Project Excalibur

Project Excalibur was a United States government nuclear weapons research program to develop a nuclear pumped x-ray laser as a directed energy weapon for ballistic missile defence. It became part of the Strategic Defense Initiative (SDI). Conceived and developed by nuclear scientists Edward Teller, George Chapline, Jr. Peter L. Hagelstein and Lowell Wood the concept involved packing large numbers of expendable soft x-ray lasers around a nuclear device. When the device detonated, it would fire soft x-ray laser beams in many directions. The goal was to aim these beams to shoot down enemy nuclear missiles near the end of, and after the missiles boost phase stage of flight. The kill mechanism of the X-ray laser was ablative laser propulsion shock; that is, the x-rays would heat the surface of the missile, causing it to vaporize explosively, destroying it or knocking it off course.

The Excalibur project was proposed as a solution to the problems of using more conventional satellite based optical lasers to shoot down missiles. This original proposal was to place many infrared or x-ray laser satellites in orbit - as there needed to be at least one between the U.S. and its enemies when a massive launch of intercontinental ballistic missiles (ICBMs) occurred. With the Soviet Union viewed as the primary foe technologically able to accomplish such a massive simultaneous launch. If a large nearly simultaneous launch of ICBMs occurred, in a saturation attack, the single beam and power limited Space Based Laser(SBL)s would not have enough time to destroy them all, since each satellite would only be capable of firing upon them one at a time. Moreover, it was felt that the large optics of the SBLs could not be re-positioned to point from one enemy missile to the next quickly enough. A considerable amount of research went into rapidly re-targeting the Space Based Laser concept so that many missiles could be destroyed in a short space of time to deal with the massive saturation attack. However, this approach remained out of reach, giving rise to the Excalibur approach, which was viewed as something of a desperate approach even by those who worked on the project.

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