Small Scale Aquaponics

A discussion of making habitats and growing food on Mars broke out in comments on this Mars Posting about mushrooms on Mars.

As luck would have it, a YouTube video presented as “recommended” since I’d gone off to look at some indoor greenhouse things. It is from Purdue (who have a GREAT bunch of Ag oriented things including their stellar Famine Foods page – that I need to scrape a copy of one day…).

It starts off a bit too Whole Earth Green Fuzzy but then gets down to business. Of particular interest is just the simplicity and scale of the Aquaponics systems they demonstrate / video. One is “in a small basement” while others have exterior windows, so also indicates what would work in an underground tunnel on Mars.

Were I setting up something like this on Mars (or the Moon), I’d also include a Poultry House. Chickens just love eating kitchen scraps (stems and roots and such that you don’t care for) along with fish heads, fins, etc. Basically they are a mobile compost heap with a 2 day processing time.

Now your fish tanks / grow area are tightly linked but with “fish food” in and “plants out”. Then the “harvested fish & plant trim and trash” get linked through the chickens and turned into eggs and Kentucky Fried. What’s missing?

The base feed to the fish (and perhaps chickens) depending on how many you want.

On earth that is mostly corn and soy made into a meal. For some farmed fish, like salmon, it will include a lot of shrimp processing “waste” of shells (for color) and shrimp guts, or krill. For others, like Tilapia, it can be just plant products. There’s even a shrimp growing pond system based on, basically, a bit of ‘green waste’ and sunshine to make algae the shrimp eat. I believe that with a choice of an herbivore fish you can fairly easily feed them off of pellets made mostly of spirulina / chlorella algae (see further below for more).

So putting a second tank / grow area together to make the feedstock would “close the loop”. Also, in a sealed environment, water “lost” to evaporation would return as condensate. Note that most of the material mass needed is water, already on Mars. We also know how to make plastics from plants so after the first few were shipped up from Earth, they could start making their own plastic parts. That mostly leaves motors, pumps, lights, and some electronics as “imports” along with any trace minerals to get the system started that can’t be found on Mars (likely phosphorus will be in short supply, IMHO). Once running, as this will have 100% recycle of those elements, the need for additional minerals ought to be minimal. Frankly, I’d expect the “specialty foods” shipped from Earth as a “treat” will supply plenty in the crew poo.

Here’s the Perdue Aquaponics video:

There are shrimp and even some fish that live on algae, and it is very easy to grow LOTS of algae in sealed glass pipes or tanks. I would expect that to form the foundation of the fish / shrimp feed process.

Here’s a guy working on something similar.

This is the new design. Technically, what I’m creating is called an Integrated multi-trophic aquaculture (IMTA) system because it will provide the by-products, including waste, from one aquatic species as inputs (fertilizers, food) for another. “Integrated” refers to intensive and synergistic cultivation, using water-born nutrient and energy transfer. “Multi-trophic” means that the various species occupy different trophic levels, i.e., different (but adjacent) links in the food chain (Wikipedia). I was kind of surprised to find that the Asia Institute of Technology (AIT) is working on a similar project. I mean, I’m not surprised that they have an excellent idea, I’m surprised that I managed to stumble onto the same thing independently. I think there are a lot of differences, though, as they have different goals (see this link). I’ve offered to exchange information, but I doubt they will take me up on it. Academic institutions are, for the most part, owned by corporations.
Spirulina (Arthrospira platensis) is widely known as a dietary supplement (miracle drug). There are all kinds of edible alga, but spirulina sort of takes the cake. Its nutritional profile is outstanding (60% protein), and since it actually thrives in highly alkaline water that other types of algae cannot withstand, it can be monocultured by keeping the PH high. For this reason the culture water for the spirulina will be completely independent of the aquaponic system water.

Spirulina can be harvested with a very fine mesh cloth.

Normally, spirulina is fed a complicated mixture of nutrients plus CO2. I’m not going to be too scientific about it, as I’m not trying to get maximum yield, so they will get some of the waste solids I remove from my system (a bit like putting manure in a pond to induce an algae bloom) including some system water to make up for evaporation, ordinary aeration (until my mushroom growing rooms are built, then they will get CO2 enriched aeration), and perhaps some ordinary urea (I’ll resist the urge to pee in the algae troughs). Spirulina can be harvested easily as the photo shows, another advantage. 10g per square meter would be a mighty fine daily harvest generating 120g per day. That’s only 2.5 to 5% of my feed needs, so you may wonder if it’s worth the space, but it’s got double the protein of standard feed and provides other goodies. Also, if I were to eliminate the shallow algae ponds and extend Trough #2, I’d have to extend the aisleway, too; as it is, I figure that boards could be laid on top of the algae ponds for access. So, I think I’m saving 4 to 5m2 of productive floor space.

Has lots of interesting photos of shrimp too ;-)

Chlorella or Duckweed are also decent candidates. (It is also possible that you would have enough slash / discard plant matter to make fish food pellets. But here’s another page on fish food growing:

DIY High Protein Fish Food from Algae

Posted by Ecofilms on Sep 7, 2011 in Aquaponics, Fish Food | 5 comments

Growing your own fish food for aquaponics is the holy grail for many folk wishing to be autonomous and not dependent on commercial fish food pellets.


Growing duckweed in your own tank is one solution during the warmer summer weather. Its not an algae but a very small aquatic plant. Because the water in an aquaponics system is rich in nutrients, it is well suited to also grow duckweed which is 30% to 40% rich in protein providing the water is undisturbed and slightly shaded. Many fish will readily eat this tiny plant that doubles in size rapidly and is an excellent supplement to feeding your fish, but you will need heaps of it to keep your fish alive.

Recently while filming The Urban Permaculture DVD with Geoff Lawton we came across a family who were growing around 100 silver perch fish in their family swimming pool. They said they don’t feed their fish any fish pellets at all. So how did the fish survive? By eating the insect larvae and tiny crustaceans that grew in the pool but mainly – the algae that naturally formed on the sides of the pool.

