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.”
The same protection against solar storms (which does nothing against cosmic rays) WILL also protect against exposure to the Van Allen belts.
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.
Well, those confused people mainly ignored the flight profile - Apollo spent a very little time in Earth orbit & boosted for Moon. As a result they flew through Van Allen belts very quickly, so the radio was not an issue.
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.
I remember reading about the Belts in the early 60s (IIRC). It most definitely spooked me. How will men (erm humans) ever get thru the Belts safely ? But then they disappeared from any and all discussions of spaceflight.
(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
I get your point, but fighter pilots don't wear armor. There is no reasonable amount of it that can protect against cannons and missiles, and the added weight and bulk of even a bulletproof vest would make high-G-force maneuvers impractical for the pilot.
Both A-10 & SU-25 have an armored bathtub made form titanium to shield the cockpit (somewhat) from ground fire, aimed mainly against heavy machine gun and auto canon fire + splinters. Sure, those are ground attack aircraft, not fighter aircraft but IMHO good enough.
Also IIRC some WW2 fighter planes had at lest armored glass front panel, to provide some protection from tail gunners when attacking bombers.
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.
There more ways than just brute forcing massive shielding. If you know where the radiation is coming from & is directional (Sun, nuclear reactor) you can put the shielding some way from you & put the hab module in the shadow created by the shield - AKA a "shadow shield".
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.
Yeah, I’m guessing there would be at least some directional weighting to the shielding. I guess the question then is how worthwhile it is to shield against background cosmic radiation versus point sources.
Mass requires reaction (generally: fuel) both to accelerate and decellerate. Absent alternative delta-V mechanisms (usually: aeroraking, as lithobraking is perceived as generally too extreme), this rapidly runs into the tyranny of the 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.
Right, I don't think it makes sense to have our long distance transit vehicle be the same one that needs to decelerate/aerobrake - I'm assuming we'd do something like an Aldrin Cycler for transit between Earth/Mars, where we have taxis that go to/from the cyclers.
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.
That long-distance transit vehicle has to change trajectory somehow. Orbital transfers may be cheap but they're not free, unless you're talking about a free-return trajectory in which case your specific transits are limited, and often fairly slow.
Though yes, that does make the option of providing a radiation-hardened shelter available with less concern as to total mass.
I thought i read somewhere that the soil on mars is probably pretty toxic to humans, so maybe getting there safely isn't as concerning as what you'd do once you are there...
> Cosmic ray radiation is unpredictable, high-energy, and is ...
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.
Definitely outside my realm of expertise, but I'd expect that particles have a range of energies, and that the most energetic, or most damaging (not necessarily the same) occur somewhat rarely.
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.
A spacecraft with a 4m diameter spherical living space and 4m of water shielding around it will weigh about 1,000 tons. The propellant tanks needed to move it around the solar system will be similarly titanic.
How many orders of magnitude were you figuring for your "dramatically cheaper"?
Yeah, I think that’s the longer term solution. But even before we get that infrastructure in place, I don’t think lifting 1000 tons is as absurd as people seem to think. SpaceX’s entire plan is dependent on doing many orders of magnitude more than that on a regular basis to feed their satellite constellations.
That's 5 Starship block 4 launches, seems fine? Propellant, presumably for long duration voyages we're not relying entirely on chemical combustion. If we're using cyclers, once they're up to speed, you need barely any fuel for corrections, just to taxi to/from the cycler.
Maybe when its actually demonstrated that it can actually launch with that payload. The largest payload they'd lifted so far is ~45 tons, and the claims I see on Wikipedia say its estimated 200 tons for LEO, not even for geosynchronous orbit much less a lunar trajectory.
20 launches would also be doable, though, if there's a reasonable launch cadence? And yeah, I don't expect they'd assemble for a Mars mission or other long range mission where they need a radiation shielded craft in geo or lunar.
And just for comparison on that number, the entire Apollo spacecraft (command+service+lunar modules) was about 50 tons to lunar orbit. And that took a gigantic Saturn V to launch.
SpaceX is planning on launching the significantly more gigantic Starship daily. It's not there yet, but they're steadily grinding toward regular launches, and they supposedly are retiring Falcon 9 from commercial launches within the next couple of years.
And "From a technology standpoint, Tesla will have a car that can do full autonomy in about three years, maybe a bit sooner.". Uttered by Musk in 2015. So ... yeeeeaaah.
Musk has 10+ years of history we can go by that says: Nobody has to follow anything closely to know that he will just say whatever he wants to say and you should give a rats ass about it timeline wise.
