Oddity

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discord
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Re: Oddity

Post by discord »

charlie: the problem with such is when grown ups believe in santa and that we have a democracy, a ruler of a people bloody well should be informed about and base decisions on reality not fairy tales or other non factual data, given that we live in a democracy EVERYONE is the ruler, therefor no one of voting age should believe things which are blatantly not true....

not talking about moral values, which is what terry pratchet mentioned but simple things like gravity exists and in most cases if you throw a ball it will fall down, or other basics of reality....another fun one, "war can't happen to us"...it may be unlikely but it bloody well CAN, especially if you go around pissing everyone off, when you grow up leave childish illusions and fantasies where they belong, you may very well enjoy a good book or movie, i do, but i do not BELIEVE in it.

and finally, everyone has 'fantasies' and some kind of crazy, in my case i believe humans are better than they are....more tolerant, more honest, etc. but i try to keep my crazy to myself.

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Arioch
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Re: Oddity

Post by Arioch »

I love fantasy. I don't believe that knowing the difference between fantasy and reality in any way reduces my love of fantasy and imagination. Kids know the difference between make-believe and reality; that doesn't stop them from pretending. If I had kids, I would tell them about Santa and observe the customs of setting up stockings and leaving milk and cookies, but I would be clear that it was pretend. I'm pretty sure they would still enjoy Christmas just as much as if I lied to them and tried to trick them.

Luckily, most democracies (like the US) are republics rather than direct democracies; the people are not the rulers, but they vote for the ruler. Direct democracy tends to devolve into mob rule. That's why I'm not a fan of the California proposition system; ordinary people are barely qualified to vote for leaders, and are certainly not qualified to decide on specific issues.

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Re: Oddity

Post by fredgiblet »

I've long thought some for of limited suffrage would be better, the problem is designing a limited suffrage system that isn't discriminatory. The only setup I can think of that would be fair would the Starship Troopers path where you're required to volunteer for civil service (usually miilitary) before you can vote.

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Arioch
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Re: Oddity

Post by Arioch »

I think it's important that people not feel disenfranchised... for a democracy to work, people need to feel invested in the system; they need to feel like they could have a say, even if they usually choose not to. So I don't think limiting suffrage would work very well.

I think the current republican system works pretty well. There will always be ups and downs... when things aren't going well, people need to wake up and take an interest in what they think the government isn't doing right. But I don't think the electorate should be involved in making the day-to-day decisions of how to run government. The California proposition system is rendering the elected government impotent by heaping more and more voter-imposed restrictions on it. At some point you have to let your elected officials do their job during the term for which they're elected; if you don't think they did well, then elect someone else when the time comes.

Otherwise there's no point in having an elected government at all. I'm for small government, but I'm not for no government.

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Charlie
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Re: Oddity

Post by Charlie »

I discovered early on that the world can be harsh and unforgiving, sometimes life just isn`t fair. I will do my best to make sure that the same would not happen to my children, if that means pretending about Santa, dragons, cops-n-robbers and what not then so be it. Almost everyone grows out of it at some point, why not let them live in pretend land. They will eventually learn whats real and whats not, everyone grows up.

As for governments, more voter power isn`t a good thing. Since anyone whom meets the requirements can vote, people who might be considered "disruptive elements" would be able to effect change in large numbers. Fortunately, there arn`t enough of these types to be a concern. If only service members were allowed to vote, the recruitment process would screen out all of the undesirables.

Police states and dictatorships can sometime be far more stable than current "western" government.
No sorcery lies beyond my grasp. - Rubick, the Grand Magus

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Arioch
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Re: Oddity

Post by Arioch »

Telling children that dragons are real is not wonderful or fanciful or imagination-fueling. It's terrifying.

Children have no trouble at all being imaginative while knowing full well that imaginary things are quite different from real things. There's no need to deceive them about it. This notion that knowledge stifles creativity is absurd. If anything, I've found the exact opposite is true; it's the well-educated people who are the most imaginative.
Charlie wrote: Police states and dictatorships can sometime be far more stable than current "western" government.
But that's a myth; they aren't. Functioning democracies are far more stable than authoritarian governments, which have to deal constantly with suppressing insurgency.