Which brings up the important point that many fish who will not eat algae or plants directly, will eat the many different kinds of aquatic bugs / grubs that DO eat them While I’d prefer not to have that loss of feed in the “feed conversion ratio” of the bugs, if things were going great and you REALLY wanted that Predator Fish (perch, bass, trout…) adding a “bug growing room / tank” would get you there.


There are many varieties of algae but one of the champion varieties, Spirulina is one that has been written about a great deal. Mainly because it is extremely high in protein (60% – 70%) and has many other nutritional benefits as well. It is said to be rich in vitamins, minerals, and carotenoids (a type of antioxidant that can help protect cells from damage). Its full of all sorts of goodies, B complex vitamins, beta-carotene, vitamin E, manganese, zinc, copper, iron, selenium…in fact the list goes on and on.

Test tube and animal studies suggest spirulina may boost the immune system, help protect against allergic reactions, and have antiviral and anticancer properties. So many companies are now marketing Spirulina tablets in health food shops around the planet.

Recently a new documentary on Spirulina is being released advocating its super food status. If it’s good enough for NASA astronauts to eat in space – then it might be good enough for your fish to eat as well?

But not just a hypothetical…

Turning a Problem into a Solution

In Ferende, Togo West Africa
Dr Ripley Fox turned a problem into a solution. He had the right climate and pH. He found a way to turn malnutrition in the village and marginal farming into a thriving opportunity – growing Spirulina to feed their fish grown in concrete raceways. All human waste went through a bio-digestor that also supplied methane gas and output compost for their dirt gardens. Lack of sanitation had caused disease. Now it was under control.

The villagers were able to now earn a living selling fish in the community. A problem was turned into a solution.

So if you can get it to work in a village in Togo, it ought to work in a controlled Lunar or Mars station environment…

But, if you choose your species well, you don’t really need special Spirulina production facilities:

Mozambique Tilapia: The Best Algae Eating Fish for Ponds
Typically, Mozambique Tilapia will start to consume filamentous algae post-stocking, once the acclimation period is over. This period can be as few as a couple of hours and at most a few days. Most pond owners typically start to see a noticeable reduction in the growth of filamentous algae within one month of stocking. Once water temperatures increase to a reproductive ideal, spawning takes place. The fish that were stocked increase in number, and therefore, increase the quantity of hungry mouths that eat the algae.

Benefits to Predatory Fish

Largemouth Bass are perhaps the most common pond species, aside from Channel Catfish and Bluegill. Keeping them fed and in good condition requires abundant forage resources. Stocking Mozambique Tilapia as biological control of filamentous algae has the added benefit of providing piscivorous (fish eating) species, like Bass, with an abundant forage supply. Smaller Tilapia that hatch within the pond are an easy meal for most Bass. Reproduction by Tilapia occurs often, and the results are small juvenile Tilapia that make easy targets for a hungry Bass. Therefore, stocking Tilapia to consume filamentous algae also benefits a pre-existing Bass population by providing high protein prey items once spawning commences.

Since Tilapia are a decent eating fish on their own, the major advantage of having a predator tank as well is that, as noted, Tilapia are, erm, “prolific”… I’ve grown several hundred gallons of them at one point, and rapidly ended up with hundreds of fish from one breeding pair. (Which was why I ended up with several hundred gallons…)

In Conclusion

I think this shows that whether using shrimp or tilapia as the herbivore fish, and be it spirulina, chlorella, or filamentous algae / duckweed as the base plant food level, it isn’t that complicated to set up a system to turn sunshine and shit into fish, then add on a hydroponic plant farm. Add a chicken coop for the “leftovers” and I think you are pretty much set.

No, this is not well suited for growing “field crops” like rice, wheat, corn, soybeans. It is best for “leafy vegetables” like all the saladings, herbs and seasonings, vegetables like squash, tomatoes, peppers, peas, etc. For root vegetables (carrots, radishes, potatoes, etc) you really need some kind of “grow medium” to support the root; but that’s pretty easy too. From sand to rock wool works.

At one time Disney World had a giant sized The Land hydroponics dome. In it they DID grow things like corn, and even a palm tree or two. (They have since converted it to a “Flying” ride that is more popular). They still have the “back room” aquaponics system and the “Behind The Seeds” tour is well worth taking. They demonstrate all the various hydroponics systems (including aeroponics, sand bed, and more). What was very surprising was to see big melons hanging at head height from trellises with their main stem / roots down in a tube of hydroponics on the floor. Many of their restaurants are stocked from their hydroponics operation; it isn’t just for show. They grow a large variety of things not traditionally thought of as hydroponics crops, and they grow well.

Note, too, that many urban hydroponics systems are in use to make salad fixings just because the perfect (bug and dirt free) vegetables with minimal shipping costs make it profitable. It is coming to dominate that part of the market. Tomatoes, too, especially “off season” are largely from greenhouses of one kind or another. Similarly you can easily grow many other vine crops like cucumbers. So none of this is a hypothetical.

Just putting it on another planetary body is the hypothetical.

Largely all you need are water, warmth, light, and some starter minerals. Then the right balance of species.

For more about other systems, I covered some of them here:

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About E.M.Smith

A technical managerial sort interested in things from Stonehenge to computer science. My present "hot buttons' are the mythology of Climate Change and ancient metrology; but things change...
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29 Responses to Small Scale Aquaponics

  1. Larry Ledwick says:

    An interest spin off of the fuel ethanol boom was efforts to produce ethanol from algae – this proved to be uneconomical but as all industrial pushes things were learned and processes developed and different markets were found.

    In this link we find that one of the limiting factors for high production of algae plant mass was an adequate source of CO2. This would not be a problem on CO2 rich planets like Mars.

    The other essential minerals might be at least partially limiting until local sources were found and mining methods developed.

    Keeping in mind that this idea (terraforming a planet or setting up local grow house systems sufficiently to set up self supporting colonies) is a 100 – 200 year long venture, those things which seem to be hurdles today may be advantages from a different view point.

    Throw in all the work being done on indoor grow factories in areas like Japan and we are slowly accumulating the technology and understanding to put together a viable system. It might take 50+ years but the Thomas Newcomen steam engine was developed in 1712 and steam technology was not really fully developed until the early 1900’s and for Rail Road locomotives did not reach its zenith until the 1930-1940’s so a bit over 200 years to mature the technology.

