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I'm interested in knowing if in terms of cost/efficiency/quality would be better to grow crops(food) in Earth and then sending it to space habitats on orbit, or would it be better to grow them in those habitats?

However, there are some conditions that need to be taken into consideration:

You can freely recharge shuttles that come down, as there are large fuel storages available.

Food need to be grown on special greenhouses, because Earth's spinning speed is down 90% (this is an expansion of a previous question).

Let's say that a total of 25.000 people live in orbit.

I´m asking this mainly bacause since its possible to freely recharge the shuttles, it would be possible to transport a lot of soil to the space habitats. However, you would still need to have large rooms to house the crops, and everything else needed to keep production going.

So far, in this scenario, I think that the best option would be to come down, build the greenhouses, use automated caretakers to run and to harvest, then just come back down to collect the already stored goods.

New edits for extra clarification

The concept is that on earth things are really rough, its a horrible place to live. Rich citizens, and others who could afford, stablished themselves on space habitats. Those habitats are amazing and offer all the luxury they need. People are sent down (to Earth) as a punishment for crimes and such.

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    $\begingroup$ Isn't this Elysium? $\endgroup$ – JohnP Jan 12 '15 at 19:27
  • $\begingroup$ do you have a en.wikipedia.org/wiki/Space_elevator ? $\endgroup$ – njzk2 Jan 12 '15 at 19:44
  • $\begingroup$ If you have that much abundantly cheap energy, you can do pretty much anything and solve the in-story problems. Lifting to orbit is more demanding than you realize. $\endgroup$ – JDługosz Jan 12 '15 at 22:44
  • $\begingroup$ Not worthy of an answer - but I'd assume rich citizens and those that can afford it really won't care if it's cheaper to grow food anywhere. They will want the luxuries regardless of price....wine, caviar...I mean they can live in space at the expense of others, I'd fully expect them to exploit Earth's resources than to try to manage their own. $\endgroup$ – Twelfth Jan 13 '15 at 18:30
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25000 people eat a lot. Even with cheap lifts from Earth, it would still be expensive and what happens if something causes a few missed deliveries in a row?

I could see getting supplies from earth (or as Peter pointed out) the moon, but I think it would be wise to have some food generating capabilities on the habitats. Fresh fish or steak would likely need to come from the planet, but large amount of needed calories, vitamins and minerals should be available.

Many stories talk about using microorganism vats to produce enough food to help feed people and keep them alive. This might be needed. Having gardens to produce more food (even small bits to help subsidize incoming shipments could help a lot) It also doubles as a 'green space' for humans which could be very therapeutic psychologically.

You also have a lot of 'waste' that needs to be dealt with, this could easily be used to fertilize any crops and help create a soil instead of needing to haul it all up from the moon or earth.

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  • $\begingroup$ The bit about fresh fish/steak needing to come from the planet is exactly what I was thinking. It is premium-food, for special ocasions or important citizens. $\endgroup$ – mcbecker Jan 12 '15 at 18:48
  • $\begingroup$ Neither Fish nor Steak need come from a planet. Tanks could be stocked on the station and fish bred. If you had any ability to grow crops off planet, livestock is just as easy. $\endgroup$ – Oldcat Jan 16 '15 at 1:27
  • $\begingroup$ While I agree fish would be reasonable, large livestock need space, vets, and a lot of food. Unless you are hollowing asteroids it would still be cheaper to bring up processed steaks. $\endgroup$ – bowlturner Jan 16 '15 at 3:09
  • $\begingroup$ Not if the earth has stopped rotating, which is what requires the crops up here in the first place. $\endgroup$ – Oldcat Mar 18 '16 at 19:04
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First, the planet would still be more habitable than space. Second, moon would still be more habitable than space as it has some gravity and plentiful resources. (In comparison to the orbit, which has to import everything except sunlight.) So people would probably live on either the planet or the moon rather than on orbit.

But if you really want to have people living on orbit...

They would get bulk of their food from something like algae farming in tubes using sunlight distributed with optical fibers. Such optical fiber based lighting systems already exist, and they'd work pretty well in the stronger sunlight of space. Without needing large windows or huge amounts of space.

The reason for this is simply that they'd need some extremely robust way of handling the basic carbon, oxygen and nitrogen cycles. You need something that recycles your carbon dioxide and organic waste, and you are not going to want that to be reliant on exports or complex machines.

A system like this would be reasonably compact, fairly low-tech (after construction), and capable of providing basic recycling and nutrients. Food quality would start with tasteless goo, but there is no particular limit on taste given time. Texture could be baked in at the food preparation stage.

That said, they'd probably also have the planet based food sources. I think the scenario was for the evacuation to be fairly sudden and developing robust algae based ecology that supplies all the necessary nutrients would take time. So they'd start with normal agricultural plants and those would never be grown in quantity in space as they are much less space efficient than the algae farms. It would be a long time before the habitats would have enough extra space for normal agriculture.

And lots of these planet based plants would likely remain valued even after the habitats get independent food supply. Imported fruit, vegetables, and herbs would have value as delicacies and justify the cost of maintaining the already built green houses by improving the quality of life in the habitats. And unlike bulk food lifting them to orbit would be a fairly effective way of replenishing the organics lost to leaks and other inevitable inefficiencies of space habitats.

