Terr_ 12 hours ago

> Dose rate matters. Particle type matters. Direction matters. Shielding matters.

There's an old story where a professor quizzes his physics class about how to most-safely distribute different kinds of radiation sources. A common variation involves three baked cookies, emitting alpha particles, beta, and gamma respectively. One must be eaten, one must be held in your hand, and one must be placed in a pocket.

A hint, and what I think is the interesting part of the answer, involves the idea that a victim is a lot like shielding. Things which are difficult to block are also things that are less-likely to stop and ruin your day.

  • voidUpdate 11 hours ago

    Are we protecting the person with the cookies, or everyone else? I'm struggling to think of the best answer

    Alpha: In the hand held away from the body would be reasonably safe. In a pocket of a lab coat might provide a little more shielding from the body with the coat material, but it is physically closer. Eaten would be very bad for the user, but protect the outside world the best

    Beta: Medium penetration, would likely not be safe in any of these three situations

    Gamma: High penetration, definitely not safe in any of these situations, best would be to get it as far away from you as possible, so held at arms length would mean you might only get high radiation exposure in your hand. Hospital visit is probably needed in any of these three situations

    • Terr_ 10 hours ago

      IIRC:

      * Alpha in hand. Eaten, the "shielding" that blocks it will actually be very active living cells, leading to severe health outcomes. Your external layers of dead skin cells will be be fine, putting it in your pocket would be excessive.

      * Gamma in hand, because whether it's in your hand or in your pocket, it's roughly the same risk, and most of it is actually going through you without stopping to have an effect. (Compared to other two.)

      * Beta in pocket, where the additional clothing layer(s) offer some meaningful protection compared to your hand.

      The "twist" behind the exercise involves how people often assume penetrative power is proportional to danger, when in some ways it's really the opposite. (Consider the danger profile of neutrinos.)

      • voidUpdate 10 hours ago

        Oh, I thought you have to choose one of the options for each cookie, no repeats

        • bennettnate5 10 hours ago

          I guess in that case it would be to eat gamma? Assuming you're keeping all three long-term, the gamma particles will be washing over you whether they're inside you or out.

        • Terr_ 3 hours ago

          You're quite correct, the light of the morning and flu-medicine what I should've written is:

          * Gamma is [eaten], because whether [wherever it is], it's roughly the same risk, and most of it is actually going through you without stopping to have an effect. (Compared to other two.)

          Naturally there's a whole bunch of unstated "all else being equal" going on, where no cookie's' elements are extra-likely to be permanently incorporated into your bones versus excreted, etc.

      • K0balt 8 hours ago

        Same with x-rays. People tend to think “soft” X-rays are safer because they are quickly absorbed by tissue without passing through.

        The radiation that passes through is not the problem.

    • SiempreViernes 10 hours ago

      Sure, using the ambiguous wording to assume the cookies all have such a large activity they are unsafe no matter how they are stored is technically a solution. But it's equally possible the teacher is imagining the cookies as only slightly radioactive such that it is indeed possibly to safely store them according to the alternatives given if you choose the correct pairs.

    • Eddy_Viscosity2 8 hours ago

      Can these cookies be weaponized? Are there secret cookie enrichment factories? Would weapons-grade cookies still be good with milk?

      • mwigdahl 6 hours ago

        Only weapons-grade milk.

        • BuyMyBitcoins 5 hours ago

          Heavy milk (whole) is required for cookie enrichment. But depleted milk (skim) still has value.

          • dgacmu 5 hours ago

            Commonly used as a projectile

    • tyho 8 hours ago

      Eat the gamma cookie, it's the worst option for any, but with gamma it won't matter much whether it's in your hand, pocket or gut.

      Pocket the beta emitter, a little bit of shielding will make a big difference.

      Hold the alpha emitter, if you hold it with just a pair of fingers you will be able to reduce you dosage a lot compared to holding it tightly.

      • PunchyHamster 4 hours ago

        wouldn't alpha be mostly stopped just in pocket ? I'd hold beta emitter, less area of body affected by the radiation if you hold it at distance

  • throwanem 8 hours ago

    Eat the gamma, pocket the beta, hold the alpha. Nothing in the picture here stops gamma rays so it doesn't matter what you do with those; skin will stop alpha particles, but so will mucosa (and you die of that); in your pocket, the beta source will spall X-rays off your trousers at least some of the time so the beta burns will be mitigated.

voidUpdate 11 hours ago

I enjoy how moon-landing deniers will use the van Allen belts as a reason for why the astronauts could not have made it to the moon because of radiation exposure. Like, you don't believe NASA that they went to the moon, but you believe NASA that the van Allen belts exist?

