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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?

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rshow55 - 07:53am Feb 22, 2003 EST (# 9203 of 9215)
Can we do a better job of finding truth? YES. Click "rshow55" for some things Lchic and I have done and worked for on this thread.

Before I deal more with international relations, I'll think a little about gisterme's excellent 9197 http://forums.nytimes.com/webin/WebX?8@28.e3fGayV23tI.0@.f28e622/10723 about the Columbia tragedy.

I'm wondering - as I start - does gisterme know about how turbulence works - what shock waves are - what vortices are - and what stagnation pressure and temperature are?

If he does, he could understand how easily the loss of a single tile, or a single chunk of insulation - could lead to catastrophic failure.

Technical solutions - including many involving missile defense - are often logically brittle - with just a small flaw - they crack apart.

It is important not to have too much confidence in their toughness. To fit human needs - we need solutions that are inherently stable, when we can get them - rather than brittle.

That looks possible to me.

lchic - 09:53am Feb 22, 2003 EST (# 9204 of 9215)
~~~~ It got understood and exposed ~~~~

JARGON ""Politicians are the real experts at being vague. The following are some constructs that are inherently vague.

http://www.geocities.com/Athens/Styx/8877/mj/mj.html

rshow55 - 10:13am Feb 22, 2003 EST (# 9205 of 9215)
Can we do a better job of finding truth? YES. Click "rshow55" for some things Lchic and I have done and worked for on this thread.

Beautiful reference ! A whole dictionary of jargon. http://www.geocities.com/Athens/Styx/8877/mj/mj.html

To do better than vagueness, you need things connected to something solid to refer to.

Here's something solid to refer to:

Stagnation temperature is the temperature a flowing gas rises to when it is brought adiabatically to rest, thereby converting its kinetic energy into enthalpy.

Conservation of energy requires that the energy balances:

energy at rest = energy in motion

from Relationship between temperature, stagnation temperature and Mach number http://www.optimal-systems.demon.co.uk/appendix-c.htm

Stagnation temperature for an ideal gas follows this relation:

Stagnation temperature = temperature of the fluid at rest

TIMES

(1 + (about .2 ) times Mach Number SQUARED )

For an atmospheric temp of 200K - a low estimate where the shuttle broke up - T stagnation at mach 20 is 16,200k -- far higher than the melting point of any material.

So anything coming in from orbit will melt, and vaporize - unless heat transfer rates between that object and the gases flowing around the object are low enough.

And those rates can vary by 10 - 100 - 1000 - 10,000 fold - depending on flow geometries. Geometries that determine turbulence, eddy formation - and heat transfer.

If flow geometry is bad enough in even a small locality near the leading edge of a flowing body - so that local heat transfer is high enough - things burn through.

For instance - the substrate of a missing tile can quickly melt - and the adhesive from adjacent tiles can quickly be burned-ripped away in the turbulence.

Geometry is critical . Including local geometry around a single tile - or the place where a single tile was supposed to be.

Or local geometry that has been changed by a surface collision.

If you look at flow visualization pictures, it can be easy to see how critical geometry is in the kinds of flows that had to be occurring around the shuttle.

It should have been clear that the shuttle was vulnerable if tiles were injured - and a report from Stanford and Carnegie Tech a decade ago assumed that people could see that.

But people, much too often "believe only what they want to believe." That's how it is for human beings - unless enough crosschecking occurs that people can see for themselves in enough detail for good decisions.

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