A Scientific Critique of the Accident Risks from the Cassini Space Mission
By: Dr. Michio Kaku
Henry Semat Professor of Theoretical Physics
Note: This article is also available in a
german translation courtesy of the Netzwerk Friedenskooperative (Network of the German Peace Movement).
City University of New York
New York NY 10031
Abstract: If we carefully re-examine, line-by-line, the physics
analysis behind NASA's Final Environmental Impact Statement, we
find that the FEIS has consistently underestimated the possible
risks of an accident with the Cassini space mission. Originally,
NASA estimated the number of cancer fatalities from a maximum
credible accident over a 50 year period to be 2,300. We detail
how this figure of 2,300 deaths could easily be off by a factor
of 100, i.e. true casualty figures for a maximum accident might
number over 200,000. Furthermore, property damage and lawsuits
could be in the tens of billions. In addition, the FEIS has over-
estimated the difficulty of using alternate sources of energy,
such as solar and fuel cells. In line with the new NASA philosophy
of faster, cheaper, better, the Cassini mission should be
downsized and made into smaller, more frequent solar-powered
missions to Saturn with less power requirements.
Table of Contents:
- I. Introduction
- II. Calculation of Casualties from a Maximum Accident
- A. Launch Phase
- B. Fly-by
- III. Calculation of Risk
- A. Launch Phase
- B. Fly-by
- IV. Calculation of Solar Alternative
- V. Conclusions and recommendations
- VI. Short biography
The Cassini mission contains about 400,000 curies of plutonium-238,
making it the largest space mission ever undertaken
involving plutonium power packs (RTGs). The plutonium, about 72
pounds in weight, is distributed in 3 RTGs, with 18 modules each.
If that quantity of plutonium is somehow dispersed into a populated
environment, there is no question that such an accident
could cause significant health effects resulting in thousands of
casualties. All scientific experts are agreed on this point.
What divides the experts is:
- (a) how much plutonium can be realistically released in a maximum
credible accident and
- (b) the likelihood of such an event.
All parties are agreed that such an event is unlikely. It
may happen that the Cassini mission may be a resounding, flawless
success. However, it's only a matter of time before some disaster
strikes. Instead of relying on misleading computer programs which
tell you what you want to hear, one should carefully examine the
actual track record of accidents in the space program, with
numerous booster rocket failures and space probes which malfunction.
Unfortunately, the true risks from such an accident and the
consequences have been downplayed. In a democracy, the American
people can make rational decisions only on the basis of scientific
truth, not simplistic, misleading press releases. It is inevitable
that there will be spectacular accidents with the space
program, some involving casualties, and the American people have
a democratic right to know what the true risks are. Thus, it is a
matter of scientific interest to go over line-by-line the calculation
of the FEIS.
NASA calculates in its FEIS that up to 2,300 people might
come down with fatal cancer over a 50 year period from the dispersal
of plutonium-238 over a populated area. More recently, it
has lowered this figure to 120. However, the calculation of these
figures depends on three important steps, each of which has been
underestimated by NASA:
In each category, we will show that:
- the calculation of the "source term," i.e. the amount of
plutonium-238 which actually escapes and is dispersed into
- the calculation of the land contamination area over which
the plutonium-238 is spread
- the calculation of the population density and how many may
come down with cancer.
- a) the FEIS consistently underestimates the possible risks,
avoiding the maximum credible scenarios.
- b) since NASA has never conducted a full-scale test of a
realistic accident scenario, the FEIS simply makes up numbers to
compensate for its ignorance. However, the FEIS consistently
fabricates these numbers in a certain way: to arrive at the lowest
- c) the FEIS disguises this fact by giving the results to three
significant figures, which makes the figures seem authoritative
and accurate, when in fact they are largely created by fiction.
Of course, it is justified to make estimates. But it is then
standard procedure within the scientific community to give error
bars or estimates of uncertainty. However, one immediately spots
a glaring error: no uncertainties are ever given in the FEIS,
which is a serious flaw. No uncertainties are given because their
numbers are simple educated guesses, not real experimental
numbers at all.