  2. Graeme No.3 says:

    while the atmosphere on Mars has a high percentage of CO2 I believe that it is about what is on Earth.
    Supply of sunlight? Or electricity for GroLights?

  3. E.M.Smith says:

    @Larry L:

    When your “cost of stuff” is about $10,000 / lb lifted from Earth, it’s a whole lot easier to make the economics work of “growing your own”…. Basically, if you can do it at all, it is economical…

    I think this will drive such integrated “farming” in a can systems into rapid and early use…

    NASA has already done a lot of work on growing food in space, including developing a wheat with a 6 inch stem (don’t need the hay…) and figuring out what plants are almost entirely edible (things like beets, carrots… both root and leaves for both are fully edible…). They clearly recognize the need and benefits.

    So an algae growing process that can’t compete with $2 / gallon gasoline is a whole lot different from one that just has to give you tilapia at less than $5000 / fish ;-)

  4. Bill in Oz says:

    Mars has no ozone layer. So even though the amount of sunlight reaching Mars is less, I suspect that the amount of UV light reaching the Mars surface is much higher. Definitely an issue to think about for any living things being grown outside of hardened shelter.

    Mars is also very quiet volcanically – with no hot liquid core. This is why there is no magnetic field surrounding the planet as on Earth. It is the magnetic field which deflects a lot of heavy duty solar radiation from solar flares etc. Another aspect to consider if crops are being grown in sunlight on the Martian surface.

    I have wondered if arranging to crash a mostly metal asteroid like 2Psyche ( diameter 200ks ! ) into Mars would reignite & heat up again the Martian core & re-establish a magnetic field; as well as bulking up Mars and so boosting Martian gravity somewhat.

    A project needing lots of time !

  5. H.R. says:

    With the potential for bass fishing on Mars, I’m sure there will be no lack of volunteers for a colony.

    I’ve mentioned before that we have a small koi pond. The fish over-Winter just fine even though the ice on the pond can get as thick as 150mm. We stop feeding food pellets to the fish in the Fall when water temperature drops below about 53F and they are left to snack on algae until Spring.

    In the Spring, we don’t feed them fish pellets until the pond is cleaned, even though the water temperature goes well above 53F. We like a nice clean, clear pond so we can enjoy the colorful koi, so that’s why we do a Spring cleaning (coming up May 2nd). I don’t fuss with the cleaning until air temperatures are in the upper 60sF or low 70sF since I don’t care to freeze my fingers and toes while cleaning.

    The koi would do just fine if we didn’t clean the pond and just let them eat the algae and insects, but we feed them pellets so they will grow faster. Large koi are expensive and I’d dare say we have a couple of thousand bucks worth of koi in our pond right now… until a heron gets past the guard Scotty and Cairn terriers and the decoy heron and eats a few.

    It just isn’t that hard to get a self-sustaining pond eco-system going, with the point of my shaggy dog story being that the system can keep going under fairly harsh conditions.

  6. E.M.Smith says:

    @Bill in Oz:

    At about 10^4 less mass, it won’t make Mars much heavier… then the best theory so far for volcanic power is nuclear decay where the lighter Mars ran out of fissionables before us due to less mass – whacking with a rock, even a big one, doesn’t fix that and doesn’t restart vulcanism or magnetism.

    FWIW, I thought it was (16) Psyche?

    Good points on the UV and particle protection… Leaded Glass greenhouse? ;-)

    Probably a lot easier to just put LED lights in a tunnel…


    Mars Bass Derby? Not “shooting fish in a barrel” but “casting in a barrel”?

    Maybe we could have a big “grow out” pond stocked with cattail reeds… They have many edible parts too

    Typha /ˈtaɪfə/ is a genus of about 30 species of monocotyledonous flowering plants in the family Typhaceae. These plants have a variety of common names, in British English as bulrush, or reedmace, in American English as reed, cattail, or punks, in Australia as cumbungi or bulrush, in Canada as bulrush or cattail, and in New Zealand as raupō. Other taxa of plants may be known as bulrush, including some sedges in Scirpus and related genera.

    The genus is largely distributed in the Northern Hemisphere, where it is found in a variety of wetland habitats.

    The rhizomes are edible. Evidence of preserved starch grains on grinding stones suggests they were already eaten in Europe 30,000 years ago.

    So I could see making a very large cavern tunnel, with bulrush plantings along the edges, and stocked with Bass… As a large tunnel, it might be a bit boring running an electric boat just straight up the middle, casting to both sides, knowing that it’s just full of large bass… but I’m sure you could cope with that ;-)

    Periodic harvesting of the tubers would provide a nice starch source. There are other parts that are edible or useful for animal feed:

    Culinary uses

    Many parts of the Typha plant are edible to humans. The starchy rhizomes are nutritious with a protein content comparable to that of maize or rice. They can be processed into a flour with 266 kcal per 100 grams. They are most often harvested from late autumn to early spring. They are fibrous, and the starch must be scraped or sucked from the tough fibers. Plants growing in polluted water can accumulate lead and pesticide residues in their rhizomes, and these should not be eaten.

    The outer portion of young plants can be peeled and the heart can be eaten raw or boiled and eaten like asparagus. This food has been popular among the Cossacks in Russia, and has been called “Cossack asparagus”. The leaf bases can be eaten raw or cooked, especially in late spring when they are young and tender. In early summer the sheath can be removed from the developing green flower spike, which can then be boiled and eaten like corn on the cob. In mid-summer when the male flowers are mature, the pollen can be collected and used as a flour supplement or thickener.

    The roots may also be boiled, steamed, fried, or mashed with butter or sour cream much like potatoes.


    The seeds have a high linoleic acid content and can be used to feed cattle and chickens.
    They can also be found in African countries like Ghana.

