STOP CASSINI Newsletter #21 -- July 8th, 1997

Copyright (c) 1997

STOP CASSINI Newsletters Index



As I write this, a check of the COUNTDOWN CLOCK at has just crossed under 90 days before the first launch opportunity for Cassini. Here is a letter to President Clinton, which I submit for comments, critics, and companions. Please distribute this widely! I promise all of you who sign on to this message, that you will NOT be alone! There are many people opposed to Cassini, and these are just some of their reasons.

Sincerely, Russell D. Hoffman, Editor, STOP CASSINI NEWSLETTER

Sincerely, Russell D. Hoffman, Editor, STOP CASSINI NEWSLETTER

**** STOP CASSINI NEWSLETTER Volume #21 July 8th, 1997 ****
Today's subjects:

* Yes, that's us in the SEIS
* A comment on NASA's new biasing values
* Is Russia's MARS 96 accident relevant?

****** VOLUME #21 July 8th, 1997 ******

By Russell D. Hoffman
Copyright (c) Russell D. Hoffman

A letter to President Clinton:

From: Russell D. Hoffman
Subject: ESSAY ABOUT CASSINI. Based on my latest interpretations of NASA's documents.
Date: 7/8/97

Dear Mr. President:

Space is big news these days.

The Russian Space Station MIR, with two Russians and one American astronaut aboard, is in trouble because of a docking collision. It is currently thought that the ultimate cause of the accident was the very human error of packing too much garbage onto the supply vehicle, which then didn't maneuver as gingerly as the controller (astronaut) had thought it would when they practiced docking maneuvers. Human error on top of human error. Any way you look at it, Russia goofed.

The current shuttle mission is a rerun of a mission cut short in January of this year. The original mission was stopped because of fear that a fuel cell problem could become explosive. NASA now says it turns out it didn't require a mission abort after all. Thus, human error (failure to assess the situation properly) was probably the actual cause of the mission abort in January. (Not to mention any human failure associated with the actual failed part, or with developing a way to monitor the situation so they knew that an explosive environment did not exist.) Any way you look at it, NASA goofed.

Right now, we are celebrating NASA's successful unmanned landing on Mars over the July 4th holiday weekend. None of the glitches associated with the mission so far have been significant and the full objectives appear to be within reach. By going to Mars we are paving the way towards a possible visit by humans within the first decade of the new millennium. Having visited the moon more than 25 years ago, we are now thinking about planting a foot on another planet.

One should note that in the past 25 years, society (which has added billions of people to its ranks in that time, and lost a billion or so as well) has not found any compelling reason to colonize the moon with even so many as half a dozen of us -- about one out of every billion people.

What society has done instead in the past 25 years is we have put an incredible amount of NEW space debris in orbit around the Earth. In fact, the increase has been approximately a straight line. The present rate of space debris creation is absolutely unsustainable and is an environmental disaster. So while NASA and the Russian Space Agency struggle with glitches, crashes, leaks and human errors, their accomplishments on Mars are overshadowed by the continued shame of what they are doing on and near Earth.

Soon, NASA plans to launch a space probe called Cassini. Cassini is designed to go to Saturn by way of Venus, Earth, and Jupiter. It will use each planet in one or more "gravity assist maneuvers" to attain the speed necessary to make it all the way to Saturn. When Earth is used for the Gravity Assist (EGA), NASA will fly Cassini just 496 miles above the surface of the Earth, at about 43,000 miles per hour (19.4 Kilometers per second, or 63,600 feet per second). The actual stated height above Earth which NASA will use has changed many times, and was 312 miles for several years prior to the latest published number.

To say Cassini is a risky mission is an understatement. It will contain over 72 pounds of Plutonium Dioxide consisting of over 60 pounds of pure plutonium 238. This is a health risk of virtually unprecedented proportions. In the past, all the weapons testing, which the world felt it was necessary to do, put an incredible amount of plutonium in the atmosphere. But that was a WAR -- albeit, a cold (blooded) one, but it was war nonetheless.

If such actions were inexcusable (and this writer and many others believe that the vast majority of past nuclear weapons testing was certainly inexcusable) then it surely is inexcusable to risk the same sort of contamination of our home turf (Earth) for NASA's next science experiment. But that is just what Cassini is capable of if an accident occurs during the launch, late launch, or during the gravity assist.

This is not a peaceful use of the mighty atom (if indeed there can be such a thing).

The purpose of 99% of the plutonium on board Cassini is to provide merely 745 watts (nominal) to power the science experiments. It is not for propulsion, it is not a "fuel" for attitude control or anything like that: it is just a small heat source used to create a very modest amount of electrical power via thermocouples. Is it necessary? No. While NASA claims that the current mission objectives would be severely hampered by insistence on a reliance on solar, in truth, there is little doubt that one of the following solutions would work:

1) NASA could reduce the mission objectives to power requirements that could be supplied by solar.

2) NASA could work harder on perfecting solar options -- with continuance of the Cassini mission, and the benefits to mankind of better solar technology, as two powerful incentives.