II. Calculation of Casualties from a Maximum Accident
A Launch Phase (Phase 1,5 and 6)
We will investigate all three steps for two crucial phases,
the early launch phase and the fly-by phase.
- a) Source Term
The most important component of the calculation is the
determination of the "source term." The FEIS admits that plutonium
will escape from the RTGs during an accident both in the
launch phase as well as the fly-by. However, the FEIS typically
concedes that only a tiny fraction of a percent of the plutonium
inventory will escape. This severely underestimates the true
impact of a maximum credible accident and results in artificially
low casualty figures. This is the main weakness of the FEIS.
The FEIS admits that plutonium in the RTGs will be
subject to three extreme conditions during a launch phase accident:
high temperatures, shrapnel, and explosive over-pressure.
However, the essential problem is that NASA engineers have failed
to perform a full-scale, realistic test of an explosion involving
In other areas of engineering, we have a good understanding
of what happens when many different types of catastrophes happen,
e.g. plane crashes and train wrecks, because we have a large body
of experimental data. However, we have no experimental data by
which to estimate the true dispersion of plutonium during a
launch phase explosion because no realistic tests have ever been
NASA, however, has conducted some partial tests, which
already reveal the vulnerability of the RTGs to extreme environments.
The FEIS in fact, concedes that plutonium will escape the
RTGs during a launch phase explosion, but its analysis is purely
hypothetical and results in only a rough estimate.
In particular, we find:
- i) High temperatures. The iridium casing surrounding the
RTGs begins to oxidize and degrade at 1,000 degrees C, and begins
to melt at 2,425 degrees C. Graphite eutectic melting points are
even lower: 2,269 C. Experiments with the fuel cladding show that
they may resist temperatures of about 2,360 C found in propellant
fires, which is just 65 degrees below the melting point of the
iridium casing, but are expected to fail beyond that.
Several conclusions can be drawn:
- The laws of thermodynamics show that there is a statistical
distribution of molecules at kinetic energies beyond the
average one, given by the Maxwell-Boltzmann distribution, indicating
that structurally the iridium casing will begin to soften
and weaken even as it approaches its melting point. In other
words, the structural integrity of the iridium casing will degrade
as it approaches its melting point and make it possible for
shrapnel and explosive over-pressure to burst open the casing.
Thus, the combination of temperature, shrapnel, and over-pressure
may be sufficient to burst most of the containers wide open.
- Temperatures even beyond 3000 degrees C can typically be
found locally in chemical explosions and reactions (e.g. an
acetylene torch typically burns at 3,315 C). This is well beyond
the melting point of the iridium casing. As a rough estimate, we
know from the Stefan-Boltzmann and Wien's law that the color of a
flame is roughly correlated with temperature, and the color red
typically found in combustive reactions (at wavelengths of 7,000
angstroms) will be correlated with temperatures of about 4,000 C.
Thus, we can expect some melting of the iridium casing due to
local heating within the fireball, although the average temperature
may be lower than the melting point.
- ii) Shrapnel. Tests have shown that aluminum bullets fired
at the RTGs at velocities of 1,820 ft/sec and titanium bullets
fired at l,387 ft/sec have caused a breach of containment. Edge-on
fragments at velocities as low as 312 ft/s can rupture the
leading fuel clads. So even at room temperature, we can expect
high-velocity fragments to pierce the RTGs. But at high temperatures
near the melting point of iridium, where the RTG casings
are weakened by high temperatures and pressures, we can expect
shrapnel to do even more damage to the RTG casings, bursting many
of them open.
- iii) Over-pressure. Chemical explosions can cause local
over-pressures of several thousand pounds per square inch. The
RTGs have been tested to 2,210 lb/ft^2 without fuel release.
However, under the weakened conditions created by high temperature,
shrapnel, etc., it is not known how much can actually escape.
The point is that a full-scale test involving the simultaneous
conditions of high temperature, shrapnel, and over-pressure
has never been done. It is likely that the combination of all
three will cause severe rupturing of the RTGs.
