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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 - 04:55pm Jul 6, 2001 EST (#6702 of 6709)
Robert Showalter showalte@macc.wisc.edu

I think this stuff, which deals with the idea of lasar weapons as "long distance death rays" is right as far as it goes. Which is pretty far . ..
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The posting above still seemed right, and right on, when I reread them, and thought about them a little, just now.

But there are issues of controls, with real actuators and control math relations, that aren't touched.

And energy considerations -- which really matter here if the lasar is to do real damage, aren't touched.

Let me take a while and try to explain something about those issues.

rshowalter - 05:01pm Jul 6, 2001 EST (#6703 of 6709)
Robert Showalter showalte@macc.wisc.edu

First cut on energy methods. Anybody ever done any welding? Or watched it being done?

Whether you're using a torch, or electric welding, the issue of intensity of energy flux is crucial -- and the equipment needed is pretty hefty.

So a first question to ask about a military lasar, considered as a device for destroying something -- is what damage could it do from a short distance.

It isn't so easy to blow something up with a lasar. Lasar welding works nicely, but some very stout lasars make some very small, concentrated (and pretty) spot welds. To destroy a booster or a warhead --even without countermeasurs -- people are talking about more damage than that -- even if problems with distance could be ignored -- and they can't be.

rshowalter - 05:03pm Jul 6, 2001 EST (#6704 of 6709)
Robert Showalter showalte@macc.wisc.edu

And energy flux has to be big enough for a long enough time, on the same concentrated physical part of an object. An impressively high sounding energy flux per unit time, for a short enough time, may not do enough.

rshowalter - 05:06pm Jul 6, 2001 EST (#6705 of 6709)
Robert Showalter showalte@macc.wisc.edu

If you're talking a chemical lasar -- the energy delivered to the target can't be any bigger than the energy in the chemical reaction inside the lasing cavity.

And for reasons of physics and geometry, the energy delivered is likely to be much less.

rshowalter - 05:13pm Jul 6, 2001 EST (#6706 of 6709)
Robert Showalter showalte@macc.wisc.edu

It seems to me that a really big question - that people should be able to answer now , about "death ray" lasars is how much damage can the lasar do from a few meters distance?

If it can't do a lot of damage from a short distance, it surely can't do so from a much longer distance.

Whatever you do, and whatever you imagine, beam spreading is going to be greater than 0.

And when you figure how much greater, with real assumptions -- you'll see that whatever damage you can do at a couple of meters is going to be a lot greater than what you can hope to do at long distances.

rshowalter - 05:15pm Jul 6, 2001 EST (#6707 of 6709)
Robert Showalter showalte@macc.wisc.edu

I'm just guessing here -- and the guess isn't even that educated.

But I'd bet that, right now, DOD couldn't impress a Congressman with a full scale destruction demonstration, using a lasar, at a range between lasar and target of 10 meters or less.

rshowalter - 05:20pm Jul 6, 2001 EST (#6708 of 6709)
Robert Showalter showalte@macc.wisc.edu

Some way or other, it ought to be possible to check this. Take a Congressman (even a Democrat) -- take him to the demo, and get real engineers, with names, to swear to him that, though he can't see the details, there is a real lasar on one side of the room -- and let him look at a realistic, real target on the other side of the room.

And show him the destruction.

Ideally. Show him how many times and how fast there can be impressive destruction.

From a short distance.

If that demo can't be done -- there's plenty of work to do before worrying about getting military damage from lasars that are also as exquisitely exact in physical geometry as Space Telescope (or much better.)

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