    So it’s not like it would be some self indulgent play area… it would a major contributor to food and feed for The Colony. Yeah, that’s the reason…. ;-)

    Sidebar on Famine Food: It amazes me just how many people, living near long stretches of cattail filled waters, have no clue it’s a large pantry for everything from seeds to cooked vegetables to flour and more. Oh Well, more for me ;-) (Though harvesting in Florida would be a challenge, one has the opportunity to get Gator Jerky in the process ;-)

    Carp ( Koi are decorative carp) are a common food fish in Asia, but not so much in the USA. They have little floating Y shaped bones in the meat – I’ve eaten one but it was a lot of work… There are ways to cook them that soften or dissolve those bones, like canning. Not saying you ought to eat your Koi ;-) just “setting the context” for folks who are not “fish people” ;-)

    So the farming of carp is particularly easy, and there are several kinds that are happy with nearly nothing in the way of feed. Many have a down facing “sucker” mouth and mostly just eat muck and stuff they find in the mud. For example, the Silver Carp is busy taking over the entire Mississippi basin:

    The silver carp (Hypophthalmichthys molitrix) is a species of freshwater cyprinid fish, a variety of Asian carp native to China and eastern Siberia. Although a threatened species in its natural habitat, it has long been cultivated in China. By weight more silver carp are produced worldwide in aquaculture than any other species of fish except for the grass carp. Silver carp are usually farmed in polyculture with other Asian carp, or sometimes with catla or other fish species.

    The species has also been introduced to, or spread by connected waterways, into at least 88 countries around the world. The reason for importation was generally for use in aquaculture, but enhancement of wild fisheries and water quality control have also been intended on occasion. In some of these places the species is considered an invasive species.

    The silver carp reaches an average length of 60–100 cm (24–39 in) with a maximum length of 140 cm (55 in)[7] and weight of 50 kg (110 lb).

    The problems are that they are filter feeders so don’t take a hook, and if they eat the wrong algae, can build up algae toxins:


    The silver carp is a filter feeder and possesses a specialized feeding apparatus capable of filtering particles as small as 4 µm. The gill rakers are fused into a sponge-like filter, and an epibranchial organ secretes mucus which assists in trapping small particles. A strong buccal pump forces water through this filter. Silver carp, like all Hypophthalmichthys species, have no stomachs; they are thought to feed more or less constantly, largely on phytoplankton. They also consume zooplankton and detritus. In places where this plankton-feeding species has been introduced, they are thought to compete with native planktivorous fishes, which in North America include paddlefish (Polyodon spathula), gizzard shad (Dorosoma cepedianum), and young fish of almost all species.

    Because they feed on plankton, they are sometimes successfully used for controlling water quality, especially in the control of noxious blue-green algae (cyanobacteria). Certain species of blue-green algae, notably the often toxic Microcystis, can pass through the gut of silver carp unharmed, picking up nutrients in the process. Thus, in some cases, blue-green algae blooms have been exacerbated by silver carp. Microcystis has also been shown to produce more toxins in the presence of silver carp. These carp, which have natural defenses to their toxins, sometimes can contain enough algal toxins in their systems to become hazardous to eat.

    So assuring no cyanobacteria (blue-gree algae) make it into a Mars pond would be very important.

    IMHO we need to assure some top predator fish are in the Mississippi who can eat (and like to eat) Silver Carp, otherwise that fishery will become very dull. (Well, other than that these fish love to jump out of the water when disturbed so many folks have been injured when the fish leap out of the water and your power boat runs into them at 20 MPH… ) Perhaps a captive breeding program for native top predators to get them past the problem of the carp filtering out all the plankton their fry need to develop…

    While not my favorite food fish and not one I’d aquaculture, I do see a future for Asian Cuisine on Mars featuring traditional carp dishes…

  7. E.M.Smith says:

    @Graeme No.3:

    Any habitable area will be pressurized as would growing areas. It would be a lot easier to pump and pressurize the high CO2 gas into a greenhouse than to extract oxygen from it, then pump and pressurize the habitable area.

    For that reason, I could easily see a system where exterior CO2 is pumped up to pressure in the growing areas as a constant feed from outside, then the plants make it into O2 that is used in the rest of the colony. Saves all that oxygen extracting and pressurizing equipment and processes….

    Electricity is easy. That’s why Elon Musk is all into Solar City. He’s developed all the tech for Mars (as that is his major goal) with solar panels and batteries. Eventually, with a large enough growing system, the “left overs” could be burned as power for heat engines, but I doubt that’s the best use of them.

    IF you make a “Light Pipe” system to bring sunshine to the grow area, that would reduce the need for electric lighting and increase the potential to use biomass for general fuel uses.

    These can be made with a big bend in them to prevent radiation getting in (so the walls only reflect the optical wavelengths of interest; or the inlet has a color filter).

    Initially I’d expect solar panels + LED lights (as a known and guaranteed tech) but over time, I’d expect light pipes from native materials and constructed into the structures to be added (as construction techniques are worked out in martian soils / rocks).

  8. gallopingcamel says:

    A trip down memory lane! Forty years ago I was running an industrial scale fish farm in the heart of London (UK). Our main tanks were 500 tonnes but we had a bunch of smaller ones too. We experimented with Carp and eels but eventually settled on rainbow trout. Here are some 20 tonne tanks:
    The plant culture part of the Purdue video is beyond my experience but I do remember the Zoology department at NCSU using the effluent from Tom Losordo’s “Fish Barn” to grow tomatoes in a very cheap greenhouse made of plastic film.
    The Purdue closed loop circulation system is a little disappointing when it comes to removing ammonia and nitrites. Their technology (plastic media) is much more expensive than what we were using 40 years ago. We used a fluidized bed bio-reactor which was a scaled down version of what the US Army Corps of Engineers installed at Dworshak fish complex in Idaho:
    Later I got together with Harry Fischer to build a 900 gallon per minute water treatment system that could be delivered by road. The tank with a conical bottom is the fluidized bed reactor and the cylindrical tank is full of plastic media (just like the Purdue one) but its function is oxygenation rather than de-nitrification. The pump has an electric motor drive backed up by a propane motor:
    Pudue points out the importance of insulation. Here is a picture of the “Sea Street Salmon” building in Eastport, Maine. The building was previously used as a cold store lined with 6″ of foamed plastic insulation. The water on the right is the Bay of Fundy with 30 foot daily tides.:

  9. E.M.Smith says:

    Um, the “file:” says it is a file on your computer, so not going to show up here (unless it is on a public web server, we can’t see it… so no URL no visibility…)

  10. Larry Ledwick says:

    I think it is clear that we are rapidly approaching the point where all the essential technologies exist for planet hopping, we just need to put together the right assortment.

