A look at NASA's own documents
With comments by Russell D. Hoffman
This document contains the entire text in order, at the time we found
it, of NASA's own document which can be found at the following URL:
We have added our comments and italicized NASA's original statements.
I'm sure I hardly need to add the we would welcome an attempt by NASA
to refute the assertions made in this article. If they do we will be
happy to add a link to it, and then tear it apart as well.
While they may have had some successes, they have also had some
dismal failures, including Apollo 13. Although not mentioned in
the recent Hollywood movie, there was plutonium onboard the lunar
lander, plutonium which was supposed to be left on the moon but instead
was brought back to Earth in a fireball somewhere near New Zealand. We
currently buy our Plutonium 238 for our RTGs from Russia which means
its use involves unlicensed and unregulated (by U.S. agencies)
nuclear sources and transport halfway around the world prior to use.
Dismal as our nuclear safety record has been, Russia's is far worse.
Spacecraft Power for Cassini
Cassini's electrical power source - Radioisotope Thermoelectric Generators
(RTGs) - have provided electrical power for some of the U.S. space program's
greatest successes, including the Apollo lunar landings and the Viking Landers
that searched for life on Mars. RTGs made possible NASA's celebrated
Voyager explorations of Jupiter,
Saturn, Uranus and Neptune, as well as the Pioneer missions to Jupiter and
Saturn. RTG power sources are enabling the Galileo mission to Jupiter and the
international Ulysses mission studying the Sun's polar regions.
And as for using it on our Ulysses mission to the Sun -- doesn't it
seem strange that NASA could not even find a solar alternative for
The fact that RTGs provided the power for past missions does not mean
it was the only solution that NASA could have used, and even if it
were, it no longer is. Solar power works.
Freedom of Information Act documents obtained by Karl Grossman show
that even NASA knows it has viable solar alternatives. That makes
this statement a lie, and even if it were true, technology is improving
as such a rate that it is inconceivable that a solar-powered
solution would not be available within the next few years -- if only
NASA would look for it.
Extensive studies conducted by NASA's Jet Propulsion Laboratory (JPL) have
shown that NASA's Cassini mission, given its science objectives, available
launch systems, travel time to its destination and Saturn's extreme distance
from the Sun, requires RTGs.
What Are RTGs?
"RTGs are lightweight, compact spacecraft power systems that are extraordinarily
reliable. RTGs are not nuclear reactors and have no moving parts. They use
neither fission nor fusion processes to produce energy. Instead, they provide
power through the natural radioactive decay of plutonium (mostly Pu-238, a
non-weaponsgrade isotope). The heat generated by this natural process is
changed into electricity by solid-state thermoelectric converters. RTGs enable
spacecraft to operate at significant distances from the Sun or in other areas
where solar power systems would be infeasible. They remain unmatched for power
output, reliability and durability by any other power source for missions to
the outer solar system."
This paragraph contains several falsehoods. First of all, there is no
"natural" radioactive decay of plutonium. The term in inappropriate.
Plutonium does not exist in nature! Every ounce of plutonium, the most
dangerous substance known to man, was created by man. Hard to believe,
isn't it? So while other radioactive substances have a "natural"
decay rate, plutonium's radioactive properties should not be thus described.
It's a little thing, to be sure. Pure semantics. But why do the
semantics always seem to fall "their" way?
Second, it is simply not true that solar energy would not work.
Additionally, new developments in computer and
machine and micromachine technology are reducing the required power
consumption of virtually every component on board Cassini. In fact,
considering how long Cassini has been in development, it is probable
that more modern off-the-shelf components would use much less power than
the RTG's are designed to deliver!
The fact that they performed as designed is irrelevant. The fact
is that in just 23 missions, 3 were failures. (Or, as NASA puts it,
"experienced malfunctions", but don't forget what an explosion
like the Challenger is to NASA: a "malfunction.") That's a lousy
percentage. Why put humanity at such risk for those lousy odds?
