You do realize, don't you, that several tons of plutonium, along with a menagerie of other radiactive isotopes, were vaporized and widely disperesed through the atmosphere during the atmospheric testing of atomic bombs a couple of decades ago, don't you?
One figure I've heard is 11,000 pounds of Pu was disperesed during atomic bomb tests by various nations, and yet we're all still alive, last I checked. The 72 pounds of ceramic plutonium oxide in Cassini amounts to 6/10 of one percent of that total.
If you do realize this, then it would seem that your alarmism over the Cassini probe RTG, even if it *was* designed to disintigrate on re-entry, is at best intellectually dishonest.
-Mike Pelletier.
Thank you for your email which I will try to answer in it's entirety:
You wrote:
You do realize, don't you, that several tons of plutonium, along
with a menagerie of other radiactive isotopes, were vaporized and
widely disperesed through the atmosphere during the atmospheric
testing of atomic bombs a couple of decades ago, don't you?
Yes I realize this. Of course, Pu 238 is 280 times more radioactive per equivalent-sized particle than Pu 239 which as I understand it was the main Plutonium component in these tests. Cassini, this one thing, has about as much plutonium radioactivity in it as mankinds worst nuclear disaster, Chernobyl. And it can be despersed in the most lethal way -- upper atmosphere incineration -- which is actually worse than the way Chernobyl burned.
You wrote:
One figure I've heard is 11,000 pounds of Pu was disperesed during
atomic bomb tests by various nations, and yet we're all still
alive, last I checked. The 72 pounds of ceramic plutonium oxide
in Cassini amounts to 6/10 of one percent of that total.
And yet we're all still alive, last YOU checked. Check again. I suggest reviewing some of Dr. Gofman's works, for instance, which are now becoming available on the web. Here's the URL:
http://www.ratical.com/radiation/
I would have to say that this rather persistent theory that "we're all alive" flies in the face of evidence, logic, and personally, in flies in the face of my brother, dead at 39 from Leukemia from God-knows-what. Just one person, can't prove a thing. But I don't think we're all alive at all. I challenge that.
You wrote: If you do realize this, then it would seem that your alarmism over the Cassini probe RTG, even if it *was* designed to disintigrate on re-entry, is at best intellectually dishonest.
Perhaps, I am intellectually challenged, but I don't think I am intellectually (or otherwise) dishonest. AND most importantly, if the RTGs ARE designed to incinerate on re-entry, then the NASA reports and studies and claims that say they aren't are dishonest, EVEN IF IT'S THE RIGHT THING TO DO (which is isn't). If NASA has designed them to incinerate, then it's NASA's job to admit that that's what they've done, and explain their reasoning. So on that issue, I think the place to look for intellectual dishonesty is definitely towards NASA.
Thank you again, for your email. If I post this response (which I assume right now I will) it will be without your name or email address, of course, unless you request otherwise.
Sincerely,
Russell D. Hoffman
Yes, but the activity is in the form of alpha radiation, which can be stopped by a sheet of paper. All radioactivity is not created equal, and your comparing alpha radiation from plutonium ceramic, in the off chance that Cassini fails in just such a way that it might be released, with the veritable menagerie of radioactive isotopes from Chernobyl, just smacks of emotional fear-mongering. What about the tons upon tons of radioactive uranium and thorium that's released by coal-burning power plants? Surely that poses a far more serious, immediate health threat than a spacecraft that would have to fail six ways from Sunday to crash into Earth.
You wrote:
"One figure I've heard is 11,000 pounds of Pu was disperesed during
atomic bomb tests by various nations, and yet we're all still
alive, last I checked. The 72 pounds of ceramic plutonium oxide
in Cassini amounts to 6/10 of one percent of that total."
And yet we're all still alive, last YOU checked. Check again. I suggest
reviewing some of Dr. Gofman's works, for instance, which are now becoming
available on the web. Here's the URL:
http://www.ratical.com/radiation/
I would have to say that this rather persistent theory that "we're all
alive" flies in the face of evidence, logic, and personally, in flies in the
face of my brother, dead at 39 from Leukemia from God-knows-what. Just one
person, can't prove a thing. But I don't think we're all alive at all. I
challenge that.