    We already have experience with sealed environments in nuclear submarines for managing atmospheres all you need it surplus energy.

    Here on earth the incident solar energy is approximately 1362 watts / meter^2 at top of atmosphere, on mars at an orbital distance of 1.523 AU that would scale by the inverse square law to about 587.2 watts / meter^2. so just a bit over 1/2 the solar intensity here on earth at noon illumination would be about like an overcast day here on earth. Two solutions for that, one would be use 2x the number of solar panels (at x thousand dollars a kg to get them there not a good solution) but by using relatively light weight reflectors to increase the illumination on the panels would be a cheaper solution. The dust storms would be an issue as they could reduce solar illumination on the ground to only 5%-10% of normal for weeks (plus the work load to keep the panels clear).

    Then of course you have the same solution as we use on nuclear submarines – ie a nuclear reactor.

    Once you get a reliable source of abundant energy there are no real deal breakers to setting up a colony on Mars.

    But in time all those issues can be sorted out by the first couple generations of Martian colonists, to create a self sustaining system.

  11. gallopingcamel says:

    Those photo files in the above comment did not show as pictures. Is there any way to fix that?

  12. gallopingcamel says:

    So how do you develop a power plant and where do you make the first field trial?

    IMHO we should try colonizing the Moon before Mars. Here is a TED talk by Kirk Sorensen:

  13. Larry Ledwick says:

    So how do you develop a power plant and where do you make the first field trial?

    Not sure I get your question?
    They have already designed multiple SNAP reactors for space, they have already designed high reliability nuclear power plants for submarines. They have already designed high efficiency sterling engine generators (again for submarines) which can harvest low grade heat for power.

    The big problem with nuclear plant designs for space is the concern everyone has if you have a launch failure. The best design would be a modular design where it is non-critical when launched, and does not go critical until it is on Mars and the components are assembled.

    The engineering is largely already done (at least in concept since their are actual production designs of all three of those power plants it would just be a matter of setting design parameters for that usage and building to meet those objectives.

    Given how unforgiving space is I would vote on design objectives which use multiple small modules who can produce power in parallel so if one is down for maintenance or repair you don’t lose all power like you would in a large singe power producer. Moon base is another option but as Zubrin points out by the time you have gotten out of earths gravity well to get to the moon you have already expended most of the energy needed to get to Mars.

  14. jim2 says:

    Biology will be the most likely deal breaker. Fungi on plants, bacteria or fungi in people. A small colony of people isn’t very resilient.

  15. H.R. says:

    @jim2 – Speaking of deal breakers, “CROATOAN” comes to mind.

  16. H.R. says:

    @E.M. re cattails – By chance, about a week ago I ran across a short video about eating cattail roots (rhizomes).

    The fellow tried them raw, then cooked. His main objection was the fibers, not the taste and the cooked ones had softer fibers. That reference you found calling them Siberian asparagus gives me an idea of what those fibers are like; you need to chew the goodies away from the fibers and then spit.

    That pond I fish (headed there after I hit ‘Post’) is overrun with cattails. I’m going to harvest some when the greenery starts to show. With a nice seasoning or perhaps a bit of Hollandaise sauce, they sound mighty tasty.

    (Just checked my bookmarks and rats! I didn’t save the link to the video.)

  17. E.M.Smith says:


    The pictures need to NOT be a “file:” on your computer but an “http” or “https” on a web server… (or you can set up a free wordpress account and upload / publish them).


    I think the question is about making a colony sized low g reactor and testing it (since we can’t do low g and vacuum here on Earth, then where?)

    I fully agree with the notion of a “Moon First” colony. MUCH shorter shipping times / distances. Emergency help a week or two, not 2 years+, away. No need to deal with weather. Once your full vacuum system is running, doing a low air pressure system is easy. (i.e. sealing rock and airlock to hard vacuum makes doing it to 1 psi easy). Starting with lunar full sun vs Mars 1/2 sun is also easier.

    Then, a lunar colony has more things it can do to “make money”. From being an Earth Observation & Communications station to a Vacation Spot (at God Awful $$$/ week) and He3 mining / research and various “observatories” and more.

    Per the “energy to Luna almost to Mars” – while true, it’s the TIME to Mars (largely unshielded) that’s the major issue. Lots more to go wrong and much harder to recover. Then, for Luna, it makes a GREAT base from which to run your Mars operation. Has some gravity (so lots of things are easier from taking a shower to drinking coffee…) but not so much that getting back on a path to Mars is low energy loss. A “water mining” operation to make rocket fuel for a Mars run would also be a nice thing. And making the heavy shielding to put around a Mars Ferry… so a solar flare doesn’t cook your colonists…

    Per Solar Reflectors:

    There are lots of concentrating solar collectors, even on Earth. Best would be to figure out how to make such reflectors from material on the Moon or Mars, so first run I’d expect to be nuclear powered, then with basic solar, then adding concentrators.


    A small ISOLATED colony isn’t very resilient. One in constant contact with the home world and growing fast from migration is…


    per CROATOAN: Lost Virginia colony… In many ways they were further from home than a Mars colony would be. 1 to 2 years for a letter (as opposed to a few minutes for video…) and very infrequent resupply… if any. No good idea what conditions were going to be before landing. Poorly prepared voyage with much sickness and not great food in transit.

    Note for Cattails how often they reference young shoots or seedheads… Just avoid the old tough ones.

    FWIW, a pressure cooker softens a lot of tough vegetables…

  18. E.M.Smith says:

    What I’d really like to see is an O’Neill Cylinder factory (maybe on the Moon)'Neill_cylinder

    and then a couple of them in a transit orbit that periodically reaches Mars then returns to Luna (with shuttles to Earth).

    Folks could choose to get off (or on) at one end or the other or just book a ‘cruise” passage.

