The long-term and permanent settlement of people on Mars will require advanced planning to satisfy their nutritional needs going beyond what has been developed for relatively short stays on the International Space Station. While some food goods may be shipped at high cost, most foods will eventually need to be produced in-situ. Accomplishing this will require the utilization of liquid nutrients, aquaponics, and hydroponics for plants, as well as new developments in synthetic and 3-D printed foods for meats and sweets. Finally, some “exotic foods” adopted from different cultures may make their way into the cuisine of Mars settlers and explorers.
1.Food shipped from Earth
In the early days of Mars settlement, food will likely be shipped from Earth, probably in freeze dried form. The technology for producing and storing such food is well established. However, a recent NASA study1 seems to indicate what many have long suspected: such food processing and storage reduces the nutrient value of the food. This is a serious drawback that might be offset with vitamin supplements. In addition, there is the matter of cost. Estimates of the cost of delivering a kilogram of anything to Mars vary widely, but right now about $10,000 per kilo is the best guess, and this assumes that the delivery infrastructure is well established and operating on a regular basis. Finally, there is the sheer boredom of eating the same processed food every day. Perhaps the reader can imagine eating nothing but frozen dinners for years on end to understand the desire for variation.
2.Hydroponically grown food
Hydroponics, which is the growth of fruits and vegetables in a non-soil, liquid medium of nutrients in controlled conditions of light and temperature, is well established food technology. Many of the vegetables you purchase at the supermarket will be labeled as hydroponically grown. Gotham Greens2 for example, grows vegetables in Brooklyn for local sale. One chief advantage to this type of farming is that crops are grown year round. Tomatoes, for example, when grown in regular soil using traditional farming methods, typically only produce one crop per growing season. However, greenhouse enclosed hydroponic farms can produce the equivalent of 2.5 to 3 crops per year because the planting of the crops can be staggered. Heat and light are provided artificially during the winter months. Also, because the nutrients are being provided as needed, plants can grow much more densely than when traditional plant in soil methods are used. Another example of hydroponic farming being used in an old Sony Electronics factory in Japan was designed by plant physiologist Shigeharu Shimamura. His farm is about an acre, the size of a football field3. Each section utilizes 17,500 LED lights to save power, and contains 18 cultivation racks stacked 15 levels high to save space. The farm produces 10,000 heads of lettuce per day! No traditional farm even approaches this. A typical American farm using traditional methods yields a little over 7000 heads in the same area per season4. The advantages of this type of farming over traditional methods for a station with limited space are obvious. Since soil, at least not in the Earth-side sense with which we are familiar, will likely not be available anytime soon, hydroponics seems like a good workaround of that problem. If the settlers themselves do not produce enough carbon dioxide to supply the plants, Mars air, which is 95% carbon dioxide, can simply be compressed and introduced into the farm. One drawback of the technology, however, is that it is highly open ended. You put in a lot of water, artificial nutrients, as well as energy, and get food and oxygen in return. My next topic addresses those shortcomings in a novel way.
The term aquaponics is a blend of hydroponics and aquaculture, which is the growing of aquatic life in a semi-closed environment. While not as well known or long and widely practiced as hydroponics, it is possibly the most promising technology for a semi-closed system such as will exist in a Mars station or settlement. There are several reasons for this. Like the station itself, an aquaponics system is semi-closed. The nutrients for both the aquatic animals and the plants are recirculated. According to long practicing experts Hank Burroughs of Salem, Oregon and Mihail Mateev of the Mars Society Bulgaria, both of whom were guests on Mars Pirate Radio5, an aquaponics garden can require as little as 10% of the inputs of water and nutrients that a pure hydroponic garden or aquaculture tank would need. The fish release ammonia and other nutrients into the water as waste which is then circulated into the plant garden. The purified water from the plant garden is then drained back into the aqua tank for use by the animals. Ideally, a portion of the crop is harvested as food for the fish as well as certain waste products from the human consumption of the produce. Thus animal protein in the form of carp or catfish as well as fruits and vegetables are all produced by the system for human consumption. The systems can be very compact. As long as heat, light, atmosphere, and other chemistry is kept in balance, the mixed system will continue to produce food. Mr. Burroughs suggests having both fresh and saltwater systems in place, despite the corrosion problems associated with the latter. The primary reason, other than varying the diets of the astronauts, is that one system may become contaminated with a blight, fungus or other disease, but the chances that both systems will become infected with the same disease are small. Fresh water and salt water animals and plants don’t tend to mix. Such an arrangement would also present another level of the systems redundancy that is of paramount importance to such an isolated community. As with hydroponics, this technology is well established and the knowledge is “on the shelf,” simply requiring modification to fit the special circumstance of an isolated station on Mars5.