The United States has an outstanding record of safety in using RTGs on 23
missions over the past three decades. While RTGs have never caused a spacecraft
failure on any of these missions, they have been on-board three missions which
experienced malfunctions for other reasons. In all cases, the RTGs performed as
Also, even if every previous mission had been a success, that would
prove nothing (but NASA would make big of it, you could be sure.)
For even I do not argue that the odds are against the worst-case
scenario. But look, if you do something that has a 1 in a million
chance of killing a million people, those are simply bad odds. No
two ways around that fact! NASA argues that various Cassini failure modes
have such long odds, but they are just speculating. The fact is, in
23 missions, 3 "malfunctions". So what if the RTG's weren't to
blame? They were there, and they didn't have to be. It's like the
guy that brings a weapon to a crime scene. Even if he doesn't
use it, bringing the weapon makes it much more of a crime. A bar
fight, and a bar fight where weapons are drawn, are very different criminal
cases. NASA should put its weapons away. There's no fight going on.
From most accidents. Not all accidents. Just most of them. What
does that mean--51 out of 100 accidents? That's most. NASA, can you
possibly be any less clear on what you really think the odds are?
There is no way NASA has engineered a solution to the problems of
a shallow accidental reentry or that of a random collision with space
debris. Neither of these are "remote possibilities". The future space
station is expected to be hit by a major piece of space debris -- one
too big to build in protection against -- once every 50 years. That's
not remote. That's a dangerous mission. But Cassini is endangering us
all, not just the highly paid and highly trained adventurers and
risk-takers we all admire called astronauts.
More than 30 years have been invested in the engineering, safety analysis and
testing of RTGs. Safety features are incorporated into the RTG's design, and
extensive testing has demonstrated that they can withstand physical conditions
more severe than those expected from most accidents.
First, the fuel is in the heat-resistant, ceramic form of plutonium dioxide,
which reduces its chance of vaporizing in fire or reentry environments. This
ceramic-form fuel is also highly insoluble, has a low chemical reactivity, and
primarily fractures into large, non-respirable particles and chunks. These
characteristics help to mitigate the potential health effects from accidents
involving the release of this fuel.
When you are dealing with a substance so
deadly that less than 1/70 of the Cassini load is enough to kill
everyone on Earth "if properly distributed" and high-altitude
incineration is just the ticket to proper distribution, dividing it into
18 smaller groups is hardly comforting! Dividing 72.3 pounds
of plutonium into 18 "small" units means four pounds of plutonium in
each one, and that's not small and that's no safety feature at all--each
module can kill everybody at least four times over! Not one of these
"modules" should be risked in upper-atmosphere incineration!
Second, the fuel is divided among 18 small, independent modular units, each
with its own heat shield and impact shell. This design reduces the chances of
fuel release in an accident because all modules would not be equally impacted
in an accident.
43,000+ miles an hour is how fast Cassini will be traveling on the
flyby -- the fastest object man has ever buzzed earth with. At
that speed, passing too close to Earth during the flyby could result
in friction temperatures which would demolish the spacecraft and quite
possibly damage the plutonium cargo. Collision at that speed with any of
the millions of pieces of space debris which man has already placed
in orbit can pulverize the RTGs protective covering. NASA knows
this and they aren't mentioning it. They have decided that any
hazard they cannot fix is irrelevant. To NASA, "unlikely" and
"impossible" are the same thing. They aren't. Cassini is a game of
chance in which the winners are the nuclear space industry and the
losers are you and I and every other living thing on Earth.
Third, multiple layers of protective materials, including iridium capsules and
high-strength graphite blocks, are used to protect the fuel and prevent its
accidental release. Iridium is a metal that has a very high melting point and
is strong, corrosion resistant and chemically compatible with plutonium
dioxide. These characteristics make iridium useful for protecting and
containing each fuel pellet. Graphite is used because it is lightweight and
It is presumably true that RTG's cannot explode. But they absolutely
can burn up on reentry. The plutonium will then disperse
throughout Earth's atmosphere. If it does this, cancers and
other sicknesses will occur throughout the
world. Acute Radiation Sickness would not occur. So what?
