“Mars has strong potential to eventually support human life because of its close proximity to the Sun and its atmospheric composition. One critical factor to assess is the potential to support and sustain plant growth on Mars. This would be achieved by setting up a greenhouse that can manipulate Mars’ atmosphere to mimic Earth’s.”

Humanity is at a crossroads, with a runaway population that is growing at a rapid pace. The rate of population growth in the past two centuries has been astonishing, and nothing less than a miracle. It took more than 100,000 years for the human population to reach 1 billion. It took just 123 years to reach 2 billion, 33 more to reach 3 billion, plus 14 more to reach 4 billion, and then 13 more to get to 5 billion. It took only 12 more years to arrive at 6 billion and then move to 7 billion, possibly 16 more to reach 8 billion, and 19 more to reach 9 billion, and by 2100, we can peak to 11 billion.

Scientists and experts project that we will need to double our food production up to 85% by 2050, which will be very challenging due to the ever-growing population overtaking farmlands, plus we are overusing nonrenewable resources such as minerals, limited fossil fuels, and water and the growing population is also causing an increase in greenhouse gas emissions, which are affecting the atmosphere negatively by increasing Earth’s atmospheric temperature and creating artificial climate change, and now we will have to grapple with the surging pandemic.

Because of these overwhelming problems, it has become important to look into other planets within or outside of our Solar System that could potentially sustain life or we can redesign to sustain life.

In the movie, “The Martian” Mark Watney is left alone on Mars with his astronaut friends and every people all over the world is thinking that he is already dead while being stuck on a planet 391.51 million km away from Earth. Watney is only left with his spacesuit and a controlled-environment habitation module (Hab), without sufficient food and water for the next rescue mission from NASA.

There are many things that can fail in this mission, and since it will take some years to reach him, this will be a struggle that is like no other human has ever faced, greater than the greatest adventures done on Earth.

If that is our next adventure, then we will likely have to tweak Mars…

Designing Mars

Mars is a planet that is harsh than that on Earth, but despite all these negative descriptions, it can be designed to be habitable like our home planet. We are exceptional beings who have minds that have the capacity to mimic the same conditions that we already know exist on Earth and adapt to the Red planet.

In short, we will redesign Mars to look like Earth (either closely enough, or at best).

Many scientists are studying Mars since the 1960s, and their spacecraft proved that the planet is indeed harsh for life on the surface, so it will have to be done underground, and true enough, we will spend most of our time down there.

Since the radiation on Mars is about 17 times higher than on Earth, that will destroy all life on the surface, so we will have to protect ourselves and our plants deep beneath the surface.

Water on Mars

We already know that Mars is dry on the surface, with only some traces of water in the form of ice.

However, researchers found that there is a giant slab of ice underneath Mars’s surface, which could be due to a snowfall that occurred tens of millions of years ago. Interestingly, the amount of water on Mars has been altered immensely due to Mars’s unstable obliquity.

The difference between Earth and Mars, in this respect, is that Mars’s moons do not prevent this wobble.

This unpredictable wobble results in regular ice ages on Mars.

Mars has northern and southern ice caps that are composed almost entirely of water ice, despite being previously believed to be mainly dry ice. This was discovered using high-resolution and thermal images from Mars Global Surveyor and Mars Odyssey, respectively.

It shows that both the south and north poles have a thin covering of dry ice, with the inner and bottom layers composed of water ice. The north pole’s layer of dry ice is thinner (1m) and melts in the summertime, whereas the south pole’s 8m thick layer does not melt entirely.

A number of different methods have been suggested for harvesting Martian water. The obvious method of retrieving this water from the soil is to dig up frozen soil and bake it in an oven until the water evaporates.

In addition to this method, a microwave beam could be used to heat up rock, which heats up the ice that can be condensed into drinkable water.

In another design, an oven-like device can be used to extract water on Mars so it is drinkable.

Water can also be extracted from the atmosphere using a humidifier type device, but it is suggested that the best method is to mine ice from the polar caps or from beneath the soil and melt it. This is because the liquid water is transient, meaning that it is only there during the warm season.

Before this water is drinkable it needs to go through a process of desalination. Perchlorates cause thyroid problems and negatively affect the gastrointestinal tract, skin, breast tissue, and placentas. Three methods of desalination are proposed include ion exchange, reverse osmosis, and biological treatment.

Ion exchange involves swapping perchlorate ions out for other molecules of a similar charge. Reverse osmosis uses pressure to push liquid through a membrane with small holes only big enough for water to go through.

Lastly, the biological treatment utilizes bacteria to eat perchlorate, which has the advantage of not requiring maintenance in treating the waste.

Once the water is collected and treated, it must be applied to the plants.

This can be accomplished by using underground irrigation systems similar to ones used on earth that apply water directly to roots.

Mars Regolith

Like every terrestrial planet, Martian soil already contains most of the nutrients required for plant growth, with the exception of one special requirement (reactive nitrogen), which is a necessary nutrient to the growth of plants.

The nitrogen atoms that are currently present on Mars need to be “fixed” or separated so that they are then able to become “reactive.” Without being fixed, it will remain as nitrogen gas and will not become reactive, which will not allow full, successful plant growth.

A nitrogen “fixer” such as Cyanobacteria utilizes an enzyme that gathers nitrogen gas and converts it into reactive nitrogen.

Martian soil holds water very well, which in turn benefits the performance of plant growth because the soil will not easily dry out. Martian soil has also been found to contain nutrients such as sodium, potassium, and some magnesium, amongst other things.

