NASA's nuclear gamble.

• Author: Grossman, Karl
• Position: October 1997 launch of a Cassini space probe which will carry 732.3 lbs of potentially dangerous plutonium: includes information on anti-launch activities - Cover Story

In October, NASA is planning to launch the Cassini space probe to Saturn. The probe will carry 72.3 pounds of plutonium, the most ever put on a space device.

Plutonium is the most toxic substance known. "It is so toxic," says Helen Caldicott, president emeritus 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."

NASA intends to launch Cassini on October 6 on top of a Lockheed Martin Titan IV rocket. Titan rockets have had a series of mishaps, including a 1993 explosion in California that occurred less than two minutes after the launch. The blowup destroyed a $1 billion spy-satellite system. Fragments from the satellite fell into the Pacific Ocean.

If the Cassini probe blows up, we will be in a heap of trouble, as plutonium could rain from the skies.

The true death toll "may be as much as thirty to forty million people," says Ernest Sternglass, professor emeritus of radiological physics at the University of Pittsburgh School of Medicine.

"Remember the old Hollywood movies when a mad scientist would risk the world to carry out his particular project?" asks Horst Poehler, a scientist who worked for NASA contractors at the Kennedy Space Center for twenty-two years. "Well, those mad scientists have moved to NASA."

The plutonium used on space probes is not the Plutonium-239 isotope used in atomic bombs and built up as a byproduct in nuclear power plants. It is another isotope, Plutonium-238, which is 280 times more radioactive than Plutonium-239. It is more radioactive because it has a far shorter half-life, 87.8 years compared to 24,500 years for Plutonium-239. The plutonium on Cassini is to be used for fuel in the three generators to produce an average of just 745 watts of electricity to power the probe's instruments. Its shorter half-life means it produces a great deal of heat as it decays. Radioisotope thermoelectric generators (RTGs) translate that heat to electricity.

"They call the RTGs indestructible," says Alan Kohn, a thirty-year NASA veteran-turned-whistleblower. "They're indestructible just like the Titanic was unsinkable."

Nasa insists the Cassini mission is safe. The odds against Cassini exploding on launch and releasing plutonium into the air are 1,500 to one, the agency says.

Those are pretty poor odds," Kohn says. "You bet the lottery, and the odds against you there are fourteen million to one."

In its final environmental-impact statement dated June 1995 for the Cassini mission, NASA warns that, "Approximately five billion of the estimated seven to eight billion world population could receive 99 percent or more of the radiation exposure" if an "inadvertent reentry occurred."

NASA defines a launch accident as one of the potential problems with the Cassini probe. The environmental-impact statement outlines several scenarios in which plutonium might be released, including an explosion of the Titan IV, which is to loft the Cassini into orbit, or an explosion of a small rocket, a Centaur, which is to propel it on to Saturn.

In January, a Delta Il rocket created a fiery explosion during its launch at the Cape Canaveral Air Station. A toxic cloud of chemicals floated down the Florida coast. Residents as far off as Vero Beach, seventy-three miles away, were told to remain indoors to avoid contamination. "This is a sample of what could happen on Cassini -- except this time the cloud could contain plutonium," says Bruce Gagnon of the Florida Coalition for Peace & Justice.

NASA's environmental-impact statement does not predict much danger of an accident for Cassini...