On the Island of “the Forgotten,” ARPA Planted a Seed Called TRADEX

Before and after: ARPA’S Tracking and Discrimination Experiment radar on Roi-Namur at the Reagan Test Site in the Marshall Islands.

Jordan Vinson, for the U.S. Army Garrison-Kwajalein Atoll’s Kwajalein Hourglass

The roots to Roi-Namur’s critical role in American military radar applications lie with TRADEX. Here’s the story.

In the late 1950s, the Navy was ready to begin mothballing the naval base at Kwajalein. The last round of nuclear weapons testing in the Marshall Islands, Hardtack I, had drawn to a close, and negotiations with the Soviet Union in the early 1960s would, indirectly, prohibit further atomic testing in the archipelago. With the island’s critical logistics role in supporting the nuclear campaigns in the northern atolls closing, the Navy slated Kwajalein for abandonment the next year.

Then Nike Zeus came to the rescue .

The base got a new lease on life when personnel with the Army Rocket and Guided Missile Agency, Bell Telephone Laboratories and Western Electric Co. poured over maps, looking for the ideal place to build and test America’s first ABM system: Nike Zeus.

Kwajalein, was ideal, planners agreed, because of its modern infrastructure: An airport and pier, new housing and recreational facilities and more already existed on the island. But more importantly, it lay far enough from Vandenberg Air Force Base, California to allow the Air Force to test launch intercontinental ballistic missiles at full range. On the receiving end, the Nike Zeus missile and radar suite could be built up on the island for full-scale intercept testing of ICBM-class targets.

But what about Roi?

In response to the Soviet Union’s launch of Sputnik and the R7 Semyorka ICBM-class missile, Eisenhower’s secretary of defense Neil McElroy established the Advanced Research Projects Agency (ARPA, now known as DARPA) in 1958, the same year the Navy was planning to shutter Kwajalein. ARPA was assembled with the purpose of coordinating America’s missile programs and rally them against Soviet advances in rocketry and satellite development.

One of the top concerns at ARPA was how little American scientists and the DOD knew about the physics and phenomenology of ballistic missiles as they re-enter the planet’s atmosphere. To gather this data, the organization established a re-entry measurements projects called Project PRESS—the acronym meaning Pacific Range Electromagnetic Signature Studies—and put Massachusetts Institute of Technology’s Lincoln Laboratory, itself only seven years old, in charge.

But where could these scientists and engineers set up an outpost to study ICBM warhead re-entries at full range? Kwajalein, of course.

Because the Air Force was planning frequent Atlas shots to Kwajalein Atoll as part of Nike Zeus testing, ARPA and Lincoln Lab could count on plenty of targets of opportunity to gather the data they were looking for. To gather this re-entry data, the PRESS team would be able to use the Nike-Zeus Discrimination Radar and Target Track Radars on Kwajalein.

But there was the need for a separate radar dedicated solely to the Project PRESS focus on phenomenology studies. That radar would eventually take the name of Target Resolution and Discrimination Experiment (TRADEX). Interestingly, a bit of a fight sprung up between Team ARPA/Lincoln Lab and Team ARGMA/Bell Labs about where to put this new sensor. ARPA and Lincoln Laboratory had chosen the North end of Kwajalein, but Bell Labs—the technical director for Nike Zeus—was concerned about TRADEX’s radio frequency interfering with the Nike Zeus radars. ARPA’s and Lincoln Lab’s attempts to prove there would be no such interference fell on deaf ears.

Forced to take TRADEX elsewhere, ARPA and Lincoln Lab’s attention soon drifted northward, to the conjoined islets of Roi and Namur, where the Japanese had built an airstrip and piers and docks for servicing submarines during WWII. At 419 acres in size, it was big enough for the Project Press mission, and it was far enough away at 43 miles distance to alleviate any concerns Bell Labs might have about radio interference. Roi-Namur, was the solution.

There were, of course, a few logistical downsides to choosing Roi-Namur. The infrastructure on the island had been left to rot since 1946, turning Roi-Namur into a jungle ghost town in the passing years. All of the Japanese facilities were, of course, destroyed, and no airplanes could land on an air strip swallowed in overgrowth. To get there, PRESS planners and Army Corps of Engineers staff were forced to make the trips up to the islet in tugboats. Still, the teams would make progress.

The Corps, which had already been hard at work Kwajalein on the Nike Zeus project, sent equipment and men to Roi to perform vibration and seismic tests on soil around the island to pinpoint the best location for TRADEX. A few months later, the jungle overgrowth on the airstrip was cleared away, and one of the Navy’s Grumman HU16D Albatrosses landed on the airstrip. Lt. Col. Ken Cooper of ARPA joined Lincoln Laboratory’s Glen Pippert, Leo Sullivan and Bill Ward on a final preconstruction tour of the island. They confirmed the location of TRADEX to be the north point of Namur.

By the start of 1961, Corps crews were on Roi-Namur to begin construction. They and employees of RCA—the subcontractor to Lincoln Laboratory on the TRADEX build—lived aboard a rehabilitated barracks ship, APL-24, which was moored near the long-since-demolished Jackaroo Club (just southwest of the terminal).

Interestingly, while the TRADEX technical facilities and office spaces were under construction, onsite PRESS staff had no choice but to adapt and use what they could find. The two-story Japanese bunker near the intersection of Copra Road and TRADEX Road was renovated, becoming the first Project Press office.

Despite the logistical and environmental challenges on the remote, overgrown jungle island, the Army Corps of Engineers, RCA, ARPA and Lincoln Laboratory banded together and had a world-class research radar ready to track ICBMs in a little over a year.

During the spring of 1962, the radar powered on. And on June 26, 1962, TRADEX successfully acquired and tracked the first ICBM launched at Kwajalein Atoll, picking it up in the vicinity of Hawaii with its large antenna and high power. In the series of Nike Zeus intercept tests revving up at Kwajalein and Vandenberg, TRADEX would play a major role in helping ARPA and Lincoln Laboratory understand the physics of ICBM re-entry. In subsequent programs, it would be crucial in helping the organizations understand and improve radar discrimination—picking out re-entering warheads from decoys and other threat cloud clutter.

More than 55 years after that first intercept tracking success, TRADEX remains a regular workhorse at the Kiernan Reentry Measurements Site, and Lincoln Laboratory still has a strong presence at the sensor. Upgraded in several stages throughout the years, TRADEX still performs its classic ICBM re-entry acquisition and tracking role. But outside of re-entry test windows, you can see the radar busy with other tasks like acquiring and tracking new foreign launches and satellite orbit transfers and deep-space object tracking as part of U.S. Air Force Space Surveillance Network activities.

LEFT: TRADEX under construction in the 1961-1962 time frame. RIGHT: Modern configuration of TRADEX today.

SOURCES: “Project History.” ABM Research and Development at Bell Labs; “History of Lincoln Laboratory at the Reagan Test Site.” John Nelson and Kenneth Roth, Lincoln Laboratory Journal; “The History of the Kiernan Re-entry Measurements Site.” Michael Holtcamp, Kwajalein Missile Range Directorate, Ballistic Missile Defense Systems Command, Huntsville, Alabama.

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