  • arowthway 9 hours ago

    I'm not disputing that conspiracy theorists tend to lack rigor but there is a full spectrum of positions between "space is fake" and "one specific extraordinary achievement with high incentive to fake it is fake".

    • glimshe 8 hours ago

      There's indeed a full spectrum of positions in this case, but they are all worthless in the sense that they add nothing to someone's understanding of reality.

      • zurfer 8 hours ago

        You know some people grow up in untrustworthy environments and auto didact their way to something like first principles thinking and depending on things shaking out you might only believe what you've personally seen with your own eyes. And well, earth looks pretty flat in daily life.

  • JumpCrisscross 8 hours ago

    Any entertaining “Artemis II is a hoax” takes?

    • hydrogen7800 7 hours ago

      I haven't been actively looking for them, but a friend sent me something about the launch tower escape zipline/gondolas and how that somehow indicated something fraudulent. He is not a denier, but works with one and is always asking me to refute that person's claims.

      • Tangurena2 7 hours ago

        If your friend is trying to "cure" the denier, then it might be helpful for them to learn some of the tactics for reaching/deprogramming cult members. One that might be helpful is "street epistemology".

        Link: https://en.wikiversity.org/wiki/Street_Epistemology

        • hydrogen7800 6 hours ago

          That's a bit too much to ask of these folks, I'm afraid, but I did boil it down for him by saying that the real question is understanding why he is inclined to believe its a hoax, rather than trying to pile up evidence in front of him. I suppose that's what "street epistemology" is, though. Nice to have shorthand terms for these ideas.

          I also included a thought experiment for him:

          Imagine you take a conspiracy influencer and actually put them in the spacecraft with the astronauts so they could see the whole thing with their own eyes and wouldn't be able to deny it. They return to earth to tell their followers that it's all real. Do you think everyone will be convinced, or would they say he's now in on the conspiracy and find a new person to lead the conspiracy theory?

          (I wonder if there is a sociological shorthand term for this?)

          • pgalvin 6 hours ago

            > Imagine you take a conspiracy influencer and actually put them in the spacecraft with the astronauts so they could see the whole thing with their own eyes and wouldn't be able to deny it. They return to earth to tell their followers that it's all real. Do you think everyone will be convinced, or would they say he's now in on the conspiracy and find a new person to lead the conspiracy theory?

            https://en.wikipedia.org/wiki/The_Final_Experiment_(expediti...

            "The participating flat Earthers all admitted that the midnight sun was a real phenomenon. The larger flat Earth community has largely rejected the results and accused the participants, including the flat Earthers, of having faked the expedition and of being part of a larger conspiracy to promote the spherical Earth model."

            • hydrogen7800 5 hours ago

              Ha of course! Entirely predictable.

            • chileRick 5 hours ago

              The Final Experiment (https://www.the-final-experiment.com/) essentially did this by inviting "prominent" flat earthers to Antarctica to witness 24 hours of daylight. Very few did, but they are now shunned by the true flat earthers.

              • barbazoo 4 hours ago

                So what is it really? A social club? A church? A religion?

                • dhosek 4 hours ago

                  Church/religion. Flat-earthers believe in a very literal interpretation of the Bible which dictates that the earth is flat.

                  When I was doing my student teaching, one of the teachers in my department was a creationist, but he didn’t seem to have read Genesis 1 at all because when I asked him about the firmament in the heavens separating the waters above from the waters below, he had no idea what I was talking about. At least the flat-earthers know enough scripture to follow their dogma all the way to its absurd endpoint.

                • Tangurena2 3 hours ago

                  "Flat Earth"[0] is more like a cult[1]. One introduces a significant barrier to entry. New members learn the approved vocabulary/jargon that identifies "in group" and "out group" people. Outsiders tend to reject new members[2]. New members tend to stay due to the "sunken cost" fallacy. The high barrier to entry and cost of leaving (losing your community - because you will be shunned for doing so) prevents people from leaving or associating with people who have left.

                  Notes:

                  0 - https://rationalwiki.org/wiki/Flat_Earth

                  1 - https://rationalwiki.org/wiki/Crank_magnetism

                  2 - This is why religions such as Jehovah's Witnesses require members to proselytize (including going door-to-door) because outsiders are so adverse to the members that the other insiders remark things like "those outsiders are so depraved, that's why you can only be with 'true believers' like us".

              • pgalvin 3 hours ago

                I believe that is the same event as in my comment.

          • Tangurena2 2 hours ago

            > the real question is understanding why he is inclined to believe its a hoax, rather than trying to pile up evidence in front of him

            This is one of the primary techniques of SE. People are open to answering questions and with some skill with Socratic questioning, you can get results. Dumping data just causes cult/hoax members to feel threatened because you're attacking some core beliefs and they will try very hard to avoid losing a sense of self value[0].

