The SEIS includes a complete rebuttal by NASA to my comments on the DSEIS.
This is my reply to NASA's comments. My original text was published in
the SEIS and is also available at this URL:
NASA's rebuttal has been scanned in and is available at this URL:
Comment numbers are based on NASA's comment numbers which are, conveniently, based on my original 36 numbers plus my commentor number, which was 2. Thus the numbers are 2-a, 2-1, 2-2, etc. through 2-36.
Comment number 2-a resulted because NASA answered one point prior to the numbered section (that is, one point in the introduction). I will quote the section which NASA answered, which was signified by NASA with a vertical bar next to the text in my commentary.
In all other cases, NASA's numbers match the item number in my original commentary. (For once, NASA's numbers make sense!!)
Dr. Morgan explained to me that the way plutonium works is basically like this: when a particle of plutonium lodges in the body, the localized radiation dose to the nearby living cells from one of the "fine particles" can be 1000's of REM per year if the plutonium stays fixed in one place. If it moves around in the body, the dose will be spread out among the cells it is in close proximity to.
At that high level of radiation, nearby cells will die, but ones a little further away will survive -- and be irradiated, and possibly mutate into a cancerous form.
Dr. Morgan also explained that the incineration of an RTG would produce "a spectrum of sizes" and he added "any one of them -- they could all be inhaled. I hope our government will be more cautious in using plutonium."
"The health physics community has generally used the radiation dose model presented in ICRP-30 which used the dose-averaging approach (ICRP 1979). The International Commission on Radiological Protection (ICRP) establishes recommendations and guidelines for assessing radiation doses. The U.S. Departement of Energy, the U.S. Nuclear Regulatory Commission (NRC) and the U.S. Environmental Protection Agency (EPA) use these recommendations and guidelines to assess potential radiation doses. The concerns of Dr. Morgan and others have been taken into consideration by the health physics community in developing the ICRP recommendations regarding radiation dose estimates."
I do not understand why NASA thinks the "hot particle" debate is what Dr. Morgan was referring to. I think what Dr. Morgan meant was that it is not the mere presence of a certain quantity of plutonium in the body that causes a lung cancer or other health effect, but rather, it is the random chance that any particular particle which is present will cause a health effect; the greater the total mass of particles one has in one's lungs, the higher the probability of a health effect.
When considering Cassini's health effects potential, it is improper to simply use ICRP's averaging techniques, especially when one considers all the separate averaging steps that occur (# of years is "averaged" at 50 years, type of person is "averaged" at adult male, type of health effect is "averaged" at lung cancer, etc. etc.) All these averaging factors and searching for a threshold of noticable effects denies the excruciatingly obvious point that Dr. Morgan was making: If you release billions and billions of particles in a spectrum of respirable sizes into the atmosphere, people will breath them and health effects will occur. Dr. Morgan describes some of the health physics principals that might be involved in those events, that's all. It is not just an issue of whether or not the effects are "much greater" to adjacent cells at low dose rates. It is simply that such a great many billions of particles might be released in the first place, and each one is capable of producing a health effect.
The ICRP models that NASA is using are inappropriate, since they are based on detectible cancer rates rather than on plutonium's actual health effects capabilities. They are putting the bull before the horse.
Lastly, a partial cutback in mission goals could probably permit a solar solution as well. In any event, there are certainly other ambitious space projects that need funding which do not present this high risk.
1) They are afraid they cannot unfold such a thing properly.
2) It would block the antenna or vice-versa.
3) Circular arrays do not "pack" solar cells as efficiently.
1) I'm sorry to hear that NASA cannot unfold things properly.
2) I'm sorry to hear that NASA cannot envision the antenna (which is really quite small compared to the solar array) as being inside the center area of the circular array and capable of being aimed independently.
3) And I am sorry that NASA cannot square off the edges of a circle and build the "circular" array with standard rectangular components. The idea is to get the moment of inertia moved in nearer the space probe and a circular array made of smaller rectangles (it would have stepped edges) would satisfy that requirement. It appears from NASA's answer that they want to pack the cells into wedges like a pizza pie. Actually only the outer edge needs to conform, and then only roughly, to a circular shape. NASA's rectangular solar array drawings have large areas near the space craft where there is no array and THAT is what a "circular" pattern would use to move the weight inward.
I suggest NASA/JPL quit asserting that solar solutions are unworkable, go back to the drawing boards, and solve the problem (see also 2-12(e), below).
