Closed loop life support with Algae

[SomeGuy12]

Per atomic rockets, Spirulina is apparently fairly close to what you would need. It grows extremely fast in water, apparently it would only take about 6 liters of fluid per astronaut, in theory, to supply the opposite side of the Krebs cycle and keep the astronaut alive with food and oxygen.

Your system would be simple. The urine and feces go into a tank where there is extremely high pressure, hot water that apparently will extremely rapidly break the waste down to the base molecules. (called supercritical water oxidation). The CO2 and minerals from that probably go through some ion traps to control levels of certain metals and then into the algae tank.

The algae tank is just a stainless steel tank full of water and bright grow lamp LEDs in the walls. The whole thing can be spun to stir the algae and remove it and keep an air-water interface.

You run the room air through a metal oxide bed, then heat up the metal oxide to release the CO2, which you also pump into the algae tank. You'd probably do this in cycles, and once the CO2 concentration is low enough, you'd spin the tank and suck the oxygen produced from the tank. Filter any residual CO2, then send that oxygen to storage bottles and ultimately back into the room.

Ok, so that's the basic system. Apparently the drawback of spirulina is that it produces too much nucleic acid. You would either genetically modify it to produce less by knocking out the genes. If that doesn't work (the nucleic acid may be a critical part of the cell biology for spirulina), you'd dig up a biological enzyme that breaks down nucleic acid and produce it in a separate tank using e-coli. (you would separate the enzyme with centrifuges and add it to each batch of algae goop at harvest time)

What about taste and nutrition balancing? This would be simple genetic engineering, stuff you could do in a hackerspace at the new DIY biology labs in LA. You insert genes behind a promoter for some key stage of the algae's growth cycle that code for some form of carbohydrate. You'd insert genes for the amino acids you want to increase the concentrations of. You'd insert genes for vitamin C. (or make it via e-coli in a separate tank)

Where it gets really cool is you could make several strains of the algae. One strain is carbohydrate heavy, another is lipid heavy (maybe make the same lipids that are in fish oil!), another is protein heavy, and another one is very sweet or has a certain flavor protein. You might actually have 10 or more separate flavoring strains, similar to those Coke machines at restaurants that can make any coke product by combining different base syrups and additives.

The whole system would be a machine about the size of 3 or so vending machines. It would have the 5-10 different strains in different tanks, each on a growth and harvest cycle. When it comes to harvesting, each tank would be spun enough to pump fluid out. The fluids from the tanks for the "recipe" would go into a high speed centrifuge that would remove most of the water. The resulting goop would be pressed into molds, and probably heated to remove the remaining water and maybe bake it. You might add binding agents produced via some natural process to make the resulting algae bar "stick" together.

A crewmember would go up to the machine and press his or her thumb on the reader. (or the reader would read an RFID tag implanted in them) The machine would eject a custom algae bar for that particular crew member, using data such as their activity level, current weight and fat levels, gender, age, etc. It would also let you choose between various flavoring combos to mask the slimy taste of algae. Maybe orange or cherry or nut flavor, etc.

Sound possible? I think this is now possible with current tech, albeit it would require some significant funds to develop a reliable system. You'd want to build dozens of these and test them on Earth. Maybe we'll see them installed in a university dorm somewhere...

Edited August 2, 2015 by SomeGuy12

[Thomassino]

Interesting concept. Way better than growing "veggies" aboard ISS. Thing about I'm not sure is if those tanks would be enough to recycle oxygen.

[SomeGuy12]

Interesting concept. Way better than growing "veggies" aboard ISS. Thing about I'm not sure is if those tanks would be enough to recycle oxygen.

The basic equations says they would be. If you produce enough food, you produce enough oxygen. Supposedly it only takes 6 liters of fluid.

What I like about it is that it's light. This has potential. You could really fit this into an interplanetary rocket on a long journey, one using a high ISP drive system where the propellant tanks and the drive itself are most of the mass.

With these kinds of engineering requirements, you'd really be living in a tin can. This lightweight life support system. Carbon fibers and thin metal plates and spaced meteorite armor (whipple shielding). If the habitat were spinning, it would probably be 2 or 4 dumbbell shaped modules, spinning on a single access tunnel that is laced with carbon fibers (since the main structural stress would be tension along the access tunnel). The reason to have 4 modules instead of 2 is to make it so you can spin up and down by just counter rotating the 2 sets of modules. Since the net angular momentum of the spacecraft is still zero (2 sets of modules the same mass spinning opposite directions) you do not have to consume any propellant to do this, just electricity to run the motors to spin the modules.

All the computers would be ultrathin tablet screens, with the CPU hardware a tiny stick about the size of a thumb drive. Every bit of fixtures and furnishings would be the lightweight solution.

Edited August 2, 2015 by SomeGuy12

[Thomassino]

6 liters per astronaut, that's great! And this can have more applications, it could even solve poor countries' food crisis.

[DerekL1963]

The basic equations says they would be. If you produce enough food, you produce enough oxygen. Supposedly it only takes 6 liters of fluid.

What I like about it is that it's light.

I'm always reminded of a quote by Admiral Rickover on the difference between paper and reality;

An academic reactor or reactor plant almost always has the following basic characteristics: (1) It is simple. (2) It is small. (3) It is cheap. (4) It is light. (5) It can be built very quickly. (6) It is very flexible in purpose (“omnibus reactorâ€Â). (7) Very little development is required. It will use mostly “off-the-shelf†components. (8) The reactor is in the study phases. It is not being built now.

On the other hand, a practical reactor plant can be distinguished by the following characteristics: (1) It is being built now. (2) It is behind schedule. (3) It is requiring an immense amount of development on apparently trivial items. Corrosion, in particular, is a problem. (4) It is very expensive. (5) It takes a long time to build because of the engineering development problems. (6) It is large. (7) It is heavy. (8) It is complicated.