In spite of all these factors and uncertainties, the FEIS on
p. 4-48 confidently concludes that a maximum of 28.7 curies, or
less than .01% of the plutonium, will escape during a launch
Several points can be made:
- This estimate is sheer speculation. The number is made up.
Since no one has ever done a full-scale test of the RTGs in the
explosive environment of a booster rocket failure, it pure guesswork
as to how much plutonium will escape.
- However, the estimates are given as a statement of fact,
with no error bars or indications of reliability. We have no
indication of the confidence level of this number. This is a
severe statistical mistake.
- The figure of 28.7 curies of plutonium is given to three
significant figures, which is rather surprising, revealing a lack
of grasp of statistical analysis on the part of the engineers.
According to the laws of statistics, the propagation of errors
determines that a calculation is no more reliable than its largest
source of error. The largest source of error in this calculation
is the fact that the engineers have made up many of the
numbers out of thin air. Thus, calculating the plutonium release
to three significant figures reveals a remarkable lack of
understanding of even elementary statistics.
- Given the fact that the simultaneous effect of high
temperature, shrapnel, and over-pressure has never been fully
tested, and given the fact that in combination they will probably
cause a large failure of the iridium casing, a figure of 30% to
40% release is probably more realistic.
- b) Area of Impact.
In typical radiological computer programs conducted by the
military and the commercial nuclear industry, the area of impact
of the accident is largely a function of wind conditions. Computer
calculations involve solving a simple second-order partial
differential equation (the standard Helmholtz equation with
source term) by iterations. Because we have the conservation of
mass, the source term is the driving term within this second
order differential equation, sometimes called the diffusion
In addition, actual experiments have shown that micron-sized
particles of natural uranium, U-238, can be dispersed by the wind
over 25 miles. In nuclear power plant accidents, radiation has been
dispersed several thousand miles from the original accident.
(For example, in the Windscale disaster in England in 1957, which
was completely hushed up by British authorities, the radioactive
cloud emerging from the carbon-moderate reactor was tracked going
over London, sailing over the English channel, and finally dispersing
over Cairo, Egypt. More recently, the radiation from Chernobyl
was widely tracked over Europe and even the U.S.)
However, what is rather remarkable is that the FEIS totally
ignores wind conditions and merely postulates that the plutonium
will be dispersed, in one scenario, within an area of 7.18 x 10^-2
square miles. This is a roughly a square area 1,000 feet on
each side. Again, the fact that this is presented without any
error bars, and to three significant figures, shows the ignorance
of the engineers who calculated this number.
But what is revealing is that the FEIS assumes that almost
all the plutonium will be confined to the launch facility.
According to the FEIS, no plutonium is expected to leave the launch
pad area. In other words, NASA engineers have discovered a new
law of physics: the winds stop blowing during a rocket launch.
But anyone who lived through the Challenger explosion, the
Delta rocket explosion, etc., will realize that debris has been
pulverized and spread over a significant area. Eyewitness accounts
of the recent Delta rocket explosion indicated debris
scattered over several miles.
In fact, experiments conducted on metal oxides have shown
that a significant percent of the inventory can be pulverized
into a fine dust of micron-sized particles, which can then be
blown miles from the original site by the winds. These micron-sized
particles are especially dangerous because they stay lodged
deeply in the lungs for decades, where ciliary action is useless
in expelling these particulates. Thus, these particles can emit
radiation at close range to nearby lung tissue for decades to
come, causing cancer.
- c) Population density.
Yet another reason for attaining low estimates of risk is
the FEIS's assumption that the population density is rather low.
In this calculation, one problem is determining the number of
person-rems which will initiate a cancer. One can reasonably
assume that 5,000 person-rems will induce a single cancer.
(Although some critics have placed the true figure as low as 300
However, what is in dispute is the fact that the FEIS assumes
a rather average density of people per square mile. This is
therefore not a maximum credible accident, which would assume
that the winds blow the plutonium into a major city.