4.Synthetic and 3-D printed foods
Unlike the aforementioned technologies, synthetic and 3-D printed meats and food products are not yet “on the shelf.” Synthetic meat, for example, utilizes stem cells harmlessly extracted from the animal product you wish to replicate. Those cells are then grown is a special nutrient medium to produce the final product7. For example, in theory, using a simple syringe, one would extract a sample of flank steak stem cells from a cow, and then use that sample to culture and grow flank steaks. The animal remains unharmed, suffering no more than when you give a blood sample at the doctor’s office. In the end, however you get the same product that the slaughterhouse and butcher would produce, only without harming the animal in the process. This procedure has yet to be perfected, the principal problem seeming to be finding the exact makeup of the growth medium, but researchers including Bernard Roelenat of Utrecht University in the Netherlands, beleive they are close to solving the problems.
Similarly, 3-D printing, which we usually associate with the manufacture of metal and plastic products, is being explored as a means of producing food products, including meat substitutes. In a July 2015 article in the Wall Street Journal, it was stated: “Production systems are also advancing from initiatives such as NASA’s project to print food in deep space8; SMRC, a NASA contractor, created pizzas and chocolate from processes integrating dry and liquid ingredients. Cornell University9 and TNO in the Netherlands are working on food material properties.” As with synthetic food products, 3-D printing of food is still an unperfected technology.
It should be noted that the impetus to develop these alternative technologies is strong. The potential market demand for meat products that do not involve the actual killing of animals is great and growing. One need only consult social media to note an increasing revulsion at the cruelty associated with the new industrial model of what used to be known as animal husbandry. I believe market forces as much as the needs of space exploration will fuel these new developments.
Grasshoppers are but one example of insects that might prove to be a useful source of protein for Mars explorers and settlers. They serve that purpose in many cultures including Thailand, Southern Mexico, and Uganda among others. First, they will eat almost any type of plant material and turn it into protein. Second, they are more efficient at converting a given amount of plant material than for example, beef cattle. Ten grams of feed produces one gram of beef or three grams of pork, but it can yield up to nine grams of edible insect meat, according research from Arnold van Huis, an entomologist at Wageningen University in Holland10. Third, they have a short life cycle, about 90 days, and the beginning of the cycle could be staggered when managed under controlled conditions, therefore making it possible for a continuous supply. Fourth, since any long-term Mars mission is likely to be international in nature, an equally international diet might be in order. And fifth, they are light, durable and thus easily transportable. A species that can jump a distance 20 times its own body length is unlikely to be harmed by any acceleration that a human can endure.
On the cautionary side, however, great care must be taken to insure that they and any other food insects are contained within their “grazing” area and not allowed into vegetable gardens. In my opinion, it is imperative that NO unwanted species be introduced into the station or its farms. Plagues of any kind are a luxury our settlers will be ill able to afford. Such a policy not only protects the desired flora and fauna, but obviates the need for insecticides or other extreme pest control measures such as are practiced here on Earth. This policy must extend to everything. Mars settlers and explorers will have no use for fleas, mosquitoes, body fungus, lice, mice, or other pests, and the station must be kept free of such. As some garden plants and flowers, yes, flowers can be nice, require pollination, honey bees may be a useful addition to the animal population, producing honey as a valuable by-product of their work.
