4 ms·

I am skeptical that this fungus absorbs radiation significantly more than the equivalent amount of water would. The paper [1] isn't very clear about possible in

I am skeptical that this fungus absorbs radiation significantly more than the equivalent amount of water would. The paper [1] isn't very clear about possible inaccuracies in the results and I don't understand why this experiment hasn't been repeated down on Earth. The mass attenuation coefficient of the fungus is 0.234 cm^2/g at 100MeV whereas water is 0.0166 cm^2/g according to this paper [2]. [1] https://www.biorxiv.org/content/10.1101/2020.07.16.205534v1.full https://www.biorxiv.org/content/10.1101/2020.07.16.205534v1.... [2] https://apps.dtic.mil/dtic/tr/fulltext/u2/a278139.pdf https://apps.dtic.mil/dtic/tr/fulltext/u2/a278139.pdf Edit: I made a mistake in this comment, see child comment for correction.

seesawtron 6y ago
>> it could be shown that the melanized fungus C. sphaerospermum can be cultivated in LEO (Low Earth Orbit), while subject to the unique microgravity and radiation environment of the ISS. I believe this "small scale" experiment was meant as a "proof of concept" to illustrate the idea whether this could be done in house in adverse conditions (unlike Earth's conditions) and could be a potential long term solution for radiation attenuation. I would hope that these somewhat promising results would allow them to conduct a large scale experiment.
barbegal 6y ago
Reading the paper again, I made a mistake in my comment above. The mass attenuation coefficient was at 10keV not 100MeV. Water has a mass attenuation coefficient of about 5cm^2/g at 10keV. Table 1 [1] in the paper shows the true comparison with water at 100 MeV where it can be seen that there is not a large difference. On a weight basis stainless steel outperforms the fungus. [1] https://www.biorxiv.org/content/10.1101/2020.07.16.205534v1.full#T1 https://www.biorxiv.org/content/10.1101/2020.07.16.205534v1....
- Hnrobert42 6y ago
  Maybe it’s because you have to ship stainless steel from Earth. Maybe the mass of the fungus can be grown from CO2 from respiration. The carbon originally coming from food, which has to be shipped up. Lots of maybes, but you know, maybe...
  - lopmotr 6y ago
    To grow fungus from CO2, don't you first have to grow a plant then let the fungus eat dead plant? Plants require (heavy) equipment to support them.
    - labawi 6y ago
      If it can photosynthesise (on gamma rays no less), then perhaps not. Mold can grow on concrete walls and stuff, so not sure what it needs.
      - lopmotr 6y ago
        It sounds like this fungus only produces energy, and doesn't fix carbon like photosynthesis does. Mold growing on concrete walls is actually living off the dust and other organic debris that accumulates on the surface if you don't clean it.
  - dnautics 6y ago
    > Maybe the mass of the fungus can be grown from CO2 from respiration. That's not a thing. Fixing carbon to a usable form [0] using "general biological energy source" to the carbon pool is extremely difficult (there are only four and a half, counting c3 vs c4 as a half, pathways known) and requires complex machinery to achieve. [0] assimilating carbon dioxide in general is not difficult, even humans do it but it does not enter the general carbon pool and is effectively only transiently converted out of CO2, and net does not contribute to biomass.
    - lowdose 6y ago
      Zeolites can do this. https://en.m.wikipedia.org/wiki/Zeolite https://en.m.wikipedia.org/wiki/Zeolite
  - DuskStar 6y ago
    Either you ship steel, or you ship biological material - you're shipping things either way. (And if you can do ISRU, then steel or just plain cast iron is available)
- rch 6y ago
  I wonder if material degradation factors like neutron embrittlement would tip the scales in favor of a fungal barrier at longer timescales.
agumonkey 6y ago
still worth for the conversion of radiative energy to biological activity nuclear waste may become green :)
- barbegal 6y ago
  Not really, almost all the radiation is converted to heat just like in any shielding material.
  - agumonkey 6y ago
    hum isn't it more efficient to divert it into "productive" chemical active than average heat (then used for whatever) ?
- acidburnNSA 6y ago
  Well technically it already is pretty darn green in that the energy system concentrates its waste into tiny generally well-contained packages that have, per TWh generated, a relatively miniscule negative impact and footprint on the biosphere. I recognize this is controversial but the numbers are pretty solid.
  - beowulfey 6y ago
    Totally true and nothing disappoints me more than the push away from nuclear energy
  - TouchyJoe 6y ago
    totally untrue they dump the western nucular waste in front of the Somalian coast.

