Missile Away!

The Frigate Bird test of a fully-armed Polaris missile took place in the east-central Pacific on 6 May 1962. The launching ship, USS Ethan Allen, was stationed 1,300 miles southeast of the Hawaiian islands and established an aim point some 1,100 miles away – 525 miles east-northeast of Christmas Island, from which most of the support efforts were staged.

TF-8 had originally scheduled the Frigate Bird shot for 5 May, but dry runs with Ethan Allen on the 3rd and 4th revealed long-range communication problems between the launch area and Christmas Island. This setback necessitated delaying the firing a full day, by which time Pacific Fleet had assigned exclusive use of more reliable radio frequencies to the participants.

On the morning of 6 May, as the accompanying destroyers and the carrier’s air group performed range safety and security functions under the command of RADM Mustin on Norton Sound, Ethan Allen submerged to firing depth. Adverse weather in the impact area delayed the start of the initial countdown for approximately two hours – unfortunately after the missile safety systems had been switched to internal battery power. Finally, the countdown was started and had reached within 30 seconds of launching the primary missile, when the fire control system bypassed the first weapon because of a “muzzle hatch” limit-switch failure and cued up a second Polaris. The backup missile was also bypassed – because of a false “safe/ready” indication – and although both problems were easily correctable, RADM Mustin declared a range-safety hold to be sure that observation aircraft in the impact area were still correctly positioned. Then, just before the new launch time, the weather deteriorated in the firing area, and a further hold was imposed. By this time, the batteries in the onboard tracking-beacon and destruct systems of the first two missiles were running down, which necessitated replacing them before countdown could be resumed. But just as that procedure was getting underway, favorable cloud conditions materialized overhead, and the decision was quickly taken to fire the third of the four test missiles on hand. Following only a short delay caused by a minor hydraulic problem, Ethan Allen successfully launched this third weapon – somewhat after 1400 (launch-area time).5

Safety considerations demanded that the missile be “acquired” by the tracking system before it disappeared into the usual low-lying clouds. Thus, as soon as the Polaris broke the water, Norton Sound trained her tracking radars at the missile and locked on. As the weapon disappeared downrange, all indications were that the trajectory and flight time would fall within nominal limits: For a range of approximately 1,100 miles and an apogee of roughly 400 miles, flight time to the burst point was on the order of 12-13 minutes. Alerted by reports of the launch event, submarine and airborne observers in the target area readied their instruments.

At approximately 1330 local time in the sky above 4° 50’ North, 149° 25’ West, a brilliant, nuclear flash briefly overpowered the equatorial glare, followed quickly by a roiling fireball and a symmetrical mushroom-shaped cloud, suffused initially with a rosy glow. Surface observers 120 miles away saw the flash and then a half-minute long fireball several degrees above the horizon, about the size of a rising sun. As the debris cloud moved upward, the winds aloft gradually dispersed its compact structure as it drifted away to the east.

(far left) In this still image, from a motion picture taken to document the Frigate Bird event, the nuclear-armed Frigate Bird test missile clears the water shortly after launching from Ethan Allen.

Swordfish, the only full-service test of a nuclear-tipped ASROC missile, took place on 11 May 1962 several hundred miles southwest of southern California. In the foreground of this photograph of the spectacular underwater burst that resulted is the firing ship, USS Agerholm (DD-826), standing off at a range of only 4,000 yards.

ASROC and Swordfish The surface-launched Anti-Submarine Rocket (ASROC) became operational in 1961 in two variants – one carrying a parachute-retarded Mk 44 torpedo and the other a low-yield W-44 nuclear depth charge. ASROC’s solid-fuel motor could loft either payload to a maximum range of approximately 10,000 yards. Operation Dominic’s Swordfish trial on 11 May 1962 was the only full service test of the nuclear-tipped ASROC missile, which was retired in 1989. Since the Christmas Island region was heavily fished by local natives, Swordfish was executed in an area some hundreds of miles southwest of southern California, where there had already been an underwater nuclear test – code-named Wigwam – in 1955. USS Agerholm (DD-826) was the firing ship, with USS Richard B. Anderson (DD-786) as a backup. Agerholm and Anderson were elements of Joint Task Group 8.9 (JTG-8.9), to which – following Frigate Bird – RADM Mustin was brought by Yorktown, where he shifted his flag to USS Monticello (LSD-35), the Swordfish command/support ship. In addition to a five-mile floating array of shock and acoustic sensors streamed from Monticello, two “target ships” were positioned to measure weapon effects – the unmanned destroyer USS Bausell (DD-845) just over a mile from the aim point; and the fully manned diesel-powered submarine USS Razorback (SS-394) at periscope depth 4,000 yards from “surface zero.” Originally planned for 10 May, the Swordfish test was delayed for a day by a cloud ceiling that prevented aerial photography. However, at 1300 on the 11th, Agerholm successfully fired a nuclear ASROC at an instrumented target raft 4,000 yards down range. After some 40 seconds of flight and sinking time, the weapon detonated at an undisclosed depth and produced both a powerful shock wave and a prodigious water plume and base surge fully captured on film. The resulting data was used to formulate tactical doctrine for ASROC and to refine the Navy’s understanding of underwater weapon effects on both platforms and sensors.

