STOP CASSINI Newsletter #147 -- June 30th, 1999

Copyright (c) 1999

STOP CASSINI Newsletters Index

To: Subscribers, Press, Government Officials

Subject: David Grinspoon takes the bait: STOP CASSINI #147

Date: June 30th, 1999

Time Frame: Cassini is scheduled to do the flyby of Earth August 18th, 1999 (August 17th in the USA) near Africa.

Today's Subjects:

(1) David Grinspoon responds (+ response)

This next item is in response to item #3 in newsletter #140 and item #1 in newsletter #142 (both are available online at our STOP CASSINI web site.)


Date: Wed, 30 Jun 1999 21:01:59 -0600 (MDT)
From: David Grinspoon (
Subject: your clairvoyant properties

Dear Mr. Hoffman,

Yes, I'm sure that once you read my Astronomy Magazine article you will tear it to shreds. In fact, you don't even need to wait to read it! You have already analyzed it, dismissed it and insulted me, with absolutely no idea what it says! Doesn't that strike you as the slightest bit foolish?

I would be most interested in reactions to my article from any thoughtful and concerned environmental activists. However, you are clearly not in this category, and thus I am not really that interested in your reactions.

You were right about two things, but you need to look in a mirror: One of us is acting predictably, its true. And yes, one of us does owe the other an apology.

In fact, if you began your response to my article with an apology for your foolish and incorrect pre-judging, you might recover a shred of credibility. If you really care about your cause, you should consider doing so.

We need concerned, informed and involved people to act in defense of the environment now as never before. Those who discredit the cause of legitimate environmental activism with foolish behavior such as this are traitors to the Earth.

David Grinspoon

** David H. Grinspoon **
** Assistant Professor of Astrophysics and Planetary Science **
** CB392, LASP, University of Colorado, Boulder, CO 80309 **
** (303) 492-6230 **
** email: **
** Web Page: **


----- MY RESPONSE -----

Re: Your own clairvoyant properties

Dear Sir,

I didn't judge the article (unless I'm clairvoyant, how could I?), my judgements were based on the statements that were written about it. I really don't see how you could assume I was doing anything else.

One thing I received was the following statement in an email from Tracy Staedter:

"The article specifically addresses the misconception raised by activists that Cassini will pose a nuclear threat when it flies by Earth this August. Author David Grinspoon provides sound evidence for why the fly by will occur safely and why anyone worried about it should just relax."

I judged that statement and the blurb at the web site together. They certainly are a pretty clear indication of at least what Tracy Staedter, an Editor at Astronomy magazine, thinks the article is "specifically" about.

I indicated that it is absurd to frame the debate as between "environmentalists" and "space explorers" as the blurb at Astronomy's web site describing the article did. I stated that if the article frames the debate the way the blurb says it is being framed, then it is chasing a red herring because the mission, or perhaps two slightly smaller ones (that's according to Michio Kaku) could have been flown with two smaller solar probes instead of one large plutonium-powered mission. So why call it a debate between space explorers and environmentalists? The space explorers have ignored the alternatives by convincing themselves that the dangers are not very great. Why would an astronomer care, frankly, if the probe is powered by solar panels or by RTGs? It's just juice either way. (Admittedly, the handling characteristics would be somewhat different, but that's not THAT big a deal.) They were offered ONE power solution -- nuclear. They took it.

As to putting the Cassini activists at rest, I stated (based, of course, on Tracy Staedter's description of your article) that you would have to fall into one of the three corners to permit Cassini. I stated that I was eagerly waiting to see which one you fall into. And I challenged Staedter to back up some statements with Staedter's own knowledge and viewpoints, because the email to me takes a stand on the issues itself.

If the article is completely different from the statements I've been given, then perhaps I'll be delighted and I'll owe YOU (though not Astronomy magazine) an apology. It would mean the statements about the article were wrong and misleading.

