Could use empty plastic water tanks in the walls and have a satellite in orbit that already has the water onboard and they just transfer the water back to the satellite before returning to earth. Water blocks radiation very well it’s the reason we use pools of it to store fuel rods when they are not in reactors.

I remember reading, long ago, an assertion that most shielding ideas were counterproductive for astronauts.

It was stated that most shielding would turn high energy photons into much more harmful showers of particles, worse than the original photon going directly through tissue. Was this an untested myth?

HDPE has been around since the beginning of the space race, so it seems like someone ought to have considered this before? Has the understanding of particle interactions improved a lot since then, such that HDPE shielding would not have been considered before?

This targeted shielding is a classic aerospace mass tradeoff much like armoring a fighter pilot instead of the entire plane.

Thought it might be useful for the untapped market for air crews on passenger airlines but the company said it does not block cosmic gamma rays.

This seems sort of interesting as a sort of emergency backup, but it seems like the real solution for any sort of long distance/long duration in space is just making mass to orbit dramatically cheaper and shielding the spacecraft.

The NASA Space Radiation Laboratory uses HDPE panels to attenuate neutrons, protons, and heavy ions. The lab sits at the tail end of a particle accelerator which is used to test radiation effects on various materials including electronics and mice. When I saw the plastic panels, I asked one of the NSRL physicists about it as we had just finished setting out some tungsten blocks to isolate the beam only a certain area on our experiment. Why plastic? Why not a dense metal? He explained that HDPE is dense with hydrogen that does really well against slowing down particles and that most importantly, HDPE is made from low atomic numbers that do not emit secondary radiation effects. This prevents radiation from hitting sensitive electronics outside the beam and also making nearby objects radioactive. When the beam hits an object with high atomic numbers (metals, especially dense ones), it can create very strong x-rays that can knock neutrons out of nearby stable metal nuclei and create unstable isotopes, effectively creating a bunch of unintended radiation sources. This isn't a big deal for the experiment, that goes away at the end of the day but not good for permanent equipment.

You can see the HDPE sheets in this photo, they can be lowered or raised to adjust attenuation:

https://www.flickr.com/photos/brookhavenlab/52979144013/

“It still gets people surprised,” Milstein says. “Everybody asks, what about the head? But we’re actually able to reduce the effective dose by 60 percent without protecting the head, the arms, or even the legs.”

Whilst I understand the maths here, I can see why someone would be nervous!

The use of “we” in this headline is really jarring.

Why wouldn't it?