Nemo
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Re: Oddity

Post by Nemo »

Absalom wrote:A reactor-powered Vasimr used as the "plasma injector" for a larger MHD-ish engine (Hall effect thruster derivative, perhaps?) would at sufficient power levels and engine lengths presumably be useful for much the same thing, and a fusion reactor would work even better. At any rate, why exactly are we talking about Alpha Centauri? Did SpaceX ever say they wanted to go there?
Because when dealing with humans time matters. Its contrasting the best available plasma based drive to a NSWR. Vasmir's 6 months to the moon is unacceptable. Contrast that with the jaw dropping realization that we are within reach of the nearest star using NSWR. I even pointed out we have no reason to but it is possible. If you followed the rest of the thread Titan, the moon, Mars, and Phobos were the focus of in system destinations. Using the other kinds of drives mentioned is simply not practical for human transit. Hall effect thrusters are even worse in this regard than a vasmir. Yes they're efficient, but have no thrust. High ISP low thrust is fine for long running probes and satellites, or maneuvering engines on a station but not for a human rated primary drive.

The risk isn't in Sieverts per say, it's in the fallout risk.
*snap*

Image



Someone please help me.

Absalom
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Re: Oddity

Post by Absalom »

Arioch wrote:
Charlie wrote: Police states and dictatorships can sometime be far more stable than current "western" government.
But that's a myth; they aren't. Functioning democracies are far more stable than authoritarian governments, which have to deal constantly with suppressing insurgency.
The key word is "functioning".

Nemo wrote:
Absalom wrote:A reactor-powered Vasimr used as the "plasma injector" for a larger MHD-ish engine (Hall effect thruster derivative, perhaps?) would at sufficient power levels and engine lengths presumably be useful for much the same thing, and a fusion reactor would work even better. At any rate, why exactly are we talking about Alpha Centauri? Did SpaceX ever say they wanted to go there?
Because when dealing with humans time matters. Its contrasting the best available plasma based drive to a NSWR. Vasmir's 6 months to the moon is unacceptable. Contrast that with the jaw dropping realization that we are within reach of the nearest star using NSWR. I even pointed out we have no reason to but it is possible. If you followed the rest of the thread Titan, the moon, Mars, and Phobos were the focus of in system destinations. Using the other kinds of drives mentioned is simply not practical for human transit. Hall effect thrusters are even worse in this regard than a vasmir. Yes they're efficient, but have no thrust. High ISP low thrust is fine for long running probes and satellites, or maneuvering engines on a station but not for a human rated primary drive.
6 months to the moon, yes, but is that for the actual route, or is that to adjust the orbit to follow the path that you want? As I best recall, on a cycler orbit you can go from the Earth to mars in 2-3 years. I somewhat suspect that if you used the Vasimr to induce a cycler orbit between Earth and moon, the actual transit time after orbital "finalization" would be less than the time mentioned (which is not to say that I know cycler times between Earth and Moon). At any rate, the 6 months is for a specific model of Vasimr, so you shouldn't be treating it as some maximum limit.

As for Hall thrusters, if you look back, I was suggesting them as a possible technological basis for producing an MHD effect to further accelerate the exhaust from a Vasimr. The Wikipedia page said that the exhaust tops out at ~10% of lightspeed, so even if you ignore relativity you can get better thrust if you can just produce more acceleration (and if you keep adding energy after relativistic effects become noticeable, then you keep dragging more thrust out of it). The main question is what you'd need to do to avoid component damage. If you're already running it from a fusion or fission reactor than you shouldn't lack for power capacity, the question will simply be how to use all of it.

Would it be enough for interstellar flight? Maybe not, but I wouldn't dismiss it unless someone did some actual analysis. For that matter, if it doesn't need to sustain itself, the basic Vasimr design could be modified to act as an honest-to-goodness fusion engine, and those have been suggested for interstellar travel before.
Nemo wrote:
The risk isn't in Sieverts per say, it's in the fallout risk.
*snap*

Image



Someone please help me.
Request denied. But seriously, a massive nuke with no fallout would be more acceptable than a small nuke with lots. Not that it matters, since that comment was prompted by my previous misimpression that you were talking about using NSWRs for planetary launch.

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Re: Oddity

Post by Nemo »

The Wikipedia page said that the exhaust tops out at ~10% of lightspeed
Here again, you do not understand specific impulse and thrust and are confusing exhaust velocity for vehicle velocity. I gave a link to ISP, read it. The appeal of these engines is their high fuel efficiency not their thrust. You must understand this concept and that of mass requirements for fuel affecting mission parameters before we can continue. They provide very very very very small amounts of delta v over long periods with only a little mass used. As I said before, unmanned vehicles and station keeping devices only.