3) NASA could realize that mankind, while we love the quest for knowledge, does not want to take unnecessary risks, and Cassini is too risky RIGHT NOW. Therefore, in addition to perfecting the solar option, NASA should redesign the scientific tools to be used on the mission to have even lower power requirements. Probably within 10 years NASA would be able to fly the exact same mission with one tenth or at most half the power requirements -- then they could use solar options. We have waited over two decades to return to the moon -- we can wait for NASA to perfect its tools. Cassini is not necessary RIGHT NOW.

Cassini, if it is not stopped, will be launched some time in October or November of this year (1997), with a number of backup launch opportunities extending to the year 2001. Holding up Cassini will not do. It must be permanently prohibited until it can be launched with solar alternatives.

In 1964 NASA had a mission abort of a nuclear-packed mission that resulted in 17,000 Curies of plutonium being intentionally incinerated in the upper atmosphere. Opposition estimates range to hundreds of thousands of people -- or more -- who may have died from that one accident, known as SNAP-9A. In 1967, in response to a worldwide atmospheric test ban treaty, NASA changed its policy of intentional incineration of nuclear fuel packs, so that their newest RTG (Radioisotope Thermoelectric Generator) design does not intentionally incinerate.

But now, NASA is carrying many times more plutonium. Cassini is scheduled to carry about 406,000 Curies of plutonium! In an EGA reentry accident during the Earth Gravity Assist (EGA) maneuver of Cassini, NASA estimates that 4/5ths of the time there will be a fuel release. According to NASA, in an EGA reentry accident, 3/4's of the time about 13,000 Curies of the fuel will be released at high altitude, and several times more than that will be released near Earth's surface if the plutonium pellets impact on hard surfaces. But unlike the SNAP-9A, this time, somehow, it will be considered an accident! Yet virtually the same amount is EXPECTED to be released in a flyby reentry accident as was released in the SNAP-9A intentional incineration! That's some accident!

How does this work? What NASA does is it puts the plutonium into 108 separate units called GISs (Graphite Impact Shells). These units are then placed in pairs into 54 units called GPHSs (General Purpose Heat Sources). 18 of these are packed into each of 3 RTGs.

If a reentry accident occurs, the RTGs are expected to melt away and release the GPHSs. Then, the GPHSs are expected to slow down, and also melt a bit, but not entirely. Most of the time. But it's not expected to work 100% by any means.

If the GPHSs are cracked or smashed in some way while still traveling at high speed (for example, by smacking into each other or other pieces of the disintegrating spacecraft) then the GISs and the plutonium within will probably melt and be released. Every one of those 54 GPHS's must remain intact, since each one contains over a pound of deadly plutonium. But even NASA admits that it is unlikely that all of them will remain unbroken. Current NASA estimates are that 1.7 of the GPHSs will crack or "ablate" (melt away) sufficiently to release their GISs (two in each GPHS). Those GISs are expected to release their plutonium contents as vapor and small particles.

What does NASA do about this? While they could give up and go to a solar option, instead they consider this to be okay! And how do they do that? NASA does not think that a slight increase in radioactivity is anything to worry about. Since "background radiation" is already about 360 millirem per year per person, adding a fraction of a millirem to everybody is A-OKAY. But it isn't.

Plutonium 238 is a highly radioactive (i.e. "hot") substance. It is 280 times more radioactive than plutonium 239. This means that a given weight of Plutonium 238 emits about 280 times more "alpha particles" per second than the same amount of Plutonium 239 does. So a given mass of Plutonium 238 is much more dangerous, especially when inhaled, than the same mass of Plutonium 239. A Cassini reentry accident can create literally billions and billions of respirable pieces, and both sides -- pro and con -- agree that inhaling even a millionth of a gram of plutonium is a fatal dose. But NASA would risk spreading anywhere from several pounds to many pounds of this stuff in an accident. The half-life of Plutonium 238 is 87.75 years; while the half-life of Plutonium 239 is about 24,400 years. About 10% of the nuclear fuel will be plutonium 239 and most of the rest will be plutonium 238.

NASA claims that the chance of a reentry accident is less than one in one million -- but NASA bases this number on complex mathematical estimates based on "educated guesses". Past NASA flight experience suggests a much greater danger. Yet every time NASA figures out what it did wrong on a previous disaster, it discounts the obvious fact -- that they blew it again!

For example, the Titan booster rocket that NASA plans to use for the Cassini launch has successfully been used just 18 times -- and failed catastrophically once. Yet NASA's estimate of a Titan launch failure is one in several hundred -- not one in 19!

Furthermore, they have based their guess that usually only 1.7 of the GPHS units will break apart on studies done with very, very few actual units and a lot of simple computer modeling. (While very time consuming to run, the actual programs do not appear to be terribly complicated.)

