I decided to start a separate discussion on this topic. This is one of the places where a lot of good ideas have been put forward in science fiction, but I'm not sure they've ever made studies of how feasible they are.
To grow food (as in plants), you need:
(1) Light - More abundant in space than on earth.
(2) Gravity - One of the few bits of "real science" produced by the ISS has been a series of experiments that have shown that plants don't grow well in microgravity (http://lsda.jsc.nasa.gov/scripts/cf/exper.cfm?exp_index=234
). So, it seems that you'll either need simulated gravity (a rotating space station) or grow them on the surface of a celestial body like Earth's moon.
Is this true for water plants as well, eg plankton?
(3) Water - This can come from several places. You can ship it up from Earth (read Heinlein's TheMoonIsaHarshMistress
), you can find it locally where you are (Europa and the lunar poles, perhaps), or you can get it from a comet (perhaps redirecting it to crash onto the moon).
Water can be renewed. Food can be grown and dehydrated prior to earth shipment.
(4) Air -- Particularly Carbon Dioxide -- This can be shipped up from Earth, or from places with a an oversupply of it but a smaller gravity well like Mars... Don't forget about nitrogen. If you can't get your plants some nitrogen, either in the air or soil, they will not grow.
(5) Trace minerals, carbon compounds, etc. (e.g. "soil") - This can be formulated from lunar regolith (adding additional trace elements shipped from earth) or perhaps carbonaceous chondrite asteroids can provide sources of the necessary compounds. Additional trace elements include phosphor, nitrogen-rich compounds, etc. You can't grow plants without a lot of nitrogen, and it is hard to find outside of our atmosphere.
Pure nitrogen, sure, but ammonia is pretty common, isn't it?
Heinlein's "The moon is a harsh mistress" also had a brief analysis of the economics of transporting grain or other foodstuffs from the moon via electromagnetic launchers.
Other ideas and comments?
On the one hand: no locusts, no weird food diseases, therefore, no pesticides necessary! On the other hand: no need for immune systems, so they might just rot faster once they get back.
Also, one wonders what effect reduced or artificial (as opposed to micro) gravity will have on crops. ArtificialGravity?
through rotation is an interesting problem in and of itself, and it's not likely to fool anyone into thinking they're on Earth.
Regarding point 5: Very little of the carbon in plants grown on earth comes from the soil in which they grow. If it did, hydroponicists would need to use feed solutions resembling engine oil. And forests would always be in valleys. The carbon is scavenged by plants from the carbon dioxide in the air, which comes in turn from the respiration of animals (and plants), vulcanism, humans burning fossil fuels, and the oxidation of dead plant material. Doesn't Heinlein propose that the loonies get their farming carbon from dried sewage shipped from the Earth to Luna?
More generally, mightn't whatever effort and money went into building space farms be more usefully applied to, for instance, getting the sediments that once naturally, cheaply and effectively fertilized Egypt's farmland up from the behind the Aswan high dam and back onto those farms, which, for want of that sediment, are now fatally ill synthetic fertilizer junkies?
After all, it's not that the Earth isn't capable of producing enough food to support the current population (or a significantly larger one) perfectly well, it's just that the human race doesn't choose to have it do so. Sad to say, a hugely expensive, time-consuming but conspicuous high-tech fix to the food "problem" would probably be a more politically acceptable solution than a local, sustainable, appropriate-technology one.
And what is the definition of
- Pardon me for butting in, but this discussion arose from postings on TheBottleneck, the premise of which is that when Earth's population reaches 10 Billion or so around 2050, we will have reached the upper limit of the planet's capacity to feed all of us. Thus, the idea was floated (no pun intended) to make food in space so people won't starve to death. -- PrestonRickwood
appropriate-technology ? It sounds suspiciously like
technology I like to me.
Anyway, appropriate technology, is for instance, the old-fashioned bulb-mirror-and-lens overhead projector, plus blank acetates, slides and dry-wipe pens, that we use for presentations in our office, rather than a data projector to show PowerPoint
animations. In comparison, the slides and OHP get the job done, are cheap to buy, easy to use, robust and can be easily, quickly and cheaply maintained by their users. If the problem being addressed above is shortage of food, then space farms are not appropriate technology, since, as it happens, the hungriest people on Earth are also the poorest, and so the least able to build and run such things. That's not to say that structures in orbit aren't exactly the appropriate technology for something else.
I'm still confused. How is
appropriateness decided? Why should the starving people be the ones to foot the bill for their food infrastructure? It's akin to asking the heart attack patient to run his own code blue.
In this case, appropriateness means that the poor get control
of their food supply. After all, they're the ones who are going to live and die by it. Who actually foots the bill is irrelevant as long as control is where it belongs.
Note that many people (especially in power) think that the third-world shouldn't control their food supply. They prefer that the third-world governments not be able to feed, teach or care for their own populations and that private charities from the first-world do all these things instead. This is why money flows out of the third-world because of debt servicing only to flow back in through NGOs ("private" charities funded by governments). Since more money flows out than in, it's still the third-world that pays for all of its services, but it's the first-world that controls it.
Many (most?) cases of substituting expensive technologies for cheap technologies is so that rich people and bureaucrats acquire control over the technology. Perhaps this isn't intentional but just a "happy coincidence" that those in power don't question too closely (don't look a gift horse in the mouth and all that). OTOH, it's easy to show that technology is chosen by the people in power to advance their needs foremost. So every technology is researched, and every application of technology is deployed, with the desires of the rich and bureaucratic in mind.
I suppose it's better to starve nobly than eat food from someone else?
Hardly. I'm just pointing out how revolting it is to try to control starving people's food source. Just why is it that FoodFactoriesInOrbit
are more politically realistic than leaving the third-world in peace (ie, stop sucking billions in dollars and resources from it) and letting it feed itself? Because politicians are scumballs who want to control the third world's food source. That's all I said and that's all I mean.
- Forgive me for being idealistic, but my idea was that we wouldn't let greedy corporations and the rest of TheUsualSuspects try to charge starving people for food that we grow in orbit specificly so they won't starve. If we didn't care about them starving, we wouldn't need the extra food. I know that I am both a) an incureable romantic and b) mistakenly optimistic about our chances to overcome evil corporations, but damn it, I have to believe that we can or what point is there? -- PrestonRickwood
The closest thing I'm aware of to a feasability study is NASA Pub SP-413 "Space Settlements, A Design Study". It gives a summary of ten week workshop on space settlement design in 1975 at Stanford. The resulting design is sometimes called the Stanford torus. It covers details like mass/energy balances in the agricultural system in more depth then I could ever use, although at less then 200 pages I'm sure it only scratches the surface.
The design they propose is built on an assumption of 100% recycling (at least I can't find any mention of mass loss/replenishment in the study), so apparently once started it would be relatively self-sufficient.
The purpose in the study was not to produce food for earth, but to provide food for 10000 colonists without having to ship it from Earth.