So they'd start with importing all the food from the planet since that is there they have already been producing food and have most resources and infrastructure. Then as the habitats get more self-sustaining and permanent, they'd move to closed cycle production of bulk food in the habitats with specialities and delicacies requiring more space to grow imported from the planet. Given enough time they'd start building gardens on habitats and later expansion of the "green house" agriculture might be built on the moon to take advantage of the free but lower gravity.

All this providing they'd want to live in space habitats...

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Cheaper is grow food on Moon and use non-rocket space launch to launch food containers to the orbit.

This way all you need is free electricity from Sun, and water (land some comets on the Moon when you run out of water from Moon itself).

Obviously in orbit you need life-supporting habitats with hydroponic plants to make oxygen from CO2 and grow some staples, (fungi tofu, rice, wheat etc). But those plants will be more to create oxygen than to provide 100% of food (even if they provide 70%). And for more complicated food (chicken, cattle) you need more complicated ecologies - about how hard is to establish balanced ecological system - we don't know how to do it, our attempts (Biosphere 2) failed.

So having more volume and energy to play with, and being not restricted to orbit, may be significant difference.

Edit: I found promised link about how hard it is to run ecosystem - see above.

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  • $\begingroup$ Growing food on the moon certainly is an option. I also believe that setting up a complex ecology would be quite difficult as the balance is very delicate. Do hydroponic plants have any disadvantage regarding those cultivated normally? $\endgroup$ – mcbecker Jan 12 '15 at 18:31
  • $\begingroup$ A farm is not a "balanced ecological system". It works because there are lots of work invested in it, not by itself (stables get cleaned, water replenished, animals vaccinated / killed when ill). $\endgroup$ – SJuan76 Jan 12 '15 at 19:30
  • $\begingroup$ I am talking about the soil, which is balanced ecosystem. Farmer does not manage nematodes, bacteria and earthworms, which allows plants to grow and all else to happen. This balancing is hard part, and we don't know how to do it. We can only clean the stables. $\endgroup$ – Peter M. Jan 12 '15 at 19:50
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What you gotta eat in space, you gotta grow in space. Unless you're willing to pay 3000+ bucks for a pound of taters, that is.

Modern spoiled humans eat a ton of food per year. So either we spend $3 million/yr to feed each space-human, not use flesh-humans but rely on uploads instead, or make'm grow their own damn food in space. Realistically, once we establish a lasting space presence, and solve the issue of gas confinement, it will not make sense to use up ridiculous amounts of polluting rocket fuel just to feed space-head flesh-humans. So it would be a lot cheaper, once we know how to do it, to grow in orbit using hydroponics. Think of the advantages: 24/7 sunlight, so you can have as many growing seasons as you wish (you might have to engineer your plants a bit).

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  • $\begingroup$ Really liked the idea about the many growing seasons. $\endgroup$ – mcbecker Jan 12 '15 at 18:46
  • $\begingroup$ If you can make large rotating structures in space, you can grow crops there and raise livestock there as well. $\endgroup$ – Oldcat Jan 16 '15 at 1:28
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http://www.sciencealert.com/this-indoor-farm-is-100-times-more-productive-than-an-outdoor-one

Here's an example of how cheap it could be to grow your own food in space. You could use it to recycle waste, water and carbon dioxide as well as produce delicious textured foods. You could fit a lot of plants in very little space, and using the fibre-optic technology to bring in light would mean it requires very little energy (just moving the solution through the pipes).

Algae would, of course, be an even more efficient food and oxygen producer, and some can be quite tasty. Fungus doesn't produce much oxygen, and can be quite picky about it's habitat, so I'm not sure if they'd grow much. Leafy veggies that you buy from the supermarket are already produced hydroponically (at least they are in Australia).

Soy, wheat, rice, etc is not as efficiently grown, but perhaps legumes as a local source of proteins and carbohydrates. Eggplant is also a pretty tasty staple and can be grown hydroponically, as can tomatoes. Even some root vegetables.

I just found this list: http://www.gardenguides.com/138151-vegetables-can-grow-hydroponically.html

It could even, for the most part, be automated. If you want meat, then chicken would be a possibility. It would not be humane or pleasant however. A better alternative would Aquaponics (combine fish farming with your hydroponics) and it's already quite popular.

All these things (especially the plants) however would need gravity. This could be simulated by rotating the space station and growing the plants on the outer rim (where gravity is highest). Low gravity would have bad effects on the human body though.

Feeding the humans would be relatively simple. It's simulating / creating gravity that would be the issue.

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If you transport food from Earth to space, you will also need to transport oxygen from Earth to space, and you need to transport carbon dioxide and water from space back to Earth.

This is because all food energy originates from the photosynthesis in plants, a process which consumes water and carbon dioxide, and produce e.g. glucose and oxygen. When the glucose is used, an equal amount of oxygen is converted back to carbon dioxide and water.

So if you don't also transport oxygen/carbon dioxide back and forth, people in space would eventually suffocate as all oxygen would be used up.

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  • $\begingroup$ You can use energy from the sun to run the process backwards. $\endgroup$ – Oldcat Jan 16 '15 at 1:30

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