seesawtron 6y ago

>> it could be shown that the melanized fungus C. sphaerospermum can be cultivated in LEO (Low Earth Orbit), while subject to the unique microgravity and radiation environment of the ISS. I believe this "small scale" experiment was meant as a "proof of concept" to illustrate the idea whether this could be done in house in adverse conditions (unlike Earth's conditions) and could be a potential long term solution for radiation attenuation. I would hope that these somewhat promising results would allow them to conduct a large scale experiment.

barbegal 6y ago

Reading the paper again, I made a mistake in my comment above. The mass attenuation coefficient was at 10keV not 100MeV. Water has a mass attenuation coefficient of about 5cm^2/g at 10keV. Table 1 [1] in the paper shows the true comparison with water at 100 MeV where it can be seen that there is not a large difference. On a weight basis stainless steel outperforms the fungus. [1] https://www.biorxiv.org/content/10.1101/2020.07.16.205534v1.full#T1 https://www.biorxiv.org/content/10.1101/2020.07.16.205534v1....

Hnrobert42 6y ago
Maybe it’s because you have to ship stainless steel from Earth. Maybe the mass of the fungus can be grown from CO2 from respiration. The carbon originally coming from food, which has to be shipped up. Lots of maybes, but you know, maybe...
- lopmotr 6y ago
  To grow fungus from CO2, don't you first have to grow a plant then let the fungus eat dead plant? Plants require (heavy) equipment to support them.
  - labawi 6y ago
    If it can photosynthesise (on gamma rays no less), then perhaps not. Mold can grow on concrete walls and stuff, so not sure what it needs.
    - lopmotr 6y ago
      It sounds like this fungus only produces energy, and doesn't fix carbon like photosynthesis does. Mold growing on concrete walls is actually living off the dust and other organic debris that accumulates on the surface if you don't clean it.
- dnautics 6y ago
  > Maybe the mass of the fungus can be grown from CO2 from respiration. That's not a thing. Fixing carbon to a usable form [0] using "general biological energy source" to the carbon pool is extremely difficult (there are only four and a half, counting c3 vs c4 as a half, pathways known) and requires complex machinery to achieve. [0] assimilating carbon dioxide in general is not difficult, even humans do it but it does not enter the general carbon pool and is effectively only transiently converted out of CO2, and net does not contribute to biomass.
  - lowdose 6y ago
    Zeolites can do this. https://en.m.wikipedia.org/wiki/Zeolite https://en.m.wikipedia.org/wiki/Zeolite
- DuskStar 6y ago
  Either you ship steel, or you ship biological material - you're shipping things either way. (And if you can do ISRU, then steel or just plain cast iron is available)
rch 6y ago
I wonder if material degradation factors like neutron embrittlement would tip the scales in favor of a fungal barrier at longer timescales.

agumonkey 6y ago

still worth for the conversion of radiative energy to biological activity nuclear waste may become green :)

barbegal 6y ago
Not really, almost all the radiation is converted to heat just like in any shielding material.
- agumonkey 6y ago
  hum isn't it more efficient to divert it into "productive" chemical active than average heat (then used for whatever) ?
acidburnNSA 6y ago
Well technically it already is pretty darn green in that the energy system concentrates its waste into tiny generally well-contained packages that have, per TWh generated, a relatively miniscule negative impact and footprint on the biosphere. I recognize this is controversial but the numbers are pretty solid.
- beowulfey 6y ago
  Totally true and nothing disappoints me more than the push away from nuclear energy
- TouchyJoe 6y ago
  totally untrue they dump the western nucular waste in front of the Somalian coast.