The phrase "mark my words" does not indicate any assertion of clairvoyance, only expectation. If you truly have said something new, I can't wait to hear what it is. But you're not the first astronomer to back Cassini with technicalities and minutiae regarding celestial mechanics while ignoring manufacturing/planning/execution realities and medical dangers. Assuming of course, that that's what you've done. As I said, maybe it's something new.

Until I see the article, I rest my case. However, YOU have no excuse for condemning me so viciously without studying the facts. If you still want to call me a "traitor to the Earth" after reading some of the documents listed below, or others at the web site, then so be it.

I've been waiting a long time for a pleasant surprise in this game. Perhaps my wait will be over (and Tracy Staedter will owe ME an apology!) I certainly hope so. I'll make it a point to find out my fate tomorrow.


Russell Hoffman
Carlsbad, California

Facing facts: Learn about The Effects of Nuclear War here:

What is the Electromagnetic Pulse (EMP)? Is nuclear war winnable?

Hug a tree! Read why it should matter to you what happens to the great Redwoods in California:

Tug at your heartstrings for a bird!

What it's like to die of leukemia (approximately):

On race relations and my last visit with my grandmother:

----- END OF MY RESPONSE -----

My guess is not a word of this will appear in Astronomy magazine (and anyway, it would appear too late, by design). Certainly there is no way we expect to be offered "equal time" (we can't be; it would be too late). Not to be clairvoyant about it or anything.

(2) Miami Herald article + response (+ response)

The following article was forwarded to us today:


Published Sunday, June 27, 1999, in the Miami Herald

Plutonium probe flyby reignites anti-nuke protest
Herald Senior Writer

PASADENA, Calif. -- A space probe powered by 72.3 pounds of plutonium, one of the deadliest substances on Earth, is hurtling back toward our planet and reawakening the vigorous controversy that accompanied its launch two years ago.

Bound for Saturn after a journey that slings it around several planets, the Cassini probe will carry its radioactive and highly toxic fuel to within 729 miles of Earth -- at 42,300 mph.

Not much room for error there.

Scientists are fine-tuning the route now. They say they have everything under control. Scheduled time for Cassini's closest approach to Earth: 10:30 p.m. Aug. 18. [NOTE: Actually, it will be the evening of August 17th in the United States. -- rdh]

``There is no chance it will cross Earth's trajectory,'' said Ralph Miles, an engineer and hazardous-materials expert at NASA's Jet Propulsion Laboratory in Pasadena, Calif., which controls Cassini. ``None.''

Nevertheless, anti-nuclear activists and environmentalists are gearing up their protests. They say hundreds, thousands, even millions of people could die if the probe crashes into Earth's atmosphere, explodes and spews its cancer-causing plutonium fuel.

``This is a chance for us to alert the world,'' said Bruce Gagnon, a coordinator in Gainesville for the Global Network Against Weapons and Nuclear Power in Space, which claims 55 chapters around the world. ``We want NASA to send Cassini into the sun,''

Even Gagnon doesn't think that's possible. The Cassini project costs $3.5 billion.

The mission

Launched from Cape Canaveral on Oct. 15, 1997, amid sit-ins, fence climbing, unsuccessful court actions and other protests, Cassini is due to arrive at Saturn in 2004.

It is designed to conduct 27 scientific investigations of the planet, its mysterious rings and some of its 18 moons, including Titan, which bears some physical resemblance to Earth.

``It's possible we can get clues as to how Earth was born,'' said Bob Mitchell, NASA's program manager for Cassini.

The 2,500-pound probe requires flybys of Earth, Venus and Jupiter to exploit the speed-enhancing gravity of those planets. By the time it reaches Saturn, it will have traveled 2.2 billion miles.

Nuclear spaceflight

NASA says plutonium is the only practical power source because Cassini is traveling too far from the sun to employ solar power.

Other unmanned spacecraft have been fueled by small amounts of plutonium, but never as much as sits aboard Cassini. Some deep-space probes now being prepared for launch also will be powered by plutonium.

