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Radiation causes genetic mutation and every (human) cell in our body have the same genes. But on Earth we don't get cancer as often in the foot as in the genitals or in the brain. Some parts of our physiology are more complex untested and sensitive than others.

  • Could an astronaut be well protected by wearing only a (perfectly shielded) helmet and a hauberk, or even a backpack to cover half of her upper body?
  • What happens to me if, say, my left foot was exposed to off the scale super radiation? Would I get acute radiation sickness? Would it give me brain cancer later on?

The idea here is that maybe we could do an 80/20 by shielding only the "upper" half of a spaceship. And of course by wearing funny clothes.

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    $\begingroup$ For the second part, consider effects similar to slow microwave cooking. Is there any part of you that you'd be happy to sacrifice for that and at the same time doesn't have high blood circulation severely affecting the rest of your body's temperature, oxygenation rate, nutrients transport, immunoresponsive system, and is also isolated enough to assure no secondary radiation damage to the rest of your body? (Warts don't count! LOL) $\endgroup$
    – TildalWave
    Aug 25, 2015 at 11:55
  • $\begingroup$ @TildalWave If my left foot once walked on Mars, it would be super happy to spend the rest of its eternity in an oncology lab. I know, I'm the one talking for it. Actually, the rest of me, the imaginary space traveller, would not care about the boring trip back to "home", but instead just lie down and become Martian dust. $\endgroup$
    – LocalFluff
    Aug 25, 2015 at 12:48
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    $\begingroup$ It wouldn't take long for leukemia (cancer of the lymphatic system) and leukemia-like symptoms to develop. I'm afraid it simply doesn't work like that, and you could just sacrifice a single body part with the rest remaining unaffected. Even just cutting the blood supply to your leg and letting it dry off would kill you (necrosis of the tissue causing sepsis, blood clots, et al.) without surgical intervention. Not to mention that if it also cooked off the bones due to severely increased radiation, you'd have to cut high above it to find soft tissue still able to heal. $\endgroup$
    – TildalWave
    Aug 25, 2015 at 12:59
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    $\begingroup$ Consider also that ships have to adjust their attitude frequently; there's no viable way to protect the crews without all-around shielding on a ship. $\endgroup$ Aug 25, 2015 at 14:19
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    $\begingroup$ You can't shield yourself from cosmic radiation with something you can wear. It is far more penetrating than that. You might be able to shield yourself from solar particles somewhat, but you'd have to be careful that the induced secondary radiation in the material isn't worse than that primary radiation you're shielding against. $\endgroup$
    – Mark Adler
    Aug 25, 2015 at 17:13

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Is radiation more dangerous to some parts of the body than to others? Yes. Health physics uses tissue weighting factors as a way of factoring in the relative sensitivity of different tissue types.

Is partial shielding practical? For the most part, no. Some of the highly sensitive tissues are the bone marrow, lungs, and intestines, meaning an effective shield would need to cover most of the body.

There's one situation where partial shielding is practical, though: since the hands are relatively insensitive to radiation, you don't need to shield them. A radiation-armored spacesuit would have heavy armor covering most of it, while the gauntlets would be thin to give the user reasonable dexterity.

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To my knowledge the only in-space study was that on Apollo 17, when pocket mice were flown in a closed container in the command module. (Note this means that the mice never made it to the moon.)

Apollo mice container

Four of the five mice survived. One cage was left empty. On their return, the courageous Mousetronauts were killed, dissected and examined for after effects. The results were inconclusive though - brain and eye lesions were found but there wasn't enough data to statistically point to any particular part of the body that suffered more.

Since Apollo 17 all manned flights have been in low Earth orbit, so I don't think we'll find such a study that's been done since.

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    $\begingroup$ LEO mice have also developed lesions IIRC, so it's not really conclusive. $\endgroup$ Aug 25, 2015 at 20:15
  • $\begingroup$ By the way, the picture is figure 3-34 of the Apollo Program Summary Report. $\endgroup$
    – DrSheldon
    Jul 11, 2019 at 1:43

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