For example, the FEIS assumes that, for a Phase 5 accident
over Africa, the expected health risk would be 1.5 x 10^-4 over a
population of only 1,000 people. This is low even for Africa. Not
to mention that the rocket may misfire during the launch phase
and tumble in a partial orbit, thereby landing almost anywhere on
the earth, rather than in Africa.
A Phase 1 accident would release plutonium in an area populated
by only 100,000 people. But if the winds blow, then the
area affected within 5 counties of the launch site could total
over a million people.
B. Fly-by Phase (VVEJGA Phase)
The source of greatest concern, from the point of view of
plutonium release, is the fly-by.
The Cassini probe will be whipping around the earth at
around 40,000 miles per hour, significantly faster than the
escape velocity of the earth (25,000 miles per hours) and faster
than many meteorites. If there is even the tiniest miscalculation
of the trajectory, the Cassini may burn up in the atmosphere and
spray a significant portion of land area with plutonium. There is
ample experimental evidence that space probes, without heat
shields, will vaporize upon re-entry. However, the FEIS again
takes a low estimate of plutonium release.
- a) Source term.
The FEIS admits that about 32% to 34% of the plutonium is
expected to be released high in the atmosphere. However, the FEIS
then dismisses this factor by diluting it over the population of
the entire earth. This neglects the fact that the mixing of
plutonium in the atmosphere takes a considerable amount of time,
and in the meantime it may concentrate or hover over certain
regions of the earth. This effect is ignored by the FEIS.
The FEIS then calculates how much plutonium may actually
land on the earth, and again underestimates the real risks.
The FEIS first divides the source term into three parts: a
rock impact, soil impact, and water impact, and then calculates
the percent distribution of each on the planet earth. For example,
the FEIS estimates that 4% will hit rock, 21% will hit soil,
and 75% will hit water.
This is a rather odd way of calculating maximum risks,
because it confuses probability of an accident with the consequences
of that accident. The calculation of how much surface
area of the earth is divided into rock, soil, and water belongs
in a calculation of the probability of mishap, not in the
calculation of maximum risk.
The calculation of maximum credible risk necessarily assumes
maximum risk by definition, i.e. that all the plutonium will hit
rock, since that is the maximum credible scenario. Rather than 4%
of the plutonium hitting rock, one should assume that all of it
Second, the FEIS calculates the percent of plutonium that
can be released on impact with rock, soil, and water. Again,
these numbers are simply pulled out of a hat, with no justification.
For example, in one scenario, it assumes that all of the
plutonium will be dispersed if it hits rock, 25% of the plutonium
hitting soil will escape, and none hitting water will escape.
However, no justification is given for these estimates, because
there are none.
The important point is that no one has ever done an experiment
calculating the effect of entering the atmosphere with RTGs
at 40,000 miles per hour. Until this experiment is done (using a
replacement for plutonium), all these numbers are purely speculative.
- b) Area of impact
The estimated land contamination for this plutonium accident
is on the order of 2,000 sq. km. That is roughly equivalent to a
square about 27 miles on a side.
More recently, on April 1997, the Supplemental Environmental
Impact Statement has revised the early estimate of cancer fatalities
from 2,300 to 120 (p. 2-19). This may seem strange, until
one realizes that their assumptions have become even more conservative.
Instead of assuming that land contamination can be
2,000 sq. km, the new estimate puts it at a surprisingly small
area of 7.9 sq. km. This is a square about 1.7 miles on each
side. In other words, the new EIS assumes that the Cassini probe,
coming down in flames from outer space at 40,000 miles per hour,
will hit a bull's eye and then remain there, without any winds
This is a remarkable reduction by a factor of 250, which
once again is pulled out of a hat, without any justification. Not
surprisingly, the casualty figures have also dropped significantly,
from 2,300 to 120, a factor of 20.