Mars Atmosphere

The atmospheric composition of Mars vastly differs from the life-sustaining atmosphere of Earth, which you can see from the table above. That means that we will have to do a bit of change, but Mars still has the potential to sustain plant life on the planet due to the high concentration of carbon dioxide, as it is essential for photosynthesis.

The process of photosynthesis requires water and solar energy. In the case of Mars, both are not very abundant. Mars’s atmosphere is one hundred times thinner than Earth’s; therefore, it is difficult to capture solar energy.

The atmosphere can be made denser using a few different techniques, such as thawing the north and south poles using orbital mirrors, creating greenhouse gas factories to create more gases, or smashing ammonia heavy asteroids into the planet.

These techniques will create an increase in greenhouse gas which would effectively trap solar energy and reflect it back onto the planet’s surface. Another disadvantage is that Mars’ decreased gravity creates an atmosphere that extends four kilometers further than Earth’s.

The low gravity means more gases must be created to induce an effect. Lack of water and gravity are also factors that can be manipulated within the greenhouse to obtain desirable conditions for plants to grow.

Mars Temperature

Another important factor that we will have to upgrade on Mars is the temperature.

Two rovers sent to Mars, Spirit, and Opportunity, have played a key role in determining the temperature on Mars.

Between both Rovers, it was also found that there was an average of 30-35 degrees Celsius during the summer months on Mars. During the winter months, there was an average of negative 90-80 degrees Celsius with a low of negative 110 degrees Celsius.

Spirit was further from the equator than Opportunity and therefore there was variance in temperature. One of the theories on why the temperature varies on Mars more than Earth is due to it having a very thin atmosphere.

In fact, its atmosphere is one hundred times thinner than Earth’s which hinders its ability to create a “thermal blanket” to trap solar heat. Consequently, this extreme temperature range will have to be mitigated in order to sustain plant life on Mars. To overcome this obstacle, a multi-mission radioisotope thermoelectric generator (MMRTG) could be used.

This novel technology uses a nuclear battery that can convert heat into electricity.

This system is able to be used during the colder winter months and has been tested as a reliable radioisotope heater. Physiological processes in plants do the best in temperatures from 0-40 degrees Celsius; therefore, a thermostat will have to be implemented to ensure that the heater will turn on when the temperature is below 0 degrees Celsius and turn off when the temperature is above 40 degrees Celsius.

Artificial Light on Mars

It is no surprise that in order to successfully grow plants in any location, sufficient light is required. Mars is further away from the Sun and as a result, receives close to half the sunlight Earth does.

The low amount of solar energy reaching Mars will restrict a plant’s rate of photosynthesis and reduces the plant’s growth, development, and yield.

For the best yield of Martian crops, food production will have to be grown in a greenhouse supplemented by artificial lighting. Today artificial lighting for the purpose of plant production is better and more efficient than it has ever been. Research has shown that light-emitting diodes or LEDs are very successful in aiding plant production.

LED lights are small, durable, and they last a long time. They can be placed closer to the plant material because they don’t get as hot as traditional lighting and they emit specific wavelengths that can be manipulated to cater to specific plant needs and stages in the plant’s development.

These lights could potentially run off solar panels in good conditions but backup power will be necessary. Using LEDs in a greenhouse environment on Mars will be essential to the success of food production.

There are also dangerous amounts of solar radiation that reach the surface of Mars.

Because Mars has a thinner atmosphere solar radiation such as ultraviolet light can reach the surface and cause damage to any form of biological life making it impossible to grow plants when direct exposure.

A greenhouse will need to be built with a material that allows visual light through, blocks UV radiation and X-Rays, and traps infrared radiation. Researchers have suggested creating an igloo-like structure by harvesting ice from the Martian surface and melting it down to be 3D printed by robots into a building made of ice.

They say that ice would be a perfect material for a safe structure on Mars because it can be made from sources already found on the planet and it acts as a shield against harmful radiation but allows visual light in.

Farming on Mars

Radishes are grown by scientists at Wageningen University and Research, Wageningen, The Netherlands, in (from right) soil from Earth and simulated Martian and lunar soils.
Wieger Wamelink, Wageningen University and Research

The main purpose of the first Mars expedition is to investigate the possibility of providing a source of nutrition for future colonists on Mars. In order for the colonists to be nutritionally self-sufficient, they will need plants that provide the nutrition needed for the human body.

Scientists have conducted plant experiments simulating Martian conditions using volcanic soil in Hawaii, which is known for its similarity to Martian soil. These experiments found that plants can actually grow in these soils.

There are other aspects future Mars explorers will need to consider when growing plants on that planet. As mentioned earlier, Mars’s atmosphere is mostly carbon dioxide, and plants need this gas just as much as we need oxygen to breathe.

Also, studies suggest that watering plants on Mars could require less water than on Earth. That is because water would flow differently through the Martian soil, thanks to the Red Planet’s gravity, which is approximately 38% that of Earth’s. In other words, anything on Mars would feel about three times lighter than on Earth. Therefore, under Martian gravity, the soil can hold more water than on Earth, and water and nutrients within the soil would drain away more slowly.

It is clear that this mission is only possible if we are able to harmoniously integrate a variety of human science and understanding, and then execute them perfectly. A mission such as this is imperative to human exploration in space.

If plants can be successfully grown on Mars (not simply on simulations), there is a higher chance of sustaining human life and growth in the future, as well as extending our reach beyond our Solar System and to the stars.

References:

https://www.acs.org/content/acs/en/education/resources/highschool/chemmatters/past-issues/2016-2017/april-2017/growing-green-on-the-red-planet.html

https://usurj.journals.usask.ca/article/view/265

https://qz.com/1347735/how-many-people-can-earth-support-its-carrying-capacity-isnt-infinite/

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