By Sharon Watkins Lang (SMDC/ARSTRAT Command Historian)April 27, 2017
Fifty years ago on, April 27, 1967, the Multifunction Array Radar or MAR I, tracked five targets that had been ejected from a HIGHBALL rocket over White Sands Missile Range, New Mexico.
This multiplex tracking demonstration successfully completed an operational milestone for the MAR program: Could a radar search and acquire possible targets and continue to operate in a search and discriminate mode while tracking the initial target? In this demonstration then, the MAR did just that - locate, identify and track five separate objects.
While not widely reported, this was a significant event documented in not only the command's history but also in larger volumes that sought to capture the history of the Army's strategic air and ballistic missile defense. With this and other accomplishments, the MAR provided a unique resource for radar innovations but it was never deployed. The test program was terminated in 1967 and the MAR was ultimately discontinued in 1969.
The concept of the MAR was first introduced in 1960 with a study to determine the feasibility of using a single electronically scanned radar to perform multiple functions -- acquisition, discrimination and tracking. Initially known as the Zeus Multifunction Array Radar, this system "would feature a phased array arrangement with no moving parts and no necessity for a rotating antenna." Designed to have four radar faces situated at 90 degrees, the system could cover 360 degrees in azimuth using a modulation scan to sweep the field.
With authorization to proceed granted in July 1961, construction began in March 1963. This initial version, referred to as the MAR I, included only one hardened installation with its transmitter and receiver arrays. Nevertheless, in a series of tests beginning in 1964, the MAR demonstrated the characteristics needed to support the proposed NIKE-X deployment concept.
Not only would the powerful MAR increase the warning times, it could continuously and automatically acquire, discriminate (distinguish between warheads and decoys) and track multiple targets across a wide field of view and essentially control the battle from a single site.
Even as testing began, however, issues forced a shutdown of the transmitter in 1965. As Bell Labs reported in their "ABM Project History" "a number of design faults resulting in poor reliability were uncovered in such elements as the traveling wave tube."
With thousands of these tubes in the MAR, this discovery led to an expensive redesign and a new requirement for extensive laboratory testing for all elements duplicated in the thousands in a full radar.
On a more positive note, additional changes to the cathode design increased the life of each tube from 10,000 to 30,000 hours. This increased efficiency reduced the need for some cooling equipment and helped reduce the costs associated with the system. This is particularly important as the estimated cost to build a full scale MAR complex was $400 million.
Cost was a particular concern as noted by Col. I.O. Drewry, Nike-X program manager, in the April 27, 1966, edition of "Cost Reduction Digest."
Drewry stated that "system capability and technical performance will not be the major issue in the production decision of the NIKE-X System. Cost considerations are especially significant to the Secretary of Defense at this time because of the high cost of our defense activities in the Vietnam situation and in other areas of our national effort."
The cost, however would not be the only factor that would contribute to the demise of the MAR. First, radar technology had advanced to such a degree that engineers were able to consolidate the transmitter and receiver into one array as seen in the Missile Site Radar and the Perimeter Acquisition Radar, or PAR. Second, the MAR was the centerpiece for a city defense concept designed to protect cities and industrial areas from a Soviet attack. As deployment plans evolved with world events, the MAR and its successors, e.g. the MAR II or the Tactical MAR, played a smaller role until the requirements of the I-67 study replaced the MAR with the more modern and longer-range PAR.
Although never deployed, the MAR was the first radar of its kind. The two-year test program demonstrated the enhanced capabilities of this new technology. And, the lessons learned from the MAR program contributed to the next generation radars that would be deployed as part of the SAFEGUARD anti-ballistic missile system.