- c) Population density
Again, the FEIS assumes average figures for population
density, and totally neglects the fact that there are large
population concentrations on the earth where tens of millions
live. Within a 50 mile radius of Manhattan, for example, there
are about 20 million people, or about 8% of the entire population
of the U.S. Similarly, there are other concentrations of people
on the earth with even larger densities, such as around Tokyo,
Mexico City, and Shanghai.
III. Calculation of Risk
The analysis used by the EIS to calculate the probability
of a maximum accident with the Cassini mission uses
methods pioneered by the nuclear power industry (e.g.
single event failures, event tree analysis, Monte Carlo
Although these methods are standard for the field,
these methods have largely been discredited by the actual operating
record of nuclear power accidents. Three Mile Island, for
example, was a Class IX accident which was largely unforeseen by
MIT's WASH-1400, the standard reference within the industry,
which largely ignored small pipe breaks.
The methodology is flawed for several reasons:i) Human error and design flaws.
Most of the major accidents that have taken place in the
past are beyond the simple-minded event-tree analysis of the
FEIS. For example, one can design a car such that the chances of
an accident approach a million to one, with air bags, anti-lock
brakes, seat belts, etc. However, this does not foresee the fact
that someone might drive this car over a cliff.
The actual track record of accidents shows that computer
calculations are often misleading and give a false sense of
The real danger is that the engineers begin to believe their
own computer calculations, which are only a guide, not a law of
nature. Then they become overconfident and fail to foresee the
- Three Mile Island was caused by human error (misreading the
PORV valve light on the control panel) and design flaws (lack of
a water gauge meter in the containment vessel and poor design of
the PORV warning light). It was not foreseen by WASH-1400, which
concentrated on large pipe brakes.
- The Chernobyl disaster was caused by human error, when the
engineers and managers manually disengaged the control rods.
There were also design flaws, since the carbon-moderated reactor
was prone to a positive reactivity power surge. During the accident,
when a transient sent power levels rising, the lack of a
SCRAM system caused neutron levels to rise exponentially, causing
a steam/hydrogen gas explosion which blew the top the reactor.
- The Hubble Space Telescope was launched into space with
incorrectly ground mirrors. This mishap was also caused by human
error. Part of the fault, among others, lies in a worker who
inserted a ruler in backwards in Danbury, Connecticut, where the
mirror was being machined, thereby making possible an incorrect
shape for the mirror. Remarkably, the flaw was later detected,
but ignored by engineers. It was not noticed until the mirror was
launched into space, causing a billion dollar public relations
- Star Wars. In a well-known mishap, the Space Shuttle was
conducting a test of the Star Wars laser system, with a laser
beam sent from Hawaii. Because of human error (converting miles
to meters incorrectly), the Shuttle was oriented in space away
from Hawaii, not towards it, and missed the signal completely.
ii) GIGO. There is an expression, "garbage in, garbage out."
Even if you use the world's largest supercomputer, if your assumptions
are faulty, then your conclusions will also be faulty.
For example, one can use a supercomputer to calculate the precise
number of angels that can dance on the head of a pin. But giving
you this number to three significant figures is meaningless,
since the original assumption was in question.
iii) Similarly, the basic assumption of the FEIS is that
one can model accidents on the basis of single event failures, when
multiple failures, common mode failures, human error, and design
flaws have contributed to most accidents. Unfortunately, it is
beyond the power of computers to realistically model these more
complex types of accidents.
iv) Weakest link: the Titan IV
A chain is no stronger than its weakest link. The weakest
link is the Titan IV booster rocket, which has a failure rate of
about one in 20. And booster rockets in general have a failure
rate of 1 in 70 or so. Furthermore, there have been 3 failures
among the 23 missions involving plutonium power packs, one which
released a significant amount of radiation. In fact, everyone on
the earth has a piece of the SNAP 9A satellite in their body. The
SNAP 9A satellite also significantly increased the amount of
plutonium-238 on the planet earth.
v) Where does the one-in-a-million figure come from?
The FEIS typically has accident probabilities in the range
of one-in-a-million. By analyzing the calculation, one can see
where this figure comes from. One can see that most of the
one-in-a-million comes from the impact of a micrometeorite on the
Cassini probe. In the FEIS, very little of the probability comes
from errors in transmission, errors from ground control, etc.
