Self-replicating radiation-shield for deep-space exploration: Radiotrophic fungi(biorxiv.org)
biorxiv.org
Self-replicating radiation-shield for deep-space exploration: Radiotrophic fungi
https://www.biorxiv.org/content/10.1101/2020.07.16.205534v6
85 comments
Literally the first thing that came to mind.
Smith also had a super interesting background.
Smith also had a super interesting background.
Yes indeed. I can't find this information online but I remember an anecdote according to which Cordwainer Smith had explained the entire timeline of the Instrumentality of Mankind in terms of current goings-on on the international stage. Of (some of) which he had a certain privileged vantage point, of course.
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.
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.
For the record, here is the correct math for attenuation of high energy photons with a nice explanation from NIST:
https://physics.nist.gov/PhysRefData/XrayMassCoef/chap2.html
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.
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 don't understand the interest here. It's not like fungi are magically more effective than virtually any other mass at absorbing ionizing radiation and subatomic particles. "Self-replicating" is meaningless when it needs to consume water and carbon sources to do so which on their own would probably be denser and more effective per unit volume at shielding. Chemistry has next to nothing to do with radiation shielding let alone biology.
I imagine this might be interesting for longer distances in which broken shielding might not be so easily replaced. In such cases, regenerating your shielding via life-support systems is a feature, not a bug.
Except that in general most mushrooms produce more CO2 than then consume. In fact, they’ve been researched as a possible additional variable to the CO2 budget equation: https://phys.org/news/2016-01-mushrooms-contribute-global.ht....
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.
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.
Bring plants/algae?
Why not fly with a pre pulverized shield? There aren't many big forces on a long distance space hall and one could imagine using electrostatic forces to hold the pulverized shielding in place. No need to regrow the radiation shield then.
Why not indeed. Why not investigate growing a shield as well?
Now this is the solarpunk/biopunk future I signed up for. Symbiotic radiation shielding fungi for space exploration!
A likely way to cut the Gordian Knot of outer space radiation exposure is to prophylactically have everyone take C60. See the study below.
https://www.sciencedirect.com/science/article/abs/pii/S00410...
https://www.sciencedirect.com/science/article/abs/pii/S00410...
Where does the additional mass come from when the fungi reproduces in space?
IIUC most of the mass required to build plants comes out of the air (CO2). Of course, any astronauts wanting to utilize these fungi will have to take some amount of other resources with them.
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.
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.
> IIUC most of the mass required to build plants comes out of the air (CO2).
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.
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.
> edit: they're heterotrophs
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]
[1]: https://en.wikipedia.org/wiki/Photoheterotroph
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]
[1]: https://en.wikipedia.org/wiki/Photoheterotroph
Yes, but they're still fungi. They might be extracting some amount of energy from radiation, but they still get most of their energy (and cellular raw material) the old fashioned, biological way. It's not like they suddenly evolved replacement pathways to synthesize all the products they need.
For fungi, the carbon source is actually even more straightforward than with plants: we can just feed them biowaste. Depends on the species of course, and probably requires some treatment to not encourage growth of less desirable species instead. If they turn out to be edible, this could prove to be ideal.
Don't fungi "breath" out CO2 as well, I think I remember reading that somewhere. That might be an issue in space.
Lead does not block "all radiation". Here's a great video that explains common types of radiation and what kind of materials are effective at blocking each of these types of radiation: https://www.youtube.com/watch?v=iTb_KRG6LXo
There's plenty of radiation that we have no effective way of blocking, like neutrino radiation.
There's plenty of radiation that we have no effective way of blocking, like neutrino radiation.
Ability to block/attenuate radiation is proportional to interaction probability which is generally also proportional to biomedical risk: ergo, if we can't block it, we don't care about it.
Short version: sometimes it's not the bullet that kills you but the spray or ricochet. There are plenty of types of radiation that you want to block with light elements. If a high energy particle spalls off some hydrogen atoms, then those can be less damaging than a similar collision in steel or lead. Fungi is a mixture of mostly light elements.
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?
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?
The other advantage of fungi might be in the aftermath of a micrometeoroid event. Does it make more sense to cut a hole in your shielding and use up a store of fungal bricks that you brought with you, or to grow a somewhat custom patch with the right radius of curvature, and slightly larger than the hole, and then recycling any material that gets removed to apply the patch.