Having studied various forms of engineering and design from my armchair over the years - he hits it pretty much spot on.

[SomeGuy12]

No doubt, no doubt. Nevertheless, this appears to be the form the solution should be in. I'm not saying it would be easy - I honestly think the pricetag to get to a working, reliable system might be measured in billions - but a tank of fluid of minorly genetically modified algae sounds a lot easier to engineer into a closed system than a tray of terrestrial plants growing in hydroponics or real soil.

[KSK]

*snip*

Ok, so that's the basic system. Apparently the drawback of spirulina is that it produces too much nucleic acid. You would either genetically modify it to produce less by knocking out the genes. If that doesn't work (the nucleic acid may be a critical part of the cell biology for spirulina), you'd dig up a biological enzyme that breaks down nucleic acid and produce it in a separate tank using e-coli. (you would separate the enzyme with centrifuges and add it to each batch of algae goop at harvest time)

Yes - nucleic acid is a pretty critical part of spirulina cell biology (or the cell biology for any other species for that matter) given that genes are built from nucleic acid.

The Atomic Rockets article also mentioned gout as the problem caused by excess nucleic acid. Gout is caused by uric acid, which is already a breakdown product of nucleic acid and (in mammals) is actually the final breakdown product - uric acid (as you could probably guess from the name) is excreted in urine. You *could* add an enzyme to break it down to allantoin but I'm not sure whether eating quantities of allantoin is a great idea either. Also culturing proteins in quantity is not a trivial task and I don't imagine it will be made any easier in zero-g. Better to make it in bulk on earth and take it with you.

What about taste and nutrition balancing? This would be simple genetic engineering, stuff you could do in a hackerspace at the new DIY biology labs in LA. You insert genes behind a promoter for some key stage of the algae's growth cycle that code for some form of carbohydrate. You'd insert genes for the amino acids you want to increase the concentrations of. You'd insert genes for vitamin C. (or make it via e-coli in a separate tank)

I think we have different definitions of 'simple'. I'm not saying this is impossible but it's definitely not simple.

[Mazon Del]

You might need to rely upon some other means of removing the excess nucleic acid than genetic engineering and such. It is quite likely that the reason that spirulina is so good at this purpose ends up having the excess nucleic acid as a byproduct, and thus poking at genes that produce that byproduct also reduces the efficiency below the awesomely useful threshold that it has. Or I could be wrong, I'm a roboticist, not a biologist. But it seems to make sense that awesome levels of production of something would be coupled with awesome levels of production of a byproduct.

[PB666]

Per atomic rockets, Spirulina is apparently fairly close to what you would need. It grows extremely fast in water, apparently it would only take about 6 liters of fluid per astronaut, in theory, to supply the opposite side of the Krebs cycle and keep the astronaut alive with food and oxygen. .

It works better with diodes than sunlight, and you can feed brine shrimp spirulina to get animal protein. The problem is water.

[KerikBalm]

Well, there is normally a lot more RNA than DNA.

A lot of thar RNA may be a lot of non coding RNA that may be dispensible.

If we were to give them a pathogen free environment, you could cut out the RNAs needed for DICER to perform its antiviral duties.

Said system also regulates host genes, but there are other ways of regulating them, and in theory one could replace a lot of the silencing RNAs with protein transcription or translation inhibitors.

It would be a *very very major* engineering project though.

But gout takes a long time to develop, and its mostly in genetically pre-disposed individuals.

Just deal with it. Nobody wants to spend 10 years on a space ship anyway.

[Mazon Del]

Nobody wants to spend 10 years on a space ship anyway.

I wouldn't mind THAT badly.

[Hcube]

There is a similar closed-cycle life-arium in a FabLab in my town... it's basically a huge aquarium with algae, enormous LED panels, a lot of pipes and... some fish ! It is completely autonomous (or at least it is what they told me). I guess replacing the fish with human beings would be very hard ! since the whole thing is big already (like a whole room) and only supports a few fish

Edited August 3, 2015 by Hcube

[Mazon Del]

You can actually buy some self contained units on Amazon. Glass spheres filled with water, algae, and shrimp. The algae grow in sunlight, eat shrimp poop, and are eaten by the shrimp. The shrimp eat the algae and make poop. They apparently can go for 2-5 years before the shrimp eventually die (usually of old age).

[SomeGuy12]

You can actually buy some self contained units on Amazon. Glass spheres filled with water, algae, and shrimp. The algae grow in sunlight, eat shrimp poop, and are eaten by the shrimp. The shrimp eat the algae and make poop. They apparently can go for 2-5 years before the shrimp eventually die (usually of old age).

What do you have to do so the shrimp breed a continuous series of new generations?

Wonder if you could just eat this mix - the shrimp would provide animal protein, etc.

[Mazon Del]

They say in the sales documents that sometimes the shrimp might make a few babies, but don't expect that to keep happening. Additionally, in case you are worried about one or two dying and then having a carcass floating around for the next two years, no need to worry! Once one of the shrimp dies, the other shrimp and algae combo will get rid of it.

[SomeGuy12]

So it turns out I was just 2 days ahead of the news curve on this. Soylent is already 20% algae and there's discussion of making it 100%, with a plan to genetically engineer the algae to make each constituent part of Soylent. Apparently, per Rhineheart, a 100k square foot warehouse full of Algae tubes could feed LA. Even if he's off by a factor of 10, that's a lot smaller than the farms that feed LA, and algae tubes would recycle their water, and would cost very little per unit of food because the entire process would require minimal human labor...

If his dream worked out, we'd still have food crops, but only for pleasure. Only the best and most competitive areas would grow high grade food...