posted on Aug, 19 2013 @ 07:40 PM
reply to post by TH3S33K3R
reply to post by dlbott
No, no they don't need lead. Lead is one of the worst materials you could possibly have to shield you in space.
With Galactic Cosmic Rays, lighter is better, due to bremsstrahlung. It's also fairly easy to stop radiation from a GCR due to the type of radiation
it is. A GCR is made up of 99% nuclei of known atoms, with 90% being simple protons, 9% being alpha particles, and 1% being the nuclei of heavier
elements. Protons and alpha particles are easy to stop, using secondary shielding, such as the engine, internal components, and fuel cells. Alpha
particles on earth can be stopped with simple paper.
If you have lead, or other dense materials, then you get secondary "braking" radiation. The particle enters the shielding material, the particle
hits the atoms in the shielding, which then causes them to kick radiation out, which creates more radiation, etc. Eventually you get a ship filled
with radiation, that kills the astronauts on board. Lighter material has fewer atoms for secondary radiation to come from.