"The presence of plutonium dioxide within the environment and its availability for exposure following an accidental release would be limited due to the insoluble character of plutonium dioxide and the largely non-inhalable particle sizes of most releases. For releases within the troposphere following launch area or out-of-orbit accidents, most of the dose to exposed populations would occur as a result of direct inhalation during initial plume passage and the inhalation of resuspended material during the first year following release.
"The environmental removal mechanism of weathering would effectively remove most of the the deposited material from further interaction with the population after the first year. When potential long-term agricultural and garden ingestion pathways are considered, most of the ingestion doses result from direct deposition on above-ground leaf surfaces following the initial plume passage. The insoluble nature of the plutonium dioxide renders the bioaccumulation through root uptake an ineffective contamination mechanism. Subsequent weathering of material from the upper soil layers through runoff or downward percolation, removes such material from the surface.
"Any high altitude release of vaporized material following an inadvertent EGA reentry would be gradually removed from the atmosphere over a period of years, primarily by rainout from the lower troposphere, with ground-level air concentration peaking around 5 years following high altitude vapor release. Again, weathering following deposition would effectively remove such material from the environment during subsequent years. Any plutonium dioxide deposited in water bodies or making its way to water bodies by runoff and weathering would be largely tied up in sediment and removed from the water column."
"The effectiveness of such environmental removal mechanisms of plutonium dioxide within the atmosphere has been demonstrated by fallout studies of atmospheric nuclear weapons tests. When such factors are taken into account, extending the exposure period beyond 50 years, and even taking population growth into account would not significantly increase (i.e. less than 5 percent increase) collective dose."
The swing-by accident scenarios can produce billions and billions of respirable particles. Some reentry scenarios do not occur for 50 years or more; by that time the world population may have tripled and indeed, many projections are for that to indeed occur. Meanwhile, the various clads, shells, aeroshells and so forth around the plutonium might have become brittle from years in outer space and from being near the plutonium itself, or they might be damaged by intersellar debris.
This is by no means an impossible scenario. The radiation would have been reduced in intensity by decay, but perhaps: 1) far more will disperse than NASA estimates because the protection fails, and 2) it will disperse over a much greater population. NASA's testing on RTG containment could not possibly include a 50-year study of the various space-age material's life expectancy in space where it is subject to so many harsh environmental conditions of uncertain effect.
For all releases, including what are originally localized releases, a number of events can lead to resuspension. These include forest fires, farming, and of course inhalation of a particle followed by subsequent cremation of the victim. This can lead to two health effects from one particle! How often will it happen? That is what doing the projections out beyond 50 years might have helped us to know. Although the half-life of plutonium 238 is 87.75 years, about 10% of the plutonium will be Pu 239 with a half-life of 24,400 years. Since there is about six pounds of plutonium 239 on board, this is reason enough to present long-term radiological projections.
(Note: 1 * 10 ^(-6) reads "one times ten to the minus six" which is a decimal point followed by five zeros and a one: .000001.)
Although 1 * 10 ^(-6) does not sound like a lot of particles, there can be many billions of particles created in a EGA reentry accident, so many that 1 * 10 ^(-6) of the ground deposition could in itself be millions or even billions of particles. Also, I wonder about the accuracy of this resuspension value, because it sounds like a very difficult test to run in all possible environments, for example, in redwood forests, rain forests, deserts, wheat fields, rice paddies, etc.. Each might have a very different resuspension rate.
If there is one thing that has become clear to me from cross-checking thousands of pages of NASA documentation, it is that what NASA presents as proven, tested "fact" in one report can be orders of magnitude different from what NASA presents at some other time.
This looks like an example of NASA making vital decisions about the health risks of the planet based on complex analytical models and almost surely, incomplete information.
1/2 kilogram represents well under 2% of the total plutonium payload. This is an example of NASA averaging down the numbers before doing the health calculations. NASA can find no "credible" case resulting in full release of the plutonium dioxide so there is not one health projection based on that premise. NASA ignores all real worst-case scenarios.
NASA's previous estimate for an EGA reentry in-air vapor release, from the July 1995 EIS, was 20% to 66% vaporization of 32% to 34% of the total plutonium payload. It is not proper, I think, to claim that the technology is stable and well tested and then change the values for accidental release in an accident by so much in so short a period of time (2 years).
In the June 1997 Final SEIS, on page 2-9 in section 2.1.4, NASA states:
If what NASA says is correct, then why did the high-altitude release numbers change so much from the June 1995 EIS to the June 1997 SEIS?
