As part of my "The Apollo Moon Hoax: Why We Did NOT Not Go to the Moon" presentation (notice I capitalized the first "NOT" this time to avoid the confrontation from a few months ago), I'm trying to figure out where the claim of "you need 6 feet of lead shielding" to protect against Van Allen Belt Radiation comes from. I remember seeing someone actually go through the pseudo argument once, but I can't find it again and don't remember it well enough except that it had something to do with compressing a column of Earth's atmosphere.

Thanks.

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It's a misinterpretation of a series of statements by physicist John Mauldin in his book Prospects for Interstellar Travel, published in the 1980s and quoted by Ralph Rene. Mauldin undertakes an extensive study of the physics and engineering challenges of designing and building interstellar spacecraft.

At one point Mauldin discusses a generation ship, one on which one or more generations of humans would be born, live their lives, reproduce, and die during a lengthy interstellar voyage. This ship would travel at speeds approaching 30% the speed of light.

Mauldin estimates six feet of shielding would be needed for such a ship. When he gives the figure he does not specify a shield material, but later he identifies appropriate shielding materials for general radiation protection: water, rock, and metals.

Conspiracy theorists don't generally appreciate the significant differences between Mauldin's generation mission and an Apollo mission.

First, there is more cosmic radiation in interstellar space than in cislunar space inside the heliopause.

Second, the occupants of a generation ship require more attenuation since the effects of the environment will apply to their entire lives.

Third, a ship moving at 0.3c generates its own high-energy radiation by moving through low-energy, high-flux environments at relativistic velocities, much as a car generates "wind" by moving quickly through still air.

Mauldin's projection is entirely credible for the type of ship and mission he was proposing, which has nothing at all do with Apollo and its intended mission and environment.

__________________
"Facts are stubborn things." --John Adams
Clavius Moon Base

Well,Spacefans, you don't really need shielding. You can just cook in the radiation and expire. The smart money would probably be a large waterjacket
around the inner hull. Clean, filter, recylce. Gotta bring it with you. All of it.
Hey...nothing's easy. I took my Mother-in-law to the 100 car demolition derby.
She wanted to drive in the event, but...thay said she was too agressive!
Dan

But if I igonore your first "NOT", can I mock you?

Pete

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PJE

There's so much I don't know about astrophysics. I wish I had read that book by that wheelchair guy.

Thanks, Jay. I came across a brief mention of that during a Google search. I don't suppose you've heard the whole atmosphere compression density argument?

No.

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I don't suppose you've heard the whole atmosphere compression density argument?

No, I haven't. Summarizing it here would be great, if you have the time.

The common variant on the 6 feet of shielding claim is to render it as 2 meters and say that the CIA found out that's how much the Soviets computed would be necessary.

__________________
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Clavius Moon Base

I honestly can't remember, which is why I was asking. All I do remember is that I think the claim goes by saying that if you take the mass of a column of air, which is what insulates us from the radiaiton belts (so the claim goes), then that mass is the equivalent of 6 ft of lead shielding.

But that's just a vague memory of it, and I can't get the pseudomath to work (I get about 1 meter) ... but I'm still trying to find it.

__________________
"If not now, later." -- me

Useful astro site (yes, it's mine, but it's still quite extensive) ~ http://burro.astr.cwru.edu/stu/index.html
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Let's see the atmosphere exerts about about 10 tons of pressure per square meter. Six foot of lead would exhert about 20.7 tons over a square meter.

I don't know if this has anything to do with anything, I just thought I'd mention it. When I was a lad we were told the atmosphere gave as much protection from radiation as one meter of lead.

Yeah, see your math works out like mine. Another reason why I don't think I remember the justification right. Sigh.

I'm listening to some interviews with Bart Sibrel right now to see if he mentions it, but so far they've only showed clips of his movie which only says stuff like "it's obvious that ... ."

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How about this:

It's from a newspaper article written in 1925 about an expreiment to measure the penetration of a new ray.