    That would make the costs and risks of a colony (on Luna, or Mars, or ‘wherever’) much less as your transit isn’t “sunk cost” it’s a thriving city on its own. Then Mars also has a “tourism business” as folks on the O’Neill Cylinders may like the idea of a low energy cost visit to an exotic planet. “Weekend on Mars” becomes doable… Shuttle in at first approach, then shuttle out to catch the Cylinder before it’s too far ahead.

    For Mars, it means a regular supply / visitors / potential help every “so often” which might start at one a year, but could easily become one a month with a few dozen Cylinders running…

    But first we must get someone, anyone, off this damn gravity well rock …. and I think a Luna colony would be the easiest place to set up a minor facility (followed closely by a lunar orbiting “base” for transit services). At least, that’s the way I’d bootstrap it. Though I could see making a small skyscraper sized O’Neill Cylinder for maybe 1,000 people as an exemplar in Earth Orbit… or maybe Lunar / Earth looping…

  19. E.M.Smith says:

    Interesting that the O’Neill Cylinder wasn’t the first, it wa the 3rd of his approaches. The first is a much smaller sphere and would be very “do-able” in Earth or Lunar orbit:

    A Bernal sphere is a type of space habitat intended as a long-term home for permanent residents, first proposed in 1929 by John Desmond Bernal.

    Bernal’s original proposal described a hollow spherical shell 16 km (9.9 mi) in diameter, with a target population of 20,000 to 30,000 people. The Bernal sphere would be filled with air.
    O’Neill versions
    Island One

    In a series of studies held at Stanford University in 1975 and 1976 with the purpose of speculating on designs for future space colonies, Dr. Gerard K. O’Neill proposed Island One, a modified Bernal sphere with a diameter of only 500 m (1,600 ft) rotating at 1.9 RPM to produce a full Earth artificial gravity at the sphere’s equator. The result would be an interior landscape that would resemble a large valley running all the way around the equator of the sphere. Island One would be capable of providing living and recreation space for a population of approximately 10,000 people, with a “Crystal Palace” habitat used for agriculture. Sunlight was to be provided to the interior of the sphere using external mirrors to direct it in through large windows near the poles. The form of a sphere was chosen for its optimum ability to contain air pressure and its optimum mass-efficiency at providing radiation shielding.

    I’d go with 1 RPM and less than 1 G (1/2 G ought to be more than enough). A 500 m structure (or about 1500 feet) is well inside our ability to construct. We make ships that must take full on tropical storms while housing a few thousand folks that are about that size:

    “Length: 1,106 ft (337 m)[9]”

    # Ship Cruise line Year Gross
    tonnage Length Beam Staterooms Passenger capacity Image
    Maximum Waterline Double Maximum
    1 Symphony of the Seas Royal Caribbean International 2018 228,081[1] 361.011 m
    (1,184.42 ft)[1] 65.7 m
    (215.5 ft)[2] 47.778 m
    (156.75 ft)[1] 2,759[2] 5,518[2] 6,680[2] SymphonyOfTheSeas (cropped).jpg
    2 Harmony of the Seas Royal Caribbean International 2016 226,963[3] 362.12 m
    (1,188.1 ft)[3] 65.7 m
    (215.5 ft)[4] 47.42 m
    (155.6 ft)[3] 2,747[4] 5,479[a][4] 6,687[4] Harmony of the Seas (ship, 2016) 001 (cropped).jpg
    3 Allure of the Seas Royal Caribbean International 2010 225,282[5] 360 m
    (1,180 ft)[5] 66 m
    (215 ft)[6] 47 m
    (154 ft)[5] 2,742[6] 5,484[6] 6,780[6] Allure of the Seas (ship, 2009) 001 (cropped).jpg
    Oasis of The Seas Royal Caribbean International 2009 225,282[7] 360 m
    (1,180 ft)[7] 66 m
    (215 ft)[8] 47 m
    (154 ft)[7] 2,742[8] 5,484[8] 6,780[8]

    So seems to me we ought to be able to make something about that scale that needs to take 1/2 G of relatively constant force, with no weather or storm forces, that is kept in shape by air pressure so only has relatively pure tension forces to deal with. We make fiber wound pressure tanks that take 3000 to 4000 psi pressures so doing 7 psi ought to be pretty simple…

    Having several thousand folks “on orbit” would be more than a big enough colony to start things rolling. Put another one in orbit around Mars, and then a Mars Surface Colony becomes a relatively easy next step.

  20. Larry Ledwick says:

    I spent a good deal of time pondering some of these issues back in the early 1990’s.

    The Stanford Torus is of course the model of space station that most everyone thinks of when you mention the term but I came up with a different way of building large orbital structures.

    In terms of volume to surface area the sphere is of course the winner, and it also inherently solves some problems.

    The idea I came up with was modeled in concept to the way pioneers built colonies in a new world. First you build a core safe zone and then gradually expand it.

    The first structure would be a large spherical balloon composed of a strong fabric like kevlar that was sufficiently air tight to allow it to be inflated. Once it was inflated you assemble a pole to pole central cylinder. The original balloon membrane would have attached air lock structures the largest diameter that you could fit in a heavy lift rocket. Then inside that you would have a series of open ended tapered cylinders (think a stack of dixie cups with no ends). You would pass those cylinders into the cylinder via the air lock and by alternating direction bolt them end to end, pairing small ends and large ends to make a solid core tube that appeared slightly corrugated, due to the about 3 degree taper necessary to make them nest with each other. You now have a solid habitable core tube that you could pressurize like an airplane fuselage. It runs from pole to pole in the sphere with an airlock docking structure at both ends. Then you begin to spin the sphere on the core axis and begin to spray the interior of the fabric balloon with a UV curing resin and chopped glass fiber. Something like shotcrete or flame spray you build up a ridged liner of resin which thanks to UV exposure through the translucent bag balloon would cure into a rigid fiberglass sphere.

    At that point you have a work volume you that you can gradually build multiple rotating decks of compartments, some of which could be pressurized at habitable pressures others at just enough pressure to allow free movement without a pressure suit.

    The advantage of this is you can bring up modules which just fit through the docking ring and air lock fully finished with interior fittings, instruments and plumbing and assemble them in low gravity by bolting or welding them together. Some would be designed like a slide out structure in a mobile home / RV with full fittings in one half and an empty shell on the other half which once inside the sphere can be expanded to full volume, welded air tight and assembled into the decks starting with the equatorial deck.