Would it be enough for interstellar flight? Maybe not, but I wouldn't dismiss it unless someone did some actual analysis
It has been. Its not workable for human rated drive systems. You need more thrust.
The risk isn't in Sieverts per say, it's in the fallout risk.
*snap*
Request denied.
*twitch*

Please please...


Im going to try to do this again. What is "fallout"? A derogatory term implying any exposure to radiation is a Bad Thing™Martha Stewart Living. In short, exposure to radiation. What is a Sievert? The measurement of exposure to radiation. Useful for determining exactly what is and is not a harmful exposure to ionizing radiation. Therefore as you said, "The risk isnt in 'measured exposure to radiation' per say, its in the 'exposure to radiation' risk."

Absalom
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Re: Oddity

Post by Absalom »

Nemo wrote:
The Wikipedia page said that the exhaust tops out at ~10% of lightspeed
Here again, you do not understand specific impulse and thrust and are confusing exhaust velocity for vehicle velocity. I gave a link to ISP, read it. The appeal of these engines is their high fuel efficiency not their thrust. You must understand this concept and that of mass requirements for fuel affecting mission parameters before we can continue. They provide very very very very small amounts of delta v over long periods with only a little mass used. As I said before, unmanned vehicles and station keeping devices only.
The higher the exhaust velocity, the higher the ISP, yes I know. To rephrase, the higher the exhaust velocity, the more thrust from that same mass of exhaust. If you have an engine that doesn't destructively interact with it's exhaust, and has an exhaust velocity limited only by it's power supply and "active length", then it has the potential to take it's exhaust up to ~99% of c. If such an engine is long enough, then you should be able to use the output of your power supply to calculate the thrust of the engine, I believe with f = exhaust mass * square root( ( reactor output - power losses ) / exhaust mass ). I'm talking about using the Vasimr as an internal component of a higher-thrust via-higher-ISP engine, not as the sum-total of the engine. Are you claiming that this cannot, in fact, be done to the exhaust of a Vasimr, no matter how far to the "thrust" side of the equation it's dialed, due to an inherent engine constraint (as apparently happens with gridded ion engines)? Or have you actually just not spent enough time reading to figure out what I wrote?

Nemo wrote:
Would it be enough for interstellar flight? Maybe not, but I wouldn't dismiss it unless someone did some actual analysis
It has been. Its not workable for human rated drive systems. You need more thrust.
You'll have to convince me that you actually understand what I wrote before I'll take this seriously.

Nemo wrote:Im going to try to do this again. What is "fallout"? A derogatory term implying any exposure to radiation is a Bad Thing™Martha Stewart Living. In short, exposure to radiation. What is a Sievert? The measurement of exposure to radiation. Useful for determining exactly what is and is not a harmful exposure to ionizing radiation. Therefore as you said, "The risk isnt in 'measured exposure to radiation' per say, its in the 'exposure to radiation' risk."
Saying "radiation falls" seems rather ludicrous to me. Fallout is persistent radiative pollution. Gamma radiation? Once it's gone you just pick up the pieces. Fallout? You can't live there again until it's decayed, and the knowledge that it was ever present pollutes the mind-share of that plot of land for years, or decades, thereafter.

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Re: Oddity

Post by Nemo »

If you have an engine that doesn't destructively interact with it's exhaust, and has an exhaust velocity limited only by it's power supply and "active length", then it has the potential to take it's exhaust up to ~99% of c.
Not precisely, no. Seems you may be applying mechanical physics here. The limit on Vasmir is the strength of the magnetic bottle b-field which is derived from the super conductor used. Granting an infinite power source is insufficient without accommodating the physical limits of superconductors and the mass of the cooling systems needed. These are low thrust to weight drives that deliver delta V over long periods.