``It's clear to us that there's a major move within the Department of Energy to push nuclear power into space,'' Gagnon said, ``and NASA and the Air Force are very willing partners.''

The hazards of failure

Experts say that just one-millionth of a gram of plutonium -- an invisible particle -- could cause lung or bone cancer if inhaled or otherwise introduced into the body.

NASA's own studies estimate that if the flyby goes awry, five billion people could be exposed to low-level radiation. The agency's worst-case scenario: 120 to 2,300 people develop lung or bone cancer and die prematurely.

Opponents say many more people could be in danger. Some medical experts estimate millions of deaths if Cassini slams into the atmosphere and disperses its plutonium.

``We can and must explore space safely,'' said Karl Grossman, a New York journalism professor who has lobbied against Cassini. ``There should be no nuclear power over our heads and no weapons in the heavens, nuclear or otherwise.''

Crash `just can't happen'

But NASA says the dangers are minimal and the protesters are overreacting. They say Cassini is responding to every command and is slowly being moved into its near-miss trajectory of Earth.

Just last Thursday, NASA shepherded Cassini through a flyby of Venus. At its closest approach to that planet, the probe came within two seconds and one mile of its targeted time and spot in space.

``We've been doing flybys of planets for 40 years, and we haven't missed yet,'' said Mitchell, the program director. ``We designed this spacecraft very carefully to make sure there are things that just can't happen.''

If anything starts going wrong as Cassini's trajectory is slowly ``walked'' toward Earth, no more commands will be transmitted and the probe will pass harmlessly by, controllers said.

Originally planned to come within 320 miles of Earth, the route has been moved farther out to ease the concerns of opponents.

Activists are not satisfied.

``There are scenarios that could make Cassini re-enter Earth orbit,'' Gagnon said, ``everything from thrusters sticking to communication breakdowns.

``NASA says it can't send Cassini into the sun because then you'd be wasting $3.5 billion, but what's $3.5 billion versus the incredible catastrophe if it fell back to Earth and crashed into London or some other city?''

Won't happen, NASA says.

Said Miles: ``This is a perfect spacecraft.''



----- MY RESPONSE (JUNE 30TH, 1999) -----

cc: Karl Grossman (
From: Russell D. Hoffman (

Re: Miami Herald article on Cassini

Dear Mr. Merzer:

This article [shown above] is little more than NASA propaganda.

"Other unmanned spacecraft have been fueled by small amounts of plutonium" for example! Although Cassini has MORE than any other flight, to call 20 lbs or 30 lbs "small amounts" is crazy! Many other missions (the moon missions, for example) had about 12 or 13 pounds each. That's not "small".

And those NASA spokespersons, saying "zero" chance of failure, and "no chance" Cassini will cross Earth's path, and that the spacecraft is "perfect"!

First of all, nothing we have ever made is perfect. The list of blatant NASA failures in the past year alone is arm's length!

Those NASA employees who say such things should read NASA's own documentation (page B-4 of the June 1995 EIS for the Cassini mission, for instance) which clearly shows that any failure today which leaves the probe uncontrollable would leave it in a trajectory that "tends" (NASA's own word) to be in the vicinity of Earth's own orbit! That is NOT "zero" chance of a reentry!

I hope you will visit our web site to learn the truth -- also to learn more about the opposition to Cassini. For example, the raising of the flyby height was NOT done to "ease the concerns of activists"! It was a planned "maneuver" to keep people like YOU -- reporters -- from realizing that the activists are NOT being responded to in any democratic fashion! REAL ACTIVISTS ARE NOT SATISFIED IN THE LEAST WITH NASA'S SHENANIGANS about "raising the height" of the flyby! We want the missions STOPPED! Only the crudest and stupidest activists, or the false ones who are really agent provocateurs of the U. S. military agenda, accept such actions as being of any use at all. It's the system we object to most of all.

Thank you in advance for your attention in this matter.


