In order to colonize Mars we need to have oxygen that we inhale and we need to remove carbon dioxide that we exhale (which is toxic to us).
In the "Biosphere 2" experiments it was shown that plants alone are not enough.
This is why scientists are testing cyanobacteria for this purpose.
Cyanobacteria and Lichen
These are the creatures that made Earth habitable, and they can do the same for Mars.
Lichen is a united creature (a symbiosis or "composite organism") made from fungi and cyanobacteria or algea. the fungi supply substance for the cyanobacteria (or algea) to grow on.
All of these tiny creatures are very tough: they can live in deserts, they can live in the arctic, and they can live without gravity. They can even survive for a period in empty space!
My idea is how to make the most out of the cyanobacteria, because we need to terraform Mars soon if we want to live there not just in bubbles/domes.
The problem - can't grow on ground
The simple thing to do is just plant and grow lichen all over the ground of Mars.
What's wrong with that?
(1) There's not enough surface area. even on Earth, where the green-blue algae were MULTI-LAYERED in the oceans, the oxygenation of the atmosphere took 300 million years!
Of course we don't have so much time, So we need a lot more surface area.
(2) No Sunlight. Mars has planet wide dust storms. For example: The probe Mariner 9 had to wait MONTHS to send us clear pictures of the surface!
This means we don't have Sunlight on Mars, which is a key factor in photosynthesis!
This also means we can't grow things on the open planet surface because they will be covered in dust -
See the famous last words of NASA's Opportunity rover: "My battery is low and it’s getting dark".
(3) Abrasive "filing" (like file in woodwork or metalwork). The dust sandblast and scratch (like sandpaper) whatever it hits. So a greenhouse made of transparent glass or plastic will become opaque.
(3) No water. The lichen gets water and mineral nutrients mainly from the atmosphere, through rain and dust.
(4) No Nitrogen.
The nutrients for the lichen which means nitrate (NO3-) which means Nitrogen which is also a problem on Mars:
Would a settlement on Mars need to import Nitrogen?
Solution I - grow above ground
Basically we want maximum surface area in limited volume which makes fractals ideal for the job.
The fractal I have in mind is "Sierpinski Tetrahedron" (Tetrix) , which is a sort of hollow pyramid,
or "Menger sponge" which is a sort of a hollow cube.
So how do we create the physical fractal?
When we create a fractal, for example Sierpinski's Tetrahedron, we have 4 points of attraction (see source code in wikipedia).
In building the fractal physically we will replace these 4 magnets that will attract iron filings that will float between them.
In order for the iron filings to float I suggest we build this thing in space where gravity will be negligable.
For our purpose we want cyanobacteria to populate as much surface as possible so our iron filings will have a mixture of glue and a ground powder of lichen.
It's important to make sure that the tiny amount of glue only sticks the iron filings to the lichen and not to each other (let the glue dry after iron-lichen bonding).
The growth of the lichen (the fungi fibers) will allow the structure to solidify and keep its delicate form, and after it dried we can remove the magnets and it will not collapse.
Where do we place the "sponges"?
The wall of the ball needs to be thick enough to withstand the pressure inside (outside is the vacuum of space) and not to explode.
Then periodically we harvest the gas inside it (like pumping air into a basketball but in reverse) take the O2 rich air, and put in instead CO2 rich air.
If we put the lichen spongs on the ground of mars the gravity will collapse them under their own weight. But in space they remain "standing".
The next part is taken from the idea of a Terrarium, or the small scale version, the Bottle Garden.
If you've never seen one, it's a glass jar with a little soil inside and a plant growing in it. The plant has a little water to start with, and a little air to start with, and then the jar is sealed.
But the plant can live there for many years, because it circulates the water (the vapor from the soil, go to the jar's ceiling where it condense and drop like rain) and the air (the plant breathes O2 and also generates O2 by photosynthesis).
In fact all the plant needs is Sunlight.
So my idea is to put the fractal sponges inside big sealed jars like that, or even better create them in the jars to start with (magnetic field can pass through glass).
Ideally the jars will be completely round like a sphere, or at least cylindrical so they can be rotated and get Sunlight from every angle.
