3 ms·

The radiation level exposure on the Moon is estimated to be around 60 microsieverts every hour [1], while the limit of amount of radiation received by the gener

by drtgh 4y ago

The radiation level exposure on the Moon is estimated to be around 60 microsieverts every hour [1], while the limit of amount of radiation received by the general public in a year is set to 1'000 microsieverts (1 millisievert) [2]. It would then be necessary to be achieved the regenerative medicine in the first place, with a major revolution in radiation shielding technology. Unfortunately does not appear to be on the verge of being a reality (in short term?), if one look with cold eyes the current state of medicine is amputation. [1] https://www.supercluster.com/editorial/the-threat-of-space-radiation?xid=PS_smithsonian https://www.supercluster.com/editorial/the-threat-of-space-r... [2] https://www.jaea.go.jp/english/jishin/kaisetsu01.pdf https://www.jaea.go.jp/english/jishin/kaisetsu01.pdf

Brendinooo 4y ago
If water is plentiful and accessible, that could be used as shielding, no?
- drtgh 4y ago
  It is not my field, but if plentiful and accessible, we are talking about several thousand tonnes of water around a small habitat that could theoretically be used. Nevertheless, if I understood right, that immense amount of water would have a limited shelf life until acidification corrodes the containment structures, so it would need to be continuously treated and refrigerated, " Ionizing cosmic radiation is mostly gamma rays and protons, which are overall very similar to the radiation from nuclear waste. Protons are slightly lighter and so would have less energy at a given velocity (more easily stopped); but, because they're protons, if captured by the water they'd basically become H+ ions which could acidify the shielding water in time (not seen as much with nuclear waste). " [1] [1] https://space.stackexchange.com/questions/1336/what-thickness-depth-of-water-would-be-required-to-provide-radiation-shielding-i https://space.stackexchange.com/questions/1336/what-thicknes...
  - stametseater 4y ago
    Chemically neutralizing the shielding water should be trivial. But why would the water need to be refrigerated? Energy absorbed from radiation would be emitted as thermal radiation, and lose a ton of thermal energy during the long lunar nights. If well insulated, the water tanks could serve as thermal batteries to keep the rest of the base warm.
    - drtgh 4y ago
      I said it for to maintain undesired chemical reactions under control. My first thought after to read some papers would be below 25°C, but this is not my field so take it with a grain of salt, as the water temperature in normal operating conditions within nuclear waste water pools seems to be held below 50°C by the refrigeration systems. PS. I'm not sure if it would be trivial to treat the water for to keeping it operative more than one year as effective shield.
  - Chris2048 4y ago
    I did a few rounds with an AI on this topic, so excuse me if there are inaccuracies, but: - According to a study conducted NASA, a 1 mm layer of polyethylene reduces solar and cosmic radiation by approximately 50% - A 1mm, 1m^2 layer of polyethylene weighs approximately 0.92kg Maybe the polyethylene would decay, but maybe it can also be remanufactured, harvesting the contaminates in the meanwhile? That said, this all implies that working under a polyethylene sheet of 5mm would reduce exposure to about 33 mSv a year (assume 8hrs a day working on surface, 260 days/yr). That said, Maybe robots can work on the surface instead?
  - burnished 4y ago
    Any notion of the rate of that acidification? I can't imagine its happening quickly, still very fun to think about
ericd 4y ago
Couldn’t that taproom be subterranean? I assume that 10m of regolith is a fine radiation shield?
stametseater 4y ago
60 microseverts an hour works out to about 525 millisieverts (mSv) per year. The general public limit is set very low, so for additional reference, the annual limit for emergency worker was raised to 250 mSv per year after Fukushima, half of what you'd get on the Moon. An effective dose (whole body, sum of all equivalent doses for the organs) of 200 mSv is enough to increase your risk of fatal cancer from 25% to 26%, so 525 mSv obviously represents a substantial stochastic risk. The ICRP occupational equivalent dose limit for hands, feet and skin are 500 mSv per year, so for these you're under the limit (the 525 mSv effective dose above is spread across you, not on one organ). However the equivalent dose limit for eyes is 20 mSv average with no more than 50 mSv per year. I haven't done the math but I think 525 mSv effective dose over a year would put you at substantial risk of deterministic damage to the lenses of your eyes. In other words, Moon men probably get cataracts and are more likely to die of cancer.