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.
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.
Surely you’d need a lot more water than lead?
At least you can be using the water though.
At least you can be using the water though.
The water will accumulate deuterium and tritium over time though. Eventually, it will degrade to emergency drink status. Might be a good way to get at fusion reactor fuel though.
Maybe we should think of the fungus as self-managing water storage and plumbing.
Imagine you're an interplanetary civilization. You're building long haul ships not rated for Earth atmosphere, just ferrying supplies between planets, or landing on moons and asteroids. You might have a shipyard in orbit, though the moon seems more likely (too many pulverized metal oxides right there begging to be dumped into a smelter) or a carbonaceous asteroid (which can still be high in metals). You can still use vacuum rated engines to lift it into orbit, although you might have to design the ship as a second stage for some lifting platform to get the deltaV you need.
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.
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.
Technically light can be converted into mass, but I’m not sure that’s relevant here.
Probably water and air. Combine that with the radiation and trace elements from the water and you have enough to build tissue.
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Clearly the end goal for this research is figuring out why the fungi can block radiation and taking advantage of that for better radiation shielding. We’re not going to be flying around in spaceships coated in fungi.
I mean why not? Hard radiation tends to destroy whatever it hits on a molecular/atomic level. If you have a biological shield which is constantly refreshing itself, you can possibly have a much lighter assembly. Mycelium has also been used to purify water. It might be possible to integrate shielding with water storage/buffer and recycling.
It'll probably require layering different types of material to convert higher energy radiation (like cosmic rays) to more manageable spectra.
It'll probably require layering different types of material to convert higher energy radiation (like cosmic rays) to more manageable spectra.
If we had a fungi that could purify water and block out deep space radiation, that would be one sweet mushroom.
Better hope it doesn’t die halway to Mars!
Better hope it doesn’t die halway to Mars!
Yeah, that would be something we'd want to do long-scale simulation tests of before setting sail. Build a simulated spaceship, probably in orbit for maximum accuracy, and see how everything holds up.
Tbh I'd be more concerned about the humans cracking psychologically before the fungus dying. They are hardy buggers.
Tbh I'd be more concerned about the humans cracking psychologically before the fungus dying. They are hardy buggers.
Maybe the future of space travel are living spaceships. Some kind of crustaceans with outer shell, living main body, and human crew inside. Something between fungi, animal, and plant even.
That’s straight out of Farscape, iirc. I remember watching a living ship fly though space as a kid and it seemed like a giant stretch. But maybe it isn’t.
Good old Moya:
https://farscape.fandom.com/wiki/Moya
https://farscape.fandom.com/wiki/Moya
IMO future of everything is replicating nano-robots, artificial life-like beings. Nature can't be as good as artificially created specialized mechanisms. Right now nature have an advantage in self-replicating cells which we can't reproduce yet, but I'm sure that we will.
Maybe over 2 billion years nature has created as efficient as we can get, and it would be best to have hybrid life that is a mix of nano-tech and biological cells. Is it a given that we could create tiny factories more efficiently than cells?
Nature tends to get stuck in local optimums where things are "good enough". For reference see the recurrent laryngeal nerve, the "backwards" eye in many animals (though not octopuses or their relatives).
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.
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.
> crustacean
We’ll call it the lob-star
We’ll call it the lob-star
Why not Zoidberg, tbh?
I call it: delicious!
cool, like the yuuzhan vong
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
[0]: https://doi.org/10.1038%2F21811
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
[0]: https://doi.org/10.1038%2F21811
Maybe these competing for resources around stars is the future of life
> Something between fungi, animal, and plant even.
You mean a protista?
You mean a protista?
Because fungi are some of the oldest terrestrial organisms on the planet. Today they often enjoy shade and humidity, but at the time there was melanin and other UV blocking chemicals, or wearing other organisms as a hat (lichen).
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.
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.
We don't want a material that builds and repairs itself?
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.
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.
Check out the Martian settlers in Spin:
https://en.wikipedia.org/wiki/Spin_(novel)
https://en.wikipedia.org/wiki/Spin_(novel)
I think the end goal would be a fungi that we can layer between hulls and is low maintenance. Or even better, that also generates oxygen. Maybe even feeds on human waste.
fungi consume oxygen, or at least, most of them do. not sure why people think of fungi as plants.
