Discussion

Artemis II and the invisible hazard on the way to the Moon (Part 1)

zeristor: 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: Something they say in music: Repetition Legitimizes.

voidUpdate: 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?

Terr_: > 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: Are we protecting the person with the cookies, or everyone else? I'm struggling to think of the best answerAlpha: 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 bestBeta: Medium penetration, would likely not be safe in any of these three situationsGamma: 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

spacedoutman: 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.

Terr_: IIRC:* Alpha in hand. If you eat it, you learn to act with your important living cells in a very bad way, but your dead skin cells will protect you.* Gamma in hand, because whether it's in your hand or in your pocket, it's roughly the same situation.* Beta in pocket, where the additional clothing layer(s) offer some protection.

mazokum: 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...

adrian_b: 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, 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.

joeslide: The people who want to cut off your wang and women's boobs are making the moon-landing deniers look smarter all the time...

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