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Aucbvax.1404 fa.arms-d utzoo!duke!mhtsa!ucbvax!CAULKINS@USC-ECL Sun May 24 12:42:54 1981 Re: Empires + Modern Weapons In response to your message sent 23 May 1981 03:47-EDT

Excerpt from "Are We On The Verge of An Arms Race In Space" by Richard Garwin in the May '81 Bulletin of The Atomic Scientists:

Space Based Ballistic Missile Defense

For ballistic missile defense (BMD) one must decide whether the system is to work against an occasional ICBM, and only with some probability, or whether it is to handle with high probability mass raids of ICBMs. Assuming that the system is required to cover the entire earth to counter SLBM as well as ICBM launches, and that the orbits are circular and polar, one can determine the optimum number of orbital planes and satellites per orbit,and the cost of the (unopposed) system.

Thus, making very optimistic assumptions on laser technology and assuming 400 ICBMs launched uniformly over a period of 600 seconds, each with a vulnerable (boost) time of 250 seconds, and that the lasers can spend 70% of their time actually illuminating targets (30% switching between targets) - a booster hardness of 2 kilojoules per square centimeter would correspond to a 10-year system cost of approximately $40 billion, or about $100 million per booster destroyed. The number of satellites involved ranges from approximately 70 at 500 kilometer altitude to about 8 at 6,000 kilometer altitude. A typical spacecraft with a 3-megawatt laser and a 7-meter diameter mirror is assumed to have a dry mass of 3,500 kilograms and a cost of $150 million.

These performance goals are far from available. They require an increase of laser brightness of at least a factor of 1,000,000 over what has been demonstrated in a ground-based system.

Furthermore, this calculation assumes that the laser BMD is essentially unopposed during operation as well as during construction. Assuming a system at the lowest orbital altitude, the average kill range would be on the order of 2,000 kilometers.

The boosters might hide behind aluminum foil screens perhaps 100 meters square.

The satellites can be destroyed by nuclear weapons or by anti-satellite weapons launched together with a flight of decoys against the satellite systems. Electronic countermeasures can be used against the satellite command and control. The BMD system would either have to have some kind of overall control or would have to fend for itself in selecting targets, with several lasers choosing to illuminate some boosters and allow others to escape. The boosters themselves by sacrificing one or two MIRVs could harden their surfaces against laser energy by a factor of 10 or more.

As an alternative to failure the ICBM force could be launched simultaneously, thus increasing the required cost and number of satellites by a factor of 3 or more.The combination of booster hardening and simultaneous launch would require at least a 10-fold increase in laser BMD cost, without attending to the survivability of the BMD system itself. (end of Garwin excerpt)

Sounds to me like laser BMD systems just get us back to the same old measure/contermeasure spiral. As I've said before, what's needed is a solution to the meta-problem of weapons R&D. -------

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