Saying "radiation falls" seems rather ludicrous to me. Fallout is persistent radiative pollution. Gamma radiation? Once it's gone you just pick up the pieces. Fallout? You can't live there again until it's decayed, and the knowledge that it was ever present pollutes the mind-share of that plot of land for years, or decades, thereafter.
Gamma radiation moves at the speed of light. As soon as you measure it, it is gone :lol:

So fallout is bad because its scary. Not because it presents physical bodily harm. "Fallout" is a boogeyman. To illustrate my point again, you separated Gamma radiation and held it as a distinct case from fallout. This is inaccurate. Gamma, as well as beta and alpha, are different modes of decay of the physical material which constructs 'fallout'. Alpha decay is when an unstable element spins off a helium-4 atom. Beta spins out either an electron or a positron and either increases or decreases (respectively) the atomic number without altering atomic mass. Gamma radiation consists of high energy photon emissions. The source of which, for this discussion, is the excited state of the atom resulting from the other two forms of decay. In the end, the only thing that matters is the measurable harm from exposure, which is measured in Sieverts. Uranium Bromide enriched to 20% posses no radiological risk in the worst case scenarios here.

Mayhem
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Re: Oddity

Post by Mayhem »

Nemo wrote:So fallout is bad because its scary. Not because it presents physical bodily harm. "Fallout" is a boogeyman.
The "rational" concern about fallout as I understand it is of radioactive particulates entering the body (in sufficient quantities) via ingestion or inhalation and decaying inside the body. Also some(/many?) of the elements in various radioactive decay chains are toxic in their own right.

So it becomes a question of effectiveness and availability of filtration vs initial quantities/concentration, half-life, biomagnification, etc.

The problem is one of risk assessment - which humans are notoriously bad at - and education vs drama - ditto.

So "boogeyman" instead of somewhere on the scale: trivial - inconvenient - annoying - not worth the hassle - harmful - deadly.
Particle beam cannons are mass drivers :D
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Re: Oddity

Post by Nemo »

Mayhem wrote:So "boogeyman" instead of somewhere on the scale: trivial - inconvenient - annoying - not worth the hassle - harmful - deadly.
Which as I have maintained throughout is properly expressed on the Sievert scale. It is this measured approach which is being rejected and that is what I am reacting to. When 'fallout pollutes the mind-share' is a direct reference to people's fear not the potency of the radiological effects, which, again, are trivial in even the worst case scenario launch pad chemical booster detonation.

Mayhem
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Re: Oddity

Post by Mayhem »

Nemo wrote:Which as I have maintained throughout is properly expressed on the Sievert scale.
Indeed, however it is also necessary to explain to people - the education problem I mentioned - the difference between a becquerel, a gray and a sievert.

Simply (perhaps overly so) put:
  • Becquerel is number of decays per second
  • Gray is the energy (per kilogram) imparted by radiation to a (nonspecific) mass
  • Sievert is the effective/equivalent energy (per kilogram) imparted by radiation to a human taking into consideration the nature of the radiation - alpha, beta, gamma, etc - the nature of the exposure - internal, external; localised, full body - and the nature of the human - age, gender.
Once that is explained you can talk meaningfully to Joe Public about fallout and sievert reducing precautions and evaluate their effectiveness vs inconvenience.

For example: Fine particulate alpha emitters could be lifted into the air by wind and represent an inhalation hazard.
A suitably fine dust mask worn when outdoors would massively reduce the exposure in terms of sievert (but not in terms of gray).
The discussion then becomes whether the advantages of being able to operate in the affected area are outweighed by the inconvenience of needing to wear said dust mask.
Particle beam cannons are mass drivers :D
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Nemo
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Re: Oddity

Post by Nemo »

Precisely. Now as to why Im so certain that current launch procedures are adequate to protect launch pad workers, let me introduce the rubber room and the NASA firefighters.

Image

Link: http://scriptunasimages.wordpress.com/2 ... bber-room/
Launch Pad 39A was the starting point of all the Saturn V rockets to the moon except for Apollo 10. Before each mission, each astronaut was trained on how to use the room. An exploding Saturn V was calculated to have the power of a small nuclear bomb and an explosion would have completely destroyed the 36-story rocket and leveled the launch pad. NASA needed to come up with a series of contingencies to keep astronauts and pad workers safe in the case of a suspected problem that would lead to an explosion. One of these contingencies was a room located 40ft under the top of the launch pad. The room was accessed via a 200ft long slide from the base of the mobile launch platform. In the event of a possible explosion, astronauts would have exited the capsule and entered into a rapid descent elevator that would have got them to the base of the MLP in 30 seconds (this doesn’t seem very rapid to me). After reaching the base, they would jump into the slide taking them to the rubber room. After arriving inside the rubber room, they would take a few short steps over to the Blast Room, closing the armored door behind them. The room, with its floor mounted on a series of springs, has 20 chairs, enough for the astronauts and closeout crew and could be accommodated for 24 hours.