            Notes:

            0 - "What I believe is wrong" -> "I am wrong" -> "I am a bad person".

      • Gagarin1917 4 hours ago

        Oh because the astronauts were “really” on the escape zip lines instead of in the rocket?

        How would they do the zero gravity during the live streams? They have to actually be in space, not even the zero-G parabolic airplane sim can maintain zero gravity for as long as their live streams have been.

        I’ve heard people claim you can’t leave Low Earth Orbit due to the Van Allen radiation belts, but most Apollo deniers still believe low earth orbit is possible and reasonable. If they did fake Artemis II, it would have to be that the astronauts actually launched into LEO, and just didn’t really leave.

        There’s just no way to fake zero-G for that long.

    • blitzar 7 hours ago

      I am fairly certain that Artemis II has proven conclusively that they were right all along and the world is flat.

    • jrmg 7 hours ago

      You just need to look at the Facebook comments on any official NASA post about Artemis to see depressingly many of them. Some are joking or trolling, I’m sure, but I don’t think all.

  • rsynnott 8 hours ago

    Strictly speaking, their existence was verified by Sputnik 2 (though the Soviets only released data on it after the fact, corroborating data from Explorer 1), so if you have a highly _specific_ conspiracy theory, around NASA rather than space stuff in general, that _could_ still work, I suppose?

    • atrus 5 hours ago

      No, because the Soviets have to in on faking the moon landing. They were also landing a spacecraft at the same time as the landings. To fake the moon landing you'd also have to fake the entire cold war.

      • toast0 4 hours ago

        Wouldn't it be great for the US and the USSR if most of the cold war was fake?

        Both sides get a great boogie man to denounce. Save a bunch of money on arms if they're mostly fake. Once you learn about the Van Allen Belt, you call over on the red phone and say hey guys, we know we can't send people, but think about the ratings? Maybe we send you a case of Pepsi and we're good?

        • carlosjobim 4 hours ago

          What if large wars are coordinated by the rulers of opposing sides with the purpose of killing off as many of their own young men as possible - thus reducing the threat of an uprising?

        • dhosek 4 hours ago

          Now the whole idea of a fake cold war is burrowing into my brain.

      • windward 4 hours ago

        It's disappointingly difficult to get a positive case for what happened from deniers, that attempts to explain these things. Very eager to tell you what didn't happen, though.

  • ErroneousBosh 4 hours ago

    People live in regions far more radioactive than the van Allen belts for far longer than the amount of time the Apollo and Artemis astronauts spent travelling through.

    Like, for example, people who live in Aberdeen.

zeristor 12 hours ago

I thought one of the things with New Space is that Commercial off the Shelf parts were being used more and more. I’m assuming if that’s a case there have been more mishaps.

How does SpaceX tackle this with both the rockets, and the thousand of Starlinks.

  • ksaj 11 hours ago

    Something they say in music: Repetition Legitimizes.

  • spacedoutman 11 hours ago

    The threat of radiation is severely overblown.

    NASA is overpaying for underperforming "hardened" hardware that performs no better than non-hardened. You can see this yourself with the mars helicopter ingenuity.

    If you are desperate for extra safety then just include multiple computers, literally what spacex does.

    • adrian_b 10 hours ago

      The threat of radiation is not overblown at all.

      The errors caused by radiation are extremely frequent and you definitely must guard against them, otherwise anything will fail immediately in space.

      However that does not necessarily require hardware measures. It may be more efficient if instead of a slow antique CPU with hardware redundancy you use a fast modern CPU, even if it is more sensitive to radiation and even when it lacks hardware redundancy, but you do each computation several times, verifying that every time you get the same result, and if possible you use different algorithms or verification methods, to be able to detect some permanent errors.

      This is what the Mars helicopter did. If it had used standard smartphone software, the helicopter would have failed instantly.

      • gambiting 9 hours ago

        >>The errors caused by radiation are extremely frequent and you definitely must guard against them, otherwise anything will fail immediately in space.

        I asked this in another thread but I will repeat it here - how come that their bog standard iPhones that they use for taking pictures with are still operating fine then? If like you said, "anything will fail immediately" - doesn't sound like that's the case? They have electronic watches with no radiation hardening, they have regular laptops with no radiation hardening.....I'm not saying that it's not a problem, but it definitely doesn't seem to be in the area of "immediately failing in space" if you don't have that.

        • samus 9 hours ago

          None of these devices are mission-critical. Worst case they have to be restarted; then they are fine again and the world moves on.

