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We can mine asteroids for space food

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Re: We can mine asteroids for space food

#211

Post by AngryData »

thaumasiotes wrote: post #183
adrian_b wrote: post #172

Earlier quoted context omitted.

Plants feed on oxidized compounds, i.e. water, carbon dioxide and dinitrogen, plus solar energy. Because carbon dioxide and dinitrogen are very volatile they must be taken from atmosphere. Reduced organic compounds, like hydrocarbons, are not food for plants, but for fungi or similar organisms, which, like humans, need only dioxygen from the atmosphere. There already are genetically-modified fungi that can produce th…

Do plants take nitrogen from the atmosphere? There's plenty of it available, but my understanding was that molecular nitrogen likes being molecular nitrogen and is difficult to react into a useful form. If plants took nitrogen from the atmosphere, there would be no issue of fixing nitrogen in the ground. But instead, that's a huge issue. We also provide nitrogen fertilizer, which is another way of getting it into the…

The plants certainly don't. However there are certain plants that symbiotically harbor nitrogen fixating bacteria. Most notably legumes and the rhizobia bacteria that live inside root nodules. Common legume plants are alfalfa, peanuts, lentils, chickpeas, and bean species.

Re: We can mine asteroids for space food

#212

Post by AngryData »

Iulioh wrote: post #173
Simon_ORourke wrote: post #169

Earlier quoted context omitted.

> Hydroponics already works. I read something on wired last year on why urban vertical farming never really took off, and one of the reasons was, if I remember, that these kind of environments increase the likelihood of plant disease and the density makes it difficult to arrest any spread. So, I'm not too sure that hydroponics at scale is completely solved.

It's a price problem, not a technical one

More directly it is energy/electricity, which is the reason the cost is high.

You need atleast 35 watts per square foot of high quality grow LEDs to grow most crops outside of leafy greens. That is about 1.5 million watts per acre for 12-16 hours per day, which makes it pretty obvious why it isn't economical. And even if we could meet the theoretical efficiency limit of LED lighting technology, it would still take atleast half of that amount of electricity.

Re: We can mine asteroids for space food

#213

Post by thaumasiotes »

adrian_b wrote: post #172
Animats wrote: post #121

"but there are substantial areas of future work." Well, yes. Most plant mass comes from air and water, not the ground. Carbon, hydrogen, oxygen, and nitrogen all come from the atmosphere. This is why farms don't dig themselves into the ground. If air and water can be made from asteroids, that's most of the raw materials problem by quantity. Hydroponics already works. Direct synthesis of food from hydrocarbons has nev…

Plants feed on oxidized compounds, i.e. water, carbon dioxide and dinitrogen, plus solar energy. Because carbon dioxide and dinitrogen are very volatile they must be taken from atmosphere. Reduced organic compounds, like hydrocarbons, are not food for plants, but for fungi or similar organisms, which, like humans, need only dioxygen from the atmosphere. There already are genetically-modified fungi that can produce th…

> Because carbon dioxide and dinitrogen are very volatile they must be taken from atmosphere.

I don't follow the logic. These two ideas are definitely compatible - oxygen is very volatile, and it's present in significant quantities in the atmosphere, and therefore can be (and is) taken from the atmosphere.

But they seem to me to be in tension rather than supporting each other. Oxygen is present in the atmosphere, but _because_ it is very volatile, it's constantly reacting with stuff on the ground, which is a process that tends to eliminate it from the atmosphere. What's the reasoning that suggests that the volatility of carbon dioxide means it has to be taken from the atmosphere?

Re: We can mine asteroids for space food

#214

Post by bcherny »

foundry27 wrote: post #200

This is straight out of The Heechee Saga! The idea of synthesizing human-edible food from asteroid hydrocarbons is literally what Pohl described with CHON food. Breaking down carbon, hydrogen, oxygen, and nitrogen to create sustenance for ships, stations, even whole planets. Judging by the study’s data, converting the organic compounds in an asteroid like Bennu could feed thousands of astronauts for decades. Even the…

Also, Vinge’s A Deepness in the Sky

Re: We can mine asteroids for space food

#215

Post by spookie »

luqtas wrote: post #130
spookie wrote: post #127

Earlier quoted context omitted.

I don't think the aim would be to be able to achieve the same level of production that way :)

glad you answered. what's your opinion on the dialogue between people producing eggs in battery-cages (those classic confined chickens) vs. free-roam ones? so far the discussion points out to _way_ more disease spread in free ones, leading to more suffering and death, specially when we are doing in a commercial scale. wild animals killing those free roam animals also occurs. so far the science on battery-cages went f…

Look, I don't think you would want to produce at the same level. Because of the reason you stated.

Re: We can mine asteroids for space food

#216

Post by saaaaaam »

pavel_lishin wrote: post #88
pyrolistical wrote: post #70

Wouldn’t it be simpler to do what the Martian did? Bring low mass items: seed and bacteria. Mine high mass items: dirt and water. Concentrate sunlight

Where exactly do you mine "dirt" from on a planet that hasn't had any sort of biosphere to create it? Dirt isn't just "stuff you're standing on" - it contains a lot of stuff that's been decomposing. Plus, Mars is full of chemical compounds that we suspect are pretty terrible for you, and the Moon's regolith is full of jagged, sharp bits that aren't good for you or the plants they're growing in. Mining "dirt" from mos…

Turns out you can grow plants in lunar regolith: https://www.nasa.gov/humans-in-space/scientists-grow-plants-...
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