Image

Link: http://www.redorbit.com/news/space/2021 ... efighters/
Basically a bunker on tracks, the M113 is a Vietnam-era armored personnel carrier that offers the astronauts a safe vehicle to get out of danger. It also offers firefighters heavy protection in case they have to go into danger to retrieve the flight crew and launch pad personnel.

"These things are virtually indestructible," said David Seymour, battalion chief and the lead for the pad rescue team at NASA’s Kennedy Space Center in Florida.

Talk about over engineering. The radiation effects of enriched Uranium Bromide weve been so focused on for two pages can, as noted, be stopped by a simple piece of paper. In any catastrophic situation the radiation is a non issue, and especially so when compared to the difficulties dealing with the catastrophic fault of a rocket.

Absalom
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Re: Oddity

Post by Absalom »

Nemo wrote:
If you have an engine that doesn't destructively interact with it's exhaust, and has an exhaust velocity limited only by it's power supply and "active length", then it has the potential to take it's exhaust up to ~99% of c.
Not precisely, no. Seems you may be applying mechanical physics here. The limit on Vasmir is the strength of the magnetic bottle b-field which is derived from the super conductor used. Granting an infinite power source is insufficient without accommodating the physical limits of superconductors and the mass of the cooling systems needed. These are low thrust to weight drives that deliver delta V over long periods.
I don't know whose posts you've been reading, but you certainly have not been reading mine. Let me repeat myself, for at least the third time: I am talking about using a Vasimr as a plasma generator component inside of an electric rocket which then accelerates that plasma to a higher velocity, thereby increasing the thrust.

PLEASE make certain that you understand what I wrote above before you reply to this. The limits of the Vasimr are not directly the limitations of what I'm talking about, because the Vasimr is nothing but an over-glorified spark-plug. I have not been talking about the actual acceleration stage of this engine, except in the most generic of terms.

Your note about superconductors and cooling systems is presumably relevant, but not by way of the Vasimr. It's relevance would be in relation to the other plasma accelerator stages.

Nemo wrote:
Saying "radiation falls" seems rather ludicrous to me. Fallout is persistent radiative pollution. Gamma radiation? Once it's gone you just pick up the pieces. Fallout? You can't live there again until it's decayed, and the knowledge that it was ever present pollutes the mind-share of that plot of land for years, or decades, thereafter.
Gamma radiation moves at the speed of light. As soon as you measure it, it is gone :lol:

So fallout is bad because its scary. Not because it presents physical bodily harm. "Fallout" is a boogeyman. To illustrate my point again, you separated Gamma radiation and held it as a distinct case from fallout. This is inaccurate. Gamma, as well as beta and alpha, are different modes of decay of the physical material which constructs 'fallout'. Alpha decay is when an unstable element spins off a helium-4 atom. Beta spins out either an electron or a positron and either increases or decreases (respectively) the atomic number without altering atomic mass. Gamma radiation consists of high energy photon emissions. The source of which, for this discussion, is the excited state of the atom resulting from the other two forms of decay. In the end, the only thing that matters is the measurable harm from exposure, which is measured in Sieverts. Uranium Bromide enriched to 20% posses no radiological risk in the worst case scenarios here.
Separating Gamma radiation from fallout is not inaccurate, because a defining feature of fallout is that it decays, thereby generating radiation. Alpha and beta might be considered fallout because they are capable of decaying into further forms of radiation (I'm long enough out of school to not remember), but gamma can't.

The very fact that gamma rays are photons mean that they cannot decay. The fact that gamma rays cannot decay means that they are not fallout. Hence, gamma rays are not fallout. Neither is infrared, or the radio spectrum, or microwaves, or ultraviolet, or any other "color" of photon.
Nemo wrote:Talk about over engineering. The radiation effects of enriched Uranium Bromide weve been so focused on for two pages can, as noted, be stopped by a simple piece of paper. In any catastrophic situation the radiation is a non issue, and especially so when compared to the difficulties dealing with the catastrophic fault of a rocket.
You and I are so very much not talking about the same thing. You are talking about the initial "containment failure", basically the "boom". I'm talking about the aftereffects, which could be compared to the smoke and debris. We're talking about different time-scales here.

