Project Excalibur
Encyclopedia
Project Excalibur was a United States government
nuclear weapon
s research program to develop a nuclear pumped x-ray laser
for ballistic missile defence. It became part of the Strategic Defense Initiative
(SDI). Conceived by nuclear scientist Edward Teller
, the concept involved packing large numbers of expendable x-ray
laser
s into a nuclear bomb. When it detonated, the bomb would fire laser beams in many directions. The intention was to shoot down enemy nuclear missiles.
The plan was to place the whole apparatus on a satellite
in orbit. It would have actually required many satellites in orbit, since there needed to be at least one between the U.S. and its enemies when a massive launch of intercontinental ballistic missile
s (ICBMs) occurred. The Soviet Union
was the only foe technologically able to accomplish a massive simultaneous launch.
The x-ray laser gain medium
would be pumped by the extremely high density of high energy photon
s that appear in the first nanoseconds of a nuclear detonation. During these nanoseconds, the photon density is nearly as high as in regular matter. The pumped medium would emit a pulse of coherent
x-rays, in the direction of the long axis of the medium. The calculations showed that the extremely high gain and high energy pulse from the lasers would occur before the detonation destroyed the lasers and the rest of the satellite. If large numbers of pieces of gain media were used, each pre-aligned to point at a missile, then a large number of the missiles could be destroyed in one fell swoop.
The project was proposed as a solution to the problems of using optical lasers in satellites to shoot down missiles: if a large nearly simultaneous launch of ICBMs occurred, the Space Based Laser could not destroy them all, since it was designed to fire upon one at a time. It was felt that the large optics of the SBL could not be re-positioned to point from one missile to the next quickly enough. A considerable amount of research went into rapidly re-targeting the Space Based Laser so that many missiles could be destroyed in time to deal with the massive attack. However, it 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.
Ten known tests of nuclear-pumped x-ray lasers were conducted between 1978 and 1988. The project was determined to be out of reach of current technology and was formally abandoned in 1992. Since then, its main influence has been its appearances in science fiction
. Research was redirected to laser satellites and kinetic weapons under the Strategic Defense Initiative
.
Federal government of the United States
The federal government of the United States is the national government of the constitutional republic of fifty states that is the United States of America. The federal government comprises three distinct branches of government: a legislative, an executive and a judiciary. These branches and...
nuclear weapon
Nuclear weapon
A nuclear weapon is an explosive device that derives its destructive force from nuclear reactions, either fission or a combination of fission and fusion. Both reactions release vast quantities of energy from relatively small amounts of matter. The first fission bomb test released the same amount...
s research program to develop a nuclear pumped x-ray laser
X-ray laser
An X-ray laser is a device that uses stimulated emission to generate or amplify electromagnetic radiation in the near X-ray or extreme ultraviolet region of the spectrum, that is, usually on the order of several of tens of nanometers wavelength.Because of high gain in the lasing medium, short...
for ballistic missile defence. It became part of the Strategic Defense Initiative
Strategic Defense Initiative
The Strategic Defense Initiative was proposed by U.S. President Ronald Reagan on March 23, 1983 to use ground and space-based systems to protect the United States from attack by strategic nuclear ballistic missiles. The initiative focused on strategic defense rather than the prior strategic...
(SDI). Conceived by nuclear scientist Edward Teller
Edward Teller
Edward Teller was a Hungarian-American theoretical physicist, known colloquially as "the father of the hydrogen bomb," even though he did not care for the title. Teller made numerous contributions to nuclear and molecular physics, spectroscopy , and surface physics...
, the concept involved packing large numbers of expendable x-ray
X-ray
X-radiation is a form of electromagnetic radiation. X-rays have a wavelength in the range of 0.01 to 10 nanometers, corresponding to frequencies in the range 30 petahertz to 30 exahertz and energies in the range 120 eV to 120 keV. They are shorter in wavelength than UV rays and longer than gamma...
laser
Laser
A laser is a device that emits light through a process of optical amplification based on the stimulated emission of photons. The term "laser" originated as an acronym for Light Amplification by Stimulated Emission of Radiation...
s into a nuclear bomb. When it detonated, the bomb would fire laser beams in many directions. The intention was to shoot down enemy nuclear missiles.
The plan was to place the whole apparatus on a satellite
Satellite
In the context of spaceflight, a satellite is an object which has been placed into orbit by human endeavour. Such objects are sometimes called artificial satellites to distinguish them from natural satellites such as the Moon....
in orbit. It would have actually required many satellites in orbit, since there needed to be at least one between the U.S. and its enemies when a massive launch of intercontinental ballistic missile
Intercontinental ballistic missile
An intercontinental ballistic missile is a ballistic missile with a long range typically designed for nuclear weapons delivery...
s (ICBMs) occurred. The Soviet Union
Soviet Union
The Soviet Union , officially the Union of Soviet Socialist Republics , was a constitutionally socialist state that existed in Eurasia between 1922 and 1991....
was the only foe technologically able to accomplish a massive simultaneous launch.
