a single site. Each MAR, and its associated battle center, would process tracks for hundreds of targets. The system would then select the most appropriate battery for each one, and hand off particular targets for them to attack. One battery would normally be associated with the MAR, while others would be distributed around it. Remote batteries were equipped with a much simpler radar whose primary purpose was to track the outgoing Sprint missiles before they became visible to the potentially distant MAR. These smaller Missile Site Radars (MSR) were passively scanned, forming only a single beam instead of the MAR's multiple beams. While MAR was ultimately successful, the cost of the system was enormous. When the ABM problem became so complex that even a system like MAR could no longer deal with realistic attack scenarios, the Nike-X concept was abandoned in favor of much simpler concepts like the Sentinel program, which did not use MAR. A second example, MAR-II, was abandoned in-place on Kwajalein Atoll. The first Soviet APAR, the 5N65, was developed in 1963-1965 as a part of the S-225 ABM system. After some modifications in the system concept in 1967 it was built at Sary Shagan Test Range in 1970-1971 and nicknamed Flat Twin in the West. Four years later another radar of this design was built on Kura Test Range, while the S-225 system was never commissioned. The first military ground-based AESA was the J/FPS-3 which became fully operational with the 45th Aircraft Control and Warning Group of the Japan Self-Defense Forces in 1995. The first series production ship-based AESA was the OPS-24, a fire-control radar introduced on the Japanese Asagiri-class destroyer DD-155 Hamagiri launched in 1988. The first airborne series production AESA was the EL/M-2075 Phalcon on a Boeing 707 of the Chilean Air Force that entered service in 1994. The first AESA on a combat aircraft was the J/APG-1 introduced on the Mitsubishi F-2 in 1995. The first AESA on a missile is the seeker head for the AAM-4B, an air-to-air missile carried by the Mitsubishi F-2 and Mitsubishi-built McDonnell-Douglas F-15J. US based manufacturers of the AESA radars used in the F-22 and Super Hornet include Northrop Grumman and Raytheon. These companies also design, develop and manufacture the transmit/receive modules which comprise the 'building blocks' of an AESA radar. The requisite electronics technology was developed in-house via Department of Defense research programs such as MMIC