THE Denver Post - Perspective
Magazine
Special to the Denver Post
April 13, 1986
By Dr. Howard A. Garcia
THE major assumptions in the Strategic Defense Initiative are: (1) that a defensive weapon can be placed in orbit at the right place and the right time, can survive a pre-emptive attack, and can intercept and destroy a large number of hardened launch vehicles, all in less than 60 seconds; and (2) that a sufficient number of these flawlessly executing defensive satellites can intercept 1,400 or more Soviet ICBMs launched simultaneously.
A generally accepted scenario envisions an American fleet of defensive satellites consisting of mirrors, or laser-mirror combinations, orbiting the Earth on paths that carry them over the Soviet Union.
A plausible formation of battle at the commencement of hostilities between the United States and the Soviet Union might involve 1,400 Soviet ICBMs (about their present number), each carrying 10 nuclear warheads and decoy material, opposed by 1,000 American defensive satellites, 70 of which would be within range of Soviet launch plaforms at any given moment.
Roughly speaking, 93 percent of the defensive force would never engage the Soviet missiles. For every satellite that is over the Soviet missile sites, 15 defensive satellits will be elsewhere in their globally fixed orbits at any given time. This 15:1 absentee ratio is an approximation based on one possible distribution of ground tracks over the Soviet missile sites and an assumed maximum lethal range of the defensive weapon, about 1,000 kilometers.
Consequently, only a small fraction of the orbiting fleet of defensive satellites will be at the right place at the right tine. This represents an inordinately inefficient use of the defender's resources, particularly when it is considered that far less complicated satellites today cost in excess of $50 million each.
Some proposals have been suggested as compensation for, or elimination of, the high absentee problem such as geosynchronous satellites which could be placed on a fixed longitude that also crosses the Soviet launch platforms. But they must be over the equator and located about six earth radii 22,000 miles in altitude, effectively out of range for any conceivable defensive weapon.
The permanently orbiting defensive force could be augmented with a fleet of launch-on-warning U.S. submarines firing intercept missiles from the waters closest to the Soviet Union. But the problem here is that, even though the range may be shorter, the reaction time is essentially zero. Soviet ICBMs may have completed their crucial burn and begun warhead deployment before the Intercept vehicles could react.
But suppose the requisite number of defensive satellites arrive safely and in time to intercept the Soviet force, to obtain their respective fixes during the powered flight of Soviet ICBMs, and to aim their mirrors with sufficient accuracy (about 0.3 arc-second at a range of 1,000 kilometers), and fire. Will the directed-energy beam have sufficient power to do any damage?
An unhardened, solid-fuel booster such as a modern Soviet rocket can survive an impulse of up to 10 kilojoules per square centimeter of energy fluence on its skin (one kilojoule equals 1,000 watts of power for one second). Higher energy fluences than this will begin to inflict serious damage. Toughening the booster by spinning, applying ablative coatings, etc., can easily increase the required lethal dosage by almost an order of magnitude - i.e., times 10. At this intensity, the total energy deposition on a spot 1.5 meters in diameter would require about 1,500 megajoules (million), or 150 megawatts of power applied continuously for 20 seconds. Twenty kills in 60 seconds would more than triple this power requirement.
Moreover, the energy supplied by or to the satellite that fires the weapon will have to supply substantially more than this amount of power to compensate for losses, including beam spreading at near perfect optical performance of the laser/mirror combination.
Can the support system furnish this total concentration of power?
It may if the generating plant on Earth has almost the full generating capacity of the entire U.S. power network. However, the means for converting this enormous power into a concentrated, 60-second impulsive burst distributed among several ground-based lasers is not yet at hand. Perhaps it may never be.
If the energy is not supplied by an Earth-based generator, it must be
self-contained by each anti-ballistic missile satellite. Several schemes have
been proposed for such a space weapon and its energy supply.
The power plant on a defensive satellite may be energized by chemical burning,
explosives or nuclear power. For example, hydrogen fluoride chemical lasers
require more than a kilogram (2.2 pounds) of reactants per megajoule radiated at
the theoretical limit for converting chemical to laser energy.
