Page 185 - Lunacy and the Age of Deception

Polyethylene Spaceship

Plastic is an appealing alternative: Compared to aluminum, polyethylene is 50% better at shielding
solar flares and 15% better for cosmic rays.

Cosmic rays crash into matter, producing secondary particles.

The advantage of plastic-like materials is that they produce far less "secondary radiation" than
heavier materials like aluminum or lead. Secondary radiation comes from the shielding material
itself. When particles of space radiation smash into atoms within the shield, they trigger tiny nuclear
reactions. Those reactions produce a shower of nuclear byproducts - neutrons and other particles -
that enter the spacecraft. It's a bit like trying to protect yourself from a flying bowling ball by
erecting a wall of pins. You avoid the ball but get pelted by pins. "Secondaries" can be worse for
astronauts' health than the original space radiation!

Ironically, heavier elements like lead, which people often assume to be the best radiation shielding,
produce much more secondary radiation than lighter elements like carbon and hydrogen. That's why
polyethylene makes good shielding: it is composed entirely of lightweight carbon and hydrogen
atoms, which minimizes secondaries.
[Source: http://science.nasa.gov/science-news/science-at-nasa/2005/25aug_plasticspaceships/]

I hope you did not miss the opening sentence of this excerpt from NASA’s own website. “Protecting
astronauts from deep-space radiation is a major unsolved problem.” Just how did the Apollo
astronauts deal with all that radiation out in space? How did they cope with all of the secondary
radiation caused by cosmic rays smashing into the aluminum hull of their spaceship? The article
further stated, “"Secondaries" can be worse for astronauts' health than the original space
radiation!”