    Meanwhile another team would assemble a geodesic rib structure inside the fiberglass rigdid outer sphere anchoring to it (makes assembly much easier working on a scaffold rather than assembling in zero G with no fixed points to keep things from drifting away from each other.

    The one problem that was tough to solve is that over time, the outer fabric bag would be degraded by radiation, ablation of micro meteors and UV exposure. The question is do you just let it ablate away (in which course your structure is eventually surrounded with a cloud of bits of the shell, or to you put a top cover over the outside that resists those problems?

    For ease of working with an outer shell of thin steel plates curved to fit the dimensions of the sphere has some advantages as either workers or robot workers could “walk” the surface with magnetic traction shoes / tires. Once the outer plates were positioned you could weld them with laser or electron gun welding.

    The other possibility would be to insert steel disks in the bag every foot or so that can be used to keep attachment to the surface without the limitations of tether systems while building an outer metallic shell that stands off the surface of the bag balloon a convenient distance for workers to “stand on the balloon”and build the frame and plate structure for the outer hull at comfortable working distance over head. This of course would be hard vacuum conditions so would need to be done in full pressure suits.

    Think of the spherical volume as the cleared fields of a new colony in the hostile forest. It provides a foot hold environment to build out from.

    Several of these spheres could be assembled end to end to make a beaded chain similar to the O’Neill Cylinder but unlike the O’Neill Cylinder you would have natural compartmentalization so a hull breach in one sphere would have limited pressure and atmosphere loss.

    My idea was that instead of building one shell able to sustain full pressurization you have multiple layers each pressurized at slightly higher pressures as you go toward the core or less pressure as you moved toward the outer hull. These would in turn create a natural whipple shield against meteorite impacts.

    Penetrations for exterior windows etc would have to be engineered into bag design or methods worked out to pierce the bag to establish airlock structures allowing visual or physical access to space, working entirely from the interior of the shell. (another advantage of multiple hull construction the outer penetration could occur at very low differential pressures and as you in turn penetrate each successive inner shell you on each also have low relative pressures between the shells.

    That is about as far as I got, but my thinking was a build as you go structure consisting of a central axis core in a sphere and a double layer equatorial deck that extends out to the outer shell was a good place to start and you could build out what you need when you need it.

  21. E.M.Smith says:

    Interesting design ideas…

    Once you have the bag sprayed and shell made (rather like fiber glass “Dome Homes” – look up Baggen’s End at UC Davis ) and with a metal airlock in the ends, it would be fairly easy to add pre-pressed sheet metal cover segments that just ‘clip together’. There’s lots of clip assembly designs to choose from, and I don’t see welding as needed (or even desirable should you need to repair a small puncture…) Since each next unit of cover (call them 1 m chunks) makes its own ring and all is mutually attached and anchored to the thick air-lock structure, it really ought to be fairly trivial to assemble. Just pick a “week end” and stop rotations while a couple of folks in pressure suits with mag boots walk in spirals from both ends clipping panels in place.

    I’d likely have each panel backed by an insulating mat, or perhaps just have it be double layer so it acts like a thermos (vacuum supply is free with a tiny vent hole on the edge somewhere…

    Per windows: Really? In the era of hi-def video? Yeah, it would be “fun”, but with the need for gold plated sun shields and such, really more a PITA than it is worth. Put on $1000 of small hi def video cameras and call it done… Have a couple of your panel belts be solar cells and have all the artificial light you want inside along with any view in any direction on the flat panel…

    I’ve lived in a box with NO windows for a few months. You get used to it very quickly even for a bedroom sized box. That was without even a TV view “outside”…

    FWIW I’d expect Lunar Titanium to be a preferred material in space construction, augmented by Asteroid Nickle Steels… then with Lunar Crete for those C.E. Design needs ;-)

  22. Larry Ledwick says:

    One interesting idea would be to make the outer shell out of concrete or similar mineral matrix, perhaps fiber reinforced. You could ship it up in bags as powder, and fabricate custom panels for various locations like ferro-concrete. Once cured it would I think make a great exterior hard shell able to tolerate long term UV and radiation exposure.

    Per windows: Really? – I was thinking off visual sensors – think port holes. Big glass or plastic viewing domes would be cool / desirable if part of your functionality was a tourist destination, but could be about as big as the viewing bubble on the side of rescue aircraft.

    If they can penetrate and tap oil pipe lines and natural gas pipe lines, I am sure they can come up with a system to, from the inside, put penetrations in the structure at will. That is one of the rationals for a layered shell, you place a small bell jar like enclosure over the inner surface of the pressure hull you want to penetrate, punch a hole (or pump down) to de-pressurize and the pressure differential holds it in place and you are free to have your work crew take a skill saw or equivalent to open a big opening in the shell, weld in or epoxy the necessary penetration devices and once sealed and cured, pressurize your work capsule enough to pop it off the surface and take it back to the maintenance portal for that shell.

    One of my primary goals was to come up with a system which you can do 90% of your work from the inside at high enough pressures to avoid use of full pressure suits.

    There is also no reason that outer pressure shells could not be pressurized with CO2 or other “expendable” gas rather than having breathable air in sufficient volume to fill those outer shells.

    One of the first hurdles I had to jump mentally, is that in “space” volume is everywhere and free, all you have to do is enclose it to make habitable islands where you need them. My concept was to think in terms of three dimensional freedom and space, no need to put things right together when you have literally unlimited volume to work in, limited only by the expense and materials required to build the shell. By building with multiple pressure shells, you also distribute the stresses over multiple layers, allowing you to make each layer thinner and easier to work with, and also you gain strength of redundancy. If you had total failure or pressure integrity of one shell, you would want to have enough reserve strength in the shell below it, to prevent catastrophic failure and also to limit atmospheric mass loss to manageable levels.

    In a perfect design you would literally build an onion from the inside out, slowly expanding the exterior shells by adding layers, and after a few layers were in place, you could disassemble interior shells and reuse the materials for out shells or recycle for other uses, gradually increasing habitable volume while working mostly on the inside of the structure. Eventually you could have a huge internal hanger space of enormous volume to build structural modules in.

