Direct hit is like bowling—if you do not hit the pocket exactly, then many pins will continue to stand” Dr. Hans Mark, as quoted by Richard Lloyd in “Physics of Direct Hit and Near Miss Warhead Technology”, p. 12.
For every winner in a Defense contract competition, there is a loser. And those losers never give up trying to win a piece of the pie. So you can be sure that there were plenty of people cheering for Ted Postol and George Lewis inside the hallowed halls of the military industrial complex when they pointed out the obvious: there is more to a missile than just its warhead. (You can see a “White Paper” of their analysis here, which includes pictures.) The ranks of those organizational “losers” are filled out by the people who have invested their careers in fragmentation warheads and they were cheering because there are severe limitations to hit-to-kill; some of the biggest were pointed out by Ted and George in their article.
Instead of acknowledging the difficulties inherent in hit-to-kill technology, the Pentagon struck back by saying the shockwaves induced by the hypervelocity collision between the two extended bodies (the incoming missile’s warhead/rocket body complex and the interceptor) were sure to destroy the payload. The Missile Defense Agency’s spokesperson, Richard Lehner, stated that readings from test sensors “prove conclusively” that mock warheads “were destroyed and were no longer a threat.”
Hmmm…, what type of warhead and with how much certainty was it destroyed?
It’s true that shockwaves running up the missile body might destroy a unitary warhead (such as a nuclear bomb) but then again, they might not. The Pentagon’s scientists and engineers want a more certain kill mechanism than that, and who can blame them? Lloyd’s book is full of discussion about directly hitting warheads but failing to destroy all or even most of the (biological) submunitions it might contain. (Biological submunitions are very unpopular today among the nonproliferation crowd; I understand there was a vote taken and it was decided that biological weapons were not weapons of mass destruction. I disagree, but that is another story.)
One of the many possibilities missile defense researchers were trying to figure out was how to destroy—i.e. puncture—all the submunitions. Imagine how hard it would be to puncture a majority of submunitions if you are hitting the fuel tank several meters behind the munitions canister. It is very unlikely that any shockwaves propagating up the rocket body walls to have enough of a hydraulic ram effect would cause many of them to rupture. And if they cannot rupture thin liquid filled capsules packed shoulder to shoulder, how are they going to destroy a fairly robust nuclear warhead? On top of that, add in a warhead separation mechanism (to be blown later in flight). Could shockwaves reliably propagate across that?
Ted and George’s observations are not good news for hit-to-kill technology. The Pentagon’s reaction—basically denying the problem—is even less good news for the defense of our country. Fortunately, there will be plenty of losers from the last bureaucratic battle over missile defense technology—the one that selected hit-to-kill as opposed to fragmentation warheads—who will be eager to wade in and try to correct our missile defense systems.
UPDATE Just to be clear, Richard Lloyd’s book is about enhancing hit-to-kill technology when the interceptor comes close to hitting the warhead. It is a way of leveraging the advances that have been achieved in hit-to-kill technology in recent years. Ted and George’s paper still point out some of the problems left to be solved: ie leaving the last stage attached as long as possible etc.