and perhaps encouraging the dismissal of a laboratory director (Roy Woodruff) who had attempted to correct the error. His claims led to a joke which circulated in the scientific community, that a new unit of unfounded optimism was designated as the teller; one teller was so large that most events had to be measured in nanotellers or picotellers. Many prominent scientists argued that the system was futile. Hans Bethe, along with IBM physicist Richard Garwin and Cornell University colleague Kurt Gottfried, wrote an article in Scientific American which analyzed the system and concluded that any putative enemy could disable such a system by the use of suitable decoys that would cost a very small fraction of the SDI program. In 1987 Teller published a book entitled Better a Shield than a Sword, which supported civil defense and active protection systems. His views on the role of lasers in SDI were published, and are available, in two 1986–87 laser conference proceedings. Asteroid impact avoidance Following the 1994 Shoemaker-Levy 9 comet impacts with Jupiter, Teller proposed to a collective of U.S. and Russian ex-Cold War weapons designers in a 1995 planetary defense workshop at Lawrence Livermore National Laboratory, that they collaborate to design a 1 gigaton nuclear explosive device, which would be equivalent to the kinetic energy of a 1 km diameter asteroid. In order to safeguard the earth, the theoretical 1 Gt device would weigh about 25–30 tons—light enough to be lifted on the Russian Energia rocket—and could be used to instantaneously vaporize a 1 km asteroid, or divert the paths of extinction event class asteroids (greater than 10 km in diameter) with a few months' notice; with 1-year notice, at an interception location no closer than Jupiter, it would also be capable of dealing with the even rarer short period comets which can come out of the Kuiper belt and transit past Earth orbit within 2 years. For comets of this class, with a maximum estimated 100 km diameter, Charon served as the hypothetical threat. Death and legacy Teller died in Stanford, California, on September 9, 2003, at the age of 95. He had suffered a stroke two days before and had long been experiencing a number of conditions related to his advanced age. Teller's vigorous advocacy for strength through nuclear weapons, especially when so many of his wartime colleagues later expressed regret about the arms race, made him an