NOTE: Excerpted heavily due to poor condition of original scan, which you can view in PDF format in it's completeness.

DRAFT APPENDIX II TO THE MEMORANDUM TO THE PRESIDENT
SUBJ: PROGRAM FOR DEPLOYMENT OF NIKE ZEUS
30 SEPTEMBER 1961

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Page 5

III. Description, Status, and Technical Evaluation

The NIKE ZEUS is a terminal defense system in which the incoming targets are detected and tracked by radar, the ZEUS missile is launched, steered to an intercept point, and its nuclear warhead detonated by ground command. A special radar provides some capability of discrimination between warheads and decoys.

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A NIKE ZEUS battery is flexible in organization; the nominal ZEUS battery would consist of:

1 - Discrimination Radar (DR)
6 - Target Track Radars (TTR)
12 - Missile Track Radars (MTR)
96 - Interceptor Missiles

Such a battery is capable of firing and guiding to target simultaneously up to six salvos every twenty-five seconds until the missile supply is exhausted. Each salvo normally has two interceptors to assure target kill.

In addition to the battery, the ZEUS system requires a ZEUS defense Center (ZDC) which includes the powerful ZEUS Acquisition Radar (ZAR). A ZAR detects incoming missiles and assigns a battery to perform the interception.

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Pages 6, 7 and 8

After initial detection of a target, the time required for this ZEUS operation is:

ZAR track and target assignment

20 seconds

Missile flight to target

    25 seconds    

Total

45 seconds

This timing requires that the ZAR first detect a threatening ICBM at about 200 nautical miles and the ZEUS Interceptor be launched when the target is at 120 nautical miles. The exact ranges depend on the geometry of the battery and the protected area and on the ICBM trajectory (including re-entry angle).

Improvements in ZEUS are being considered which could reduce the total time required from first detection to interception to 35 seconds under favorable conditions and thereby reduce the required detection range to 130-150 nautical miles.

An important characteristic of ZEUS is the target altitude when the missile is launched: for typical ICBM trajectories, this altitude, depending on the decoy characteristics, lies between 160,000 and 380,000 feet if interceptor launch is delayed to the last possible moment.

If objects are not discriminated at that altitude, ZEUS must either launch against all of them or take the chance of launching a smaller number of missiles and hoping to redirect them at those which are later identified as threatening. If the cloud contains more warheads than ZEUS has launched missiles, the attack succeeds. Thus, the offense can employ decoys to saturate ZEUS. The number of decoys which defy identification down to the missile altitude at the moment of interceptor launch determines the degree of saturation. Decoys which remain unidentifiable by ZEUS down to 200,000 feet altitude are expected to be light (less than 2% of warhead weight) and consequently could be present in large numbers. (This decoy weight increases very rapidly with altitude below 200,000 feet.) These decoys, like ZEUS discrimination techniques, are under development and have not been field tested.

The current design ZEUS single or multiple battery effectiveness can be characterized as follows:

effective against missiles not equipped with penetration aids. Examples are operational ATLAS, TITAN I, MINUTEMAN (Wing 1), POLARIS A1 and A2.

marginal against missiles equipped with minimum (retrofit type) penetration aids. Examples are ATLAS and TITAN as programed, MINUTEMAN Wings 2 through 4. These are programmed in the the U.S. inventory in 1963.

ineffective against missiles with appreciable payload allocation to penetration aids.

In light of the greater pay load capability of Soviet missiles and the expected Soviet knowledge of the operational and general characteristics of ZEUS, we assume that Soviet missiles will be at least as effective against ZEUS as U.S. missiles.

Effective ZEUS operation against "bare" missiles is assured. A single ZEUS battery could successfully defeat about 14 such ICBMs arriving per minute, until the missile supply became exhausted. If the last stage tank could not be identified, which is unlikely, the rate which can be handled is reduced by one-half. Operational ATLAS, TITAN i, MINUTEMAN (Wing 1) and POLARIS (A1 and A2) are examples of such threats.