In fact, I actually said that a bigger boom was better than sustained radiation. Seriously, I said this, go back and look. I'm not worried about pad workers either, I'm worried about wherever else it might crash. To the best of my knowledge most of the launch pads that might be used for this stuff (at least here in the US) are distant enough from population centers that a containment failure there would be unlikely to have major consequences. Oh, sure, you might have a few personal tragedies, but crack the containment casing of one of these in the vicinity of a city, and you might have a year or three of school-child radiation poisoning. It's just like in war, you're sad when your guys die, but the enemy want's them to survive too, so that you'll be dragged down by caring for them.

Nemo
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Re: Oddity

Post by Nemo »

Absalom wrote:PLEASE make certain that you understand what I wrote above before you reply to this. The limits of the Vasimr are not directly the limitations of what I'm talking about, because the Vasimr is nothing but an over-glorified spark-plug. I have not been talking about the actual acceleration stage of this engine, except in the most generic of terms.

Your note about superconductors and cooling systems is presumably relevant, but not by way of the Vasimr. It's relevance would be in relation to the other plasma accelerator stages.


I understand perfectly well. I'll be more clear. It doesnt matter. Any electric drive you strap to it for any kind of afterburner is going to face the same difficulty. It won't produce any benefit past the given strength of the magnetic field. The containment b-field is your weak spot, this is true for all plasma drives, and strapping on more tubing/equipment ad infinitum (the infinite power I granted earlier) does not over come that. I say you are misapplying physical understandings because this idea can work with physical medium. Like more stages in a turbine compressor, or an afterburner, but, fluid mechanics, mechanical physics, arent what need to be applied here.


Separating Gamma radiation from fallout is not inaccurate...

The very fact that gamma rays are photons mean that they cannot decay. The fact that gamma rays cannot decay means that they are not fallout. Hence, gamma rays are not fallout. Neither is infrared, or the radio spectrum, or microwaves, or ultraviolet, or any other "color" of photon.


I dont know how else to say it, your understanding of the science is off. Gamma Alpha and Beta are all by-products of nuclear decay. An unstable isotope of an element changes into a more stable state by releasing energy. The unstable element constitutes the fallout. In our case, enriched Uranium Bromide. Radiation from fallout comes in each of the three modes, alpha beta and yes gamma too. The mode of decay and the concentration of decay determine the strength of the effect. The would be measured in the aforementioned Becquerel. This imparts ionizing energy on a mass measured in Gray. The gray is then factored for effect and finally becomes the Sievert. It is the Sievert dose of ionization which may or may not be harmful. You can no sooner separate gamma radiation from fallout than alpha or beta.

You and I are so very much not talking about the same thing. You are talking about the initial "containment failure", basically the "boom". I'm talking about the aftereffects, which could be compared to the smoke and debris. We're talking about different time-scales here.
Theres a reason for that. I was granting the worst case failure of the rocket. The effect of the radiation is directly proportional to the density of the decaying element. I said it starting on the last page:
Nemo wrote:No one gets exposed to anything harmful at a launch failure and the exposure decreases with altitude and speed.

An illustration may be helpful, think of a water balloon. The harder you throw it the more dispersed the water. The faster the rocket is traveling, and the higher its altitude, the lower the concentration of any resulting, ahem, "fallout". Quite the opposite of killing the innocent little school children, but zomg think of teh childrun!, there will be no measurable impact. I can state this definitively. Since you are not content with the highest density exposure scenario I presented, create your own and run the math. I'd like to see the numbers.


Now if you want to say Uranium bromide itself is just so dangerous that itll kill people if it leaks out from the enrichment facility or transport... First, again, a leak wouldnt create enough exposure to be a radiological risk even if it were to happen. (see above about running numbers) Which...

https://www.youtube.com/watch?v=ZY446h4pZdc
2:06 wrote:The CEGB are, however, convinced they've proved their point. They say if this doesn't reassure their critics, then nothing will.
Not a problem, I should think.





edit: to help with the math - 3 tons of Uranium bromide enriched to 20% yields .6 tons of U-235 which produces, in total, 1.2 times the radioactivity of 1 gram of radium-226 and imparts .13 milligrays per hour/1.1 gray a year at 1 meter

http://www.wolframalpha.com/input/?i=Be ... ranium+235

edit's edit: I was wrong. 3 tons of uranium listed in zurbin's titan ship was the u-235 component. Also, was done in metric not short tons, I didn't specify to wolfram last night. What I get doing that at 2 am.

http://www.wolframalpha.com/input/?i=Be ... ranium+235


3 tons u-235 is equivalent to 7.2 times one gram of radium-226 producing .79 milligray an hour/6.9 gray a year at 1 meter.

