SDI - real world

[ETS]

There is a great deal of erroneous info present about the prospects of SDI in the real world (and definitely in this forum!!) (As a military officer who watched over ICBMs before we went to the moon, and later a researcher with projects submitted to SDIO I can basically say that what I have read in this forum is far from reality)

The real world concept of Ballistic Missile Defense was pushed by a group of California hard SF fans (and writers), with plenty of contacts. The objective was to defend a field of ICBMs, from a first strike knock out blow, thus giving a certainty that SOME (enough) of the ICBMs could remain and that the concept of MAD would be real -- it would be impossible to destroy all the
birds in the silos.

To kill a silo you needed a 100 kt weapon going off within 500 yds. Weapons had that accuracy, if there was no interference.
When a warhead reenters it is a white hot object traveling a several thousand mph, with an approach angle of about 30 degrees. (There are some beautiful pictures of a set of RVs making a glowing daytime entry at our Pacific Test Range)


The path is predetermined; from a given launch point (or region) there is ONE path that leads to the target. We knew the bearings the RV would come from. What was required was a method of killing the warhead before it reached the 500 yd point.

In WW2 the US Navy was able to kill Japanese aircraft about 4 times as easily as the pre war strategists predicted (and were able to begin the offensive with far fewer ships -- about 1 year's construction worth!) because of the invention of the proximity fuse.

In the modern Navy, a sea skimming cruise missile is a similar threat that must be dealt with (low angles, short line of sight and speeds of several thousand mph). To handle this a rapid fire cannon based on the Vulcan was developed (Phalanx) and improved and improved. With radar guidance you simply walk a stream of high density shells into the path and let one of the bullets tear the missile apart.

In the silo defense you would have a set of pop up radars and guns (you are going to lose some to detonations that do not hurt the silos). On launch warning you simply put a wall of DU in front of the RV and one of several things will happen to a warhead that must work with microsecond timing on
multiple high explosive charges:
1) you break up the warhead and scatter Pu over the landscape.
2) you detonate the warhead with a low (1 kt ) yield, killing
neighboring deer, and messing up paint on your car on the surface.
3) you get a full detonation 5 miles from your silo, you have a rough ride
but survive to turn the keys. (Those on the surface within 10 mile have a bad day)
4) you miss, and your relatives supposedly collect the $10,000 insurance benefits.

The key point is that we had the technology to defend all the silos in the early '70s; not to ensure that every one survived (wars are not fought that way -- it is all a matter of statistical odds) but that enough survived to put real meaning behind our promise, that an aggressor would not win with a first strike
against our military - there WILL be someone left.


Eventually the efforts by Gen Graham managed to inspire the politicians, and that was where we drifted into fantasy land. To sell the voters it was proposed that a system that would work (about 80% for a given silo) be expanded to protect cities and assure 100% safety to all. At that time it was wishful thinking and bleeding edge technology to make that promise, but lives could still be saved with existing systems.

Given the density variations in population even a crude point defense system such as designed for silos would have a net saving of lives; but certain suburbs (generally those to the NW of the city) would suddenly lose some appeal. Instead of a situation
with 180 million casualties, the numbers could be dropped to the 20-30 million range.

Today it is possible for a missile to intercept another, but just as with naval close in missile defense you can not expect to have 1 RV : 1 missile.

[Roman]

I must say this is interesting.

[ETS]

Re effectivness. wobble, cheats

What most fail to consider is that SDI is a THREE step operation.
Boost phase, mid flight, and point defense.

Catching and killing in the first two was where all the bleeding edge work was centered, we already KNEW we could handle the RVs in the last stage.

For defense of a number of military targets in remote areas the damage done by destroying the RV in the last 10 miles was not bad. Scattering a couple kgs of plutonium was not good, but arsenic trioxide is 5 times as poisonous and we use that all the time. A fissle yield at 25,000 ft is not good, but there is little fallout and the blast radius at the surface is small.

The typical ignorant civilian has only a small worry about Bambi being under an airburst, but the idea that we wipe out Oak Park to save Chicago is hard to accept. (a study of wealth and power vs location will show that for most towns, the rich and powerful tend to live in the West and Northwest side -- right in the path of a successful intercept)

So all the sound a fury was about catching the bird 5,000 miles away. No one talked about the fact that even if nothing worked in the first two regions, the final point defense could probably save 90% of those destined for a fireball with a loss of only 20-30 million civilians. (Talk about the PR problem of selling this statistic)!


With regard to wobbles etc on a terrorist state RV.
A RV is a very delicate device, light shell with high insulation covering -- think of the Shuttle's glass skin that cracks if you bang it around). Inside it are a number of high explosive lenses that have to go off in microsecond timing. Mess up any one and the bomb blows apart with no nuclear detonation.
Aerodynamics stll requires that the RV enter in a smooth path or it will burn up at high altitude.
So there is no real difference in requirements -- (perhaps that was just disinformation to lead someone down a blind alley in their research)
In any event -- for the terminal point defense it is still a matter of sending your bullets down a path at an object that is coming right at you. (Think of the problem as a duck making an attack on a hunter armed with a Hollywood style automatic shotgun with thousands of shells)


As to using illuminators on early stage tests. Any leader in his right mind would fire anyone who did not do this. For the first dozen tests the problem is just to get the system to work at all, not to allow for discrimination. Along about test 25 they had better not be using cheats, but at this stage any engineer in his right mind is centered on the basic meeting problem.

(Check out the history of rockets -- frequently for the first half dozen or so, all we had were explosions on the pad -- no one was complaining that the rocket did not land on the moon!!!)

As for the ABM Treaty -- US and USSR were allowed to build ONE battle management system -- rockets and long range radars.
The USSR built a system around Moscow (and another near Mongolia, and another .... ). The US did not build any, the State Dept felt that any system would provoke our opponents into an Arms Race -- neglecting the fact that Soviets had already caught up and passed us on the number of birds.

It was also felt that any radar system pointing towards Russia would be provoking them even if it did not have a multi thousand mile range, so we never put the components of the point defense together to test against ICBMs (but it did work against other missiles)

[Tingkai]

Wondering what your thoughts are on the following.

I read a newspaper article that claimed SDI would not be effective against crude ICBM from rogue states. The logic is that these missles are poorly designed and tend to wobble in flight whereas advanced ICBMs are designed to spin in flight, something like a rifle bullet, for higher accuracy.

A tumbling warhead would be difficult to hit because:
- it has an unpredictable flight path
- the tumbling affects its radar image (not sure if that is the right word) and that makes it harder to detect from decoys.

Apparently the Pentagon has admitted that SDI cannot deal with crude, tumbling warheads, but a solution is in the works. Critics of SDI say this is a major problem that won't be resolved for a long time.

[dainbramaged13]

I like the MAD-insurance idea, because it would not brak the ABM treaty, and it actually has the potential to WORK!!!!!

anyway, ive seen way too many threads like this arguing over whether SDI will work or not, and my personal opinion from reading and posting in all of these is that they will not, but I hope this thread will not be lost to flaming like the others

[tniem]

I also wonder what your thoughts are on that the military has admitted that it used GPS homing beacons in the missile defense tests. And they still only worked 2 out of 4 times.

Yes I would agree that it is possible and pretty effective...