Russell D. Hoffman
Founder and Editor
STOP CASSINI newsletter now in its 146th issue


----- END OF MY RESPONSE -----


From: "Marty Merzer" (
To: "Russell D. Hoffman" (
Subject: Re: Fwd: Miami Herald Article on Cassini
Date: Wed, 30 Jun 1999 18:33:47 -0400

thanks for your note, russell.


(3) Pro-Cassini Astronomer + response

I was alerted to this item by a friend at Berkeley:

-----BIO FOUND AT -----

Frederick M. Walter
Associate Professor of Astronomy
Department of Physics and Astronomy, Z=3800
Stony Brook NY 11794-3800

-----END OF BIO FOUND AT -----

----- CONTENTS OF THIS URL (AS OF JUNE 30TH, 1999): -----

Why Cassini Cannot Kill Everybody on Earth

The anti-Cassini lobby maintains that Cassini has the potential of killing everyone on Earth if it hits the Earth on its flyby in 1999, and the RTGs vaporize. The RTGs carry 72.3 lb of Pu238, a highly radioactive substance. It has been estimated that 1 microgram of Pu 238 ingested, or in the lungs, is sufficient to kill a person.

The amount of Pu238 is 32.8kg, or 3.28X10^10 micrograms. If evenly dispersed, there is enough Pu238 to give each human being about 5 micrograms of Pu238. This seems to be the reason that the anti-Cassini activists are concerned.

Should this be cause for concern? Consider this worst case scenario: Cassini hits the Earth, vaporizes entirely, and places all the Pu238 in the atmosphere.

Now, vaporization will likely occur fairly high up, in the stratosphere (meteors vaporize at about 100-150 km altitude). But let's say Cassini vaporizes at 10km, and all the Pu238 is dispersed in the troposphere, so we can breathe it.

How many atoms of Pu238 does Cassini carry? The atomic weight of Pu238 is 238 atomic mass units (AMU); one AMU is the mass of a proton, or 1.67X10^(-24) gm. Cassini carries 8.3X10^25 atoms of Pu238. One microgram of Pu238 contains 1.5X10^15 atoms.

What will the density of Pu238 in the atmosphere be? The volume of the troposphere is the surface area of the Earth (4pi R^2, where R is 6387 km) times the height of our atmosphere (assumed to be 10km), or 5.13X10^24cm^3. The density of Pu238 is 8.3X10^25/5.13X10^24, or 16 atoms per cubic centimeter (for comparison, the density of air is about 10^19 molecules per cubic cm).

Pu238 is relatively harmless unless ingested or breathed, because it emits alpha radiation, which does not penetrate far through air, or into skin. There are 2 ways to get this Pu238 into your system.

you can breathe it in. Let us assume that the Pu238 stays in the atmosphere, and does not settle out onto the ground. Let us further assume that every Pu238 atom breathed in becomes lodged in the lungs (this is not likely to happen). Now, each breath has a volume of about one liter (1000 cubic centimeters). If you breath every 5 seconds, you add 16 Pu238 atoms to your collection every 5 seconds. How long does it take you to breathe in one microgram (1.5X10^15 atoms) at this rate? Twentyfive thousand years! Even if you live that that long, it is unlikely that you will likely die of Pu238 induced radiation damage because Pu238 has a half-life of about 88 years, so after a few hundred years most of it has decayed into less lethal elements.

you can eat it. If the Pu238 all settles out of the atmosphere and sits on the surface of the earth, the density is 1.6X10^7 atoms per square centimeter. One microgram, the lethal dose, will sit in every 120X120 meter square (about the size of 4 football fields). Note that the plutonium is in form of an oxide, and is chemically inert. It will not be taken up by plants, or digested by animals. Now, suppose the lettuce crop is dusted with Pu238. Each head of lettuce has a diameter of about 20cm, or a surface of 300 square cm. How much lettuce would you have to eat to ingest a microgram of Pu238? 490,000 heads of lettuce (that's one a day for 1300 years). However, simple precautions, like washing your vegetables, or not eating dirt, would suffice to prevent ingestion.

