Artemis II and the invisible hazard on the way to the Moon

https://www.ansto.gov.au/news/artemis-ii-and-invisible-hazard-on-way-to-moon-part-1

by zeristor • 3 months ago

87 68 3 months ago

ansto.gov.au

Terr_3• 3 months 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.

voidUpdate4• 3 months 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_3• 3 months 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.)

SiempreViernes• 3 months 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• 3 months ago

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

tyho• 3 months 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.

mazokum• 3 months ago

I heard about this question in the MIT Ionising Radiation course. You can find it here, around minute 47:30 (wont spoil the answer).

https://ocw.mit.edu/courses/22-01-introduction-to-nuclear-en...

j33pers• 3 months ago

Thanks, I watched it. There are 4 cookies - a gamma, alpha, beta and neutrino emitter. You must eat one, pocket one, hold one and give one away.

throwanem• 3 months 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.

1970-01-01• 3 months ago

Take with iodine.

zeristor• 3 months 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• 3 months ago

Something they say in music: Repetition Legitimizes.

spacedoutman2• 3 months 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_b3• 3 months 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.

samus2• 3 months 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

cubefox3• 3 months 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.

snitty• 3 months 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.

cubefox3• 3 months ago

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

UltraSane• 3 months 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

voidUpdate4• 3 months 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• 3 months 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• 3 months 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.

JumpCrisscross• 3 months ago

Any entertaining “Artemis II is a hoax” takes?

hydrogen78003• 3 months 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.

blitzar• 3 months ago

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

jrmg• 3 months 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.

rsynnott2• 3 months 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• 3 months 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.

ErroneousBosh• 3 months 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.

baggachipz• 3 months ago

Artemis II and the invisible hazard

Decent Harry Potter book title

Artemis II and the invisible hazard on the way to the Moon

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