Self-replicating radiation-shield for deep-space exploration: Radiotrophic fungi
biorxiv.org
biorxiv.org
"I have loaded ships with life."
"Life?"
"Life. I don't know what the Great Pain is, but I did find that in the experiments, when I sent out masses of animals or plants, the life in the center of the mass lived longest. I built ships -small ones, of course- and sent them out with rabbits, with monkeys-"
"Those are Beasts?"
"Yes. With small Beasts. And the Beasts came back unhurt. They came back because the walls of the ships were filled with life. I tried many kinds, and finally found a sort of life which lives in the waters. Oysters. Oysterbeds. The outermost oysters died in the great pain. The inner ones lived. The passengers were unhurt."
"But they were Beasts?"
"Not only Beasts. Myself."
"You!"
"I came through Space alone. Through what you call the Up-and-Out, alone. Awake and sleeping. I am unhurt. If you do not believe me, ask your brother Scanners. Come and see my ship in the morning. I will be glad to see you then, along with your brother Scanners. I am going to demonstrate before the Chiefs of the Instrumentality."
https://archive.org/stream/ScannersLiveInVain/SmithCordwaine...
_____________
Smith also had a super interesting background.
I mainly read his works translated in my native Greek at a time when he was not that well-known among English-speaking SF readers anymore. I consider that lucky, for me, and sad, for everyone else. I think of him as one of the greats, one of the authors of SF whose imagination was not bound by cliché and trope, perhaps thanks to his having a day job, unlike most SF authors. I suspect he never really reached his full potential either, again because that was not his day job. His life experience certainly shaped his writing in any case.
The coefficient in the exponential is 0.0161/mm for these data, so a 100 mm thick layer will stop 80% of their measured spectrum. A 200 mm thick layer will stop 96%.
The same relationship applies for higher energy gammas as well, but the coefficents will be energy dependent.
I doubt that radiation-loving mushrooms are edible, and if they produce CO2 rather than scrub it, I can’t consider them to be part of the life-support system.
https://www.sciencedirect.com/science/article/abs/pii/S00410...
The most important measure for any radiation shielding in space is weight. We have great technology for blocking all radiation today: lead plating. This is obviously way to heavy for space. Alternative suggestions have been to surround the astronauts with water which presents a lot of challenge in terms of plumbing and weight. Having the walls covered in fungi may actually be a much lighter option, I certainly hope the idea is well considered.
Fungi aren't plants, though.
edit: they're heterotrophs - they get their food from more complex materials than autotrophs, which generate their raw material largely from carbon extracted from the atmosphere.
Except not these ones! These are autotrophs fungi, they do some kind of photosynthesis (it's absolutely not the same metabolic path, though) gaining their energy from gamma rays instead of food.
Edit: The above comment is wrong, I though autotroph vs heterotroph was about energy input (as a matter of fact I'm very convinced it was how my college teacher explained it) but from wikipedia it looks like I'm wrong, and such fungi would be classified as Photoheterotroph[1]
At least you can be using the water though.
There's plenty of radiation that we have no effective way of blocking, like neutrino radiation.
But that's about the extent of my knowledge.
Do you happen to know if in a composite shielding situation (several layers of multiple materials) would you put the lead on the outside facing the hard radiation, or on the inside?
If the shield is actually alive (say, a layer around your emergency shelter), then you can just fill the hole with food and let the fungi patch themselves, and any damage caused by being exposed to partial vaccuum. Possibly with a mold that also acts as a temporary, reusable patch over the worst hit areas, so that a subsequent space storm doesn't catch you with your pants down.
Growing shielding could be very good. Especially if you can use waste products to do so. The right sort will be easier to find on the right asteroid, but could be available on the moon if you have a high enough volume of imported supplies being turned into effluent streams.
It'll probably require layering different types of material to convert higher energy radiation (like cosmic rays) to more manageable spectra.
Better hope it doesn’t die halway to Mars!
Tbh I'd be more concerned about the humans cracking psychologically before the fungus dying. They are hardy buggers.
Anyhow, seems like they think it is the concentration of melanin in the fungi. The melanin has been sequenced and it is the same type found in human skin. Maybe we will see this adaptation in space fairing humans... Wonder if current black astronauts are less effected by radiation.
EDIT: Probably something that will seem so obvious in hindsight.
We’ll call it the lob-star
You mean a protista?
We can do better than nature just by taking the best from everything, integrating it together, and removing all the extra junk. Imagine if we just used it as inspiration.
I'm not saying tiny factories wouldn't end up looking like cells, but I expect the similarities to be superficial, as we have access to more robust materials to serve as feedstock and can have better control of the operating environment.
in a sense a planet is one of these already, just a little less maneuverable than we would maybe prefer out of a ship, and inverts the hard shell soft interior crustacean-ship idea
for large ships maybe you could literally use a planet, e.g. swing a spare one out of the solar system in the direction you want to go... if rogue planets can hold down an atmosphere and stay geologically active [0] maybe you could have liquid water oceans and sea life and atlantean cities scattered around the seafloor drawing hydrothermal power
plus you're hidden pretty well flying dark in interstellar space, maybe civilizations deem it prudent to leave their parent stars for dark forest concerns etc, maybe you could even harness earthquakes/vulcanism to (very slowly) manipulate the angular velocity vector enough to course-correct and navigate
The coolest part about fungus is that it will grow into its environment, so I would imagine molds (no pun intended) could be used to "grow" a panel, sheet, etc almost like natural 3D printing.
More seriously, the ideal is obviously an actual radiotrophic plant, right? That honestly seems within reach of genetic engineering, if it doesn't already exist.
There's one interpretation of evolution where fungi are the original farmers. Everything from lichen up to and including trees only happening because it suited fungi to do so.
"""
radiation beneath a ≈ 1.7 mm thick lawn of the dematiaceous radiotrophic fungus was 2.17±0.25% lower as compared to the negative control. In addition, a growth advantage in Space of ~ 21% was observed, substantiating the thesis that the fungus’ radiotropism is extendable to Space radiation.
"""
I'm wondering whether the fungus could actually be grown to various thicknesses, or is 1.7mm kind of its natural thickness? Might need a layer system of some sort.
I'm really thinking I should burn some time on learning about fungi and bacteria. It'd be cool if there were some ecosystem of them capable of taking in human waste as input and outputting useful things like cleaner water and shielding.
(Replied to myself since the other comment is older.)
I'd like to see what a 10x thicker fungus could block. That would help inform how it's likely to flesh out at scale.
2.17% is when only one side is shielded: "it can be extrapolated that the biomass would reduce total radiation levels (of the measured spectrum) by 4.34±0.5% were it fully surrounding an object"
But your assumption that this thing scale linearly is far from reality, see for example their estimate for Mars:
"In a case study we estimated that a ~ 2.3 m layer of melanized fungal biomass (8.6% [wmelanin/wCWW] melanin-content) would be needed to lower Martian radiation levels to those on Earth (from 234 mSv/a to 6.2 mSv/a [6, 7, 53])"
ISS is at apporximately 144 mSv/a.
> Mycoremediation: the use of mycelium for decomposing toxic wastes and pollutants
The lower levels will get less radiation though.
https://www.buildinggreen.com/blog/greensulate---fungus-base...
Either way, you’d need to be checking it regularly as having a section die would be bad.
Earth is pretty good. A little large to change its direction of travel though.
But 2% lower radiation isn't going to do nearly enough.
Whether thicker layers can be used to provide comprehensive protection is for future research to establish. (and it's unlikely to be a linear relationship)
Serious question: How does the fungus release the energy? heat? Could we use them as some kind of biological radiation thermal panels on Mars?