How much protection do space EVA suits offer against radiation? Do they shield certain kinds of radiation more than others? Any idea how many sieverts an individual is exposed to wearing a space suit on an EVA for 1 hour?
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$\begingroup$ @alex.forencich: Thanks for the answer. I am curious to know if there has been any recorded average rate of radiation exposure for the wearer of EVA spacesuits. e.g. 10 mSv/hour $\endgroup$– CosmosNov 30, 2013 at 3:57
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$\begingroup$ i don't think that there is average rate of radiation exposure for the wearer of EVA spacesuits if the radiation level during the EVA is high the radiation exposures are going to be high. $\endgroup$– HashNov 30, 2013 at 7:05
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$\begingroup$ @Hash: Granted, the level of radiation an individual is exposed to is dependent on the radiation levels. What kind of levels are present when there is low solar activity? Mild solar activity? High solar activity? What kind of levels of radiation are the dosimeters they are using warning about (i.e. 0.01 - 1000 mSv or is it measured in rads or rems?)? Maybe this is starting to get to broad... $\endgroup$– CosmosDec 1, 2013 at 9:04
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2 Answers
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There are three ways to protect ourselves from radiation:
Keeping a distance from the source
Minimizing the time of exposure to radiation
Using shielding .
However, in space the only way to protect from radiation is by using the last two points.
Space suits provide protection from the UV rays, but they provide limited protection from particle radiation and gamma and x ray.
If particles have enough energy they simply pass through the space suit.
So EVAs are planned during low solar activity or they try to make the EVA short.
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5$\begingroup$ Space suits provide protection from the UV rays, but they provide limited protection from particle radiation and gamma and x ray. This is not quite right. A space suit provides 100% protection against MeV charged particles such as the solar wind, but your skin also protects 100% against those particles. Against very high energy galactic cosmic rays, thin shielding is worse than no shielding, because it produces secondary showers. A space suit will provide essentially no protection against gammas with energies of about 200 keV or higher, and essentially 100% protection for <~50 keV. $\endgroup$– user687Sep 27, 2016 at 19:28
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They do very little. The suit will stop alpha and I believe beta radiation. However, gamma and x-ray radiation go right through. The only thing you can use to stop those is lots of mass, and spacesuits are as light as possible.
Most 'radiation' suits, by the way, do little to stop actual radiation. They are generally intended to contain radioactive materials on the outside of the suit for easy decontamination. The dose is then monitored with dosimeters and handheld detectors. Areas of high radioactivity are simply not entered at all or only entered for short periods of time. This is done in spaceflight as well - astronauts do not perform EVAs during solar flares, for example.
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1$\begingroup$ However, gamma and x-ray radiation go right through. Low-energy x-rays (roughly 50 keV or lower) will be stopped by a fairly thin layer of material. $\endgroup$– user687Sep 27, 2016 at 19:31
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$\begingroup$ True, but those low energy x-rays probably wouldn't penetrate very far anyway. $\endgroup$ Sep 27, 2016 at 19:36
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$\begingroup$ They could give you skin cancer, for example. $\endgroup$– user687Sep 28, 2016 at 5:00
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$\begingroup$ In the nearly perfect vacuum of space, low energy x-rays will travel unlimited distances just as visible light. $\endgroup$– UweMar 16, 2017 at 15:09