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The ¬NED pin goes low on detection of a nuclear detonation [pdf]

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Re: The ¬NED pin goes low on detection of a nuclear detonation [pdf]

#81

Post by joelhaasnoot »

Nitramp wrote: post #65
pjscott wrote: post #13

Earlier quoted context omitted.

Just think how much redundancy you could get, cheaply, with the advances that have been made with Moore's Law over the years. Computers for space probes don't need to be that fancy. It's totally feasible to build processors that use error-correcting codes in their entire datapaths, have tri-modular redundancy for all their functional units, and then are arranged alongside several other identical processors for ridicu…

Redundancy in hardware is one problem. But then all those CPUs still run the same software. After Ariane 5 crashed spectacularly due to a software error that affected the two on board computers and the ground control unit likewise ( http://en.wikipedia.org/wiki/Ariane_5_Flight_501 ), there had been talk about having the same software be developed by multiple, independent teams, and then use the different versions for…

Wouldn't that just make it worse? "Oh it failed, let's see if the other team had a better idea... [5 minutes later] Nope, they used the same algorithm but it can't talk to this algorithm"

Re: The ¬NED pin goes low on detection of a nuclear detonation [pdf]

#82

Post by adavies42 »

Nitramp wrote: post #65
pjscott wrote: post #13

Earlier quoted context omitted.

Just think how much redundancy you could get, cheaply, with the advances that have been made with Moore's Law over the years. Computers for space probes don't need to be that fancy. It's totally feasible to build processors that use error-correcting codes in their entire datapaths, have tri-modular redundancy for all their functional units, and then are arranged alongside several other identical processors for ridicu…

Redundancy in hardware is one problem. But then all those CPUs still run the same software. After Ariane 5 crashed spectacularly due to a software error that affected the two on board computers and the ground control unit likewise ( http://en.wikipedia.org/wiki/Ariane_5_Flight_501 ), there had been talk about having the same software be developed by multiple, independent teams, and then use the different versions for…

IIRC, that's more or less how the DNS root servers are managed--they're not just in different locations, they're running different server software on different OS's, to minimize the chance that any one problem could take all of them out.

Re: The ¬NED pin goes low on detection of a nuclear detonation [pdf]

#83

Post by pjscott »

elliottkember wrote: post #52
pjscott wrote: post #21

Earlier quoted context omitted.

Of course! When the !NED pin goes low, duck and cover like it's 1959. (Fun fact: in a fairly large portion of the blast radius of a nuclear bomb, the main danger for people indoors is falling debris and broken glass from the pressure waves. Duck and cover actually works.)

So hiding in a fridge might actually save you?

Hiding in a fridge protects from debris and direct radiative heat from the blast, both major killers. So yes, the Indiana Jones approach could help. A more practical variant, of course, is the time-honored "hide in the basement" approach, which doesn't require you to compete for space with hastily-evicted perishable food and plastic racks.

Re: The ¬NED pin goes low on detection of a nuclear detonation [pdf]

#84

Post by ramchip »

chops wrote: post #60
ramchip wrote: post #54

Earlier quoted context omitted.

Oelewapperke posted a long and detailed reply to this post, and yet it will go ignored because all his posts are automatically killed without him being aware of it. His posts may not be perfect, but I still find this kind of false positives terrible.

It's not a false positive. He's hellbanned. Hellbanned users don't know they're hellbanned - their posts appear to them "not dead." If you look at his posting history, all of his posts starting 160 days ago are dead, and it seems to have started at a post from 175 days ago.

I know about hellbanning -- I've actually complained about this before:

http://news.ycombinator.com/item?id=1256772

But the post was killed...

Re: The ¬NED pin goes low on detection of a nuclear detonation [pdf]

#85

Post by giardini »

sophacles wrote: post #77
giardini wrote: post #70

Earlier quoted context omitted.

When an event is detected, the warhead shuts down its electronics for the duration of the EMP, and then powers back up. I doubt this, since the EMP is moving at the speed of light, whereas the delay times inherent in most circuitry and the time required to power down most circuitry would be at least an order of magnitude (most likely more) larger.

Why does the rate of propagation matter? I presume that during the course of the explosion there are several sequential phases. If phase x emits some non-EMP but detectable signal, say an X-Ray burst and phase y emits the EMP, both of which propagate at the same rate, then you have time(y) - time(x) to respond to detecting x before the EMP from y reaches you. Explosions, like all other macro scale phenomena are not i…

"If phase x emits some non-EMP but detectable signal, say an X-Ray burst and phase y emits the EMP"

No, "X-Rays" travel at the same speed as the "EMP" - both travel at the speed of light. They're both part of the electromagnetic spectrum.

Re: The ¬NED pin goes low on detection of a nuclear detonation [pdf]

#86

Post by idoh »

kennywinker wrote: post #64
idoh wrote: post #8

So, my mom is a former Maxwell employee who now does her own defense contracting, and makes this same type of part. As I understand it, when there is a nuclear event, it generates x-rays followed by the EMP. The goal is to have warheads in flight to be able to continue to their target, so the strategy is to employ an NED. When an event is detected, the warhead shuts down its electronics for the duration of the EMP, a…

Do you have mixed feelings about this? Your mom's part in WMD technology, I mean. And how does she feel about it? This is a serious question. I genuinely wonder if people who work on this kind of stuff feel conflicted about it regularly, or don't think about it, or feel strongly that they are doing good.

Sorry for the late response to this. I have had mixed feelings for a while - it gives a good living to the family, but on the other had we all want to work towards the betterment of the world.

For my mom, at first she was very gung ho about it - arsenal of democracy and the importance of having a strong nation. Now she is having second thoughts, and is looking to follow her passion which is something in the education space.

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