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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?

eurocore - 07:01pm Mar 29, 2001 EST (#1723 of 1732)

>it seems you'd have to have at least twenty >>times as much power as is required to melt a >>20cm metal radius disc,

No problem with the 20 times. That one's a piece >o cake. We are talking about trivial total >amounts of energy.

I agree for mild steel. What though for carbon composites or (very cheap!) hypereutectoid steels closer to cast iron. An insulating layer or simple smoke screening (missile has extended nodule ahead streaming thick smoke) could cause problems. We have to assume cheap countermeasure aren't available before it's worth the cost.

>assuming it were possible to correct for missile >acceleration changes at relativistic speeds.

Relativistic speeds? 20,000 miles/hr. ain't even >close.

Not the rocket! Relativistic speeds refers to the transfer of position information back to the laser and the beam back to the rocket. I should have said: 'relativistic limited information transfer speeds'. See next sentance.

>(ie: no lag between observations and correction >>to transmitted beam - instantaneous electronics!)

Direct on, the ICBM won't move a centimeter in >the time it takes light to make the trip. And >ballistic stuff is a sitting duck.

10^4km=10^7m

Therefore minimum lag of 10^7/(3*10^8)=3*10^-2s each way, or 60ms total.

60*10^-3s*(2*10^4)/60/60 ~0.3m

Not one but thirty!

Though you're right that the sideways-distance moved by a side-rocket firing is almost insignificant, so you're right in that the x-component varying is easily tracked with sufficent computational power.

(So we can't use side rockets to render it theoretically impossible, as I earlier though).

rshowalter - 07:01pm Mar 29, 2001 EST (#1724 of 1732)
Robert Showalter showalte@macc.wisc.edu

And if somebody wants to correct me -- these calculations are too elementary to be really classified, we should arrange a meeting, that can be videotaped, or a videoconference, that we can make available on the net, and bring umpires -- so that the answers are clear. These schemes are nonsense.

rshowalter - 07:03pm Mar 29, 2001 EST (#1725 of 1732)
Robert Showalter showalte@macc.wisc.edu

That might be indelicate -- no doubt I've made an impolite suggestion. But what are the stakes here?

Shouldn't the truth be morally forcing here?

eurocore - 07:11pm Mar 29, 2001 EST (#1726 of 1732)

Rshowalter - I'm not sure jiving will work. The mass of the rocket seems too large that the time delay via a targeting laser is not sufficient to keep the laser moving across the surface fast enough. But my estimate calcs could be wrong!

>The heat capacity of steel is relatively low, >>but just a thin layer of material on the >>outside of a potential future ICBM (carbon >>composite), would make the energy required to >>destroy the missile quite extravangent.

That's a wild guess. We are assuming our >scientists are better than the North Korean >ones. Lots of ways of defeating the mirror >coating issue.

Not that wild - most ceramics take huge heating thousands of degrees C, and we have that technology now.

(Several times more than CERN, for example, >uses). If the missile split into smaller >warheads, with faster sideways accelerations, >the beam radius generated would have increase >and the power correspondingly.

Like I said, the dern thing is traveling 20,000 >miles/hr. Material objects don't accelerate much >in the time it takes light to make the round >trip. It would take a brand new kind of > acceleration device.

The max. acceleration would have to be larger than I thought (see previous post), but at some engine-mass ratio, it would be impossible to target any point for greater than a certain period with a certain laser radius.

>I'd be very interested if an economically >>feasible laser plan could be created to prevent >>relatively large numbers of (slightly altered) >>ICBMs arriving at there targets. I'd be >>surprised (currently), if one missile was shot >>down given the above analysis.

Are you innocent of the fact that we sold such a >thing to Israel a few months ago? That would >explain some things.

This critter, built with chump change, will >shoot down a katusha rocket at 10 km. now. Right >now. 100 km. is a piece of cake.

Yes I was 'innocent' (ignorant?) of this fact.

And this is what we know about. Entertain the >idea that we do not tell the world the details >of our secret weapons. Entert

I assume anything sold to Israel must be old hat unless the US military are feeling particularly generous.

However I do remember the terribly effective Patroit missile sale before the Gulf War to Israel, so I like to see demonstrations (or reassurance from someone who knows - I'm happy to take your word on it) before I believe the effectiveness of new weapons!

Best Wishes,

Tom

rshowalter - 07:19pm Mar 29, 2001 EST (#1727 of 1732)
Robert Showalter showalte@macc.wisc.edu

The Patriot effectiveness, as you may remember, was praised to the sky for a while, and made hearts beat with pride -- but it turned out the Patriots never hit anything.

The Israelis will lie for us.

So here we have data points on how our sociotechnical system works -- and based on the judgement of George W. Bush and his hand picked men, we should feel confident?

I repeat what I said in 1724, 1725.

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