The research station in the San Rafael Desert (Utah, USA) has been simulating the possibility of astronauts living on Mars for a long time. The area around the station is considered a geological analog of the desert on the Martian surface. Research teams change there every two weeks. The researchers live in special modules, leave only in spacesuits, and eat food grown in a local greenhouse.
Preparing and traveling to Mars
Mars is not the best place for human life these days. However, space agencies in many countries are working tirelessly to prepare the conditions for astronauts to live to send them to the Red Planet in the future. The journey there will take seven to ten months. But such a flight can be made only once every two years, so the colonists will have to provide themselves with food.
Of course, at first, food grown on Mars will make up a very small share of the astronauts’ diet, as most of the food will still be brought from Earth. To create a colony outside of our planet, it is necessary to arrange well-thought-out ecosystems with a set of plants and animals that can perform a significant number of vital functions for humans.
What is the soil like on Mars?
Due to the lack of nutrients in the soil and the high salinity of the water, growing food crops on Mars is impossible. Therefore, for long-term missions, it is important to develop strategies to enrich it with nutrients and desalinate water. Numerous studies have shown that the upper layer of the Martian surface contains a significant amount of perchlorates (salts of chloric acid) and other potentially toxic chemicals that are extremely harmful to all terrestrial plants. The environment on Mars is barren, dry, and constantly bombarded by radiation, and the thin atmosphere is poor in nitrogen. Therefore, terraforming the planet involves a complete restructuring of its atmosphere and surface, but this is a very difficult and time-consuming process. Moderate ideas suggest creating greenhouse farms.
Growing plants in the Martian soil
At Iowa State University (USA), they were able to grow turnips, radishes, and lettuce in almost “Martian” soil in the laboratory. Although these plants do not require a large amount of moisture, they still need to be watered, and with fresh water. To desalinate the water, scientists used special marine bacteria and then filtered it through volcanic rock. For the plant-growing experiment, they used rocks erupted by Earth’s volcanoes, because the soil on Mars is mostly a product of ancient volcanism. First, the researchers grew alfalfa on a substrate that closely resembled Martian regolith. Then it was crushed and processed into fertilizer. Eventually, turnips, radishes, and lettuce grew in this “Martian” soil.
Three varieties of rice – one wild and two genetically edited to respond to drought, sugar hunger, and salinity – were also planted in the same imitation of Martian “black soil”. Potatoes, one of the advantages of which is the genetic ability to adapt to extreme conditions, were also able to grow in this dry and salty environment.
These experiments have shown that three grams of perchlorate per kilogram of soil is the threshold beyond which nothing will grow. However, modified rice varieties can take root if the soil contains up to one gram of perchlorate per kilogram. In recent years, tomatoes, carrots, and green beans have also been harvested under the same artificial conditions. Mushrooms can also be grown there quite successfully.
Legumes, rich in protein and fiber, can make up a significant portion of the Martians’ diet. Even some insects with a high protein content can be added to the astronauts’ diet. And plants such as lettuce, watercress, tomatoes, carrots, and rye are the types of food components that grow well in Martian soil, similar to that of the Earth, provided there is water. So, if farmers on Mars manage to protect themselves from low temperatures and radiation, the biggest problem they will face will be perchlorate salts.
The Dutch researchers planted watercress, arugula, tomatoes, radishes, rye, quinoa, chives, spinach, peas, and leeks in similar “alien” soil. Similar crops were planted in ordinary, earthy soil for control. Nine of the ten crops (except for spinach) grew well in the model soils and produced edible parts. The seeds of three crops (watercress, rye, and radish) were also successfully tested for germination. The amount of biomass on the simulated Martian soil was comparable to the biomass produced by the Earth’s soil. The simulation samples for the experiments in the Netherlands were provided by NASA. These model substrates were enriched with organic additives from soil that had already been used to grow crops. In general, the research confirmed the idea that it will be possible not only to grow food on Mars to feed future settlers, but also to obtain viable seeds.
And how to grow something there?
Near the Martian equator, it can be warm enough during the day to place greenhouses. But they will need to be insulated and heated to compensate for the temperature drop at night. In addition, plants need a denser atmosphere than is currently available on Mars. It is believed that they can be grown in an environment with a pressure of 0.1 bar (10% of the pressure at the Earth’s surface). The surface samples examined by the landers show that Martian regolith can be used to make good soil. However, it may be too acidic or alkaline, so it will have to be improved by adding nutrients.
According to the results of the BIG Idea Challenge 2019, NASA has chosen the best type of greenhouse for the Red Planet. Students of Dartmouth College won with their project of a dome greenhouse. It is noted that the hydroponic structure can help astronauts grow food on the Martian surface. Up to eight food crops can be planted in the rotating system. It is capable of providing 3100 calories daily for four astronauts for 600 days on Mars. It is proposed to grow soybeans, cabbage, sweet potatoes, broccoli, potatoes, wheat, strawberries, and chufa. The nutrient solution will flow from a large reservoir under the influence of gravity into a circular system of trays with plants. LEDs will provide sufficient light. This greenhouse can be transported from Earth, deployed on Mars, and maintained with limited technology and resources.
Source: Thayer School of Engineering at Dartmouth
Another study investigated whether it was possible to use the sun’s energy to grow plant food on Mars by building greenhouses with transparent walls and roofs. Since the radiation there is 17 times stronger than on Earth, cobalt-60 was used to simulate the flow of gamma radiation. The experiment lasted 28 days and showed that the food grown in this way was not suitable for consumption.
Hydroponics, or growing plants without soil in nutrient-rich water, is likely to be the most reliable way to produce crops, provided that this water is extracted and stored in a liquid state. However, the surface of Mars has relatively little sunlight and too much destructive radiation. Therefore, hydroponic chambers covered with mounds of soil or hidden under the surface in natural lava caves will function much better. With the help of artificial lighting, it will be possible to control the spectrum and intensity of lighting. The consumption of water and nutrients in hydroponics should also be strictly controlled. The greenhouse control should be autonomous and easily programmable. All this gives reason to hope for a rich harvest.
However, the most important question remains how to turn the dead soil of Mars into fertile land by enriching it with phosphorus, nitrogen, potassium, and bacteria. All of these are extremely important components for plants and will help provide astronauts with fresh and nutritious food.
Author: Anatolii Vidmachenko, marsologist
This article was published in Universe Space Tech magazine #1 (190) 2024. You can buy this issue in the electronic version in our store.