No one is mistaking anything here, except NASA. Plutonium spread in fine
particles throughout the upper atmosphere not only CAN happen, it HAS
happened. And if we don't stop the madness, it WILL happen again,
and again, and again. Not just Cassini, but every nuclear mission is
Potential RTG accidents are sometimes mistakenly equated with accidents at
nuclear power plants. It is completely inaccurate to associate an RTG accident
with Chernobyl or any other past radiation accident involving fission. RTGs do
not use either a fusion or fission process and could never explode like a
nuclear bomb under any accident scenario. Neither could an accident involving
an RTG create the acute radiation sickness similar to that associated with
Additionally, it is hardly comforting that NASA has endeavored
so hard to ensure that the plutonium pods will be intact upon impact.
If these intact pods are found by terrorist groups they could be used
for a number of hostage and ransom purposes, even if you could not make
a nuclear weapon with them. If found by children or other living things,
they could certainly be mishandled. Even if they do survive the burning
reentry, final impact could still break them into thousands of irretrievable
pieces even if they are not "vaporized". Any confined area would surely be
devastated by the needless introduction of 72.3 pounds of plutonium
chunks -- cities, lakes, rivers, reservoirs, stadiums, schools...
NASA uses the nuclear option in the first place. That's the mistake.
Any other plan for safety is going to fall short of the goal of
flying the safest possible missions. True safety is achievable.
Plutonium does not belong in space. The so-called
experts are people from the nuclear government, the nuclear industry,
and the engineering academia who want to see their little science
experiments fly. I believe most physicians who have studied the
issue are required by their own Hippocratic Oath ("First,
do no harm") to oppose risking the spread of plutonium throughout the
environment when there is no significant benefit to mankind.
NASA places the highest priority on assuring the safe use of plutonium in space.
Thorough and detailed safety analyses are conducted prior to launching NASA
spacecraft with RTGs, and many prudent steps are taken to reduce the risks
involved in NASA missions using RTGs. In addition to NASA's internal safety
requirements and reviews, missions that carry nuclear material also undergo an
extensive safety review involving detailed verification testing and analysis.
Further, an independent safety evaluation of the Cassini mission will be
performed as part of the nuclear launch safety approval process by an
Interagency Nuclear Safety Review Panel (INSRP), which is supported by experts
from government, industry and academia.
As mentioned previously, power requirements of computer and
mechanical devices are dropping rapidly due to improvements in
ceramics, chip design, and wiring techniques (many of these
improvements, of course, are coming right out of NASA!) If we could
wait a mere decade and do this safely, why not? Why not put the scientists
to work on low-energy, high-efficiency devices that would ease power
consumption requirements not just for NASA, but for everyone else?
NASA can do this. They know they can do this and we want them to do
this. Part of NASA's original and ongoing purpose has always
supposedly been to create technology we can use on Earth.
Plutonium-powered RTGs have no use on Earth, and will never be used
on Earth. If NASA would help develop solar technology, on the other
hand, that would have great usefulness here.
Non-Nuclear Alternatives to RTGs
JPL studies have concluded that neither fuel cells nor spacecraft batteries
demonstrate the operational life needed for planetary missions, whose duration
can exceed 10 years from launch. In addition, the large mass of batteries that
would be needed to power a mission such as Cassini greatly exceeds current
launch vehicle lift capabilities.
So these are things you work on, NASA -- not things you give
up on! All of these problems are solvable in due time -- not one is
an insurmountable wall. There is no need to risk the use of
plutonium for these excuses. If you folks over at NASA are so
inventive and such geniuses, why did you give up so easily? Even
the Ulysses mission to the Sun wasn't solar powered--are we supposed
to believe you are even trying? If the behavior of solar cells at
vast distances from the sun is not well understood, then
that's what your next mission should study! Low power consumption
devices and low light solar cells are needed by everyone -- NASA
could be the heroic knight in shining armor coming to save us through
technology -- but they aren't even trying. Instead they are trying
to get away with stuff they know is dangerous. We give them billions
of dollars and this is their response -- secrecy, obfuscation, lies.