I suggest, then, that you and your cohorts fighting the Cassini mission stop using the specious assertion that one pound of plutonium is enough to kill everyone on Earth. If you are actually interested in generating light, instead of heat, I expect that this would make sense to you.
If 11,000 pounds of plutonium, plus heaven knows how many tons of a wide spectrum of other radioactive elements from neutron-activiated bomb parts, dirt, water-borne minerals, and the like, weren't enough to kill everyone on Earth 11,000 times over, as is obviously the case, then the claim that one pound is enough, implying that 72 pounds from Cassini is more than enough, is patently false. I am really sick of seeing it bandied about, frankly, although it appears that your site is a little more balanced than most.
Perhaps, I am intellectually challenged, but I don't think I am intellectually (or otherwise) dishonest. AND most importantly, if the RTGs ARE designed to incinerate on re-entry, then the NASA reports and studies and claims that say they aren't are dishonest, EVEN IF IT'S THE RIGHT THING TO DO (which is isn't). If NASA has designed them to incinerate, then it's NASA's job to admit that that's what they've done, and explain their reasoning. So on that issue, I think the place to look for intellectual dishonesty is definitely towards NASA.
Suppose that they haven't been designed to disintigrate? The plutonium is in the form of a ceramic, with a melting point of 4,442F, encased in a cladding of pure iridium metal with a melting point of 4,861F, encased in graphitic material as is used in ICBM nosecones, with a considerably higher melting point than either of the other two.
Your claims that this would be insufficient protection really leave a lot to be desired in terms of technical detail and thermodynamic calculations. Simply saying "I believe...", or claiming that "the fuel/oxygen will explode. This additional heat .. will help to incinerate them" just doesn't cut it as any kind of "proof" or even "convincing argument." The RTG GPHS units could sit in a H2 fire for years and not breach -- hydrogen has a flame temperature of around 3,950F, if burned with a full supply of air, and that's almost 500F cooler than the melting point of plutonium dioxide, the piece with the lowest melting point of the entire assembly.
If you want some credibility, crack open your thermodynamics textbook and do the math, and insert cross-references for everything you have in your web page.
(Where do you get the 1000C RTG temperature, for example? http://ans.neep.wisc.edu/~ans/point_source/AEI/sep96/Apollo.html indicates that the surface temperature of a slug of Pu238 will be half that. And your claim that Cassini will be a short-term mission in the "jpltruer.htm" document is directly contrary to the JPL Cassini web page, which says that Cassini is an 11 year mission.)
Thank you again, for your email. If I post this response (which I assume right now I will) it will be without your name or email address, of course, unless you request otherwise.
Feel free to use my e-mail address.
-Mike Pelletier.
Thanks for your followup email.
This email is to acknowledge receipt of your email and let you know that I'm going to work on a response, but naturally, since I'm NOT a scientist, I'll have to talk to people, do some research, etc.. I'm sure you understand. It might take a few days. I didn't want you to think any delay in responding was due to ignoring you when the going got tough. Not at all! You've challenged me well, I think, and I appreciate it. Only by my logic surviving (in my own mind) all good challenges can I keep my opinions. When I close my mind, I should also shut my mouth.
On the matter of the RTGs, I would say that an ICBM nose cone is shaped very differently from an RTG. An ICBM is aerodynamic while an RTG isn't. I believe (I'm sorry, I have to put it that way) that the fins on the RTG's will help to pull them apart. Also, the temperature and explosion resistance values I used are mostly from page 2-19 of the "Final EIS" for the Cassini mission, June, 1995. Other values were taken from online NASA/JPL documents, which I do reference quite often at the web site. RTGs are very, very hot!
Do you have a copy of the NASA "Final" EIS from June '95?