Do NASA's calculations on the probability of a debris impact if the probe is in SHO (Sufficiently High Orbit) reflect not only these new numbers, which came out after the "Final" EIS, but do they additionally reflect the very probable exponential increase in debris population over the next few decades? (See comment 2-12(e), below.)
NASA is failing to compound accident scenarios. The GPHS modules may be released from the RTGs at a much higher velocity than would occur if the RTG first broke away from the space probe and then melted as it slowed down in one continuous step inside the atmosphere. If instead, the GPHSs are released individually at high velocity during the first atmospheric pass of a "skip" trajectory the amount of plutonium that might be released at high altitude can be significantly higher than the roughly 2% total NASA uses as an "average" from which its health calculations are taken.
NASA uses 1/40,000 for the chance of a space debris collision during a normal flyby manuever, which takes only about an hour. (Particle size 1 milligram or larger. See their answer to comment 2-18.) Any combination of skip trajectories with space debris collisions can result in damaged GPHS units and greater releases.
During several months in orbit (NASA says all skip scenarios which result in Earth capture will reenter "within months") the probe will be at risk of space debris collision. The risk can be very roughly calculated at being the "per hour" rate times the number of hours. In twelve weeks there are about 2000 hours, so that would be a 1 in 20 chance, but we haven't accounted for the slower speed of the probe after the brush with Earth's atmosphere. Since the probe must slow down to below Earth's capture velocity, which is around 25,000 MPH, I think we can therefore (very roughly) double the 1 in 20 number, since if the probe were to go half as fast, it would sweep through half as much space, which gives us about a 1 in 40 chance of a skip trajectory probe with a twelve week orbital decay rate also being impacted by space debris of size 1 milligram or larger before coming to Earth. Of course, this is a thumbnail calculation, which does not account for the relationship of the speeds and probable orbits of other objects, and perhaps worst of all it is based on NASA's "1 in 40,000" estimate for a space debris collision during an "normal" flyby. But 1 in 40 is quite high. Skip scenarios are scary. (See comment 2-12(e), below.)
That NASA has lied on various matters in the past in unequivical and well-documented. In regards to Cassini itself, deceptions (at least) continue.
NASA say's things like this (see NASA comment 2-27):
Then I am told by Mark Dahl (point of contact at NASA for the Cassini mission) that the analysis of the Russian Mars '96 accident simply concluded that the design was different and therefore not applicable. I consider NASA's answer to my comment #27 to be deceptive in light of what Mr. Dahl has stated.
If the Russian RTG design does not fail, then we need to immediately adopt their methodology. If the Russian design fails partially like our does, then it is inconceivable that there is no interesting data, not to mention that a test of recovery operations would be a good geopolitical (as well as humanitarian) move and a good indication of what we might be able to accomplish if Cassini fails. No such action occurred. Lastly, if the Russian design is to incinerate the RTGs completely NASA should state that. It's important and it's relevant.
Another instance of NASA's coming perilously close to a lie (or being woefully misinformed) can be seen when Mary Beth Murrill of NASA/JPL wrote to Frederica Russell in April of 1997:
First of all as I now well know, the RTGs specifically are designed to melt in an EGA reentry accident, releasing the 54 GPHSs within them. They are specifically NOT designed to "contain" their plutonium at all! This sort of oversimplification on NASA's part has caused this writer much effort to understand the situation. But aside from that:
On page 17 of the FSAR CDRL C.3 Updated Executive Summary - Lockheed Martin May 1997 Preliminary release, it says:
Also on the same page:
Here is a quote from an article by Seth Borenstein in the Orlando Sentinel, Saturday, June 14th, 1997, by Joel Reynolds, safety director at Kennedy Space Center, describing the containment system for the plutonium fuel:
Although admittedly these statements are not consistent with my earlier fear that the RTGs might actually have been designed purposely to simply incinerate their nuclear payload completely, they ALSO are absolutely not consistent with any statement that the RTGs are designed to contain their plutonium! A few pounds of plutonium 238 vaporized into the upper atmosphere is a very big spill! NASA continues to make misleading simplifications which they then pass on to the unsuspecting public and to Congressional inquiries as well.
In fact, when Mary Beth Murrill was responding to Frederica Russell the best available public information was the June 1995 EIS, which gave a number (on page 4-51) which is about an order of magnitude worse than the June 1997 SEIS indicates:
One third of the total (and from 20% to 66% of the released amount was expected to be vaporized) is frighteningly closer to my earlier fear that the RTG's are actually designed to incinerate! I wonder what the Russian design is?
