What crop would you grow on Mars and how would you do it? Part 1

Since the release of “The Martian” in 2015, there have been countless debates on internet forums about whether Mark Watney’s potato farm would be possible in real life. Just 20 years ago, the mere idea of us humans setting foot on another planet seemed way beyond our grasp. 20 years later, missions such as Mars ONE and SpaceX are expected to put men on Mars by 2020/2025. Elon Musk’s goal of colonizing Mars still has a long way to go, with one large obstacle of being able to sustainably produce food on Martian soil – a critical step towards the colonization of Mars by humans.

This essay is split into two parts; the first part being “What Crop?”. I first analyze suitable crops and breakdown their nutritional values. Following the nutritional breakdown, I consider the necessary fertilizers, nutrients, and conditions for the growth of crops. The second part of my essay is “How would I do it?”. Firstly, I lay down hypothetical criteria for the mission, then provide a rough estimate of the size of fields and masses of fertilizers needed. Secondly, I address the necessary habitat for astronauts and crops. Thirdly, I hypothesize the best way to climate control Mars. Finally, I estimate an ideal location for the location of the habitat as well as address any unsolved roadblocks.

Crop analysis – Corn versus Lentils

To determine which crop should be grown on Mars, the crop should fulfill certain criteria. Firstly, the crop must contain sufficient macronutrients (carbohydrates, fats, fiber , proteins, water) and micronutrients (vitamin, minerals) to keep humans alive and thus able to sustain a population. Our planet’s major crop grains fall into two large categories: Cereal and Legumes. Cereals are one of the two main categories of grains, the other being legumes. Cereals are considered “staple crops” as they are consumed in many countries around the world in vast quantities. The most commonly cultivated cereals include wheat, corn, and rice.

Figure 13 indicates corn is the most consumed cereal on the planet. It is

extremely versatile and can be transformed into many further types of food, such as corn bread. Corn requires moderately wet conditions and hot temperatures to grow, but can adapt and grow in cold and dry conditions. As seen in Figure 25, a 100g serving of corn provides a moderate amount of energy at 360kJ. Unfortunately, corn provides little other macro and micronutrients, especially minerals. Corn has a calcium content of 7mg per 100g serving. Since astronauts on mars are subject to gravity 62% 8 weaker than on earth, it is essential that astronauts consume sufficient amounts of calcium to build strong bones and maintain nervous function. Should the astronauts be subject to calcium deficiency, their bones would quickly become brittle and may even lead to cases of osteoporosis back on earth, depending on the length of their stay on mars. Another example of the lack of nutrients in

corn is its iron content. Corn contains 0.52mg of iron per 100g serving.5

In contrast, lentils contain a much higher 6.5mg of Iron per 100g. Maintaining a high concentration of iron in the body is crucial for production of healthy red blood cells8, since iron acts as a prosthetic group in hemoglobin. Even with oxygen

Figure 34 refers to nutritional value of lentils. A side by side comparison between lentils and corn show that lentils are the clear winner in terms of nutritional value in every single category. Lentils contain 25g of protein per serving compared to just 3.27g in corn. Analyzing the individual protein content of both crops, lentil is rich in Leucine (1.786g) compared to corn (0.348g). Leucine is 9 one of nine essential amino acids (cannot be produced by the human body and thus must be obtained from diet), which is the most abundant branched chain amino acid. Almost all amino acids found in muscles are Leucine. It is responsible for stimulating protein synthesis to build up muscle around the body. As previously mentioned, the weak gravity on mars means astronauts would need to exercise for longer periods of time to maintain their muscle mass, thus require a high amount of Leucine in their diet, which can be provided by lentils. Another example of a vitamin that lentil is rich in, whereas Corn is not, is Folate. Folate is another essential amino acid, which is used to synthesize DNA and RNA. Lack of folate leads to folate deficiency, resulting a type of anemia

with low red blood cell count.

Both lentils and corn contain a healthy amount of polysaccharides, but Lentils contain a much higher amount compared to corn4. Polysaccharides provide the best long term energy supply for the body, in comparison to disaccharides and monosaccharides. Since polysaccharides consist of many glucose monomers, the branches in polysaccharides allow the glycosidic bonds to be hydrolyzed quickly to release more energy.

Assuming that lentils fulfill the major requirements for a crop (contain most necessary macro and micronutrients), the focus now shifts to their cultivation and sustainability.

Growth requirements

Lentils are an extremely versatile crop, which can grow in cool conditions and are usually tolerant to droughts4. They require approximately 10-12 inches of rain annually to produce healthy seeds and the soil must have efficient drainage system, as lentils are extremely susceptible to water clogged soils4. Lentils are best suited to grow in soils with a pH value of around 7. As with all crops, lentils require the elements Nitrogen, Phosphorous and Potassium to be present in the soil to facilitate growth. DAP 7(Di-ammonium Phosphate) is regarded as the best fertilizer for lentil growth, as it provides sufficient phosphate and nitrogen requirements for the plant to grow. In addition, the bacterium Rhizobium leguminosarum7 lives in the root nodules of lentils in a symbiotic relationship with the plant. It fixes nitrogen from air to provide additional sources of Nitrogen for the plant. However, Martian conditions would mean Rhizobium leguminosarum would be unable to survive the trip, the roots would experience a slow uptake of nitrates from the soil.

Mission criteria

Since there are many variables and challenges on this mission, I will assume that all the latest and most advanced technologies are available, in addition to a sufficient budget. Furthermore, all logistical problems will be ignored for simplicity. Assuming the goal of the mission is to successfully populate mars and maintain a sustainable food supply, a sizeable team will be needed for the mission to mars, with a team of at minimum, 5 astronauts. At least 1 pilot is needed to guide the craft through space and to assist in landing and re- entries. 2 astrobiologists/botanists will be needed for the journey as well, to monitor the atmospheric and living conditions throughout the mission, assess soil composition and oversee healthy crop growth. 1 engineer must be sent to mars, to ensure that all electronics and electrical components of the probe, rover, craft and living quarters are operating properly. Finally, at least 1 doctor/qualified medical personal should travel with the crew to assist in any medical issues that the crew will face over the course of the mission. I will assume that the conditions for this mission are similar to the proposed Mars One mission, where astronauts are embarking on a one-way trip to the red planet. Due to the orbital differences between earth and mars, the 5 astronauts would have to stay on mars for at least 2.5 years (1 year for the entire journey to and from mars) before the next batch of astronauts would arrive when the planets re-align (1.5 years).

Even though lentils are rich in vitamins, minerals, and carbohydrates, they do not provide all the essential amino acids and vitamins that our body requires. For example, they provide minute quantities of fat4, which would be insufficient to keep astronauts insulated, along with many other purposes. In addition, setting up the living quarters, the greenhouse and allowing the seeds to fully grow into plants would require a few months (80-110 days). Thus, the crew will be supplied with freeze dried space food, which supplies the rest of the nutrients that lentils are unable to provide, as well as provide a food source for the crew whilst they wait for the seeds to germinate (until the freeze-dried food runs out). Assuming no major technical difficulties, catastrophes or financial troubles arise, this mission should theoretically last forever, as we continue to send groups of 5 astronauts (or more) every 2.5 years.

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