3 ms·

> To be specific: the exposure during a day of lunar living would be equivalent to ~2.6 days on the ISS, or ~200 days on Earth's surface If we do nothing to sh

by mlyle 5y ago

> To be specific: the exposure during a day of lunar living would be equivalent to ~2.6 days on the ISS, or ~200 days on Earth's surface If we do nothing to shield occupants.

woodruffw 5y ago
Yep, shielding will be critical. The paper linked above has this interesting note: > Settlements on the Moon will provide additional shielding because they will be buried beneath layers of lunar regolith. While this would decrease the dose rate from charged particles, the absolute contribution from neutrons is expected to increase for shielding constructed from in situ resources, as borne out by measurements with the Apollo 17 Lunar Neutron Probe Experiment. These showed that the flux of thermal and epithermal neutrons increases significantly up to a depth of approximately 150 g/cm2 (31). So plans to shield lunar occupants using the moon's own materials will need to compensate for the ionizing radiation that those materials are already emitting, separately from cosmic/solar radiation.
- mlyle 5y ago
  > So plans to shield lunar occupants using the moon's own materials will need to compensate for the ionizing radiation that those materials are already emitting, separately from cosmic/solar radiation. It's not really that they're emitting them "separately" -- they're radioactive (with mostly short half lives) largely because of solar bombardment. Thin shielding can paradoxically make things worse by converting high energy protons into more, lower energy neutrons. If your shielding is thick, the inner layers will rapidly become less radioactive (the important half lives are less than 30 days). The outer layers will keep getting hit by solar protons and creating more unstable elements. Another major concern in the long term: radon gas. One had better have an inner hull and never rely upon sintered regolith to hold atmosphere.

by mlyle 5y ago

> To be specific: the exposure during a day of lunar living would be equivalent to ~2.6 days on the ISS, or ~200 days on Earth's surface If we do nothing to shield occupants.

woodruffw 5y ago

Yep, shielding will be critical. The paper linked above has this interesting note: > Settlements on the Moon will provide additional shielding because they will be buried beneath layers of lunar regolith. While this would decrease the dose rate from charged particles, the absolute contribution from neutrons is expected to increase for shielding constructed from in situ resources, as borne out by measurements with the Apollo 17 Lunar Neutron Probe Experiment. These showed that the flux of thermal and epithermal neutrons increases significantly up to a depth of approximately 150 g/cm2 (31). So plans to shield lunar occupants using the moon's own materials will need to compensate for the ionizing radiation that those materials are already emitting, separately from cosmic/solar radiation.

mlyle 5y ago
> So plans to shield lunar occupants using the moon's own materials will need to compensate for the ionizing radiation that those materials are already emitting, separately from cosmic/solar radiation. It's not really that they're emitting them "separately" -- they're radioactive (with mostly short half lives) largely because of solar bombardment. Thin shielding can paradoxically make things worse by converting high energy protons into more, lower energy neutrons. If your shielding is thick, the inner layers will rapidly become less radioactive (the important half lives are less than 30 days). The outer layers will keep getting hit by solar protons and creating more unstable elements. Another major concern in the long term: radon gas. One had better have an inner hull and never rely upon sintered regolith to hold atmosphere.