Anything that can't walk around on its own is obviously a plant. /s
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.
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.
Why not? I mean, the fungi would die out in space without oxygen but if it retained its properties it could be used just like any other material: wood, steel, ceramics, etc.
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.
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.
There are a few companies that produce packaging alternatives for EPS that way.
Hmm, how would fungi be different from a self-repairing expanding foam? Other than needing to be kept alive?
species: Cladosporium sphaerospermum
"""
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.
"""
"""
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.
"""
Consider on the low end ((2.17-.25)% per 1.7 mm thick) this works out to 88.6 mm for 100% coverage or around 3.5 inches.
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'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.)
> ((2.17-.25)% per 1.7 mm thick) this works out to 88.6 mm for 100% coverage or around 3.5 inches.
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.
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.
I think it's probably fair to say this is early research and much more would need to be done. I also figure this could be done on earth and tested against various radiation sources.
I grew fungi for a living at my previous job. They will grow in any shape you like as long as they have food and substrate.
The lower levels will get less radiation though.
https://www.buildinggreen.com/blog/greensulate---fungus-base...
The lower levels will get less radiation though.
https://www.buildinggreen.com/blog/greensulate---fungus-base...
It could be grown in movable segments so that the less exposed parts got a good dose regularity. Sounds like a pain to manage.
Either way, you’d need to be checking it regularly as having a section die would be bad.
Either way, you’d need to be checking it regularly as having a section die would be bad.
Does it actually work like that or does each successive 1.7mm multiply the radiation flux by 0.98? And then the inner layers will get less radiation and grow less well also?
This is correct, each incremental layer would block 2% of what is incident on it, not knock 2% off the starting number
Yeah if it's like that, I get around .9 meters thick for blocking 99.999997%.
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.
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.
Book recommendation: Mycelium Running
> Mycoremediation: the use of mycelium for decomposing toxic wastes and pollutants
https://fungi.com/products/mycelium-running
> Mycoremediation: the use of mycelium for decomposing toxic wastes and pollutants
https://fungi.com/products/mycelium-running
You'd need about 400mm thick layer to cut radiation to 1% of incident at 2% per layer.
> 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.
Earth is pretty good. A little large to change its direction of travel though.
Earth is pretty good. A little large to change its direction of travel though.
So what is "growth advantage" and why is the 21% figure meaningul?
The fungus grows better in space. Probably because it's radiographic (uses radiation for energy). But also possibly because it came from space and incidentally populates environments on earth (I'm semi serious).
I don't think the conditions on random meteors are in any way comparable to some lab in the ISS...
It's a fascinating idea.
But 2% lower radiation isn't going to do nearly enough.
But 2% lower radiation isn't going to do nearly enough.
That's with a 1.7mm layer of fungus. This looks to be proof of concept research.
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)
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)
It is 2% with the current strain of the fungus which may evolve in the future.
When we meet some aliens they might greet the fungus instead of us
Why have they decorated their ships with dead bodies? What sort of barbarians are we dealing with here?
Decorating the ship with dead fungi would be very pointless though. You could use most any other material for the same effect.
When we meet some aliens they’re likely to be fungus, at best.
Encapsulate the entire vessel in a membrane of fungi? No windows just fungi-bubble deep-space faring?
ISS doesn’t have that many windows for a reason.
Astrophage!!!! if only we could it for fuel too.
What is it with all the fuzz a out fungi in space lately? Is Discovery so well-liked or is it the other way around?
Serious question: How does the fungus release the energy? heat? Could we use them as some kind of biological radiation thermal panels on Mars?
Serious question: How does the fungus release the energy? heat? Could we use them as some kind of biological radiation thermal panels on Mars?
My guess is that the original paper is artefactual, but there's no reason a priori that an organism couldn't take large classes of ionizing radiation and turn it directly into chemical energy, ionizing radiation, after all, effects chemical transformations.
"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...
_____________
[1] https://en.wikipedia.org/wiki/Cordwainer_Smith
[2] https://en.wikipedia.org/wiki/Scanners_Live_in_Vain