This patently violates the actual experience with space probes.
Meteorite damage is of a real concern, but human and technical
flaws are much more likely to cause failure. For example,
it has been recently estimated that the International Space
Station Alpha may suffer a 50% probability of a catastrophic
meteor impact during its 15 year life span. This is certainly a
significant danger. But actual operating experience has shown
that in almost all space missions, the real danger comes from
human and technical flaws, i.e. sending the wrong instructions to
space probes, failure of transmitters and solar panels to unfurl
correctly, etc. These are almost impossible to model by computer.
vi) Furthermore, a one-in-a-million figure assumes that one
million Cassini space probes have been fired into space, and only
one Cassini space probe malfunctioned. This is clearly untrue.
In other words, the table of probability given by NASA is just a
wish list. The one-in-a-million figure is wishful thinking
masquerading as reputable science.
IV. Calculation of Alternatives
The FEIS undertakes a half-hearted effort to calculate
alternatives to using plutonium. Since only 800 watts of power
need to be replaced, or the output of roughly eight light bulbs,
the alternatives must be taken seriously.
There is no question that, in deep space, there is not much
sunlight. At the distance of Saturn, there is only 1% of the
solar flux found on the planet earth (in watts/sq. meter).
The debate revolves around whether solar/fuel cells can make up
the 800 watts necessary to run the mission.
The FEIS on p. 2-56 claims that, if the Cassini is equipped
with massive, bulky solar panels, the probe will be 130 pounds
too heavy for lift-off. (The Titan IV can lift 13,743 pounds of
payload to Saturn). However, the calculation is incomplete, since
it does not consider some simple options:
Downsize the craft. If the probe is 130 pounds overweight,
then the obvious solution is to lose 130 pounds of equipment.
This means leaving out some experiments. However, the
Cassini is the Cadillac of space missions, and a few less redundant
experiments will still give us excellent science. This may
be the solution.
Conform to the new NASA philosophy. The new philosophy of
NASA is faster, cheaper, better. For example, the Mars Observer
was a billion dollar fiasco: bulky, costly, infrequent. The new
Mars probes were correctly downsized; the new strategy is to send
small space craft to Mars twice every two years. Similarly, space
shots to Saturn should be downsized and made more frequent, not
less frequent, and energized by solar cells.
Cassini is therefore a left-over from the old NASA philosophy
of doing big space shots once every 10 years. Since space
probes were so infrequent, this philosophy resulted in space
craft that were overloaded with experiments, and hence the RTGs
seemed a natural solution. But the new philosophy of NASA should
generate small, frequent, and cheap probes to Saturn which are
well within the capability of solar power.
Saturn is not going away. All this will cause delays, but
Saturn is not going to go away. Other windows of opportunity will
open up. Given the fact that one can whip around other planets
and change trajectory, windows of opportunities open up all the
Use a combination of solar/fuel cells. The FEIS only
considers solar and fuel cells separately, not in conjunction.
Fuel cells can be used to store energy when solar cells can no
longer receive adequate energy from the sun.
V. Conclusion and recommendations:
We all live in a world of risks. Every day, when we enter
cars or airplanes, we place our bodies at risk. Therefore, we
must be careful in how risks are handled.
But the difference with the Cassini mission is that we
voluntarily put ourselves at risk when traveling. However, no one
asked the American people if they wanted to put themselves in
danger. NASA bureaucrats, not the American people, are making
Second, if we are in a car accident, only a handful at most
will die. But no one told the American people that thousands may
die if a plutonium accident takes place.
Similarly, the FEIS justifies the figure of 2,300 cancer
deaths by stating that that figure is lost in the background
cancer levels found world-wide. This is a strange argument. That
same argument can be used to justify mass murder. Since thousands
die violent deaths in the U.S., it makes no difference if a few
hundred more die by a serial killer. They will be lost in the
Of course, we all want a healthy, vibrant space program to
explore the universe. However, it should also be made safe. Since
the American taxpayers are paying for it, they have a right to
know the true risks, and should be informed of the debate concerning
accident risks within the scientific community.
