New York Times on the Web Forums Science

Missile Defense

Russian military leaders have expressed concern about US plans for a national missile defense system. Will defense technology be limited by possibilities for a strategic imbalance? Is this just SDI all over again?

rshowalter - 07:26am Jul 31, 2001 EST (#7632 of 7772)
Robert Showalter showalte@macc.wisc.edu

Organizing facts is hard work.

Sometimes requirements of organization are different for different needs and circumstances.

To fit different minds, in real circumstances.

Sometimes, organizations of material, and human organizations, too, work well for some purposes, but badly for others.

You need both long and short forms, and forms differently organized, for different jobs.

For example, nobody thinks depositions or jury transcripts can be short. And for crucial decision making, those formats are indispensible -- but unworkably cumbersome for other purposes -- where summaries are needed. Summaries that people can trust, feel comfortable with, and understand.

On missile defense, some of the central issues might be easy "from the right distance" but are not easy for the people involved, because so much hangs on them, and because re-evaluating some facts might require reevaluation of much else.

Related issues of military balance (and it is these issues that most concern almarst MD5539 rshowalter 6/20/01 12:24pm ) make things hard, as well.

rshowalter - 07:27am Jul 31, 2001 EST (#7633 of 7772)
Robert Showalter showalte@macc.wisc.edu

The specific technical issues of missile defense that are crucial are sometimes pretty simple, but they connect to sets of problems involving huge numbers of people, many resources, great risks, over a long time - -

Concerns about the “military-industrial complex” were set out in the FAREWELL ADDRESS of President Dwight D. Eisenhower …… January 17, 1961. http://www.geocities.com/~newgeneration/ikefw.htm

and the connections of the simple facts to the larger circumstances make everything harder than it might otherwise be.

rshowalter - 07:31am Jul 31, 2001 EST (#7634 of 7772)
Robert Showalter showalte@macc.wisc.edu

For example, it is a fact that it is easy to make reflective coatings that take absorbtion of light from a lasar beam down by a factor of 1000 - - and easy to put these coatings on missiles and warhead - with something as simple as contact paper. The key fact is old, and the coating technologies involved are well known to the engineers working on lasar weaponry. They use multilayered tuned reflectie coatings. http://www.phy.davidson.edu/jimn/Java/Coatings.htm The simple fact above is fatal to the lasar weaponry programs that have been proposed.

For another example, it is a fact that the resolution of Hubble Space Telescope, one of the highest resolution optical systems in existence, is only as good as it is. The resolution Hubble shows, impressive as it is, is grossly less than the proposals for lasar based anti-missile weapons would need. One can see that, and get a sense of it, by looking at some beautiful pictures from Space Telescope.

dec97-hubble butterfly http://www.astrophys.org/high_2001.html

These are beautiful Hubble pictures --- go down, and look at the detailed ones, and get a physical sense of what astronomers mean when they say that an angle can be "resolved." . . . . These pictures are awesome - and one example, among many, of work the Americans can be proud of.

But if you look at the blurs, which are images of stars that are essentially point sources, you get a sense of the limits of optical perfection (even when power levels are low.) Eric Chaison illustrates those limits in The Hubble Wars Space telescope could just resolve the difference between a car with one headlight, or two, from a distance of 2000 miles. (Chaison's example is for a car in emply space - the smearing of the atmosphere would make the seeing much worse.) Enough resolution to resolve between one headlight and two for "a car in space at 2000 miles) is wonderful resolution. But not nearly good enough for some of the "death ray" schemes people seem to have been imagining, and drawing pictures about, and writing about without considering the numbers.

The stars are so far away, that they are essentially point sources -- with angles like 10e-12 radians -- -- the imperfection of the optics smears them into "blobs" with a resolution of 5 x 10e-7 radians, or "worse." And that just isn't good enough for a "death ray" in space. The death ray idea makes sense (if you don't remember about reflective coatings) if you forget the resolution numbers. But the numbers rule that dream out.

gisterme argued that, for "point sources" that are intense enough, the geometrical issues don't hold, and don't limit what can be destroyed. MD6695 gisterme 7/6/01 3:10pm

But that's wrong.

Now, the fact that reflective coatings are easy to make is a simple fact. The fact that resolution limits how well a "death ray" can be aimed, and the damage it can do, is a simple fact.

But these are not simple facts to people involved who are deeply committed to programs that cannot work.