U.S. Naval Cryptologic Veterans Association

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Launch and Telemetry Intercept

When a Soviet launch was imminent, keeping communications in sync was critical. Unless one of the large US missile tracking ships was in the area, our only way to get warning of the launch was via HF communications. If the VANDENBERG or ARNOLD was close by, they might be able to get the launch warning via either satellite communications or their own HF links and forward it to us via VHF radio.

We had a high-gain steerable antenna in the “golf ball” housing over the Telemetry room, but it was seldom operational. The antenna was supposed to give us satellite communications capability. The rolling motion of the DEs resulted in too much wear and tear on the aiming system servo motors and they usually failed before we arrived on station. Even if they were working, the servos couldn’t move the antenna fast enough or far enough to compensate for the ship’s motion in anything other than the calmest of seas. Since we had no satellite communications capability, we had to rely on HF radio for warning signals.

The launch warning came from other national surveillance assets: ships or tracking stations near the Aleutian Islands, or satellites. In 1970 and 1973, the US launched its first geostationary SIGINT satellites, Rhyolite 1 and Rhyolite 2. These satellites were designed to collect telemetry from launches at the main Soviet launch facility at TYuRATAM. The satellites were able to collect telemetry for the launch and intermediate phases of the missile tests, but they could not get good results for the re-entry phase of tests which impacted in the North Pacific near 180°E. My own suspicion is that the modification of the CLAUD JONES class DEs was prompted by the lack of telemetry intercept satellite coverage in the mid-Pacific impact area.

HF Launch warning messages went out to the ships in the impact area at FLASH priority. By the time the message arrived aboard the MCMORRIS, we would have about 15 to 20 minutes for the CO to position the ship and for the CTs to be ready to intercept the telemetry. If there was only one DE on station, the CO would generally put the ship right in the middle of the predicted impact area as determined from the positions of the SMRIS. That would give us the best chance to collect warhead debris and the exact position made no difference to the omnidirectional telemetry intercept antennas.

When we estimated that the missile was about 10 minutes away we would start our high-speed tape recorders and begin searching for the telemetry signals. We had to be wary of starting the recorders too early as a tape only lasted about 15 minutes. We could not risk starting too early and having to change tapes in the middle of a reentry. We had two recorders, but we always wanted to keep one as a backup in case of an equipment failure. We would generally collect telemetry in two phases separated by a blackout interval. The blackout occurred as the warhead re-entered the atmosphere. The very high speed of the reentry vehicle would heat the air around it to become a superheated plasma that blocked outgoing telemetry signals. When the blackout occurred, the Chief would announce “Blackout” and note the time on the audio log channel. The CTs with valid telemetry signals would move their hands away from the receivers lest they jar a knob and shift their receiver frequency.

After a minute or two, one or more of the CTs would announce “Reacquisition” and the Chief would note that on the log and everyone would breathe a sigh of relief. We would continue to collect terminal phase telemetry for several more minutes until the warhead hit the ocean. There would sometimes be an announcement from the bridge of a visible impact. Some warheads also had a sounding and destruction charge that exploded on impact. This charge allowed the SMRIS to pinpoint the impact area with sonar gear. It also destroyed most of the warhead electronics.

After the impact the DE would head to the impact area to search for debris. After the CTs had shut down the recorders and logged the frequencies and telemetry types, they were free to go on deck to observe the debris retrieval. The ship’s crew had long-handled dip nets to fish out any debris that they could find. All I ever saw recovered were some charred chunks of Styrofoam. Perhaps the size and curvature of the foam told CIA and Air Force analysts something about the warhead—to those of us aboard the ship it was rather anticlimactic. I think the CO and crew did find it interesting to match wits with the helicopter from the SMRIS to see who could get the most Styrofoam!