          • gambiting 7 hours ago

            Yes, but that wasn't the question. OP said anything that's not radiation hardened will fail immediately - to which I ask ok, what about all the stuff they brought up with them which doesn't seem to be instantly failing.

            • adrian_b 5 hours ago

              The radiation levels are much lower where humans live, otherwise they would not live for long. Without humans, thinner and lighter radiation shields are used, to reduce costs.

              Theoretically, one could use the same electronic devices that are used on Earth, if one would add thick enough shields, but this is impractical, so one must make a compromise, by combining some less efficient shielding with devices more resistant to radiation.

              The Mars helicopter had essentially no shielding, as it had to be extremely light to be able to fly in the Martian atmosphere.

              Moreover, as explained in the parent article, the radiation levels are not constant. A great part of the radiation comes from the Sun, and that part fluctuates continuously (i.e. the so-called "space weather"). The electronic devices must be designed to withstand the peaks of solar radiation, even if the radiation levels are less than that much of the time.

              The astronauts can shut down their personal devices, preventively, when there is a peak of solar radiation, or when they pass through the radiation belts.

            • testing22321 5 hours ago

              Sounds like Microsoft have a credible excuse for two outlook instances ruining

              “Ticket closed, not a bug, caused by radiation bit flip”

        • zimpenfish 9 hours ago

          (I have no expertise or knowledge of this area but...)

          tl;dr: people need (heavy) radiation shielding, cpus et al can live without it

          I'd imagine their bog standard iPhones and watches are generally in parts of the craft which have more radiation protection than others and, further, that it's probably only the parts where people are going to be that get that protection (due to weight savings, etc.) and if you can mitigate radiation problems by using a $30 CPU instead of a $2 CPU and save $100K of weight on radiation shielding on the CPU compartment, that's a no-brainer.

        • adrian_b 5 hours ago

          As other posters have said, the personal devices of the astronauts are already used in spaces that are much better shielded against radiation than a typical satellite or the Mars helicopter.

          Radiation shields add mass and volume, so it helps if the electronics is somewhat resistant to radiation, allowing for less efficient shields.

          Even with the enhanced shielding, the personal devices experience errors from time to time, e.g. the photographs taken may have some wrong pixels and they sometimes have to reboot their laptops or smartphones, if weird behavior happens. Like others have said, these kinds of errors are not important, unlike in the computers that control the spacecraft, where errors are not acceptable, so those must use either hardware or software means to combat the effects of radiation errors.

        • schwartzworld 4 hours ago

          Aren't the stakes a little different with an iPhone that you have for picture taking and entertainment vs the systems that manage your trajectory and life support?

          The fact that a handful of devices hasn't failed is hardly proof that they can't. Hell, I've driven thousands of times and never actually NEEDED my seatbelt.

          • gambiting 3 hours ago

            >>The fact that a handful of devices hasn't failed is hardly proof that they can't.

            Again, that's not what I'm saying. I'm just challenging OP's assertion that any device with no radiation hardening will "immediately" fail, which clearly isn't the case with these devices. That's not me saying that radiation hardening isn't needed, quite the opposite.

    • samus 9 hours ago

      Unshielded circuits are basically radiation detectors. Even here on planet Earth bitflips are an underappreciated source of unreproducible bugs.

      A bit flip in an index variable, a pointers or in native code can send the CPU on a wild goose chase around memory.

      To add insult to injury, applications like browsers use JITs, which generate and execute large amounts of native code on the fly, making them even more vulnerable for this kind of fault.

      The same issue arises from overclocking, inconsistent power sources, and from damaged RAM cells, but those problem sources can presumably be dismissed on a vehicle with pristine, well-made hardware during a short hop to the moon and back.

      https://news.ycombinator.com/item?id=47252971

    • cubefox 9 hours ago

      > If you are desperate for extra safety then just include multiple computers, literally what spacex does.

      That does nothing to protect the human body from the radiation damage.

      Talking about microchips is a distraction.

      • spacedoutman 8 hours ago

        Depending what model you subscribe too, small dose radiation can be healthy for you.

        • cubefox 7 hours ago

          The radiation in space is not "small dose". It's firmly established that it is quite bad for human health.

  • snitty 9 hours ago

    Rad Hardened parts are "Commercial off the Shelf" parts. VORAGO, TI, and others provide rad hardened parts via vendors like Mouser and Digikey. They're just much more expensive.

  • cubefox 9 hours ago

    You should read the article. The problem is the destructive effect of radiation on the human body, not on the space hardware.

  • UltraSane 8 hours ago

    The BAE Systems RAD750 radiation-hardened single-board computers used by Orion are commercial products but typically costs between $200,000 to $500,000 per unit

baggachipz 7 hours ago

> Artemis II and the invisible hazard

Decent Harry Potter book title