Here is one final example of NASA striving to build mountains of facts from molehills of data. In this case, the molehill isn't even going in the direction NASA tries to take it. In the June, 1995 EIS, NASA writes:
Using the Freedom of Information Act, Karl Grossman, after years of effort (and two months after Galileo launched) obtained a copy of the full report that NASA was quoting from, by D. E. Rockey et al., called THE SYSTEMS IMPACT OF A CONCENTRATED SOLAR ARRAY ON A JUPITER ORBITER, which was produced at JPL in 1981. Here is the full paragraph from the report summary which NASA's first segment is from, with the three words NASA took highlighted in bold:
It does not say CSA could not be used, it says it will not be used. The difference is like night and day.
The introduction to the report further indicates that my assessment of the full paragraph is more correct than NASA's assessment was of the three words they chose to take. The introduction states:
The report even states:
Add to this the fact that since 1981 when that report came out, extensive improvements in both solar array efficiencies and in battery storage capabilities have been made, yet NASA uses an old quote completely out of context to "prove" that solar options have been given a fair chance -- and failed!
Maybe nobody at NASA really knows the truth, but they are presenting conjecture as though it were fact. Maybe everyone at NASA is simply guilty of oversimplification to the point of absurdity, but it looks quite a bit worse than that.
However, I am still sure that the larger debris objects, of which there are certainly hundreds of thousands or perhaps millions, could still cause a reentry if the impact occurs while the probe is still far way, but within the Earth Orbital Debris area. Although NASA implies in the first sentence of their comments in 2-12(g) and again in 2-18 that they track all objects (about "7000" of them) that are larger than about 10 cm, in fact at 25,000 miles NASA can only track objects that are much bigger in size.
If a prior problem causes Cassini to be on an Earth-impact trajectory, one still must consider NASA's estimates that the probability of Cassini being impacted by Earth orbital debris of size 1 milligram or larger is "about 1 in 40,000". A 1 milligram sphere of aluminum, for instance, would be about .89 mm in diameter. For objects 1 gram or larger, the number NASA gives for a chance collision is 1 in 13 million. But an object far, far smaller than 1 gram can cause mission failure:
An aluminum sphere 1.3 mm in diameter has a mass of about 3 milligrams. The Cassini space probe is not bullet-proof.
10 km/second is the average relative velocity of Earth Orbital Debris. (See page 3 of the 1995 Interagency report.) Cassini will be traveling much faster, at 19.4 km/second, and if it impacts Earth Orbital Debris the closing speeds can also be higher. It can hit something head-on at more than 30 km/second. Cassini can run into something traveling at 10 km/second in the same direction Cassini is traveling, and still collide at a whopping 9.4 km/second!
Kinetic energy increases with the square of the velocity.
Lastly note that NASA uses the figure "7000" at least twice in the June 1997 SIES (in their answers 2-12(g) and 2-18) for the number of tracked objects in Earth orbit. This is the 1989 figure. The 1995 figure is 8000, clearly indicating which figures and which orbital debris report was used for the Cassini risk calculations. The 1995 figures, which are based on actual tests done by leaving a "collector" in Earth Orbit for nearly six years, are many times worse than the analytical estimates presented in 1989. (See comment 2-10, above.) The EIS needs to be rewritten on this basis alone.
NASA is correct that the supplemental information has better graphics, but still the SEIS and the EIS were/are sorely lacking in them, which are the reports most interested parties refer to.
It is absolutely erroneous to make a claim that there are "no credible accident scenarios which would lead to the release and dispersal of the full inventory of plutonium dioxide".
While I can concede that they are not nearly as likely as partial releases, it is absolutely NOT impossible! NASA's assurance that such accident scenarios are "not credible" is clearly not based on the obvious fact that there is RIGHT NOW debris in orbit, both around Earth and in interstellar space, which can completely destroy an RTG. If Cassini passes through a cloud of such debris, all three RTGs can be destroyed, leading to full release when the remnants impact Earth. It is a crap-shoot.
It is impossible for a car's tank of gasoline to explode like a nuclear bomb. It is impossible to become younger. But it is NOT impossible that Cassini will randomly collide with one of the bigger pieces of debris (for example on the order of the size of a golf ball) that are out there rather than a micrometeoriod. NASA has no right to refuse to consider the consequences.
