Cosmic Radiation

--- In spacesettlers@yahoogroups.com, Al Globus wrote:
>
> On Tuesday, September 23, 2003, at 03:12 AM, victoriatangoman
>
> > Then it occured to me that this "Earth blocking" feature
presupposes
> > that the Earth's atmosphere on the other side of the world
doesn't
> > exist. If the atmosphere above your head blocks the radiation, so
> > too does the atmosphere down under. T
>
> The effect of the blocking from atmosphere 'down under' is trivial
> compared to the blocking by 6,000 miles of rock. The reason you
need
> double the atmosphere is that I assume *no* cosmic radiation comes
from
> under your feet on Earth. Thus, on a colony, you get cosmic
radiation
> from twice as many directions, requiring twice the shielding
provided
> by the atmosphere.
>

In a habitat there is shielding above your head, and this shielding
is approximately as effective as Earth's atmosphere. Under your feet
in a Habitat you also have this shielding, so in effect you're
surrounded by atmosphere, just as you are on Earth.

The fallacy as I see it, is that your model presupposes that the
Earth has has to block the radiation equivalent of what the
atmosphere does. It doesn't. For the radiation to make first contact
with any point of the Earth it has to traverse the "Earth Enveloping
Atmosphere" and thus is attenuated, so what the Earth under your
feet blocks is the radiation that is present at the surface of the
Earth. This is a small amount of the radiation that starts the
journey towards the Earth's surface so to reduce that down to zero,
you don't need the equivalent of another atmosphere.

Your model is intuitive which is why I was flumoxed for so long.
Think it through. The surface of the Earth will not encounter full
strength radiation.

TangoMan