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Many of us have seen the Martian, in my opinion, a great film about surviving on the Martian
surface.
One part of the film focused on growing potatoes using Martian soil, but, how practical is
that in reality?
Does Martian soil really have the nutrients needed for plants to grow?
And would there be any adverse side effects from eating produce grown on Mars?
As it turns out, Martian soil does in fact have a lot of the essential nutrients needed
for plants to grow, depending on where exactly you are on Mars.
Just like Earth, with some areas that have nutrient poor soil and some with nutrient
rich soil, some parts of Mars would be better suited for growing plants than others.
However, the soil on Mars is more like regolith, it hasn’t had a history of worms, insect
and plants mixed in.
In 2016, researchers grew tomato, rye, radish, pea, leek, spinach, garden rocket, cress,
quinoa, and chives in an imitation Martian soil on Earth, producing only slightly less
produce than they would have in Earth soil.
Interestingly, they did the same experiment again with imitation Moon soil, which produced
about half the amount of produce, yet these crops still grew, with only spinach really
struggling to perform!
However, it should be noted that organic matter was added to the soil, in this experiment
cut up grass, to fertilise the soil, and fluff it up, allowing water to pass through the
soil to the roots.
Without that, the plants wouldn’t have lasted long.
Another barrier scientists would have to get over though is the abundance of heavy metals
and most importantly, something called calcium perchlorate in the Martian soil.
Calcium perchlorate is a salt, which – like heavy metals - is toxic if consumed in large
quantities.
This perchlorate and metals in the soil would be absorbed into the plants, not so great
for the plants anyway, but humans would then also absorb it into their system when they
eat the plants.
But perchlorate isn’t all bad, in fact it could help humans survive on Mars.
For one thing, it sucks water out of the air, which can then be used as liquid water.
It also can give off oxygen, again, another critical checkbox for survival ticked.
So, in short, it seems there are two major problems to be overcome when growing plants
on Mars.
First is the need for fertiliser.
Going back to the film and book “The Martian”, Watney overcame this problem by using feces
from the toilet as fertiliser.
Typically, this is dangerous as feces contain pathogens, however if the feces have been
processed to kill the pathogens, it can then safely be used as fertiliser.
Once production gets underway, you could always use the compost collected from old plants
and food.
The second problem is the toxic perchlorates.
Well, this has a simpler solution than you may think.
Running water through the soil would rinse the perchlorates out, and you could then separate
the water and perchlorates later so nothing is wasted.
The alternative is to use perchlorate eating bacteria, which give off oxygen as a by-product.
There is a reason why growing plants in future colonisation efforts is so important, not
only does it make the colony self-sufficient but there is also evidence that fresh foods,
such as tomatoes, blueberries and red lettuce are a good source of antioxidants.
Having fresh food like these available in space could have a positive impact on people's
moods and could also provide some protection against radiation in space.
But without actually doing it, it’s hard to say how well it will work on Mars itself.
Although, it should be said that plants have been proven to be versatile.
They have grown in Mars simulations on Earth, they’ve even grown on the International
Space Station.
The key will be whether plants grown on Mars are safe to eat, or not.
And the only definitive way to find out is to grow some plants on Mars.
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