CNN.com article "New fabric touted as radiation-proof"

It sounds a bit like the polyethylene that was used out on the ISS. It
does work to some extent- it cuts the radiation by a few percent, and
weighs comparatively little, but apparently it doesn't work as well as
was hoped. I'm beginning to think that we're never going to get around the fact that more protection is always going to mean more mass. On the other hand, some people go too far with that. They advocate burrowing many meters into the interior of asteroids, and tout protection from radiation as an advantage of that approach. I always tell them that anything over 2 meters is overkill.