Re: SPACE: Cassini Mission Consequences

Damien Broderick (
Sun, 21 Sep 1997 22:11:33 +0000

At 12:19 PM 9/20/97 -0800, Amara wrote:

>My personal opinion is that the antagonists are using this as a banner for
>their personal causes. I honestly don't know why it has carried so far.
>My scientist friends are perplexed also. You may be interested
>in a "back-of-the-envelope" calculation that Jeff Cuzzi performed
>to demonstrate that the Plutonium risk is pretty small.

If I have understood this risk evaluation, we learn the following bottom line:

There seems to be a one in a million chance of a plutonium dispersal
accident into the biosphere, which would be the direct cause of 100 to 500
deaths during the next half century.

Despite the waffle about this being the same odds of a billion people dying
in a dino-killer asteroid impact, we have no control over an asteroid and
every control over Cassini.

A better comparison might be with deaths by batphone cranial cancers, or
crossing the road. We cannot avoid crossing the road, and will not give up
the convenience of mobile phones (which might be altogether benign, in
fact, and raise our IQs for all I know).

We do not, however, have any pressing need for a nuclear powered Cassini
mission, except for the admirable hunger for knowledge of the scientists
involved, and the interest of their supporters such as ourselves. It is
therefore their and our choice to expose up to 500 people to the risk of
death by cancer (a very small risk, true, but an avoidable one). This
cannot be compared with the use of coal-fired powerplants that produce more
radio-isotope dispersal than nuclear plants - although here, too, the most
forceful objections have to do with the comparative risks of catastrophic
one-off failures and persistent pollutants.

In other words, while I personally am devoted to space programs and
enthralled by their findings, I do see the rational force of the objections
to Cassini, and I don't think it helps to diagnose their proponents as
driven by malevolent personal motives. The reasoned solution, as always,
has to be found in a candid risk analysis - not in misleading references to
dinosaur busters (which sounds to me like a shrugging appeal to the Will of

Damien Broderick