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!" ;)
Can you tell me what the difference is between "technologically" and "safely" standpoint?
"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.
Yeah, even unprocessed Lunar or Martian regolith will help, provided the added mass does not cause issues - fine for space stations, more difficult for ships that have to drive the shielding around.
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?
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:
“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!
You need to protect anything with relatively fast dividing cells best because this is where the cancer risk is highest. The brain with its slow dividing cells and fast killing tumors is the last thing to protect.
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.
this is a common concept in space-craft thought experiments because of the dual-use nature; can shield yourself with a big water balloon essentially at the tip of the space craft to catch all those pesky extra energetic particles that are bombarding you against your fantastically high velocity, while also providing water to grow things in, or whatever.
then neutron activation becomes even more nuanced because it affects not only your craft/infrastructure/armor but your semi-perishable goods.
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:
I agree actually. I understand the use of "we" to mean an achievement of humanity (like: we've been to the moon) but I find that often "we" is a substitute for "someone not me" - as in "we should make healthcare free" coming from someone who doesn't perceive a role in actually doing any of it.
In this case it's kinda just confusing. The headline should be "Israeli startup + NASA ..."
The difficulty is making it protective but light enough to not significantly hinder the spacecraft or person wearing it, all of which is covered in the article.
Poor design, flawed assumptions, manufacturing defects, inability to bear the gravitational and rocket launch forces, inability of the jacket to last the duration of the radiation exposure - these are some reasons that come to my mind on why a radiation-blocking vest wouldn't have worked for the journey to the moon and back (i.e. your question "Why wouldn't it?".)
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...
The same protection against solar storms (which does nothing against cosmic rays) WILL also protect against exposure to the Van Allen belts.
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.
Well, those confused people mainly ignored the flight profile - Apollo spent a very little time in Earth orbit & boosted for Moon. As a result they flew through Van Allen belts very quickly, so the radio was not an issue.
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.
I remember reading about the Belts in the early 60s (IIRC). It most definitely spooked me. How will men (erm humans) ever get thru the Belts safely ? But then they disappeared from any and all discussions of spaceflight.
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
This targeted shielding is a classic aerospace mass tradeoff much like armoring a fighter pilot instead of the entire plane.
I get your point, but fighter pilots don't wear armor. There is no reasonable amount of it that can protect against cannons and missiles, and the added weight and bulk of even a bulletproof vest would make high-G-force maneuvers impractical for the pilot.
Both A-10 & SU-25 have an armored bathtub made form titanium to shield the cockpit (somewhat) from ground fire, aimed mainly against heavy machine gun and auto canon fire + splinters. Sure, those are ground attack aircraft, not fighter aircraft but IMHO good enough.
Also IIRC some WW2 fighter planes had at lest armored glass front panel, to provide some protection from tail gunners when attacking bombers.
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.
There more ways than just brute forcing massive shielding. If you know where the radiation is coming from & is directional (Sun, nuclear reactor) you can put the shielding some way from you & put the hab module in the shadow created by the shield - AKA a "shadow shield".
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.
Yeah, I’m guessing there would be at least some directional weighting to the shielding. I guess the question then is how worthwhile it is to shield against background cosmic radiation versus point sources.
Mass requires reaction (generally: fuel) both to accelerate and decellerate. Absent alternative delta-V mechanisms (usually: aeroraking, as lithobraking is perceived as generally too extreme), this rapidly runs into the tyranny of the rocket equation.
<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.
Right, I don't think it makes sense to have our long distance transit vehicle be the same one that needs to decelerate/aerobrake - I'm assuming we'd do something like an Aldrin Cycler for transit between Earth/Mars, where we have taxis that go to/from the cyclers.
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.
That long-distance transit vehicle has to change trajectory somehow. Orbital transfers may be cheap but they're not free, unless you're talking about a free-return trajectory in which case your specific transits are limited, and often fairly slow.
Though yes, that does make the option of providing a radiation-hardened shelter available with less concern as to total mass.
I thought i read somewhere that the soil on mars is probably pretty toxic to humans, so maybe getting there safely isn't as concerning as what you'd do once you are there...
If you mean the perchlorate concentration, it's water soluble, I think we just rinse it off as part of going inside.
> Cosmic ray radiation is unpredictable, high-energy, and is ...
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.
Definitely outside my realm of expertise, but I'd expect that particles have a range of energies, and that the most energetic, or most damaging (not necessarily the same) occur somewhat rarely.
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.