I absolutely disagree that the Cassini mission as flown does not violate International Space Treaties as signed by the United States and more than 90 other countries, because of the use of Price-Anderson, and because it's simply too dangerous.
Although I am not fully versed in insurance/indemnification matters, I do not believe I have "taken out of context" the "monetary amounts authorized by the Price-Anderson Act for indemnification." Price-Anderson is not so much an "indemnification authority" as the NASA comment states (my italics), but rather, Price-Anderson acts as an indemnification limit of responsibility. Price-Anderson limits the amount of money that the United States will pay in liability damages outside the United States to 100 million dollars. If this is not true, I encourage NASA to simply come out and say that.
The need for nuclear power has not been proven to be worth the risks for Cassini, and certainly it was not needed for previous missions even though at the time NASA claimed it was vital there as well. (See answer to comments 2-1 and 2-12(e), above.)
Ongoing? This is the SEIS, there are less than three months to the first launch opportunity, and we are talking about plutonium dispersal, which should have been well-studied by now. How reliable is the data NASA is using to base its guesswork on?
This is an example of NASA's inablitity to distinguish between events with a "vanishingly small" likelihood of occurence, and NO likelihood of occurence. They are absolutely unequivically without question NOT the same.
It sounds like NASA has done very little testing in this area. By how many orders of magnitude might they have misunderstood the problem?
Regarding NASA emergency response capabilities, I remain unconvinced that NASA's efforts at preparation are adequate, and in any event, I do not feel that NASA's answer relates to the scenarios I presented in the original comment #26.
An article by Seth Borenstein in the Orlando (FL) Sentinel, June 14th, 1997, interviewed Alan Kohn, a 30-year NASA veteran who retired in 1994. Kohn was an emergency preparedness operations officer and was commended by NASA for his work on the Ulysses and Galileo launches. He is quoted as saying: "They [NASA] are jeopardizing the public and they're not telling the public" about safety hazards.
Where would contaminated soil be placed? On top of more contaminated soil? And what will that sit on? Still more contaminated soil, or perhaps a water aquifer? The nuclear waste problem has not been solved, so how can NASA assure us they will be able to handle it at all?
The true effects of low doses of radiation have not been thoroughly or properly studied. To be risking so great an impact on humanity is wrong. I stand by my statements in item 34.
"Please see response to comment 2-12(c)."
The Draft SEIS was accompanied by a document called NUCLEAR SAFETY ANALYSES FOR CASSINI MISSION ENVIRONMENTAL IMPACT STATEMENT PROCESS which was prepared by Halliburton NUS Corporation, 910 Clopper Road, Gaithersburg, Maryland under Contract No. DE-AC01-92NE32165 and dated April, 1997.
If America proceeds with this mission, it will be flying in the face of reason, compassion, and logic. I urge a Congressional hearing on the whole matter of using nukes in space, on the matter of low level radiation effects, on the way NASA runs its shop, and also on the problems of space debris.
For my stand against Cassini, I have been called -- by outside supporters of NASA's plan -- uneducated, a technophobe, a Luddite, an idiot, and worse: A misrepresenter of the truth. I do not believe I am any of those things. I am a concerned citizen. I am confident that I am right in opposing the folly and madness of Cassini.
In the past few months I have corresponded with hundreds of people on both sides of this issue. I remain unconvinced that this project is safe. I hope others will join me in helping NASA to find a new way to lead the world to a better use of space, and not force us to abandon our dream of conquering the heavens in a reasonable, honest, open, truthful, peaceful way. Of course space exploration and any new thing has risks. However mankind normally endeavors to reduce the risks as much as possible in everything we do.
Cassini would have been an exciting, expensive, but relatively benign endeavor were it not for its nuclear component, and certainly no one would be objecting to it, or at least not me. I believe that NASA could rework Cassini to be a solar mission. At worst NASA could put the mission on hold for a few years to accomplish a solar conversion.
But NASA has clearly demonstrated that it avoided the solar option, that it has taken one step after another to reduce the indications of health effects from the nuclear option, and that it has obfuscated the facts to the point of nearly utter confusion. Something is very rotten at NASA. Now is the time to find it and fix it.
Submitted to NASA August 1st, 1997 by
Russell D. Hoffman
[current address:] P.O. Box 1936 Carlsbad, CA 92018-1936
Source URL of this document: http://www.animatedsoftware.com/cassini/dsei9707.htm