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SDI ensures our retaliation

To the Editor:

I feel a pressing need to correct some of the falsehoods and flawed reasoning in Alan Szarawarski's guest column ["SDI is impractical and fatally flawed," Oct. 18].

Szarawarski notes that the head of SDI, General Abrahamson, "does not say that a 100 percent effective missile defense is possible;" then he follows by declaring himself that "an SDI system that is 98 percent effective will not prevent the destruction of the United States in a nuclear war."

The point of SDI is not to guarantee that no warheads will hit their targets in a Soviet first strike. Rather, the intention is that a high attrition rate on a Soviet strike would ensure that most of our retaliatory force would survive, so the Soviets would realize that attacking the United States would be suicidal. In short, the intention is to make the Russians realize that they cannot carry out a successful pre-emptive first strike, and so they will not attack, nor will they be in a position to blackmail the United States.

Szarawarski's next claim is that "SDI is only effective against ICBMs," leaving the United States "vulnerable to attack by submarine-launched missiles and cruise missiles." Are we to believe that SDI defends only against some missiles and not others, and that therfore SDI is inappropriate? Such an implication would be ridiculous; we need different defenses against different offenses. To reject SDI on the grounds that it cannot defend us from all kinds of enemy missiles would be as ridiculous as rejecting submarines on the grounds that they cannot stop a land invasion.

Having discussed the implication, let us return to the initial claim, that SDI would leave us vulnerable to submarine-launched missiles. Only a fraction of the SDI satellites will be over the Soviet Union at a time (SDI satellites will not be in geosynchronous orbit). At any time, most of the satellites will be over oceans, watching for launches from Soviet submarines.

The satellites can shoot down sub-launched missiles like ICBMs. While the flight time may be shorter, our satellites would still detect the missiles within seconds and the laser beams travel at the speed of light, so even while the flight time is just a few minutes instead of around half an hour (ICBMs), we should still get them.

Further, submarines cannot launch all their missiles at once, making it easier for our defense since we can shoot them down one at a time. Also, sub-launched missiles generally travel slower than ICBMs, making it easier to track and destroy them.

As for cruise missiles, it is important to note that these travel at speeds in the hundreds of miles per hour, many times slower than ICBMs (10,000 mph), making them much easier targets. It can be argued that cruise missiles may hide under clouds; however, it is unlikely that they would benefit from cloud cover for their whole flight.

Szarawarski argues that the Soviets will develop countermeasures, such as building more missiles. This time he assumes only a 75 percent effective defense, so the Russians only need to quadruple their missile force to achieve the same number of hits. Surprisingly, Szarawarski fails to make the argument that they would not need a full four times the offense since the extra load on our system may reduce its percent effectiveness. Nevertheless, 75 percent effectiveness is a conservative estimate, so let's analyze his proposal.

What would it cost the Soviets to quadruple their arsenal? Their current missile force cost about half a trillion dollars; quadrupling the arsenal would cost approximately $1.5 trillion. Though we do not know exactly what an SDI system would cost, reasonable estimates are far lower. Where does Szarawarski get the notion that the United States will spend a trillion dollars on a 75 percent effective system, and the Soviets could quadruple their arsenal for less?

Other countermeasures he suggests for the Soviets include cheap decoy warheads, hardening existing missiles and developing anti-anti-missile weapons. Decoys could be distinguished from real warheads by tapping them with a weak laser pulse and observing the recoil. If the Soviets made their decoys as heavy as warheads, foiling the tap/recoil technique, they would have to displace real warheads in the payload of a missile, since the main limit on a missile is its weight.

Similarly, hardening existing missiles, presumably by adding the shell, would reduce the number of warheads they could carry. A half-inch protective shell on the Soviet SS-18, the largest missile in the world, would increase the weight of the missile by approximately the weight of the warheads it can now carry. If Szarawarski chooses to elaborate on "anti-anti-missile" weapons, maybe there will be a legitimate countermeasure to consider.

Szarawarski's biggest technical bungle is his declaration that "shooting down warheads is not much different from shooting down SDI battle stations." Does he know anything about missiles and satellites? One of the major vulnerabilities of missiles to be exploited in proposed SDI systems is their lack of armor, required by the weight constraints on ICBMs.

The shell of the SS-18, for example, is about 1/10-inch thick aluminum. Typical SDI proposals for hitting these include puncturing the skin with lasers and small chunks of metal. While the Soviets are working on killer satellites, satellites are much more defensible than missiles because orbiting satellites are weightless and so can be armored as heavily as necessary. Armoring a missile would make it much too heavy.

The bulk of this letter addresses flaws in Szarawarski's infeasibility argument; however, what is most disturbing is the reasoning that infeasibility is cause to abandon research. Infeasibility means that research needs to be done; that's how things become feasible.

In closing, I request of Szarawarski and others wishing to discuss the SDI issue that they learn about their subject before offering us uninformed arguments. Much of my information comes from the book How to Make Nuclear Weapons Obsolete by Robert Jastrow and the pamphlet "SDI: The `Star Wars' Project" put out by the George C. Marshall Institute.

John F. Pitrelli G->

Kevin B. Theobald G->