The Aftermath

Subsequent analysis of the recorded data and cloud samples taken by Air Force B-57 Canberra aircraft revealed that the air burst took place 1.25 miles from the nominal aim point and that the Polaris W-47 thermo-nuclear warhead performed up to expectations, with a yield in the 600-kiloton range.6 Five days later, the destroyer USS Agerholm (DD-826) executed Swordfish by launching a nuclear-armed ASROC into a well-instrumented test area 370 miles southwest of San Diego. The resulting underwater detonation was even more spectacular than Frigate Bird. [See sidebar.]

If any adversary had doubted the credibility of the sea-borne leg of the nation’s nuclear triad before, the Navy’s end-to-end Polaris test in May 1962 certainly eliminated any remaining uncertainty. In vectoring Ethan Allan so quickly to the Pacific and demonstrating convincingly that a front-line submarine – loaded out with standard operational missiles – could execute its strategic mission on short notice, the Submarine Force struck a solid blow for nuclear deterrence. A full-system, strategic-weapon test had never been done before, and because the Limited Test Ban Treaty among the United States, the Soviet Union, and the United Kingdom ended atmospheric testing by those three nations only a year later, it was never done again.7

Dr. Whitman is a former Senior Editor of UNDERSEA WARFARE Magazine and continues to be a contributing editor.

Bibliography:

Light, Michael, 100 Suns – 1945-1962, Alfred P. Knopf, New York, 2003.

Ogle, William E., An Account of the Return to Nuclear Weapons Testing by the United States after the Moratorium 1958-1961, U.S. Department of Energy-Nevada Operations, Report NVO-291, October 1985.

U.S. Department of Energy-Nevada Operations, United States Nuclear Tests, July 1945 through September 1992, Report NVO-209, Rev. 15, December 2000.

U.S. Department of Energy-Nevada Operations, Pacific Nuclear Tests – 1962, VHS video tape # 0800043.

1 As part of the Republic of Kiribati, established in 1979, Christmas Island is now called Kiritimati. Readers are cautioned that there is another Christmas Island – an Australian territory – in the eastern Indian Ocean just south of Java.

2 General Starbird’s scientific deputy was Dr. William Ogle, whose now-declassified report on the resumption of U.S. nuclear testing in 1961-62 is an authoritative account of these events.

3 It is certainly worth noting that Frigate Bird took place less than two years after the first successful underwater launch of a Polaris missile from USS George Washington (SSBN-598) in July 1960.

4 A “bhangmeter” is an optical measuring device that determines the time interval from the first of the two peaks of the characteristic visible light signature of a nuclear detonation to the minimum between them. This brief period is related loosely to the warhead yield – more time, more yield – and has been used to provide a rough estimate of the latter. As a reflection of the disdain then felt for this methodology by some members of the scientific community, the root-word “bhang” is a kind of Indian hemp which is smoked for its hallucinogenic properties.

5 Navy authorities were at great pains to explain that in a real-world situation, none of these delays would have had tactical significance, because each of the problems was resolved quickly. Frigate Bird’s experimental protocol, however, required that timing and observation conditions be near optimum.

6 However, at least one source – Ogle’s report – claims a burst altitude of 8,300 feet, vice the “official” figure of 11,000, a curious discrepancy.

7 Irreconcilable safety concerns prevented approval of the proposed U.S. Air Force test of an Atlas intercontinental ballistic missile from Vandenberg AFB or from a deployed ICBM silo in the U.S. heartland. Subsequently, France, China, India – and possibly South Africa – also conducted atmospheric tests, but the last of these explosions seems to have been staged by China in 1980, and none involved operational missiles.