In reality, what is likely to happen? First of all, an impact is extremely unlikely. The laws of celestial mechanics are quite precise. Trajectories can be predicted to accuracies of kilometers or better (the Mars Global Surveyor arrived at Mars, on time, and within 1 km of the expected point, after a 140 million mile, 9 month trip).

In the unlikely event of an impact, it is not likely that the Pu238 will vaporize, because ceramics have a high melting point, and the collision will be quick. The spacecraft body and the RTG shielding will need to melt first, and this will take some time. The Pu238 is in ceramic form, as an oxide, and is designed to break up into small pieces (as when you break a dish) on impact. These pieces will not stay airborne for long, are chemically inert (and so will not be taken up by plants of animals), and will not be dangerous (unless eaten).

Any Pu238 that may be vaporized will be spread out globally by winds on timescales of days, so fears of all the airborne contamination being concentrated at the impact site seem unfounded. The Pu238 will wash out (fallout) of the atmosphere in rain on timescales of a few years to tens of years. It does not seem likely that anyone will be able to breathe enough Pu238 to get a lethal dose.

Remember that, in the 1950s and 60s, there were about 500 above-ground nuclear tests (including underground tests that vented to the atmosphere) which released a few tons of Pu239 as well as fair amount of radioactive Strontium 90 and Iodine 131. Coal burning over the past 150 years has put additional tons of Uranium and Thorium (which occur naturally in coal) into the atmosphere. This has certainly caused increases in the global cancer rate, but personally, I am far more concerned by chemical pollution of groundwater supplies.

disclaimer: these are my own calculations, and represent my point of view.


----- CRITIQUE OF -----

I know of no activist (notice they aren't named!) who says Cassini will kill everyone on Earth if it reenters our atmosphere August 18th, 1999 (local time; it will be August 17th in the USA).

The writer is assuming a perfectly even dispersal (an absurd assumption) and also, that there is, somewhere, very exact studies about exactly how dangerous a microgram of plutonium is! (Notice too that the writer suggests that a single microgram of Pu 238 is sufficient to cause lung cancer; but I think the more common figure is a tenth of that. About 27 micrograms is sufficient for Pu 239 (about 15% of the Pu payload on board Cassini is Pu 239)).

The writer also thinks that if perchance there is a low-level release (certainly possible!) that it will all be in chunks. IN FACT, a single RTG could get "hung up" in the descending probe and release vaporized plutonium all the way to the ground (each RTG has about 130,000 Curies of plutonium within it). This would require permanent relocation of all people and animals in the area, at a potential cost of billions of dollars. It is also entirely possible that the plutonium will come down ON something like a gas tank. There are hundreds of millions of them all over the world (mostly near where people are) and it CAN happen that the Cassini probe will vaporize some or even ALL of its payload at ground level.

The writer also ignores completely a phenomenon known as bioaccumulation.

When someone says they will consider a worst-case scenario, that is what they should do. But that is not what this writer did. The writer claims they will assume a troposphere vaporization, but in fact, the only time the writer does so is when he says he will make that assumption. The rest of the document assumes no local accumulations of vaporized plutonium whatsoever.

The document assumes there is NO chance the vaporized plutonium will be brought down upon some unlucky city or area of teaming masses (or into the waters or croplands that nourish them) by rains in the area where Cassini comes in. (Noctilucent clouds form well above the troposphere (45-54 miles high, according to the New York Public Library Science Desk Reference (1995 edition), and who knows where their icy cargos go?) If Cassini actually released a vapor trail all the way to the troposphere, where cumulonimbus clouds can reach to the very top of, then -- if it were raining at that place and moment -- it would create a hellish accumulation on the ground over a widespread area, in a matter of minutes. The writer ignores this type of event, despite claiming he will do otherwise.

