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Missile Defense

Technology has always found its greatest consumer in a nation's war and defense efforts. Since the last attempts at a "Star Wars" defense system, has technology changed considerably enough to make the latest Missile Defense initiatives more successful? Can such an application of science be successful? Is a militarized space inevitable, necessary or impossible?

Read Debates, a new Web-only feature culled from Readers' Opinions, published every Thursday.

rshow55 - 02:45pm Jan 21, 2002 EST (#10920 of 10922)

http://www.phy.davidson.edu/jimn/Java/Coatings.htm plays it pretty straight. It reads in part, with some italics added for emphasis.

Reflective Coatings

"Utilizing the phenomena of constructive and destructive interference, engineers may create a multitude of thin-film coatings with different reflective properties.

( Fowles, Grant R. Introduction to Modern Optics. 2nd ed. New York: Dover Publications, 1975 is a recommended reference, and there are other good ones as well.)

" Ideally, one could produce a surface with any desired reflectance. Using a material with index of refraction n = 1.2247, one could completely cut out the reflection from the above lens. Due to the limited availability and cost of materials, however, an exact match to the desired index of refraction is not always possible; magnesium fluoride has an index of refraciton n = 1.35 and can reduce the reflection to less than 1 %.

There's a very nice demo here, and below it two keys

"Set index of refraction: for middle layer"

" Set film width: Width of middle layer"

(Then http://www.phy.davidson.edu/jimn/Java/Coatings.htm speaks of mirrors: )

"For applications that require mirrors with very high reflectance (such as a laser mirror), several layers ... may be used. Often, many layers of alternating indices of refraction may be used to increase the reflectance to more than 98%.

"In the following example, the mirror is made of alternating layers of zinc sulfide (n=2.3) and magnesium fluoride (n=1.35) film Add layers and observe how the reflectance changes.

(There is a very nice demo here, as well, and adding layers to 10 pairs gets reflectance above 99.9% - - with additional reflection with additional layers.)

The example happens to use zinc sulfide and magnesium flouride, but different layers of plastics, flexible and easily carried on a decal, would work just as well. There are MANY choices of plastics to choose from for this.

99.9% or 99.9999% reflection for the specific frequency of the COIL system (which has been published) is achievable, without anything fancy, in a flexible, easily made decal.

95% reflectance would be more than enough to defeat an ABL system tactically.

There would be other ways of getting the reflection, too. Silvered mylar, which is quite common stuff, is quite reflective. A reflective coating on top of silvered mylar would have extreme reflectivity over one range of frequencies - - with reflectance reinforced, all over the frequency range, by the "silver" on the mylar. (Reflective coatings that are flexible, and used in packaging, are common articles of commerce.)

This isn't available at WalMart - - but with a market, it could be -- in weeks.

rshow55 - 02:49pm Jan 21, 2002 EST (#10921 of 10922)

mazza9 1/21/02 12:36pm . . . no, stealth coating is not the same as reflective decals. But stealth coating is standard equipment for some Russian missiles (I got this from the Nuclear Threat Initiative web site's news service).

rshow55 - 03:04pm Jan 21, 2002 EST (#10922 of 10922)

MD10909 rshow55 1/20/02 7:56pm reads in part:

"For example, The Air Born Laser program has many technically beautiful things about it - at many levels of detail. A tremendous amount of hard creative work has gone into it. http://airbornelaser.com/special/abl/

" Unfortunately, the system is trivially easy to defeat with reflective decals, using physics that is both quite old and quite basic http://www.phy.davidson.edu/jimn/Java/Coatings.htm - - and known all over the world (to all sorts of people, including people who make reflective and "holographic effect" decals.)

For something like a millionth of the cost of a "working" ABL system (if the system can be made to "work" - assuming 100% absorbtion) the system can be defeated.

That means the program isn't worth continuing. The teams and people involved should be redeployed, and plans that depend on laser weapon function should be abandonded.

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