On the length of the mission, I think NASA's "11 year mission" includes 7 years to get there. I guess four years is better than nothing, but it's not the DECADES I believe NASA could and should shoot for.
I wonder if NASA is afraid to shackle itself with such long-term missions because they are too afraid of funding cutbacks, so they don't want too many "infrastructure" programs going on that can't be cut. NASA funding has gone down considerably as we all know. Has this made NASA short-sighted? I think it would benefit the Agency, and the world, to see NASA engaging in 20, 30, even 50 year and 100 year missions. It would maybe make the world start looking further into the future. Maybe if NASA had some guaranteed multi-decade funding they would build mag-lev launch systems and such...
I was shocked that they shut down Pioneer after 25 years, just because... Because what? I thought the long life of the probe and it's great distance was enough reason to keep studying it until it stopped, not simply stop listening. Why did they do that? Budget cutbacks, I assume. (But then, I was shocked when another agency mothballed the SR-71 fleet, too.)
My dad keeps bugging me to add more references too, by the way. You're in good company on that complaint.
Thanks again for your followup email,
Sincerely,
Russell D. Hoffman
This email is to acknowledge receipt of your email and let you know that I'm going to work on a response, but naturally, since I'm NOT a scientist, I'll have to talk to people, do some research, etc.. I'm sure you understand. It might take a few days. I didn't want you to think any delay in responding was due to ignoring you when the going got tough. Not at all! You've challenged me well, I think, and I appreciate it. Only by my logic surviving (in my own mind) all good challenges can I keep my opinions. When I close my mind, I should also shut my mouth.
Thanks for letting me know. I'll look forward to your reply. I'm glad we each feel the same way about our opinions, it's the best way to have a productive discussion of an issue.
On the matter of the RTGs, I would say that an ICBM nose cone is shaped very differently from an RTG. An ICBM is aerodynamic while an RTG isn't. I believe (I'm sorry, I have to put it that way) that the fins on the RTG's will help to pull them apart. Also, the temperature and explosion resistance values I used are mostly from page 2-19 of the "Final EIS" for the Cassini mission, June, 1995. Other values were taken from online NASA/JPL documents, which I do reference quite often at the web site. RTGs are very, very hot!
The real question is, why do you believe that the fins on the RTGs will help pull them apart? Let's see facts, instead of opinions. Facts in the form of solid modelling, finite element analysis, atmospheric density and the induced bending force vs. tensile strength of the particular alloy used in the fins and the casing, etc, etc.
Do you have a copy of the NASA "Final" EIS from June '95?
No, do you have a web page reference for this?
I wonder if NASA is afraid to shackle itself with such long-term missions because they are too afraid of funding cutbacks, so they don't want too many "infrastructure" programs going on that can't be cut. NASA funding has gone down considerably as we all know. Has this made NASA short-sighted? I think it would benefit the Agency, and the world, to see NASA engaging in 20, 30, even 50 year and 100 year missions. It would maybe make the world start looking further into the future. Maybe if NASA had some guaranteed multi-decade funding they would build mag-lev launch systems and such...
Talk to Congress about all that. However, the main plan for mission objectives covers the 11 years, but after those main objectives are accomplished, there's a variety of options, provided that the spacecraft is still functioning well after years of pummelling by Saturn's radiation belts. One option is to aerobrake it into orbit around Titan for ongoing study of that moon. I believe all this is covered on the JPL web page.
I was shocked that they shut down Pioneer after 25 years, just because... Because what? I thought the long life of the probe and it's great distance was enough reason to keep studying it until it stopped, not simply stop listening. Why did they do that? Budget cutbacks, I assume. (But then, I was shocked when another agency mothballed the SR-71 fleet, too.)
I was under the impression that one of the Pioneer probes' transmitters finally died out due to lack of power, and that the other one was still transmitting, based on a couple of Pioneer web pages I've seen. The level of monitoring of the transmissions was cut back, though, since it wasn't returning a whole lot of useful data at one bit per second or whatever.
-Mike Pelletier.
rhoffman@animatedsoftware.com