I challenge NASA, in the interest of free inquiry and presenting a
balanced view, to link to our site as we have linked to theirs!!
JPL's rigorous analysis has also taken into account the advances in solar power
technologies that have occurred over the last decade. The conclusion reached by
the researchers at JPL is that solar technology is still not capable of
providing sufficient and reliable electrical power for the Cassini mission. The
mass of solar arrays required would make the spacecraft too heavy for available
launch vehicles. Even if a sufficiently powerful launch vehicle were available
for an all-solar Cassini, other limitations exist with current and near-term
solar technologies, including:
- The behavior of solar cells at vast distances from the Sun is not
well understood and would add significant risk to the success of a
solar-powered mission to Saturn. Saturn is located approximately 1.42 billion
kilometers (882 million miles) from the Sun, nearly twice as far from the Sun
as Jupiter, the next closest planet.
- The size of solar arrays that would be needed, about one-quarter
the area of a football field, would not only be difficult to deploy reliably,
but would significantly increase the orbiter's moments of inertia, making turns
and other timely maneuvers extraordinarily difficult to perform This would
severely inhibit Cassini's ability to achieve its science objectives.
- The large arrays would seriously interfere with the fields of view
of many of the science experiments and navigation sensors, further limiting
the Cassini mission's ability to achieve the science objectives.
- Large arrays could generate serious electromagnetic and
electrostatic interference, which would adversely impact the operation of the
science experiments and the spacecraft's communications equipment and computers.
Aiming off to the side until ten days before the Earth swingby sounds
like a safety procedure, and to some extent it is, but the fact is
that doing it this way can actually increase the danger to
mankind. How? Simply this: To make the swingby work, they will
HAVE TO perform a manuever which forces Cassini towards Earth. If
they fire the rocket for even a second or two longer than they
should, the Cassini probe will be forced towards an upper Earth
atmosphere incineration. Understeer can be just as deadly as
oversteer. This is not a safe manuever at all but is presented as
such to give us the impression that they have done all they can.
Cassini's Earth Swingby
By aiming a spacecraft so that it passes very close to a planet or moon, it
is possible to boost the spacecraft on to still more distant destinations with
greater velocity. Called the "slingshot effect" or, more properly, a
this maneuver has become an established method of launching massive,
instrument-laden spacecraft to the outer planets. Cassini plans to make use
of this technique when it swings by Venus twice, then the Earth and Jupiter to
reach its ultimate destinaton of Saturn.
The Earth swingby does not represent a substantial risk to Earth's
population because the probability of a reentry during the maneuver is
extremely low, less than one in one million. NASA's robotic planetary
spacecraft have performed numerous similar maneuvers with extraordinary
precision. The redundant design of Cassini's systems and navigational
capability allows control of the swingby altitude at Earth to within an
accuracy of 3 to 5 kilometers (2 to 3 miles) at an altitude of approximately
500 kilometers (310 miles).
In addition, NASA has taken specific actions to design the spacecraft and
mission in such a way as to ensure the probability of Earth impact is less than
one in one million. For example, until 10 days before the Earth swingby, the
spacecraft is on a trajectory that, without any further maneuvers, would miss
the Earth by thousands of kilometers. The biased trajectory also strictly
limits the possibility that random external events (such as a micrometeoroid
puncture of a spacecraft propellant tank) might lead to Earth impact.
Also, it should not go unmentioned that ten days out, when they start
to manuever towards Earth, they will be approximately 10 million
miles from Earth. At that distance the target area is something in
the neighborhood of about 1/10,000 (one ten thousandth) of a
percent of one degree away from Earth itself, whose entire
cross-section takes up less than 1/5th of one degree on
Cassini's horizon. Talk about putting it in the barrel. This is a
knothole at a million paces.
Lastly, to call this "an established method of launching massive,
instrument-laden spacecraft to the outer planets" is begging
complacency from familiarity. We've done it a few times in the
past, it's true. And it's worked those few times. That hardly is an
"established method." The shuttle was an "established method of
launch" prior to the Challenger disaster which NASA claimed would have
a 1 in 100,000 failure rate. Now NASA says about 1 in 73 shuttle
missions will fail on average. If you are boldly going where no man
has gone before, NASA, you aren't "established" in anything.
