alt Hacker NewsWe've flown a radiation-blocking vest to the Moon and back, and it worked
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This targeted shielding is a classic aerospace mass tradeoff much like armoring a fighter pilot instead of the entire plane.
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 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.
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.
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.
the longest human exposure ever to cosmic rays
(which are physical particles with mass, not waves, moving at 99.999~9x21% the speed of light) which space is flooded with
was set by the 75 hours of a lander on the moon with 22 hours of those in moon walks
(space-walks in earth orbit, longest was 9 hours)
when NASA inspected the helmets of the moon walking astronauts, they found deep microscopic grooves which often made it completely through the protection
this is why moon walking astronauts reported seeing bursts of light even with their eyes closed
when they simulated comic rays hitting mice for days, the mice slowed down, learned things much slower and forgot things much faster, their brains and CNS were being damaged
humans will never make it to Mars, forget surviving on the surface, without advanced protection from cosmic rays, technology that does not exist yet
this vest is a great start but it's not enough
“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 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:
It's kind of buried in the article, but it's worth noting that this vest is meant only to guard against solar storms, not cosmic rays; those remain a significant problem.
> The vest, though, does nearly nothing against galactic cosmic rays (GCR), which are the other major radiation source astronauts face. Unlike solar storm radiation, GCR arrive continuously at much higher energies, which makes them harder to shield against. “Using the vest against these rays would not be reasonable,” Houri says. “You’d have to wear it at all times.”
See for instance this article on how the cosmic ray problem would affect a Mars mission: https://mceglowski.substack.com/p/radiation-tradeoffs-for-ma...