The x-ray laser gain medium
Active laser medium
The active laser medium is the source of optical gain within a laser. The gain results from the stimulated emission of electronic or molecular transitions to a lower energy state from a higher energy state...
would be pumped by the extremely high density of high energy photon
Photon
In physics, a photon is an elementary particle, the quantum of the electromagnetic interaction and the basic unit of light and all other forms of electromagnetic radiation. It is also the force carrier for the electromagnetic force...
s that appear in the first nanoseconds of a nuclear detonation. During these nanoseconds, the photon density is nearly as high as in regular matter. The pumped medium would emit a pulse of coherent
Coherence (physics)
In physics, coherence is a property of waves that enables stationary interference. More generally, coherence describes all properties of the correlation between physical quantities of a wave....
x-rays, in the direction of the long axis of the medium. The calculations showed that the extremely high gain and high energy pulse from the lasers would occur before the detonation destroyed the lasers and the rest of the satellite. If large numbers of pieces of gain media were used, each pre-aligned to point at a missile, then a large number of the missiles could be destroyed in one fell swoop.
The project was proposed as a solution to the problems of using optical lasers in satellites to shoot down missiles: if a large nearly simultaneous launch of ICBMs occurred, the Space Based Laser could not destroy them all, since it was designed to fire upon one at a time. It was felt that the large optics of the SBL could not be re-positioned to point from one missile to the next quickly enough. A considerable amount of research went into rapidly re-targeting the Space Based Laser so that many missiles could be destroyed in time to deal with the massive attack. However, it 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.
Ten known tests of nuclear-pumped x-ray lasers were conducted between 1978 and 1988. The project was determined to be out of reach of current technology and was formally abandoned in 1992. Since then, its main influence has been its appearances in science fiction
Science fiction
Science fiction is a genre of fiction dealing with imaginary but more or less plausible content such as future settings, futuristic science and technology, space travel, aliens, and paranormal abilities...
. Research was redirected to laser satellites and kinetic weapons under the Strategic Defense Initiative
Strategic Defense Initiative
The Strategic Defense Initiative was proposed by U.S. President Ronald Reagan on March 23, 1983 to use ground and space-based systems to protect the United States from attack by strategic nuclear ballistic missiles. The initiative focused on strategic defense rather than the prior strategic...
.
Further reading
- American Physical Society. Study Group on Science and Technology of Directed Energy Weapons. Science and Technology of Directed Energy Weapons/ Report of the American Physical Society Study Group.. New York: American Physical Society, 1987.
- Anti-Satellite Weapons, Countermeasures and Arms Control. Washington, D.C.: Office of Technology Assessment, U.S. Congress, September 1985. OTA-ISC-285.
- Ballistic Missile Defense Technologies. Washington, D.C.: Office of Technology Assessment, U.S. Congress, September 1985. OTA-ISC-254.
- Bloembergen, N., C. K. Patel, P. Avizonis, R. G. Clem, A. Hertzberg, T. H. Johnson, T. Marshall, R. B. Miller, W. E. Morrow, E. E. Salpeter, A. M. Sessler, J. D. Sullivan, J. C. Wyant, A. Yariv, R. N. Zare, A. J. Glass, L. C. Hebel, G. E. Pake, M. M. May, W. K. Panofsky, A. L. Schawlow, C. H. Townes, and H. York APS Study Group Participants, APS Council Review Committee. "Report to The American Physical Society of the Study Group on Science and Technology of Directed Energy Weapons". Reviews of Modern Physics 59, no. 3 (July 1987): S1–S201.
- Carter, Ashton B.Ashton CarterAshton Baldwin Carter is a United States national security professional. He is is the United States Deputy Secretary of Defense. Prior to that, He served as Under Secretary of Defense for Acquisition, Technology, and Logistics for President Barack Obama. He is currently on leave from his post as...
Directed Energy Missile Defense in Space. Washington, D.C.: Office of Technology Assessment, U.S. Congress, April 1984. OTA-BP-ISC-26.
- Goodchild, Peter. "Meet the real Dr Strangelove". The GuardianThe GuardianThe Guardian, formerly known as The Manchester Guardian , is a British national daily newspaper in the Berliner format...
, April 1, 2004. Accessed 8 October 2008.
- Hecht, Jeff. Beam Weapons: The Next Arms Race. New York: Plenum Press, 1984. ISBN 0-306-41546-1.
- Perlman, David. "The Dilemmas of Decision-Making from AIDS to SDI". In Golden, William T., Science and Technology Advice to the President, Congress, and Judiciary, 2nd ed. New Brunswick, U.S.A.: Transaction Publishers, 1995, pp. 255–261. ISBN 1-56000-829-6. Accessed 8 October 2008.
- Ritson, David M. "The Nuclear-Pumped X-ray Laser, a Weapon for the Twenty-first Century". NatureNature (journal)Nature, first published on 4 November 1869, is ranked the world's most cited interdisciplinary scientific journal by the Science Edition of the 2010 Journal Citation Reports...
328, 487–490 (7 August 1987). DOI: 10.1038/328487a0.
- Thomsen, Dietrich E. "Strategic defense of X-ray initiative - X-ray laser research". Science NewsScience NewsScience News is an American bi-weekly magazine devoted to short articles about new scientific and technical developments, typically gleaned from recent scientific and technical journals. Science News has been published since 1922 by Society for Science & the Public, a non-profit organization...
, December 14, 1985. Accessed 8 October 2008.