SMDC History: TPQ-18 conducts first mission on Kwajalein

By Sharon Watkins Lang (SMDC/ARSTRAT Command Historian)August 14, 2018

(Photo Credit: U.S. Army) VIEW ORIGINAL

The Land-based Instrumentation Handbook for the Western Test Range describes the AN/TPQ-18 as a "high-accuracy, long range amplitude comparison, 5400 to 5900 MHz, monopulse radar capable of manual or automatic acquisition and tracking of objects in flight or in orbit."

The handbook further explains that the radar antenna is automatically constrained to follow a target "with a minimum of tracking jitter or biases." Specifically the radar can acquire and track both missiles and satellites at ranges out to 32,000 nmi. The TPQ-18 provides trajectory or orbital data, including range rate, in real-time for operational analysis. It has the additional benefit of operating in either coherent (skin) or transponder (beacon) tracking modes and displaying either or both of the video returns.

The AN/TPQ-18 radar set, is actually the transportable version of the AN/FPQ-6 radar set. It incorporates an antenna and pedestal, nine 8 foot by 16 foot equipment shelters, a data interface van, a maintenance van, an office and a computer annex trailer, and a boresight tower. The data handling, timing and communications equipment located in the data interface van enabled the radar to support the launch and tracking operations.

In January 1960, NASA installed the AN/TPQ-18 radar, Serial No. 1, and initiated construction for telemetry operations on Canton Island in the Pacific Ocean, in support of the Mercury and manned space flight missions.

The Mercury program began in 1961. At this point, the TPQ-18 became part of NASA's Manned Space Flight Network, a series of 26 land-based C-band pulse radars/tracking stations that monitored space flights throughout the program.

The Canton station provided monitoring and recording of telemetry data and voice communications. As improvements in communication equipment allowed NASA to monitor operations with fewer sites, NASA ceased operations on Canton on Dec. 31, 1967.

In 1969, the radar transferred to the U.S. Air Force and the U.S. Space and Missile Systems Organization, which incorporated the TPQ-18 into its missile tracking operations part of an anti-ballistic missile program. After five years, the Air Force ceased operations on Canton in 1975.

With this transition in the tracking program, the TPQ-18 radar on Canton was decommissioned by the Air Force's Space and Missile Test Center. At this point TPQ-18, serial no. 1, began its journey to Kwajalein Island. Personnel began to disassemble the radar beginning Oct. 18, 1975. Two months later, on Dec. 6 it arrived on Kwajalein Island.

The next phase was site construction for the new home atop Launch Hill or Mount Olympus (during the Nike-Zeus era) - of the TPQ-18. The system installation then began April 16, 1976. The installation and check out phases took two months. Another month was dedicated to initial calibration and operator training.

Finally, the TPQ-18 radar was declared operational on an engineering and test basis Aug. 16, 1976, when it supported mission 5688, an instrumented RV mission. Mission 5688, also known as SAMAST 3/MINT2, was a metric and signature mission conducted on behalf of SAMSO.

Days later another RV mission (Mission 8446 designated GT-129M), a Strategic Air Command operational test, was tracked in skin mode. In addition, the Kwajalein Missile Range Historical report noted that various local launches and Robin sphere tracks had also been supported by this new radar. To ensure accuracy, calibration and testing continued through February 1977 when the accuracy evaluation and operational certification came. The TPQ-18 was declared operational on Kwajalein Island in March 1977.

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