Despite protests around the world, the Cassini space probe—containing more deadly plutonium than had ever been used on a space device—was launched 20 years ago. And this past weekend—on Earth Day—the probe and its plutonium were sent crashing into Saturn.
The $3.27 billion mission constituted a huge risk. Cassini with its 72.3 pounds of Plutonium-238 fuel was launched on a Titan IV rocket on October 17, 1997 despite several Titan IV rockets having earlier blown up on launch.
At a demonstration two weeks before in front of the fence surrounding the pad at Cape Canaveral from which Cassini was to be launched, Dr. Michio Kaku, professor of theoretical physics at the City University of New York, warned of widespread regional damage if this Titan IV lofting Cassini exploded on launch. Winds could carry the plutonium “into Disney World, University City, into the citrus industry and destroy the economy of central Florida,” he declared.
Four months before, at an earlier demonstration at the same site, Allan Kohn, a NASA career official from 1964 to 1994 who had been the emergency preparedness officer at the Kennedy Space Center, noted that “we were told by NASA that the odds against the Cassini blowing up and releasing radiation [are] 1,500 to one. These are pretty poor odds. You bet the lottery and the odds against you are one in 14 million.” As to NASA’s claim that the plutonium system was “indestructible,” he said it is “indestructible just like the Titanic was unsinkable….It’s time to put a stop to their freedom to threaten the lives of people here on Earth.”
And, indeed, on an Earth “flyby” by Cassini , done on August 18, 1999, it wouldn’t have been a regional disaster but a global catastrophe if an accident happened.
Cassini didn’t have the propulsion power to get directly from Earth to its final destination of Saturn, so NASA figured on having it hurtle back to Earth in a “sling shot maneuver” or “flyby”—to use Earth’s gravity to increase its velocity so it could reach Saturn. The plutonium was only used to generate electricity—745 watts—to run the probe’s instruments. It had nothing to do with propulsion.
So NASA had Cassini come hurtling back at Earth at 42,300 miles per hour and skim over the Earth’s atmosphere at 727 miles high. If there were a rocket misfire or miscalculation and the probe made what NASA in its “Final Environmental Impact Statement for the Cassini Mission” called an “inadvertent reentry,” it could have fallen into Earth’s atmosphere, disintegrating, and releasing plutonium. Then, said NASA in its statement, “Approximately 7 to 8 billion world population at a time … could receive 99 percent or more of the radiation exposure.”
The worst accident involving space nuclear power occurred in 1964 when a satellite powered by a SNAP-9A plutonium system failed to achieve orbit and fell to Earth, breaking apart and releasing its 2.1 pounds of Plutonium-238 fuel, which dispersed all over the planet. According to the late Dr. John Gofman, professor of medical physics at the …read more