Absalom
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Re: Oddity

Post by Absalom »

Nemo wrote:
Absalom wrote:PLEASE make certain that you understand what I wrote above before you reply to this. The limits of the Vasimr are not directly the limitations of what I'm talking about, because the Vasimr is nothing but an over-glorified spark-plug. I have not been talking about the actual acceleration stage of this engine, except in the most generic of terms.

Your note about superconductors and cooling systems is presumably relevant, but not by way of the Vasimr. It's relevance would be in relation to the other plasma accelerator stages.


I understand perfectly well. I'll be more clear. It doesnt matter. Any electric drive you strap to it for any kind of afterburner is going to face the same difficulty. It won't produce any benefit past the given strength of the magnetic field. The containment b-field is your weak spot, this is true for all plasma drives, and strapping on more tubing/equipment ad infinitum (the infinite power I granted earlier) does not over come that. I say you are misapplying physical understandings because this idea can work with physical medium. Like more stages in a turbine compressor, or an afterburner, but, fluid mechanics, mechanical physics, arent what need to be applied here.
I still can't help but think there's probably some electric drive capable of the 1g range under sufficient power, but you properly aimed at my point this time, so I'll ignore that.

Nemo wrote:
Separating Gamma radiation from fallout is not inaccurate...

The very fact that gamma rays are photons mean that they cannot decay. The fact that gamma rays cannot decay means that they are not fallout. Hence, gamma rays are not fallout. Neither is infrared, or the radio spectrum, or microwaves, or ultraviolet, or any other "color" of photon.


I dont know how else to say it, your understanding of the science is off. Gamma Alpha and Beta are all by-products of nuclear decay. An unstable isotope of an element changes into a more stable state by releasing energy. The unstable element constitutes the fallout. In our case, enriched Uranium Bromide. Radiation from fallout comes in each of the three modes, alpha beta and yes gamma too. The mode of decay and the concentration of decay determine the strength of the effect. The would be measured in the aforementioned Becquerel. This imparts ionizing energy on a mass measured in Gray. The gray is then factored for effect and finally becomes the Sievert. It is the Sievert dose of ionization which may or may not be harmful. You can no sooner separate gamma radiation from fallout than alpha or beta.
Merriam-Webster's Collegiate Dictionary, Tenth edition: fall-out 1a: the often radioactive particles stirred up by or resulting from a nuclear explosion and descending through the atmosphere; also: other polluting particles (as volcanic ash) descending likewise b: descent (as of fallout) through the atmosphere 2a: a secondary and often lingering effect, result, or set of consequences

When reading the entry, it's quite clear that it favors persistent particles with a half-life, a.k.a. not photons of any form that I have ever heard of, but I can see the room for misunderstanding, so I'll rephrase:
This is bad because of radioactive "dust". The photon burst from detonation doesn't matter, so forget about it, it'll do nothing more than distract you. What matters is that the consequence of containment failure is radioactive pollution.



At any rate, this doesn't matter to me anyways. I see no need for the things in the foreseeable future because an Earth-Mars cycler is supposed to take ~2-3 years for the trip (one way, I think), which should be a perfectly acceptable time frame (if it isn't, then I have to ask either why you built your one-time cost cycler station so small, or why someone so impatient is being considered for such a mission at all). A Vasimr (or likely a number of other technologies, in sufficient numbers of thruster units) should be perfectly acceptable as a way to insert the cycler into it's orbit, no need for a NSWR. I'm of the opinion that if you need to go somewhere under power, then it probably isn't somewhere to send a manned mission right now.

At the same time, it has little to no chance of spewing radiative pollution in the case of an accident, which makes it politically superior. People don't like having stuff thrown around their property, e.g. Australia made the US pay up for littering when SpaceLab (or was it the other one?) crashed on their territory. To help you understand what I mean, bring me your car fore a paint job. I'll be using a rough-texture brush instead of spray paint, and you'll be running the risk of me using the ugliest shade of green imaginable, but you've just got to accept that risk, and it's harmless so obviously it's the Right Thing To Do (TM), right? Oh course not, it's a stupid idea because there is no sensible reason to do it.