Every bottle will be sealed except 2 holes openings (on opposite sides of the round jar), which will be closed in a way which we can open at will (like screw cap of a bottle or a jar's lid, or cork stopper etc).
This holes openings will be used when the jar is ready, which means when it got to it's highest oxygen capacity or close to it, we will suck out the oxygen through the hole, and fill it instead with CO2, and this jar working start again.
I think sucking the gas (oxygen) out of one hole, while pumping in the other gas (CO2) into the other hole, is the most efficient way.
Before I'll start to explain how the Solarium is made, I want to point out that it should be located in the Lagrangian Point so it will stay fixed in space near Mars and won't "fall" on Mars.
So we want to pack all these glass balls tightly but at the same time give each of them time to be in the Sunlight.
So I took inspiration from the Emperor Penguins in Antarctica who huddle (crowd together) and switch between themselves, in a way that each one of them will get to be part of the time inside and the other part of the time outside, in a fair way, and no one will freeze.
It's interesting to know that it can really be modelled mathematically, see this mathematical paper by Aaron Waters, Francois Blanchette, Arnold D. Kim :
Modeling Huddling Penguins
The balls will be held (from the two oppsing lids or caps) by two screws (together forming a gentle vice like in a workshop) between two firm grids made of metal.
The grids can be something like a 2-D "Rebar" - the grid of reinforcing steel bars that's used in reinforced concrete.
There will be utility robots that run on these "tracks" and switch between the balls in the same algorithm as the penguins.
Each layer of glass balls is sandwiched two metal grids, but it's not a simple sandwich, it's more like Bagel
If you don't know what a bagel is, think of a doughnut or a torus shape: a ring with a hole in the middle.
So this hole that is in the middle our bagel is used for skewering (impaling) the bagel on a long shaft. This shaft is basically a big pipe.
We have many bagels skewered on the shaft, one above the other, like Shish kebab.
The whole structure will look from the side like a Corn on the cob, served on a stick (skewer) which is the shaft pipe.
I apologize for all the food metaphors it just seems to be the best way to explain visually what I mean (or it's my brain signaling that it's now 23:21 and I should make supper!)
The tiers or "bagels" or layers of sandwiches of grid-glassballs-grid are seperated by the distance that allows the robots to work.
If the utility robots are impractical, we can leave the idea of switching, and use another system: If the balls won't come to the light, the light will come to the balls!
In this alternative system we don't want the corn-on-the-cob to rotate in space. Instead we want it to stay for example with the sharp tip of the skewer (head of the shaft) towards the Sun.
Then we will use mirrors to concentrate the light of the Sun, and Optical fiber cables to run the Sunlight down to all the plants using a Beam Splitter on each tier (bagel).
In each tier the Sunlight will be brought without waste through pipes with Optical fiber, In the same way that Drip irrigation is used with water.
The big pipe has a hole opening with non return valve (that let's the gas flow in one way and not back), imagine the whole pipe like a flute with holes, but each hole is one directional inwards.
These holes drain the oxygen from all the tiers into the big pipe of the shaft, and from there we collect it with a space shuttle and take it to Mars for the people to breath!
Solution II - grow underground
An alternative approach which some might find more "grounded" (ha ha pun intended) is to use the only point that rises above the storms -
Olympus Mons which is the largest volcano, and the tallest planetary mountain in our Solar System.
One obvious drawback is that it may still be an active volcano with the potential to erupt!
Ok so what we do is make a set of mirrors on the top and concentrate the Sunlight into lava tubes (which are empty now) and grow the lichen there where it's protected from dust!
If the lava tube goes all the way to the surface (Olympus Mons is 2.5 times the height of Mt. Everest) then we can use the fact the O2 is lighter then CO2. So at the ground there is only CO2.
So after we clean the lava tube from dirt, we put the lichen there (of course it will not be in fractal formation, because of the gravity, hence less effective) and blow air from the bottom end of the tunnel.
We can use fans like they use in tunnels through mountains on Earth to keep the air fresh. Here we are keeping the air full of CO2 for the lichen.
On the other side, at the top, we need to somehow collect the O2 by centrifuge or something. The air will be richer in O2 but we should purify it more.