> 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...
Remember the van allen belt radiation is what spawned a lot of fake moon landing theories that suggested transit thru the van allen belts was not survivable with the limited/no protection that our astronauts had at the time.
If for example you built a space ship on low Earth with efficient but low thrust ion drive & wanted to take it to Moon or Mars, it would take it possibly months to slowly (but efficiently) spiral out to higher orbit and eventually towards its destination. Many of those months would be spent inside the Van Allen belts.
So for these mission profiles I have seen the suggestion of the ship being radiation hardened for autonomous flight & the crew arriving by a small fast craft only once it is out of the radiation belts.
(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
Also IIRC some WW2 fighter planes had at lest armored glass front panel, to provide some protection from tail gunners when attacking bombers.
<https://en.wikipedia.org/wiki/Tsiolkovsky_rocket_equation>
Even without earth-to-orbit costs, that mass has real costs, and reduces available payload.
If that shielding mass can be dual-use (e.g., water), reactive (e.g., electromagnets), or reduced to a very small amount (emergency shelters, wearable garments), it becomes more practicable. That still doesn't make it easy.
There's also a discontinuity in radiation exposure. Passing through radiation belts (e.g., Earth's van Allen belts, or those around Jupiter), and solar storms, are both predictable and special precautions can be taken. Cosmic ray radiation is unpredictable, high-energy, and is far harder to guard against. Some risk is inevitable.
In KSR's Mars Trilogy, they had an emergency shelter, seems reasonable if the bulk of the radiation exposure is predictable. But I'd personally feel better being shielded the entire time, given cosmic radiation.
Though yes, that does make the option of providing a radiation-hardened shelter available with less concern as to total mass.
IIR, the big problem is that the cosmic ray background radiation is far too predictable - there is a concerning amount of it 24x7x365. So your baseline choices are gritting your teeth and bearing it, or spending most of your time in a seriously hard shelter.
But yes, generally, it's at the very least a constant background flux (with occasional peaks), and all of it high-energy enough to make lightweight shielding of limited use.
Some types of radiation can be deflected by strong magnetic fields - based on the technology and power source of your craft, this might end up lighter than pure mass based shielding.
Or you can just have your crewed ships go as fast as possible, reducing exposure & avoiding some radiation sources all together - zipping through radiation belts & doing fast transits in the quiet part of the solar cycle.
How many orders of magnitude were you figuring for your "dramatically cheaper"?
[0] https://en.wikipedia.org/wiki/In_situ_resource_utilization
(https://arstechnica.com/space/2026/06/a-falcon-9-booster-tur...)
Now, do not get me wrong: I got frickin' goose bumps when I saw the first Falcon touchdown. Goose bumps again when they did the first landing out in the open ocean. Of course I still love you! The pincers catching a starship booster were super awesome. Did I mention goose bumps? I am getting them as I write this, thinking back to those moments and now I want to re-watch all of those on youtube after I finish typing this.
But believing a single timeline prediction by Musk? No, forget it.
EDIT: haha, and yeah I did go re-watch and this is so super awesome when I got reminded of it: https://www.youtube.com/watch?v=bvim4rsNHkQ&t=1s No this is not meant as a jab btw. I love that they have this up. This is what many of us do in software development. Just we don't blow up actual frickin' spaceships to do it "It's just a rapid unscheduled disassembly!" ;)
"Technologically we can do self-driving, we'll just be killing any person that happens to stand in our way" does not qualify even as "technologically" for me ;)
The technology has to take into consideration the safety part. Legal, sure I'll give leeway. If you've seen some of the stuff Teslas have done past that predicted timeline, then no, they really did not qualify.
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?
https://www.sciencedirect.com/science/article/abs/pii/S01685...
I can't find a good source but it seems that the radiation shielding properties of polyethylene were discovered some time after WWII. But I think this was an inevitable discovery, not some sort of accident. HDPE has a lot of hydrogen atoms which are perfect for blocking high energy particles without creating secondary radiation. A block of solid hydrogen would be ideal but that's not practical. Water works well but it's heavy and needs a container which adds more weight.
Dense metals and concrete do a fine job but are heavy relative to amount you need to stop the same amount of radiation as HDPE. Plus you get the secondary radiation effects from metals that can harm humans or sensitive electronics. It's like being behind armor that's hit with a round. The armor may stop the round from getting through but very hot fragments of the backside of the armor (spalling) can fly off and injure someone. Now you need additional protection from the spalling too.
Here's a photo from 2017 of a NASA facility using white HDPE sheets to attenuate high energy particles:
https://www.flickr.com/photos/brookhavenlab/33642244296/in/a...
Whilst I understand the maths here, I can see why someone would be nervous!
then neutron activation becomes even more nuanced because it affects not only your craft/infrastructure/armor but your semi-perishable goods.
You can see the HDPE sheets in this photo, they can be lowered or raised to adjust attenuation:
In this case it's kinda just confusing. The headline should be "Israeli startup + NASA ..."