page_title: Nike Zeus
section_title: Battery layout
hierarchical_section_title: Nike Zeus / Description / Battery layout
caption_attribution_description: English: Photo of "Mount Olympus", the Nike-Zeus launcher complex on Kwajalein Island. Since the Zeus was stored in silos, and Kwajalein was only inches off the ocean, the Army built up Mount Olympus to be able to use the production-type silos while still being above the waterline. Mount Olympus was located on what was then the extreme south-western end of the atoll. The location of the road and ocean in the background suggest this image is taken looking west. The atoll has since been extensively backfilled, the area of ocean in this photo is now reclaimed land.
context_page_description: Nike Zeus was an anti-ballistic missile system developed by the US Army during the late 1950s and early 1960s that was designed to destroy incoming Soviet intercontinental ballistic missile warheads before they could hit their targets. It was designed by Bell Labs' Nike team, and was initially based on the earlier Nike Hercules anti-aircraft missile. The original, Zeus A, was designed to intercept warheads in the upper atmosphere, mounting a 25 kiloton W31 nuclear warhead. During development, the concept changed to protect a much larger area and intercept the warheads at higher altitudes. This required the missile to be greatly enlarged into the totally new design, Zeus B, given the tri-service identifier XLIM-49, mounting a 400 kiloton W50 warhead. In several successful tests, the B model proved itself able to intercept warheads, and even satellites.
  The nature of the strategic threat changed dramatically during the period that Zeus was being developed. Originally expected to face only a few dozen ICBMs, a nationwide defense was feasible, although expensive.
context_section_description: Data from the ZARs were passed to the appropriate Zeus Firing Battery to attack, with each ZAR being able to send its data to up to ten batteries. Each battery was self-contained after handoff, including all of the radars, computers and missiles needed to perform an intercept. In a typical deployment, a single Zeus Defense Center would be connected to three to six batteries, spread out by as much as 100 miles (160 km).
  Targets picked out by the ZAR were then illuminated by the Zeus Discrimination Radar (ZDR, also known as Decoy Discrimination Radar, DDR or DR). ZDR imaged the entire cloud using a chirped signal that allowed the receiver to accurately determine range within the cloud by passing each frequency in the chirp to a separate range gate. The range resolution was 0.25 microseconds, about 75 metres (246 ft). As the signal was spread out over the entire cloud, it had to be very powerful; the ZDR produced 40 MW 2 µs pulses in the L-band between 1270–1400 MHz. To ensure no signal was lost by scanning areas that were empty, the ZDR used a Cassegrain reflector that could be moved to focus the beam as the cloud approached to keep the area under observation constant.
  Data from the ZDR was passed to the All-Target Processor (ATP), which ran initial processing on as many as 625 objects in a cloud. As many as 50 of these could be picked out for further processing in the Discrimination and Control Computer (DCC), which ran more tests on those tracks and assigned each one a probability of being the warhead or decoy. The DCC was able to run 100 different tests. For exoatmospheric signals the tests included measure of radar return pulse-to-pulse to look for tumbling objects, as well as variations in signals strength due to changes in frequency. Within the atmosphere, the primary method was examining the velocities of the objects to determine their mass.
  Any target with a high probability was then passed to the Battery Control Data Processor (BCDP), which selected missiles and radars for an attack. This started with the assignment of a Target Tracking Radar (TTR) to a target passed to it from the DCC. TTRs operated in the C band from 5250–5750 MHz at 10 MW, allowing tracking of a 0.1 m² target at 300 nautical miles (560 km), a range they expected to be able to double with a new maser-based receiver design. Once targets were being successfully tracked and a firing order was received, the BCDP selected available Zeus missiles for launch and assigned a Missile Tracking Radar (MTR) to follow them. These were much smaller radars operating in the X-band between 8500–9600 MHz and assisted by a transponder on the missile, using only 300 kW to provide missile tracking to 200 nautical miles (370 km). The wide variety of available frequencies allowed up to 450 MTRs to be operating in a single Defense Center. Information from the ZDR, TTR and MRTs was all fed to the Target Intercept Computer (TIC) which handled the interceptions. This used twistor memory for ROM and core memory for RAM. Guidance commands were sent to the missiles in-flight via modulation of the MTR signal.
  The nominal battery consisted of a single DR, three TTRs, two TICs driving six MRTs, and 24 missiles. This basic battery layout could attack three warheads at once, normally using two missiles per salvo in case one failed in flight. More typically, two targets would be attacked while the third system stood by as a hot backup that could take over in-flight. A maximally expanded battery included three DRs, ten TTRs, six TICs driving eighteen MTRs and 72 missiles. Sites requiring higher traffic handling would not build larger systems, but instead deploy additional batteries fed from the same ZAR and Defense Center.
  It was expected that the ZAR would take 20 seconds to develop a track and hand off a target to one of the TTRs, and 25 seconds for the missile to reach the target. With these sorts of salvo rates, a fully expanded Zeus installation was expected to be able to successfully attack 14 "bare" warheads per minute. Its salvo rate against warheads with decoys is not recor
caption: Photo of "Mount Olympus", the Nike-Zeus launcher complex on Kwajalein Island. The built-up hill allowed full-sized Zeus silos to be built into land only feet above sea level.
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