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

ansto.gov.au

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

#11

Post by SiempreViernes »

voidUpdate wrote: post #5
Terr_ wrote: post #2

> 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,…

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 lik…

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.

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

#12

Post by voidUpdate »

Terr_ wrote: post #9
voidUpdate wrote: post #5

Earlier quoted context omitted.

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 lik…

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.…

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

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

#13

Post by joeslide »

voidUpdate wrote: post #6

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?

[flagged]

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

#14

Post by bennettnate5 »

voidUpdate wrote: post #12
Terr_ wrote: post #9

Earlier quoted context omitted.

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.…

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

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.

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

#15

Post by samus »

spacedoutman wrote: post #7
zeristor wrote: post #3

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.

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.

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

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

#16

Post by gambiting »

adrian_b wrote: post #10
spacedoutman wrote: post #7

Earlier quoted context omitted.

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.

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…

>>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.

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

#17

Post by arowthway »

voidUpdate wrote: post #6

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?

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".

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

#18

Post by samus »

gambiting wrote: post #16
adrian_b wrote: post #10

Earlier quoted context omitted.

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…

>>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…

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

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

#19

Post by snitty »

zeristor wrote: post #3

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.

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.

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

#20

Post by zimpenfish »

gambiting wrote: post #16
adrian_b wrote: post #10

Earlier quoted context omitted.

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…

>>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…

(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.

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