Marginal ZEUS operation can be expected, however, whenever missiles are retrofitted with penetration aid devices. ATLAS E and F (nose cone weight about 3000 lbs.) will, by 1963, be equipped with penetration aid pods weighing about 250 lbs. Against such a threat ZEUS would be forced to fire between 2 and 18 interceptors depending on the extent to which ZEUS interceptors can be diverted with successful discrimination after launch and on the assumptions concerning the number of warheads in the cloud. A reasonable number might be 12. ATLAS E and F fired with full payload at shorter than design ranges (4500 instead of the designed 5500 nautical miles) can come in at a sufficiently steep re-entry angle to make complete identification of tank fragments impossible before the last possible commitment time.

This would increase the number of missiles fired against a single ATLAS by a factor of two or more. This leads to the conclusion that at least two and probably four or more ZEUS batteries working in close cooperation would be required to shoot down a single ATLAS retrofitted with penetration aids. However, radar field measurements and laboratory development work comparing ATLAS tank fragments, as determined by by ground burst, with the ATLAS E and F warheads show high confidence for the elimination of tank fragments by scintillation filtering techniques outside the sensible atmosphere, providing that the discrimination radar is not jammed and is sensitive enough to see the target.

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e. A Counter to Soviet Anti-Missile Development

Intelligence found solid evidence 18 months ago that the Soviets were developing anti-missile. systems on a more ambitious scale than the United States. Developmental radars of advanced configuration and many times larger than any planned by the United States were observed. Launching installations indicate a more advanced Interceptor (SA-4) than NIKE ZEUS. Also observed were launching installations associated with SA-2, which is deployed at 70 defense centers in the U.S.S.R., and which might be upgraded to kill ICBMs with inadequate penetration systems.

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V. Growth Capability of NIKE ZEUS

If a decision to deploy ZEUS is made now, there are some desirable changes which can be incorporated into the present ZEUS system, either meeting first deployment or phased-in later.

The major area that should get attention for growth in the present ZEUS is the Discrimination Radar (DR). Improvement would be directed toward increasing range against small targets and and resistance to electronic jammers.

Reduction of flight time for a 20 mile interception from 25 seconds to about 15 by design of a new short-range, high performance "Sprint" missile, would gain invaluable time for discrimination at lower altitudes. Dead zones would also be reduced. Such an interceptor missile could be retrofitted to a deployed ZEUS system with relative ease.

More (DELETED) of the cost of a ZEUS interceptor is in the nuclear warhead. If a cheap, effective non-nuclear warhead can be developed the problems of exhaustion of missiles can be overcome to a great extent. Since the missiles are now only a small part of the ZEUS cost, the cost per intercept of the radars would also have to be reduced in order for an important overall reduction in cost per intercept to take place.

Development of a phased array radar, known as ZMAR, has recently been initiated. If successful it will:

1. Perform all of the radar functions with one equipment.

2. Remove most of the radar restrictions on multiple, high-rate-of-fire intercept.

3. Greatly increase resistance to jamming and overcome the ZEUS discrimination radar vulnerability to low cross-section targets accompanied by tank fragments.

4. Eliminate acquisition delays inherent in the mechanically scanned ZEUS acquisition radar.

5. Provide tracking performance adequate for the short ranges envisioned. Many of the components of the present ZEUS system would have to be changed if ZMAR is incorporated in ZEUS, so it would in effect be a new system.

Effective defense of hard targets can be achieved with a low-power, hardened radar system similar to ZEUS-ZMAR described above. Such a system would have very small intercept ranges (under 5 miles) and could therefore hold its fire until the attacking missiles reach very low altitude. The difficulties of discrimination are greatly eased or eliminated and firepower problems alleviated. Such a system must be hardened but otherwise can have less complex and expensive components than ZEUS-ZMAR.

The two types of defended targets of interest are command centers and retaliatory forces. For command centers,the per-installation value defended is probably high enough to justify a version of ZEUS-ZMAR with its expensive radar.

VI. Funding and Planning for a limited Deployment

The recommended program would defend six cities and about 39 million people using six ZDCs, 12 batteries, and 1200 missiles.

Each of the 12 batteries would consist of one discrimination radar, six target track radars, 12 missile track radars, the associated guidance monitoring ground support equipment, and 96 missiles. After the 48 month lead time the first unit would be operational. Total equipment would be delivered and installed in a two year period.