And there's the question of why (other than impatience, or Zubrin's pulp-scifi fantasies) we would want such a power of rocket at this early stage of space travel. I don't think you ever explained why SpaceX (or any other rocket company) would even want to launch a NSWR. The only possibility that I can think of is that Zubrin wants to, and I don't care what Zubrin wants.

Nemo
Posts: 277
Joined: Tue Apr 26, 2011 1:04 am

Re: Oddity

Post by Nemo »

The photon burst from detonation doesn't matter, so forget about it, it'll do nothing more than distract you. What matters is that the consequence of containment failure is radioactive pollution.
You still misunderstand. Yes gamma is produced by fissile reactions, as are other forums of radiation, but it also is produced as a by-product of nuclear decay. Cobalt-60 undergoes beta decay. Its decay chain is: 60/27Co → 60/28Ni + e− + νe + gamma rays.
Cobalt 60 decay energy wrote:Energy transfers between the three levels generate six different gamma-ray frequencies
The gamma is spit off to equalize energy states, you can treat it almost as you would the remainder in a whole number fraction. 7 divided by 2 is 3 with a remainder of 1. 1 would be shot off as gamma energy to balance the equation, if that helps. So, in effect, what you said was true. The photon burst from detonation doesn't matter. You are still being bombarded by ionizing photons anyway.




While on the topic of nuclear detonation/fissile reaction as opposed to decay we should note in that context "fallout" is much much more than just the transuranic chain resulting from fission. This is because of a process known as neutron activation. The excess neutrons from the detonation impact with surrounding material adding neutrons and imparting energy (kinetic form) to otherwise stable isotopes. They become unstable and the material decays, generating more ongoing radiation in alpha beta and gamma forms. This is largely what is referred to as 'fallout' from the above definition. If we refer to the Castle Bravo and Crossroads test series (particularly the Baker shot) we find that ground based detonations are more lethal than air burst. Air burst detonations produces less of this kind of sympathetic radiation in part because oxygen can take up to 3 neutrons before becoming unstable. Ground burst detonations have a ready supply of more easily activated material which is cast off by the explosion and carried down wind. This is also why the US pursued the Enhanced Radiation Weapon aka: Neutron Bomb for use against tank columns in a European theater war. Air burst detonation in the vicinity of a tank column would create an extreme local radiation effect in the short to mid term while limiting down range fallout when compared to a ground based detonation of a conventional nuke that would otherwise be required to neutralize the column.



Conventional nuke? :lol:

Absalom
Posts: 718
Joined: Sat Sep 24, 2011 4:33 am

Re: Oddity

Post by Absalom »

Nemo wrote:
The photon burst from detonation doesn't matter, so forget about it, it'll do nothing more than distract you. What matters is that the consequence of containment failure is radioactive pollution.
You still misunderstand. Yes gamma is produced by fissile reactions, as are other forums of radiation, but it also is produced as a by-product of nuclear decay. Cobalt-60 undergoes beta decay. Its decay chain is: 60/27Co → 60/28Ni + e− + νe + gamma rays.
No, I do not misunderstand. Fallout emits radiation, such as: alpha rays, beta rays, and photons. If something does not emit radiation, then it is not fallout, because fallout emits radiation. Gamma rays (and other "colors" of photons) do not emit radiation, and therefor are not fallout.

I am NOT talking about the radiation, I am talking about it's precursors, the actual fallout. The assorted particles that produce radiation are what I am talking. How are you so consistently failing to grasp this, despite the fact that I am intentionally writing it in the plainest way that I can think of?
Nemo wrote:While on the topic of nuclear detonation/fissile reaction as opposed to decay we should note in that context "fallout" is much much more than just the transuranic chain resulting from fission. This is because of a process known as neutron activation. The excess neutrons from the detonation impact with surrounding material adding neutrons and imparting energy (kinetic form) to otherwise stable isotopes. They become unstable and the material decays, generating more ongoing radiation in alpha beta and gamma forms. This is largely what is referred to as 'fallout' from the above definition.
Dust such as that is included in fallout, correct. Particles of this sort are what I am talking about. I am talking about emitters, radio-actives, metaphorical ticking time bombs; not something that had already cleared out before you realized it was there, and itself can therefor be relegated to history books. I am not talking about the radiation, I am talking about a classification of things that are defined by the fact that they emit radiation. Those are the things that nobody wants littering their backyards.

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