What's wrong here? This: upper-atmosphere incineration is a
perfectly plausible possibility. It is only by denying that possibility
that they can claim any reduced risk from capsule containment,
external doses, or nuclear safety through clothing and unbroken skin.
Inhalation is the danger here, NASA, inhalation from incinerated RTG's.
Furthermore even if it lands largely intact, we all have broken skin on
occasion and do not all wear full-body clothes all the time. Someone
should tell NASA this.
Radiation Hazards of Plutonium-238
Isotopes of plutonium such as Pu-238 characteristically give off short-range
alpha particles, helium nuclei that usually travel no more than about three
inches in air. While the fuel is contained within its iridium capsule, the
alpha radiation does not present a hazard, and the external dose resulting
from the low levels of gamma and neutron radiation associated with the
plutonium dioxide RTG fuel generally would not represent a significant health
hazard, either. External alpha radiation would be stopped by clothing, an outer
layer of unbroken skin, or even a sheet of paper. The point at which Pu-238 can
become a health hazard is when it is deposited into the body.
If an individual were to inhale plutonium dioxide particles of a
sufficiently small size to be deposited and retained in proximity to living
lung tissues, the alpha radiation could alter or kill nearby living cells.
Over years or decades, the altered cells could become cancerous and form
tumors in the lung. Additionally, some of this material could be dissolved in
body fluids and transferred by the blood to be deposited in other organs,
generally the liver and skeleton, with similar potential consequences. The
ceramic form of plutonium used in RTGs, however, is not likely to shatter into
fine particles that could be readily inhaled. Other exposure pathways, such as
ingestion, contribute far less to health effects.
The ceramic form of plutonium dioxide fuel also has low solubility in water,
so its migration in ground water and potential for uptake by plants is limited.
The actual proportion of plutonium released from an RTG that could enter the
food chain, if any, is small.
A common misconception is that a small amount of plutonium, such as one
pound, if evenly distributed over the entire world, could induce lung cancer
in every person on Earth. While plutonium can alter or kill living cells if
deposited directly onto sensitive human tissue, the important point is that it
must be in a form that enables environmental transport and intake by humans.
Research has demonstrated that the mechanisms of plutonium dispersion into and
transport through the environment, and hence in to humans, are extremely
This is flat-out wrong. First of all, grammatically, they say in the
first sentence that this is "a common misconception." What they go
on to say is that it is not a misconception at all but rather, they
claim they will not disperse the plutonium that way -- "the important
point is that is must be in a form that enables environmental
transport and intake by humans." So what they actually argue in the
paragraph just cited is that they will not disperse the plutonium in
a manner which will allow intake by humans --NOT that there are any
misconceptions about the hazards of plutonium!
These are two very different points!
In fact, NASA can do nothing to ensure prevention of
distribution of the plutonium in just about the most efficient means
possible short of clinical inhalation or injection -- which of course,
the government actual did in the 40's and 50's. NASA has not, can
not, and will not be able to guarantee that the RTG's will not
incinerate in a shallow descent to Earth, will not be hit by one of
the millions of pieces of space debris that they have already placed
in Near Earth Orbit on previous missions, and will not be blown to
smithereens in a launch explosion. Yes, they have strived to reduce
the risks on all of these things. But the one thing they could have
done to eliminate the risks they have not done -- which is, of
course, to not use plutonium in the first place. Why accept a
level of risk at all when the plutonium is absolutely not
Plutonium has no place in space.
And no place on Earth, either. Stop manufacturing this junk.
Related pages at this web site:
- Stop Cassini Home Page
- No Nukes In Space! Not now, not ever.
- Space Debris Home Page
- A series of articles on this shameful problem.
This article has been presented on the World Wide Web by:
The Animated Software Company
First placed online February 7th, 1997.
Last modified June 5th, 1997.
Webwiz: Russell D. Hoffman
Copyright (c) Russell D. Hoffman