October 4, 1997
Demonstrations across the country occurred protesting the scheduled launch of the space probe Cassini because its power source was three plutonium-fueled Radioisotope Thermoelectric Generators.
The probe carried 72.3 pounds of plutonium, the most ever put on a device to be launched into space. The concern was for an accidental release in the event of a launch mishap. Plutonium is the most toxic substance known.
