So for a "city," all the solar needs to be shipped for a long, long time. Glass, OTOH, seems like an easier thing for early industry there to produce along with Fe and Al.

 

 

 

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8 hours ago, tater said:

Using solar seems dumb if you have a 25 hour day. Why take ~20% of less insolation instead of 100%? Solar radiation is ~590 W/m2 at Mars (vs ~1000 W/m2 here). PVs will get you 20%? So at Mars PVs get you ~118W/m2. LEDs are 40-50% efficient. Call it 50%. So we're at ~55W/m2 of light for every m2 of PV on the surface. So for the "price" of the same surface covered with glass on a greenhouse, you need roughly 10X that area covered with glass that happens to be PVs. My PVs are ~3-4mm of glass, so the glass use is almost a wash if the windows are strong enough for people to walk on them on Earth (~30mm thick, laminated). But high end glass is still far cheaper than PVs.

Well the question is if Mars-level insolation is even enough for the plants to start with. Half the irradiation is only comparable to dawn/dusk on Earth, so I imagine you need to put lights on anyway to make sure that the plants receive enough light (plants doesn't do photosynthesis if it thinks it's nighttime). Increased PV area can be offset by increased plant throughput. Also clorophyls only absorb certain wavelengths of light, so while the LEDs and PVs might not be more efficient in the whole-spectrum it might be more efficient in the specific spectrum that the clorophyls work in.

EDIT : Forgot to say that, because the plants don't photosynthesize at night, they actually increase the load of the ECLSS rather than decrease them during that time. This is something to keep in mind too regarding artificial vs. natural lighting.

Edited by YNM
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10 hours ago, YNM said:

There're a lot more things that you can grow hydroponically

And you need a lot of pumps, pipes, and still thick glass roofs for that hydroponics.
That's why they still grow crops on plowlands rather in comfy and controllable hydroponic farms.

Hydroponics is nice if you grow vegetables or algae. With crops and potatoes it looks expensive.

10 hours ago, YNM said:

The most impressive numbers coming from them are for vegetables like tomatoes, carrots, chili and pepper,

The things which you need in much lesser amounts than crops/potatoes.

***

9 hours ago, tater said:

I can see a lot of futuristic pictures and inedible green leaves ботва in this doc, but neither any calculations, nor any descriptions of at least what they are farming, actually nothing but another eco-village fancy trash.

Of course, no animals. Who needs that meat?
(The meat needs several times more plants to grow).

Also, as I can understand, they haven't run any isolation experiment.

→ /dev/null

Any actual serious project with a barn full of actually grown potatoes?

Spoiler

EWQLROPUMAAu-kF.jpg?w=632

 

Edited by kerbiloid
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20 minutes ago, YNM said:

Well the question is if Mars-level insolation is even enough for the plants to start with. Half the irradiation is only comparable to dawn/dusk on Earth, so I imagine you need to put lights on anyway to make sure that the plants receive enough light (plants doesn't do photosynthesis if it thinks it's nighttime). Increased PV area can be offset by increased plant throughput. Also chlorophyls only absorp certain wavelengths of light, so while the LEDs and PVs might not be more efficient in the whole-spectrum it might be more efficient in the specific spectrum that the chlorophyls work in.

Good point.

There might be a sharp disconnect from food greenhouses (hydroponic, max light, maybe even all the time as @mrfox said), and green spaces for humans. Both are required, and the former don't have to worry about anything, if they are compartmentalized, any failure doesn't harm people.

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21 minutes ago, kerbiloid said:

And you need a lot of pumps, pipes, and still thick glass roofs for that hydroponics.
That's why they still grow crops on plowlands rather in comfy and controllable hydroponic farms.

Hydroponics is nice if you grow vegetables or algae. With crops and potatoes it looks expensive.

Well ECLSS need all those things too. You need air ducts, blowers, potable water pipes, waste water pipes, the whole lot.

Adding some more for hydroponic isn't that drastic of an increase in requirements, esp. if it means spaces/volumes to be saved (pressurized spaces are at a premium here, remember).

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21 minutes ago, kerbiloid said:

The things which you need in much lesser amounts than crops/potatoes.

Speak for yourself, lol, I eat much more mass of tomato, carrot, and chile than potato. I probably eat 2 large potatoes a year, maybe 3 (in all forms, combined). I'd say they'd want good, green veggies (not lettuce). Spinach, kale, broccoli, Brussels sprouts, etc. Something that is more than raw starch. Aslo, we have no idea what taste buds will be like on Mars. In LEO, everything starts tasting bland, and they love spicy things. Mars might be somewhere in between, and they become like here in NM where chile is life :D .

Just now, YNM said:

Well ECLSS need all those things too. You need air ducts, blowers, potable water pipes, waste water pipes, the whole lot.

Adding some more for hydroponic isn't that drastic of an increase in requirements, esp. if it means spaces/volumes to be saved (pressurized spaces are at a premium here, remember).

With 3D printed facilities, the pipes can be printed into the structure.

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1 minute ago, tater said:

I eat much more mass of tomato, carrot, and chile than potato

You get calories from starch and fat.
The vegetables don't contain it. THey are just vitamines, and you can deliver a starship of them in piles.

So, you eat a lot of bread, oil or many murdered animals.
The latter eat ten times more plants than you per kg of your food.

Anyway, the green is not a color of food, it's a color of its wrap.