A spacecraft with a 4m diameter spherical living space and 4m of water shielding around it will weigh about 1,000 tons. The propellant tanks needed to move it around the solar system will be similarly titanic.
How many orders of magnitude were you figuring for your "dramatically cheaper"?
Also you should be able to ISRU[0] water from Moon/Mars/asteroids.
[0] https://en.wikipedia.org/wiki/In_situ_resource_utilization
Yeah, I think that’s the longer term solution. But even before we get that infrastructure in place, I don’t think lifting 1000 tons is as absurd as people seem to think. SpaceX’s entire plan is dependent on doing many orders of magnitude more than that on a regular basis to feed their satellite constellations.
That's 5 Starship block 4 launches, seems fine? Propellant, presumably for long duration voyages we're not relying entirely on chemical combustion. If we're using cyclers, once they're up to speed, you need barely any fuel for corrections, just to taxi to/from the cycler.
Maybe when its actually demonstrated that it can actually launch with that payload. The largest payload they'd lifted so far is ~45 tons, and the claims I see on Wikipedia say its estimated 200 tons for LEO, not even for geosynchronous orbit much less a lunar trajectory.
20 launches would also be doable, though, if there's a reasonable launch cadence? And yeah, I don't expect they'd assemble for a Mars mission or other long range mission where they need a radiation shielded craft in geo or lunar.
And just for comparison on that number, the entire Apollo spacecraft (command+service+lunar modules) was about 50 tons to lunar orbit. And that took a gigantic Saturn V to launch.
SpaceX is planning on launching the significantly more gigantic Starship daily. It's not there yet, but they're steadily grinding toward regular launches, and they supposedly are retiring Falcon 9 from commercial launches within the next couple of years.
And "From a technology standpoint, Tesla will have a car that can do full autonomy in about three years, maybe a bit sooner.". Uttered by Musk in 2015. So ... yeeeeaaah.
And they are saying they will land that Flacon rocket on its tail! What nonsense, that will never work!
(https://arstechnica.com/space/2026/06/a-falcon-9-booster-tur...)
Have you been following Starship development closely?
Musk has 10+ years of history we can go by that says: Nobody has to follow anything closely to know that he will just say whatever he wants to say and you should give a rats ass about it timeline wise.
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!" ;)
I mean technologically they can, just not due to safety and legal reasons.
Can you tell me what the difference is between "technologically" and "safely" standpoint?
"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.
Cheaper mass to orbit is undoubtably good, but not all mass, shielding or otherwise, needs to be lifted from Earth.
Yeah, even unprocessed Lunar or Martian regolith will help, provided the added mass does not cause issues - fine for space stations, more difficult for ships that have to drive the shielding around.
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?
It's not a new idea, here's an article from 20 years ago:
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...
Long video but informative: https://www.youtube.com/watch?v=DJcbevbBzsc (~26 min)
“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!
You need to protect anything with relatively fast dividing cells best because this is where the cancer risk is highest. The brain with its slow dividing cells and fast killing tumors is the last thing to protect.
It's ok, everything except your brain will be protected from radiation!
You’ll be cancer-free on average!
Your brain is quite robust against cancer and when it gets it, if is often a relatively fast death.
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.
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.
this is a common concept in space-craft thought experiments because of the dual-use nature; can shield yourself with a big water balloon essentially at the tip of the space craft to catch all those pesky extra energetic particles that are bombarding you against your fantastically high velocity, while also providing water to grow things in, or whatever.
then neutron activation becomes even more nuanced because it affects not only your craft/infrastructure/armor but your semi-perishable goods.
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/
Bullet proof vest for really really small bullets. Nice.
The use of “we” in this headline is really jarring.
I agree actually. I understand the use of "we" to mean an achievement of humanity (like: we've been to the moon) but I find that often "we" is a substitute for "someone not me" - as in "we should make healthcare free" coming from someone who doesn't perceive a role in actually doing any of it.
In this case it's kinda just confusing. The headline should be "Israeli startup + NASA ..."
We Flew to the Moon and Back So You Wouldn't Have To!
You're welcome!
Screw that. I want to go and I think it is horrible that we didn't bother for 50 years.
Why wouldn't it?
The difficulty is making it protective but light enough to not significantly hinder the spacecraft or person wearing it, all of which is covered in the article.
Poor design, flawed assumptions, manufacturing defects, inability to bear the gravitational and rocket launch forces, inability of the jacket to last the duration of the radiation exposure - these are some reasons that come to my mind on why a radiation-blocking vest wouldn't have worked for the journey to the moon and back (i.e. your question "Why wouldn't it?".)