by drtgh 4y ago

Brendinooo 4y ago

If water is plentiful and accessible, that could be used as shielding, no?

drtgh 4y ago
It is not my field, but if plentiful and accessible, we are talking about several thousand tonnes of water around a small habitat that could theoretically be used. Nevertheless, if I understood right, that immense amount of water would have a limited shelf life until acidification corrodes the containment structures, so it would need to be continuously treated and refrigerated, " Ionizing cosmic radiation is mostly gamma rays and protons, which are overall very similar to the radiation from nuclear waste. Protons are slightly lighter and so would have less energy at a given velocity (more easily stopped); but, because they're protons, if captured by the water they'd basically become H+ ions which could acidify the shielding water in time (not seen as much with nuclear waste). " [1] [1] https://space.stackexchange.com/questions/1336/what-thickness-depth-of-water-would-be-required-to-provide-radiation-shielding-i https://space.stackexchange.com/questions/1336/what-thicknes...
- stametseater 4y ago
  Chemically neutralizing the shielding water should be trivial. But why would the water need to be refrigerated? Energy absorbed from radiation would be emitted as thermal radiation, and lose a ton of thermal energy during the long lunar nights. If well insulated, the water tanks could serve as thermal batteries to keep the rest of the base warm.
  - drtgh 4y ago
    I said it for to maintain undesired chemical reactions under control. My first thought after to read some papers would be below 25°C, but this is not my field so take it with a grain of salt, as the water temperature in normal operating conditions within nuclear waste water pools seems to be held below 50°C by the refrigeration systems. PS. I'm not sure if it would be trivial to treat the water for to keeping it operative more than one year as effective shield.
- Chris2048 4y ago
  I did a few rounds with an AI on this topic, so excuse me if there are inaccuracies, but: - According to a study conducted NASA, a 1 mm layer of polyethylene reduces solar and cosmic radiation by approximately 50% - A 1mm, 1m^2 layer of polyethylene weighs approximately 0.92kg Maybe the polyethylene would decay, but maybe it can also be remanufactured, harvesting the contaminates in the meanwhile? That said, this all implies that working under a polyethylene sheet of 5mm would reduce exposure to about 33 mSv a year (assume 8hrs a day working on surface, 260 days/yr). That said, Maybe robots can work on the surface instead?
- burnished 4y ago
  Any notion of the rate of that acidification? I can't imagine its happening quickly, still very fun to think about

ericd 4y ago

Couldn’t that taproom be subterranean? I assume that 10m of regolith is a fine radiation shield?

stametseater 4y ago

60 microseverts an hour works out to about 525 millisieverts (mSv) per year. The general public limit is set very low, so for additional reference, the annual limit for emergency worker was raised to 250 mSv per year after Fukushima, half of what you'd get on the Moon. An effective dose (whole body, sum of all equivalent doses for the organs) of 200 mSv is enough to increase your risk of fatal cancer from 25% to 26%, so 525 mSv obviously represents a substantial stochastic risk. The ICRP occupational equivalent dose limit for hands, feet and skin are 500 mSv per year, so for these you're under the limit (the 525 mSv effective dose above is spread across you, not on one organ). However the equivalent dose limit for eyes is 20 mSv average with no more than 50 mSv per year. I haven't done the math but I think 525 mSv effective dose over a year would put you at substantial risk of deterministic damage to the lenses of your eyes. In other words, Moon men probably get cataracts and are more likely to die of cancer.