Saturn Probe Pu Power?

[Chris Davey <cdavey@med.phys.ualberta.ca>]

I got this message from a friend of mine today, and wondered if radsafers
in a position to know the answers could respond:

>"This is a message regarding your future. It is intended to reach as many
>internet users as possible as fast as possible. Thank you for taking the
>time to read the following and forwarding it to friends, listservs,
>newsgroups, should you judge it necessary.
>
>Excerpt from the article "Risking the World" by Karl Grossman,
>Professor of American Studies/SUNY:
>
>	"Despite enormous danger, huge expense, and a clear
>alternative-solar powerthe US government is pushing ahead with the
>deployment of nuclear technology in space. In October 1997, NASA plans to
>launch the Cassini probe to Saturn. Carrying 72.3 pounds of plutonium-238
>fuelthe largest amount of plutonium ever used in space, the probe will sit
>atop a Lockheed Martin-built Titan IV rocket. This same kind of rocket has
>undergone a series of mishaps including a 1993 explosion in California
>soon after takeoff which destroyed a $1 billion spy satellite system and
>sent its fragments falling into the Pacific Ocean.
>
>	Space News, the space industry trade newspaper, reported that "the
>high risk and cost of the Cassini mission to Saturn troubled NASA
>Administrator Daniel Goldin so much that he would cancel the program if it
>were not so important to planetary science."
>
>	But it is not science alone that is driving the project or causing
>scientists, politicians, and the military to discount the risks. NASA
>Chief Scientist Frances Cordova acknowledges that the Titan IV "does not
>have a 100 percent success rate" and admits that using it for Cassini "is
>truly putting all your eggs in one basketyour 18 instruments on one
>firecracker." She says, "We can't fail with that mission. It would be
>very, very, damaging for the agency."
>
>	To say nothing of the Earth and the life on it if something goes
>wrong. Plutonium has long been described by scientists as the most toxic
>substance known. It is "so toxic," says Dr. Helen Caldicott, founder of
>Physicians for Social Responsibility, "that less than one millionth of a
>gram is a carcinogenic dose. One pound, if uniformly distributed, could
>hypothetically induce lung cancer in every person on Earth."
>
>	In addition to the specter of radioactivity spread by an accident
>on launch, another, potentially more lethal, scenario is causing concern.
>Because Cassini does not have the propulsion power to get directly from
>Earth to Saturn, NASA plans a "slingshot maneuver" in which the probe will
>circle Venus twice and hurtle back at Earth. It will then buzz the Earth
>in August 1999 at 42,300 miles per hour just 312 miles above the surface.
>After whipping around Earth and using its gravity, Cassini would then have
>the velocity, says NASA, to reach Saturn. But during that Earth fly-by, if
>Cassini comes in too close, it could burn up in the 75 mile-high
>atmosphere and disperse plutonium across the planet.
>
>	Dr. Michio Kaku, professor of nuclear pLysics at the City
>University of New York, explains the catastrophic consequence of such a
>fly-by accident:
>
>	If there is a small misfire [of Cassini's] rocket system, it
>will mean that [it] will penetrate into the Earth's atmosphere and the
>sheer friction will begin to wipe out the heat shield and it will, like a
>meteor, flame into the Earth's atmosphere ... This thing, coming into the
>Earth's atmosphere, will vaporize, release the payload and then particles
>of plutoninm dioxide will begin to rain down on populated areas, if that
>is where the system is going to be hitting. [Pulverized plutonium dust]
>will rain down on people's hair, people's clothing, get into people's
>bodies. And because it is not water soluble, there is a very good chance
>that it could be inhaled and stay within the body causing cancer over a
>number of decades.
>
>	Indeed, NASA says in its First Environmental Impact Statement for
>the Cassini Mission, that if an "inadvertent reentry occurred" during the
>fly-by, approximately five billion of the seven to eight billion people on
>Earth, "could receive 99 percent or more of the radiation exposure."
>
>(...)
>
>	Starting in 1961, General Electric's RTGs were put into use for
>space satellites until a 1964 accident in which a SNAP-9A (Systems for
>Nuclear Auxiliary Power) fell to earth burning up in the atmosphere.
>According to a 1989 report by European nuclear agencies, the satellites
>2.1 pounds of plutonium-238 "vaporized" and "dispersed widely." After
>conducting a worldwide sampling, scientists found "SNAP-9A debris to be
>present at all continents and all latitudes." Dr. John Gofman, professor
>emeritus of medical physics at the Unversity of California at Berkeley, an
>M.D. and Ph.D. and a codiscoverer of isotopes of plutonium and uranium as
>a member of the Manhattan Project, has long attributed an increased rate
>of lung cancer to the SNAP-9A incident."
>
>For access to the article in its entirety or for further action, please go
>to http://userwww.service.emory.edu/~icousin/
>