In fact, every possibility that might be other than a global 100% even dispersion is utterly ignored, and even with a "perfect" dispersion, with 6 billion people, some will get more, and some will get less, despite the "even" dispersion. Some will be more susceptible to the plutonium than "average" people, some will have greater lung capacities than "average" people, some will have less access to health care than others, some will be infants, or elderly, or have Aids or some other immunity-damaging disease (such diseases are more and more common these days). These people are EACH -- and there are hundreds of millions, all told, in these subcategories -- they are EACH going to be more susceptible than the mythical "average" person is, who is stated as being susceptible to 1 microgram of Pu 238, although again, I think the more commonly accepted value is a tenth of that.

Nowhere does the writer account for the idea that Cassini could have been done with solar panels, perhaps as two separate but slightly smaller missions. (Technology is bringing the power needs of the same missions down all the time; this trend WILL continue.) And of course the writer ignores the idea that several hundred billion lethal doses of plutonium could have made the "no fly" option (as NASA described it) very attractive back in 1990 or whenever the mission was (ill-)conceived.

The writer mentions nuclear weapons testing but forgets that most people believe that said testing caused millions of deaths -- mostly cancers, leukemias, and birth defects. In fact, just about everyone except Edward Teller (and the writer of the attached document) accepts this as a Cold War reality. And we all know "Dr. Strangelove" -- the father of the hydrogen bomb -- is exactly what we mean by "mad scientist".

Lastly, I should add that personally, I too am far more concerned by chemical pollution of groundwater supplies than I am about Cassini. Period. No question there at all. But Cassini is wrong, we said it was wrong before the launch, it remains wrong, and it remains my duty as an American citizen and civilian who has studied the facts carefully, to try to expose the fraudulent actions by which it was passed off on an unsuspecting public, and the illogical thinking its supporters delude themselves with. I will continue to do that, even after the flyby. Some will then call it sour grapes, no doubt. But justice is not served by ignoring crimes after they have been committed, and as I like to say, those who do not wish to repeat the mistakes of the past are condemned to learn about them.

-- Russell Hoffman

----- END OF CRITIQUE -----

(4) Should Cassini be redirected towards the moon?


Yeah........we want this idiotic space mosquito stopped. but not much hope now. [My son] thinks if it hits the moon it could break a chunk off which would crash to earth and not be good either.


----- MY RESPONSE -----

[Your son] may be right! He's certainly got a good head on his shoulders. It's good to have him looking at the problem.

Perhaps I have underestimated the force of the impact. It could be aimed for as deep a crater as we know of, with very steep sides or something -- after all, they say they can get it accurate to a kilometer or so! ALSO, we could smash it into the far side -- that might help reduce the chances of anything escaping the moon AND landing on us. And of course, we can fire off all the thrusters in turn, slowing the probe down with each one as much as possible. So I suspect it could be pretty certain that it would stay there.

But I'll ask around and see what everyone says.

----- END OF MY RESPONSE -----

(6) What you can do today to stop the Cassini flyby of Earth:

To learn about the absurd excuses NASA used to launch Cassini in 1997, ask them for the June, 1995 Environmental Impact Statement for the Cassini Mission. At the same time, be sure to ask them for ANY and ALL documentation available on future uses of plutonium in space, including MILITARY, CIVILIAN, or "OTHER" (just in case they make a new category somehow!). To get this information, contact:

Cassini Public Information
Jet Propulsion Laboratory
4800 Oak Grove Drive
Pasadena CA 91109
(818) 354-5011 or
(818) 354-6478

NASA states that they do not have the resources anymore to answer most emails they receive. Liars! They have $13 billion dollars to play with. They can answer the public's questions!

Here's NASA's "comments" email address:

Daniel Goldin is the head of NASA. Here's his email address: or

Here's the NASA URL to find additional addresses to submit written questions to:


Be sure to "cc" the president and VP and your senators and congresspeople, too.

Always include your full name and postal address in all correspondence to any Government official of any country.

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