Mass is no longer a factor in rad-shielding (was Travel-time to GEO)

>Why would one choose *lightweight* materials for it?

The question might be rephrased...Why would one choose
to use only old methods of shielding cosmic radiation?

The previous discussions concluded naively that:

a) only thick layers of something (ref. Periodic Table
and Wiki) could shield cosmic rays

b) it would be massive (weight)

and thus we are merrily led by the writers to the
conclusion that

c) it's improbable due to the cost factor.

Of course, this expertise is based on the venerable
NASA research of the last century and the outdated
forms of space transport, most notably the now 30 year
old Space Shuttle.

However, advances in shielding have led to
nanotechnolgy research where the density of the
material at the nano level may provide a lower profile
of material.

We could use nanotechnology to create a solid - say an
aerogel - which intercepts and then reflects and
refracts the cosmic ray, something that NASA uses to
intercept cosmic rays right now. (Google: wiki nanogel
or wiki stardust nasa)

For those naturally inclinded, but planning a trip
beyond the van Allen belt, go green and take along
your own magnetic field generator for protection...

Reduce the weight of magnetic solutions by using solar
power electromagnet arrays to generate the magnetic
field.

You probably want to use Halbach technology for
magnetic arrays or cylinders. (wiki halbach array)

Finally, no one technology appears to be able to
handle all the cosmic radiation possibilities.
Combining the above techniques with the old school
thick plating might at least reduce the weight
significantly to affordable levels at least for a
government.

David

> > Lightweight materials for shielding
>
> Given that cosmic-radiation shielding is generally
> functional
> based only on mass and hydrogen-richness, why would
> one choose
> *lightweight* materials for it?
>
http://en.wikipedia.org/wiki/Health_threat_from_cosmic_rays#Shielding