Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: Seany on 16/04/2007 16:49:41
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I've heard somewhere that when you leave the Earth's atmosphere, there is a huge radiation which is enough to kill or severely damage us. To avoid it, we need a 6 metre thick wall of lead to shield us from the radiation.
So, I was wondering what is going on? Many astronomers have gone out to space just for a short while, and have left the Earth's atmosphere, then came back - or am I mistaken of these facts?
A rocket surely doesn't have a 6 metre thick lead wall? Or have I heard this radiation thing wrongly all from the beginning?
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There is significant radiation in space, and even people flying high in the atmosphere (e.g. when Concorde was flying, passengers in Concorde were flying at 60,000, rather than the normal 30,000 most commercial aircraft fly at) do receive increased radiation, but most of that radiation can be stopped by the fairly thin metal of the spacecraft or aircraft. There is a slight increase in radiation that actually does get through to the passengers of a spacecraft or aircraft, but so far I am not aware of any detected clinical effects from that slight increase.
No, there is absolutely no need for 6 metres of lead, or even 6 inches of steel, but most of the radiation is strongly charged, and will be stopped by a few millimetres of aluminium.
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I think this answers your question:
http://en.wikipedia.org/wiki/Van_Allen_radiation_belt
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You have part of the answer already Seany, the fact that any trip by astronauts is just for a short time.
Any space trips are calculated so that the actual time spent in any radiation hazard area is very short.
The space vehicle and the space suits worn make sure the astronauts are exposed to as little radiation as possible.
Bee
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the fact that any trip by astronauts is just for a short time
Except for the deliberately long endurance flights on (for example) Mir. Those astronauts recieved doses of radiation, at about 100 times the rate that they would have experienced on earth.
However the radiation flux changes substantially with solar activity (by more than a factor of three according to measurements on ISS and Mir) and the real concern is solar flares that could result in a very significant dose.
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100 times the rate they would experience on earth? Isn't that really bad for your health? Because taking X-rays aren't good for you, if you take too many of them...
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Its all a matter or risk and benefits.
When doctors decide you're going to have an x-ray it's because they can see a benefit in knowing whether or not your bones are broken etc... Go to a hospital and ask for an x-ray for no good reason and you won't get one.
Radiation doses vary a lot on the surface of the earth and some activities e.g long-distance flying will give you a substantially higher dose (less atmopshere shielding you from sloar radiation).
Ask yourself this: If I was offered the chance to spend a few weeks on the ISS, would I be preared to accept a statistically higher chance of cancer in later life?
(Me! Me! Me! [8D])
In risk terms the best people to send into space are Old People - they have less "residual life" in which to develop cancer following the radiation dose!
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SEANY
There's also the danger of tiny cosmic particles from distant supernovae that travel with such energy that they burrow their way through the skin of the spacecraft and then through the heads of the astronaut's leaving microscopic holes and are viewed as bright flashes by the astronauts on the occasions when they actually pass through there eyes.
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The little particles pass through their eyes and make holes in them? [:o]
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Yes. When they were trying to work out what the bright flashes were they looked at the helmetS of the astronauts and found many holes where the particles had burrowed their way through.
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So.. If it went through their eyes.. Won't it have a tiny hole in the eye? And maybe into the brain?? [:o]
What picture is that of by the way? The particles coming from the bottom, piercing upwards?
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So.. If it went through their eyes.. Won't it have a tiny hole in the eye? And maybe into the brain?? [:o]
What picture is that of by the way? The particles coming from the bottom, piercing upwards?
Yes to the holes in their eyes ,skulls and brains. I'm not sure what lasting damage they do.
I Don't know what part of the helmet that is from :)
Space is a dangerous place.
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OK.... (some of this from another thread)
The flashes were actually Cerenkov Radiation. It's caused (for example) by high energy electrons tavelling in water - or in this case through the fluid in the eye. The radioactive charged particles are actually travelling faster than the natural speed of light in water (< c) and this results in something a bit like an electromagnetic sonic-boom = Cerenkov radiaton.
Another place you can see it is the glow from radioactive fuel if it is underwater:
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Thanks ukmicky and Batroost. Very interesting [;)]
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Yes. When they were trying to work out what the bright flashes were they looked at the helmetS of the astronauts and found many holes where the particles had burrowed their way through.
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Excellent piccy Michael !!
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Yep.. But Neil, explain the picture to me. [;)]
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When they were trying to work out what the bright flashes were they looked at the helmetS of the astronauts and found many holes where the particles had burrowed their way through.
Seany that says it all. Basically it a small section of an astronauats helmet placed under an electron microscope showing the holes the cosmic particles made as they went through the helmet . Rather than just blasting a hole through the helmet they sort of stretch the material and pull some of it through with it before it pops out of the other side.
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Oh right.. I get it.. Thanks UK [;)]
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I don't want any high speed electonics in my brain [:-'(]
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Yes.. Nor do I..! Do you think it would hurt? Or too miniature and quick to realise?