 

3 minutes ago, tater said:

Aslo, we have no idea what taste buds will be like on Mars. In LEO, everything starts tasting bland

They lack the sense taste due to the blood circulation issues.
Mars is closer to the Earth in this sense.

(Btw, isn't thiat why Northern countries got first to the space? They historically got used to eat bland food, while the Southern can't swallow such junk.)

 

10 minutes ago, tater said:

With 3D printed facilities, the pipes can be printed into the structure.

A lot of 3d printing. It's good for auxilliary purposes, but not for planetary colonisation.

Are the new 3d printers to replace the spent ones, and the energy to power them lying by the side of the road?

***

Once again, the very first photos of any "Lunomars Foods" prohject should be a barn with bags of food and lazy fat cats on it.
The sole purpose of it.
Otherwise they are just selling greenhouses.

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40 minutes ago, tater said:

Speak for yourself, lol, I eat much more mass of tomato, carrot, and chile than potato. 

Ironically written by someone called “tater”:D

Like it or not, potatoes (and sweet potatoes) are the best bang for the buck - literally, when resource constrained.
 

TABLE 4.1 - Comparison average energy and protein production of selected food crops In developing countries (per hectare and per day)

Crop

Growth duration (days)

Dry matter (kg/ha/day)

Edible energy ('000 kcal/ha/day)

Edible protein (kg/ha/day)

Production value (US$/ ha/day

Potato

130

18

54

1.5

12.60

Yam

180

14

47

1.0

8.80

Sweet potato

180

22

70

1.0

6.70

Rice, paddy

145

18

49

0.9

3.40

Groundnut in shell

115

8

36

1.7

2.60

Wheat

115

14

40

1.6

2.30

Lentil

105

6

23

1.6

2.30

Cassava

272

13

27

0.1

2.20

Source

http://www.fao.org/3/t0207e/T0207E04.htm

 

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3 minutes ago, mrfox said:

best bang for the buck

If you want to sell them, that is... but it's only second to sweet potatoes in calories, so I guess it's good enough ?

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And to keep the production high you should either produce synthetic fertilizers, and/or use the crop rotation, most part of time getting much less calories from same field.

To synthesize the fertilizer you should have a chemical plant, and it hardly can be scaled down without efficiency drop.

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12 minutes ago, kerbiloid said:

To synthesize the fertilizer you should have a chemical plant, and it hardly can be scaled down without efficiency drop.

Or from waste. The Dutch I quoted earlier does a combination aquaculture-hydroponic setting. The potato farm in that article says they only make fertilizer out of their own waste material as well.

If you were concerned with lack of fat sources then aquaculture might be the easiest way out.

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13 minutes ago, YNM said:

aquaculture

Just redistributes the nitrogen and alcali metals, it doesn't provide them.
So, the fishes are handy to use on the watered planet, but not bring something to the chemical cycle. And they eat the calories instead of you.

You anyway should bind the atmospheric nitrogen and replenish the elements sucked out by the grown plants.

So, you anyway need either crop rotation (to replenish the soil with nutrients, slowly and not massively), or a synthetic ammonia (all heil Fritz Haber) plant.
Since XX cent. both, because the former is  much less productive.
The modern situation when 3% of population feeds other 97% is only thanks to the chemical industry. The modern agriculture is just its addon.

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12 minutes ago, kerbiloid said:

Just redistributes the nitrogen and alcali metals, it doesn't provide them.
So, the fishes are handy to use on the watered planet, but not bring something to the chemical cycle.

tbh the human population there should really close the cycle as well... Probably from waste, like I said.

I do agree that we need to put in the materials in the first place (when setting up the place) but when running it in the long term there shouldn't be anymore input needed apart for expansion (energy input is mandatory). Since I don't see the latter happening a lot (at least not until everyone's settled down and can get as comfortable as back here on Earth and people from here can easily move there as easily as the 'Martians' can return) then we should pursue closed-cycle as much as possible.

This is why I said that even if living on Mars is difficult there are still the ways of thinking that'd make for better living on Earth as well. So far we've relied on the uncontrolled part of nature to close the loop for us but it'd be nice if we can close the loop ourselves.

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12 minutes ago, YNM said:

tbh the human population there should really close the cycle as well... Probably from waste, like I said.

No.
If it was so, they were not using cattle manure for compost and still lack fertile lands until the synthetic ammonia production since 1912.
1. Don't overestimate the human "productivity", it's puny.
2. Most part of soil nutrients don't go into the human, they get lost before, with leaves (unless somebody eats them calling "broccoli").
(Btw that's why the crop rotation works, by definition.)

And when you anyway need an ammonia & methane plant, the human breathing/drinking is a such microscopic thing, that the whole idea of "greenhouse  air&water regeneration" mentioned in the pdf above loses any sense at all. You just shoul d burn all wastes to H2O and CO2 and add to the chemical process input.

Edited by kerbiloid
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1 hour ago, kerbiloid said:

If it was so, they were not using cattle manure for compost and still lack fertile lands until the synthetic ammonia production since 1912.

It's only partly because of we didn't have the methods to separate them from the toxic/infectious part of the waste. Wastewater contains quite a lot of the same things in fertilizer. Back on Earth we have to treat wastewater before throwing them away because they otherwise would cause algal blooms, which thrives on the nutrient content contained in it. There's a entire field dedicated to waste reuse already.

Edited by YNM
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