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Radiation and astronauts


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Ok I'm watching 'mission to mars' on itv4 at the moment and it just reminded me of a question that bugs me.

How do astronauts not get zapped (fried) with solar radiation and their suits not get punctured by micro asteroids amongst other seemingly unavoidable nasties.

Are their suits super heated to counteract the coldness of space?

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It is a major issue. The atmosphere provides no protection at that altitude (300km for Low Earth Orbit; even aircrew at 10km worry about the increased radiation doses). The radiation levels on the ISS are about 3-400x higher than for us on the ground, I believe. It does also I think have a specially enhanced 'refuge' area they can use if there is a particularly high burst of radiation (solar storm).

The suits are both heated and cooled. If you're in the shade of the Earth, it's really cold. If you're in the full glare of the Sun -- it's really warm!

For micrometeorites? I suspect it is just a numbers game; the longer you're outside, the more likely you are to get hit by one...

Edited by FraserClarke
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The Apollo astronauts saw flashes of light as cosmic rays burned through their eyeballs. A number of them have developed cancers, but that could be a coincidence.

I think that astronauts in low Earth orbit are protected slightly by the magnetosphere, with some radiation channelled away into the van Allen belts.

I read in the New Scientist that anyone undertaking a Mars trip would lose something like 25% of their brain tissue to radiation damage by the time they got to Mars - their brains would have more damage than that seen in advanced Alzheimers.

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The Apollo astronauts saw flashes of light as cosmic rays burned through their eyeballs. A number of them have developed cancers, but that could be a coincidence.

In "quiet sun conditions", the radiation received by Apollo astronauts in 10 days - 2 weeks was about what is permitted for a worker in the nuclear industry in one year. About half of this was received in the few minutes they were passing through the van Allen belts. This level of exposure is supposed not to be a serious risk; after all, about 1/3 of adults who have not been exposed to high levels of radiation develop cancer in later life, and there is no reason why astronauts should be exempt from this.

The Apollo spacecraft however did not provide a refuge against radiation which could have been received if a medium to large coronal mass ejection was aimed at them, the consequences would have been serious, this was well known at the time but the risks were considered to be worth taking. In today's risk averse environment, they probably wouldn't be.

The ISS, in a low earth orbit, is well protected by the same magnetosphere that creates the van Allen belts ... it also has a radiation refuge providing adequate protection agains solar storms.

Cosmic rays are a little more serious in space, as the atmosphere provides protection against the higher energy events; in fact, you lose most of your protection against cosmic rays simply by flying in a commercial jet transport; a transatlantic crossing gives about the same extra radiation dose as a medical chest X-ray. The flashes seen by Apollo astronauts were likely caused by high energy cosmic ray events; similar flashes have been reported by astronauts manning Mir and the ISS; it's quite probable that airline passengers would see some, if the environment was darkened and they were left without distraction.

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Here is a good link explaining some of the effects of radiation and cosmic rays.

ESA - Lessons online - Radiation and life

I was trying to find the picture of an astronauts helmet that showed all the tracks left by the cosmic rays under magnification. Couldn't find the one I was looking for but here is another article explaining that further.

http://discovermagazine.com/2003/sep/featspace

Edited by Pibbles
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