Mushrooms and other edible fungi are not what most people think of as a dietary mainstay, but on Mars, they may well emerge as just that. Their advantages are several. First, they require little light and can live in a cool environment. Thus they can be grown in storage areas and such places within the settlement. Second, there is little wastage, according to the USDA only about 3%. Third, they are low maintenance, not requiring the “tending” that many other plants require. Fourth, they can thrive on soil made up of what we regard as waste, including human waste. And fifth, as the USDA chart link shows11, they have good nutritional value. It is likely that mushrooms will be an important part of will likely come to be known as Martian Cuisine. . While none of the above listed foods would necessarily be considered exotic in some cultures, all are outside what one would ordinarily consider “space food.”
6.Energy, Water, Oxygen, and CO2 on Mars
All of the above possibilities presuppose several conditions. First, that sufficient electrical energy is available to power the habitats and provide lights for the plants. Arrays of photo electric cells would be a likely primary power source. Being very light, they could be easily transported to Mars and assembled robotically. They would be backed up by rechargeable batteries and fuel cells for use at night. A small nuclear decay reactor should be part of the energy mix to provide additional redundancy in the event of the failure of any of the primary systems. Given sufficient energy, the generation of oxygen from the 95% carbon dioxide atmosphere or from water will be fairly simple.
Water is also essential for a sustainable settlement and shipping it from Earth over the long term is simply impractical. Even with a 90% recycle rate12 such as is done on the ISS, a minimum of 3 liters per day per crewmember would still need to come from an outside source. That’s roughly 11 metric tons of water per year for a crew of 10. And this assumes no wastage occurs, probably an unwarranted assumption. Clearly an in situ source is preferable. While we know Martian soil is 2% water, this water would be expensive in energy and equipment to glean. Assuming a 50% recovery rate, which is high for any industrial process, 3 metric tons of regolith would have to be mined, shipped and processed simply to meet the minimum needs of the settlers.
Recently there has been evidence that frozen water exists just beneath the surface in the temperate and possibly equatorial regions13. It has long been known there is plentiful water in the form of ice in the Polar Regions, but placing a settlement at either pole would be problematic. The winters are long, cold and dark. Assuming however that a source of water is available, the establishment of a semi-self-sufficient settlement on Mars is feasible. Without it, the possibility is questionable. In any event, given that all these conditions are in place, the agricultural technologies outline above are good possibilities.
Each of these technologies will very likely have a place in the food chain of a permanent or long term Mars settlement. Certainly foodstuffs imported from Earth will be the primary source of sustenance in the early days of a settlement. But as time goes on both as an economic necessity and a desire on the part of the astronauts more dietary variety, in situ cultivation of food will develop. After all, those people will be living and working on Mars for years, possibly for their entire lifetimes. I ask the reader to think about it. Freeze dried and dehydrated food is palatable, but would you like to eat nothing else for years, possibly for the rest of your life?
On August 13, 2015, at the annual Mars Society Convention in Washington DC, I presented a slide show with narration on the subject of possible methods of in situ food growing for Mars explorers and settlers. The link below is to the YouTube I prepared after the presentation. This recording runs a little over 15 minutes.
– Doug Turnbull (Frankfort, Kentucky, USA. )
(Doug Turnbull is the author of several science fiction books including Zachary Dixon: Officer Apprentice, Footprints in Red, Jupiter IV, The Future Revisited, and The Man Who Conquered Mars, as well as numerous short stories and novellas. In addition he hosts Mars Pirate Radio, podcasts on the subjects of science, science fiction and the future. He has been a guest of Alan Boyle on NBC News, at the University of Hawaii Astronomy Department, and at The Mars Society speaking on space science subjects. In 2013, his short story Tenderfoot won The Mars Society-Bulgaria’s Editor’s Choice award for short science fiction.)