If each satellite consumed 1,500 megajoules of energy per kill and were charged
with destroying 20 Soviet launch vehicles, it would have to carry 33 tons of
fuel, about four space shuttle payloads.
The economic/logistic implications of supporting, say, 2,000 such satellites to
cope with 1,400 fastburn, hardened Soviet boosters, illuminate the absurdity of
this plan.
A second option, one that has received considerable attention owing to recent well-publicized underground atomic tests, is the X-ray laser. This laser is pumped by exploding a nuclear bomb carried aboard the satellite which also carries a number of packets of lasant rods, each aimed at a different high-velocity target. When the bomb goes off, the radiant flux focused onto the rods excites the electrons in the lasant material to million-electron-volt energy. This energy is re-released in the form of X-ray laser beams directed toward the targets. The strike must be successful the first time because the satellite and all of its weapons are destroyed in the blast.
A one-megaton bomb releases about 4 billion megajoules of energy, but because of the inability to contain this energy or focus the Xray beam to visible-light standards, only a small fraction of this energy would reach the target. Moreover, the blast in space would release a cloud of energetic charged particles which could disrupt communications between the command and control system and the defensive fleet of satellites.
The problems associated with managing, controlling and stabilizing many independent bundles of lasant rods, each aimed at a different target for each bomb blast, are understandably stupendous.
One may appreciate the Soviets' stormy reaction to star wars in view of the prospect of hundreds of such devices overflying the Soviet Union in peacetime, even if they recognize the futility of the system to defend against their missiles. Exploding many of these devices in the space of a minute during hostilities would not exempt the Soviet people from the ravage of space war as Reagan avers, but might cause many civilian casualties.
A third option, particle beams, is restricted to a narrow range of target altitude, 160-200 kilometers, in which to operate. They are only marginally effective against today's slow booster performance and will be totally ineffective against a future generation of fast-burn boosters.
A final option, kinetic energy weapons (such as powered homing projectiles), are too slow by orders of magnitude to intercept Soviet boost vehicles at the considered ranges and in the considered reaction times. During mid-course flight they would still have the decoy problem to contend with, and during re-entry they must again face target discrimination and broad regional dispersion difficulties over the United States.
Finally, suppose that all of the above problems are surmounted, then the Soviet Union launches an all-out strategic attack. Suppose further that all the attacking missiles are shot down by the space-based defensive system. The inescapable fact remains that star wars is totally ineffective against atmospheric, radar-evasive, low-altitude, terrain-maneuvering cruise missiles and bombers. These alternative systems can traverse great intercontinental distances or short submarine-launched distances with high delivery accuracy. Apparently, Reagan has so deluded himself with star wars as to have overlooked, ignored or concealed this possibility.
Mortimer Zuckerman, editor-in-chief of U.S. News & World Report, gleefully reported last November after a presidential interview, that star wars will also defend against mobile and cruise missiles. Astonishingly, he goes on to say that star wars might even give the United States a first-strike capacity by interdicting a retaliatory Soviet strike. (Gee, all this time we thought star wars was a purely defensive system !)
It appears that many people in the United States - some very credulous folk and of course those who advise Reagan - have swallowed the fiction of star wars. Our European allies have been far more circumspect, calling instead for peaceful applications of developing laser and particle beam technology. Willy Brandt, former chancellor of West Germany, has called star wars a delusion that presents a danger of further destabilization.
If human history has any message at all to convey to this frightened and propaganda-freighted world on this subject, it is that advances in defensive warfare only spur the enemy's efforts to devise the means to overcome each new threat. Any shield that protects one adversary against his enemy can only be perceived by his opponent as a potential threat.
Still there remains a sizable segment of American society that is willing to endorse star wars, even while harboring doubts about its probable effectiveness on the misguided belief that it alone will deter the Soviet Union from increasing the lethality of its own arsenal, and thus reduce the threat of war. Recently the Soviet leadership has demonstrated an uncharacteristic willingness to bargain, perhaps because of the specter of star wars, but there is not a shred of evidence that they will actually yield another inch of ground in the face of continued American intransigence on this issue.
Far better that President Reagan concentrate his efforts at Geneva and future meetings to find accord specifically on the arms control and reduction issue rather than continue to pursue an expensive and technically dubious policy.