Unfortunately, the American people, being constantly told
that the probability of an accident is on the order of one in a
million or a one in a billion, will feel betrayed when a catastrophic
accident does occur in space. Such a space tragedy could
cause a backlash from the American people, who will correctly
feel that they were lied to by NASA bureaucrats. This could be
the end of the space program, which would be a disaster to
Furthermore, there is no mention of property damage in such
an accident. The Three Mile Accident, for example, reputedly
released just 13 curies of iodine (compared to 400,000 curies in
the Cassini mission) yet it generated two billion dollars in law
Even if no significant amounts of radiation are released in
a plutonium accident, property values are expected to plummet.
And if significant amounts of plutonium are released, then whole
areas must be quarantined, earth dug up and placed in 55 gallon
drums, houses hosed down with fire trucks, crops impounded, etc.
That was one terrible lesson from Chernobyl. The loss to home
owners and the agribusiness in the area around the Cape could
amount to tens of billions of dollars.
Therefore, the mission of a critic is to save the space
program from NASA bureaurcrats.
Unfortunately, NASA commits the worst mistake that a scientist
can ever make: believing your own press release. A casual
observer, reading the FEIS, may be deceived into thinking that a
careful analysis has been done. But when actually reproducing the
calculation, the observer will be shocked at how many guesses,
hidden assumptions, and minimizations of risks there are in the
A true scientist carefully writes down the error bars and
the confidence level he or she places in their figures. A careful
scientist does not do what NASA has done:
- a) fail to perform full-scale accident tests
- b) pull numbers out of hat to compensate for this ignorance
- c) dress up these fake numbers with complex computer pro-
grams that cannot measure the true risks from human error, etc.
- d) publish the results with an accuracy of 3 significant
figures, with no mention of error bars, confidence levels, or a
list of assumptions.
This borders on scientific dishonesty.
It is no accident, therefore, that the FEIS comes up with
consistently low numbers for a maximum accident.
The simplest way to solve our problem is to use solar cells
with fuel cells. This will require downsizing the space craft by
at least 130 pounds. But this is also in tune with the new
philosophy of faster, better, and cheaper. The Cassini mission,
however, is a relic of the old thinking of slower, more expensive,
A new program to explore the planets would have these probes
downsized and launched much more frequently, using non-nuclear
In the interim, this may cost more and cause some delays,
but it may also have the lives of thousands, prevent law suits
numbering in the tens of billions, and save the space program
from NASA bureaurcrats.
VI. Short biography
Dr. Michio Kaku is the Henry Semat professor of theoretical
physics at the Graduate Center of the City Univ. of New York. He
is one of the world's leading authorities on Einstein's Unified
Field Theory. He is the co-founder of string field theory. His
textbooks on quantum field theory, superstring theory, quantum
gravity, and conformal field theory are used by Ph.D. students in
leading institutions around the world. He has lectured to the
Soviet Academy of Sciences in Moscow, at Oxford Univ., Cambridge
Univ., Univ. of Rome, the Univ. of Tokyo, and CERN in Geneva,
He received his B.A. in physics from Harvard in 1968. He
graduated summa cum laude (with highest honors), Phi Beta Kappa,
and number one in his physics class.
He received his Ph.D. at the Radiation Laboratory at the
Univ. of Calif. at Berkeley in 1972. He was a research associate
at Princeton University in 1973, and has been a professor at CUNY
for the past 25 years. He has been a visiting professor at Cal
Tech, the Institute for Advanced Study at Princeton, and New York
He has published 9 books and 70 articles in the scientific
literature (including Nuclear Physics, Physical Review, Physics
Letters, Physical Review Letters).
He is a Fellow of the American Physical Society, and honor
held by the top 10% of physicists in the U.S.
Reprinted online by permission of Dr. Michio Kaku.
First placed online August 9th, 1997.