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A Geek will think he can use that to pick up a girl in a bar.
A Dork knows he can't pick up the girl with it, but will hang around for hours anyway, just in case she asks.
She might. You never know.

Well, I'm guessing here, but I would suggest the "argument" might be that because 1 metre gives the equivalent protection of the atmosphere, and entering the Van Allen Belt is like "entering a nuclear explosion" (as I have seen mentioned) then this would add another metre to the "equation".....

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Jay:
Browsing this thread encouraged me to read your page at Clavius dealing with the radiation environment of Apollo.
Your sentencegets neat visual support from the recent APOD reproduction of the widely-known "Blue Marble" view from Apollo 17. This view of Earth makes it clear that Apollo 17 was departing along a line well south of the equator, with the centre of the Earth's disc corresponding pretty much exactly to 30° south latitude.

Grant Hutchison

Of course 2 metres is correct; that why the (then) Soviets built their lunar lander and spacecraft with 2 metres of lead shielding.

Or did they?

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Lonewulf

While I hate to admit it, Hoagland, actually his associates, do a pretty good job discussing this aspect of the Apollo missions. Link.

Also if you go to the NASA Techincal Reports Server (NTRS) you can find many documents which discuss the radiation problem and the control methods. Many of these documents are downloadable in a pdf format.

...about an expreiment to measure the penetration of a new ray.

The absorption equivalence might work for that ray, but not for any other form of radiation.

A cubic meter of air is largely transparent to visible light, but somewhat absorptive to low-energy x-rays. In fact, a cubic kilometer of air is fairly transparent to visible light while a thin sheet of balsa wood pretty much stops those photons.

Okay, I think we all agree it's a simplistic approach, but it's good to know where it came from so that we can supplant it with better information.

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Clavius Moon Base

While I hate to admit it, Hoagland, actually his associates, do a pretty good job discussing this aspect of the Apollo missions.

I don't hate to admit it. If you don't give credit where credit is due, then your criticism won't stick very well.

You don't have to agree with all the Enterprise Mission's other conclusions just because one of them appears to be well-supported. Rejecting their conclusions as having come from biased or clueless people would be an ad hominem argument we wouldn't make anyway. Hoagland's crystal towers on the Moon can be adequately discussed according to the facts and lines of reasoning he presents. His associates' arguments regarding NASA and Freemasonry can be criticized without necessarily having to criticize his handling of the hoax theories.

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Clavius Moon Base

Oh, I agree that it's useless for measuring anything other than that one ray. But, in a world where hammers can weigh 500 kg and lunar landers can hover in a polar orbit over the daylight side of the Earth for three days, surely all rays in space can be identical in every way.

I was just suggesting that story, or one similar, might have been the original source for the "6 feet of lead" claim used sine it mentions the same amount of lead and deals with absorbing a space ray of an (in that article) unidentified nature. Anyway, that was the first thing I came across that looked to be a good candidate. We'll see if rings any bells.

__________________
A Nerd can figure out how long it will take the original Enterprise traveling at warp 6.5 to travel from Regulus to Antares.
A Geek will think he can use that to pick up a girl in a bar.
A Dork knows he can't pick up the girl with it, but will hang around for hours anyway, just in case she asks.
She might. You never know.

Thanks. I have no idea if that's the original argument, but it comes closer to the only other explanation that I've heard. So I can say with confidence at this version of the presentation on Thursday for our local Yuri's Night that no one really knows where this claim comes from, but it's probably a perversion of research done on one type of radiation in 1925 or a convolution of the type of shielding proposed for a craft that would take 200,000 years to go to alpha Centauri.

__________________
"If not now, later." -- me

Useful astro site (yes, it's mine, but it's still quite extensive) ~ http://burro.astr.cwru.edu/stu/index.html
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I found this on Cosmic Dave's website,

so it was Bill Kaysing who figured it out.