When Boeing or Airbus do computer simulations prior to launching a new airplane, they risk their businesses and they risk the lives of perhaps 500 people in an accident -- both high risks. But NASA numbers, if in fact 3.4 GPHS's will desintegrate rather than 1.7 of them, would mean hundreds of thousands more deaths! This is a much greater risk! Also, the possible deviation from this number is quite high depending on many accident scenario factors. In reality, no one knows what will happen if a flyby reentry occurs. It could be that only a few pounds will be vaporized in the upper atmosphere as NASA suggests, but then again it could be more like 10 or 20 pounds -- it could even be more. And it would be very hard to tell what actually had happened, even if over the years millions of deaths were to occur from the accident.

There are many things that need to be done to stop this madness, because NASA is in no mood to stop it themselves. We have made many attempts to present NASA with an alternative viewpoint to what they consider "acceptable risk". But NASA intends to launch.

People need to learn about this awful thing. This writer is personally shocked by how surprised even the staunch environmentalists he talks to are when they learn what NASA is trying to do. The average person, today, might know what PATHFINDER is and what planet it went to, but they are sure to say "What's Cassini?" if you ask them about NASA's upcoming mission.

The public needs to hear the truth. Anyone reading this message should feel free to republish it as they see fit. President Clinton, whom this is addressed to, NEEDS to be contacted, so that he knows that people care about today's Earth more than they care about NASA's weak scientific arguments for the Cassini mission.

People need to contact their congresspeople and ask for their help in stopping Cassini as the mission is presently planned, with its deadly plutonium payload.

People need to stand up and say they ARE AWARE of Cassini, and they want it stopped -- "what is Cassini?" is not a sufficient answer for the general public who funds this sort of thing. NASA loves to promote its successes, but has an amazing ability to hide its failures behind complex scientific jargon, and a dearth of press releases. We the public should not be able to say later: "Who knew?"


For more information and more "to do" ideas, please visit our web site at:

Russell D. Hoffman
Concerned Citizen

Yes, that's us in the SEIS:

Those of you who received NASA's FINAL SUPPLEMENTAL ENVIRONMENTAL IMPACT STATEMENT FOR THE CASSINI MISSION might have notices our I.Q. Test for Space Cadets was published, and answered, by NASA in it. We will be preparing answers to their answers over the next few weeks. We have until August 4th to officially comment. Comments must be submitted in writing to:

Mark Dahl Code SD NASA Headquarters Washington DC 20546-0001

We will be sure to meet that deadline.

A comment on NASA's new biasing values:

In the current Supplemental EIS on the Cassini Mission (where many of the facts used in the above letter are presented by NASA), NASA changed two aspects of mission design since the 1995 Cassini EIS. First, they raised the height of the Earth Flyby (also known as the "swingby altitude") "from 500 km (310 miles) to 800 km (500 miles)". Second, "the last trajectory correction before the Earth swingby has been delayed from ten days prior to swingby to seven days prior to swingby . . . Both of these changes work to keep the chances of an inadvertent Earth swingby reentry below one in one million." End quote. End of paragraph, end of section. What NASA neglected to say is that their decision to do this has the effect of either: 1) Slowing the mission down somewhat or 2) Increasing the risk while swinging by other planets. You can be a little further from one planet and be a little closer to another and you can still get where you're going in the same amount of time, or you can simply travel slower by getting less of a gravity assist by doing the swingby further out. These factors increase overall failure rates while decreasing the risk of an inadvertent reentry.

The point is: If NASA feels they have to change these values to "keep the chances of an inadvertent Earth swingby reentry below one in one million" the real question we should be asking is: What caused them to think the risk now would be greater than one in one million, and thus made them feel they needed to reduce the risk to achieve this holy-grail magic risk factor number which they have promised us they have achieved? I don't know, it's not obvious from the data.

Is Russia's MARS 96 accident relevant?

In speaking to Mark Dahl yesterday of NASA, I asked him where I would find documentation on NASA's statement in their answer to item 27 in our "I.Q. Test for Space Cadets" that "Accident scenarios of the Mars 96 - type have been considered as part of the Cassini mission design and safety analysis efforts." I asked where in the reports is the Russian accident discussed? Mr. Dahl told me that the Russian design was determined to be different from the American design, and therefore there is no relevant data. That's the extent of their analysis!

I find this bizarre.

There are only three possible scenarios that happened when the Russian probe crashed last November with over 1/2 pound of plutonium. 1) Either it entirely incinerated the plutonium in which case NASA should want to study the way the material dispersed. 2) There was a partial incineration in which case it is hard to believe there is no relevant real-world data that NASA could use to check it's own estimates of how RTGs and so their components behave in a reentry accident. 3) The Russian plutonium was entirely contained and did not vaporize or release in any way. If this is what happened, then NASA especially should want to study what the Russians have done, since we are not capable of building such good containers! Ours are EXPECTED to fail about 3% of the time in the case of an Earth Gravity Assist Reentry Accident!


Please feel free to post these newsletters anywhere you feel it's appropriate! THANKS!!!

Welcome new subscribers!

Thanks for reading,
Russell D. Hoffman
STOP CASSINI webmaster.


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First placed online July 22nd, 1997.
Last modified August 17th, 1997.
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