No moBananas

--- In spacesettlers@yahoogroups.com, "Ed Minchau"
wrote:
> --- In spacesettlers@yahoogroups.com, "victoriatangoman"
> wrote:
> > --- In spacesettlers@yahoogroups.com, Michael
> wrote:
> > > >I think the correct figure you meant to quote was 6 ft of dirt
> > > >around the shell of smaller Habitats will approximate the
> > radiation
> > > >dosage equivalent to Denver. Can anybody else backstop me on
> this?
> > >
> > > I've checked. It's 14 feet of concrete, a few feet of lead or
a
> > planetary
> > > atmosphere. Apparently the rare-earth elements do a better job
> but
> > they are
> > > too rare to use in large scale structures.
> >
> > I'm going to call you on this one. I need some supporting
> > documentation that I can assess for myself for your figures fall
> far
> > out of line of everything I've seen.
>
> From what I can recall, five meters of concrete will give you the
> same radiation exposure as sea level on a cloudy day. Two meters
is
> more like being in a jet plane at 40000 feet.

Quote from "Colonies in Space" by T.A. Heppenheimer, page 229,
Warnerbooks paperback edition, 1977;

"The six feet of covering will absorb all cosmic rays as well as
most secondary particles. A few of the most energetic particles will
produce so many secondaries that some will reach the colony, but
there will be no problem with solar flares, even the biggest, and no
problem with the iron nuclei in cosmic rays. Babies and mothers will
live amid radiation levels no higher than those in Denver or in some
of the cities in northern Arizona."

> >
> > > >For the larger Habitats, usually the thickness of the
pressure
> > shell
> > > >and the thickness of the atmosphere is sufficient protection.
> > >
> > > How thick are you talking?
> >
> > Four miles in diameter.
>
> That doesn't say how thick the pressure shell would be.
>
> Ed

That's a standard engineering formula. The answer depends on the
tensile strength of the material you choose, the shape of the
vessel, the atmospheric pressure to be contained, the other loads
that have to be carried, and the vessel's diameter.

The essential point is that the combination of the pressure shell
and the atmosphere serve as a means of radiation protection.

TangoMan