Reflection of only visible (safe) light on moon/mars

  • #1

Main Question or Discussion Point

I have seen many articles lately regarding planned manned missions to the moon and mars but the question of radiation protection constantly comes up. Engineers keep proposing various shelter designs that use local materials (regolith) as a concrete base to absorb harmful radiation so that the astronauts are not fried.

The problem I see is that every design also includes windows to allow some light in. I know windows can be created with heavy metal impurities to help absorb some radiation but: it is not as effective as a solid wall would be, a window with impurities is not as strong as one without impurities, and the addition of impurities also blocks some visible light that might reduce crop yields in a greenhouse.

My question is that if the habitat was built so that no window faced the sun during any point of the day or year (moon or mars), could silver mirrors (or other types) be used to reflect only the visible (safe) light but allow gamma and xrays to pass through the mirror so that they are not reflected into the habitat?

I know this wouldn't do anything for the Alpha, Beta, and Neutron particles that might be traveling in an angle to pass through the windows, but my question is only about the gamma and xray radiation.
 
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Answers and Replies

  • #2
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Cosmic rays come from all directions, not just from the Sun. Conventional mirrors mainly reflect infrared, visible light and maybe UV, but UV can be easily blocked by a window, so reflected light from a mirror is fine. A window that only points towards shielding outside plus a mirror in between would work. Maybe a two-mirror system. You would probably want to rotate the mirror to track the Sun.
 
  • #3
As I understand it, Cosmic rays are mostly Alpha, Beta, and Neutron particles. Would any of these be coming from the ground (below the horizon)? or would these particles only travel on a direct path from above the horizon (with the exception of minor reflections off of positive or negatively charged surfaces)?
 
  • #4
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Not that much alpha, more protons but also heavier nuclei. Neutrons are not part of the primary cosmic rays but they can be produced in the atmosphere and on the ground. Photons (gamma) are relevant as well. Slow neutrons will come from all directions but they are probably not a big concern. The rest won't come from below.
 
  • #5
Since glass can have a filter applied to block UV, could you apply this directly to the glass on silver mirror?

If so, is that blocked UV light converted to thermal energy or reflected along the glass?
 
  • #6
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Since glass can have a filter applied to block UV, could you apply this directly to the glass on silver mirror?
Probably, but every window that withstands the pressure difference will filter UV anyway (unless you take very special materials that don't).

It is converted to heat.
 

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