    Using technology like powdered metal sintering, 3D printing, and build up of structures out of stamped metal (which could easily be shipped to the station as large rolls of sheet metal or coils of rod or pellets) which could be remelted and cast using electrical induction furnaces or extrusion processes you could even over time move to heavy manufacturing and gradually develop local production capability directly from raw materials (future use of asteroid capture materials)

  23. Larry Ledwick says:

    Once you get a habitat on or near the moon you have effectively unlimited access to powdered stone for construction of ceramics, glasses, mineral matrix materials like concrete, and reinforcing fibers of basalt. Eventually refined metals once you locate any suitable ore bodies.

  24. E.M.Smith says:

    I think you will find robotic ships retrieving nickle iron asteroids easier than reducing ore in space. You already have free metal… just needs some melting and cleanup.

    Folks have already worked out a lunar concrete formula…

    Only comparatively small amounts of moon rock have been transported to Earth, so in 1988 researchers at the University of North Dakota proposed simulating the construction of such a material by using lignite coal ash.[3] Other researchers have used the subsequently developed lunar regolith simulant materials, such as JSC-1 (developed in 1994 and as used by Toutanji et al.).[4] Some small-scale testing, with actual regolith, has been performed in laboratories, however.[2]

    The basic ingredients for lunarcrete would be the same as those for terrestrial concrete: aggregate, water, and cement. In the case of lunarcrete, the aggregate would be lunar regolith. The cement would be manufactured by beneficiating lunar rock that had a high calcium content. Water would either be supplied from off the moon, or by combining oxygen with hydrogen produced from lunar soil.[2]

    Lin et al. used 40g of the lunar regolith samples obtained by Apollo 16 to produce lunarcrete in 1986.[5] The lunarcrete was cured by using steam on a dry aggregate/cement mixture. Lin proposed that the water for such steam could be produced by mixing hydrogen with lunar ilmenite at 800 °C, to produce titanium oxide, iron, and water. It was capable of withstanding compressive pressures of 75 MPa, and lost only 20% of that strength after repeated exposure to vacuum.[6]

    In 2008, Houssam Toutanji, of the University of Alabama in Huntsville, and Richard Grugel, of the Marshall Space Flight Center, used a lunar soil simulant to determine whether lunarcrete could be made without water, using sulfur (obtainable from lunar dust) as the binding agent. The process to create this sulfur concrete required heating the sulfur to 130–140 °C. After exposure to 50 cycles of temperature changes, from -27 °C to room temperature, the simulant lunarcrete was found to be capable of withstanding compressive pressures of 17MPa, which Toutanji and Grugel believed could be raised to 20MPa if the material were reinforced with silica (also obtainable from lunar dust)

    So it is a mostly solved problem.

    Water, metals, air, and concrete all can be made from moon dust and asteroids.

    Save Earth shipping for complex manufactures and specialty goods…

  25. Larry Ledwick says:

    I think you will see both depending on the state of maturity of the colonization and relative economics.

    The moon is abundant in Ti, so it would make sense to mine and refine it on the surface. It has some advantages and disadvantages as a construction material how ever. It is a strong tough but sticky metal, so in applications like fasteners it tends to gall. It also is hard to work with due to its high strength, and in a high nitrogen atmosphere it can pose a fire hazard as it burns in a 100% nitrogen atmosphere, eliminating Oxygen is not sufficient to extinguish fires involving titanium.

    In the case of asteroids you have nearly pure iron nickle alloy if you pick the right ones so no need to refine simply melt and form.

    The lunacrete is pretty high strength and certainly an end point but for early experimentation in orbit you could work out methods with terrestrial concrete powders and fly ash to figure out how to make the stuff in a low g environment (which may be more difficult than it sounds due to dust control issues). You don’t want to crap up every square inch of your really expensive orbital habitat with talcum powder fine abrasive dust, so they will have to work out how to handle it and how to clean up any dust that escapes. (electrostatic methods would probably be a top contender to capture free dust in the station atmosphere).

    How a concrete analog would fare under thermal shock of orbital and lunar night day may also be a difficult to solve problem. Perhaps a refractory ceramic top layer might be the solution to that problem using lasers to fuse the surface of outer shell tiles for example.

    I personally think that in 100 years or so people will scratch their head in wonder at why it took so long to make a jump to multi planet residency of humans, and they will likely see space as a resource rich environment if you know what to look for and where to look for it.

    I think for practical purposes we have already solved essentially all the fundamental challenges we just need the right ideas blended together into a consistent method of operation.

  26. E.M.Smith says:

    The thermal issue was why I mentioned hollow sheet steel cover plates. Think steel thermos, but without the need for sealing in the vacuum! :-) have clip together expansion fastners and it is a dandy thermal shield that also stops micro impact abrasions. Cheap. Easy to install and replace.

    Larger impacts, the sheet starts the impactor breakup reducing depth of defect. Unclip that panel, trowel in cement, clip in new panel. Recycle the old one.

    Only big impactors are a problem, but active defence can deal with them. Lasers are your friend :-)

  27. p.g.sharrow says:

    “The gas – liquid contacting device and method”, was created to duplicate the air and water system that created and maintains our atmosphere. Just the thing that would be needed for the atmospherics life support, cleaning and renewing the air in a sealed environment…pg

  28. jim2 says:

    RE Mars colony. I think first put up a torus-shaped, Mars-orbiting space station with artificial gravity. People with about 25. Send a supply ship every three months. Use robots on the surface, controlled by the people in the space station.

    Figure out how to grow food, create cement, and all that other good stuff from the safety of the space station. Supply ships would have to worry about Earth take-offs and landings only. The space station could send down supplies one-way.

    And when the time comes for people to move in, it sure shouldn’t be a bunch of old farts whose backs won’t last a week :)

  29. gallopingcamel says:

    “The big problem with nuclear plant designs for space is the concern everyone has if you have a launch failure. ”

    Take another look at that TED talk by Kirk Sorensen. He is talking about a molten salt reactor that will be several times lighter than any reactor design that needs a pressure vessel. The active part of the fuel is designed to survive a launch failure.

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