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Project Excalibur was an American Cold War–era research program to develop nuclear-device-powered, space-based X-ray lasers as a ballistic missile defense. X-ray lasers were conceived in the 1970s by George Chapline Jr. (pictured with George Maenchen) and further developed by Peter L. Hagelstein, both working at Lawrence Livermore National Laboratory under Edward Teller. After a promising test, Teller discussed the proposal in 1981 with US president Ronald Reagan, who in 1983 incorporated it in his Strategic Defense Initiative. Further underground nuclear tests suggested progress was being made. Reagan refused to abandon the technology at the 1986 Reykjavík Summit arms-control talks, even after a critical test demonstrated it was not working as expected. Researchers at Livermore and Los Alamos began to raise concerns about test results, and the infighting became public. In 1988 the program budget was cut dramatically, after additional problems were revealed. (Full article...)