SPECIAL NOTE: We received this email correction:
As a former Launch Control Officer on the Program 437 crew that rotated between the 10th Aerospace Defense Squadron (ADCOM) at Vandenberg AFB and our Detachment One at Johnston Island, I take exception to your quoted statement that the Program 437 Thor launch vehicle was “a thrust-augmented Thor-Delta with three strap-on solid rockets…”
The Program 437 vehicle was not a Thor-Delta, and it did not have any strap-on solid motors! It was a single-stage rocket without thrust augmentation.
In fact, the P437 Thor was simply a modified SM-75 Thor IRBM that was refurbished for space duty after being returned from the United Kingdom in 1963. The modifications included the addition of a Bell Telephone Labs guidance system, a telemetry system, and a flight termination system. The P437 Thor was designated by Douglas Aircraft Company as “DSV-2J” and by the Air Force as “LV-2D.” A total of 18 LV-2D Thors were launched from JI between 14 Feb 64 and 06 Nov 75.
Eric G. Lemmon, Principal Engineer
Boeing Delta II Facilities Engineering
Operation Dominic – Live Nuclear Tests in the Pacific Ocean launched by Thor IRBM’s
“Operation Dominic in 1962, was a series of 36 atmospheric nuclear detonations (29 dropped from aircraft, 1 Polaris submarine launched ballistic missile, 1 surface ship launched ASROC anti-submarine rocket , 1 launched atop a Nike Hercules rocket and 8 carried aloft by THOR rockets.) Except for the two submarine launched tests, all the other detonations were in the vicinity of either Christmas Island or Johnston Island.
The THOR rocket launched tests were to evaluate the capabilities of an antiballistic missile to operate in a nuclear environment and the vulnerability of U.S. reentry vehicles (RVs) to survive a nearby nuclear blast. They also provided information on the ability of a U.S. radar system to detect and track RVs. Another goal was to discern the effects of a high altitude blast on improved command and control systems, which were shown to be vulnerable in earlier high altitude tests. The final goal was to obtain information on the feasibility of testing in outer space.
The first direct nuclear test, dubbed Bluegill, was the planned launch of a THOR with a W-50 warhead in a MK-4 RV on 3 June 1962. This, and all subsequent missions, called for twelve aircraft to evacuate all non-essential personnel from Johnston Island to the USS Princeton prior to launching the THOR. Additionally, these twelve aircraft were tasked to fly designated search patterns in an attempt to retrieve NIKE missiles which were to be shot through the blast/radiation zones of the high altitude detonations. The other eight aircraft were divided into four sections with the mission of retrieving three data collecting pods which were attached to the side of the THOR rocket. These data pods were designed to be jettisoned from the rocket at a predetermined altitude, which allowed them to climb a bit higher from there own inertia and kinetic energy, as the THOR continued to roar upward. These pods were designed to float after free falling for a designated distance then parachutes would deploy easing them back to the sea with the blast data stored in their recording devices. Bluegill lifted off the launch pad at midnight (local time) but problems had been encountered with the range safety radar prior to launch, and five minutes after launch the Johnston Island missile tracking system failed. Unable to monitor the missile’s flight path, the range safety officer destroyed it 10 minutes later, prior to warhead detonation.
The next high altitude THOR launched test, dubbed Starfish, was scheduled for 20 June. The rocket with the 1450 kt Starfish device (W-49 warhead and the MK-4 RV) on it’s nose was launched that evening but the THOR missile engine cut out only 59 seconds after launch. The range safety officer sent the destruct signal 65 seconds after launch, and the missile was destroyed at approximately 35,000 ft. The warhead high explosive detonated in 1-point safe fashion, destroying the warhead without producing nuclear yield. Large pieces of the missile fell back on Johnston Island, and more wreckage along with plutonium contamination was found on nearby Sand Island.
By July 9, 1962 another THOR had been delivered and was configured the same as the previous Starfish test vehicle. This rendition bore the name Starfish Prime. Again all non-essential personnel (total personnel on Johnston Island numbered between 700 to 800) were evacuated to the USS Princeton for the night launch of Starfish Prime. Many of the people brought to the ship were relatively high paid scientists, engineers etc. who had nowhere to go and nowhere to spend their salaries. Rumor has it that many high stakes poker games could be found on the USS Princeton as these folks waited for the all clear signal to return to their work stations on the island.
At 0900Z the THOR lifted off Johnston Island and roared to an altitude of 248 miles where the W-49 warhead/MK-4RV were released and detonated. The test was quite spectacular with impressive light displays from an artificial aurora lasting up to seven minutes. The electromagnetic pulse (EMP) from the test sent power line surges throughout Oahu (800 miles away) knocking out street lighting, blowing fuses and circuit breakers, and triggering burglar alarms. This was the highest altitude test and second largest warhead detonated during the Johnston Island portion of Operation Dominic and was probably the one that lead to newspaper headlines which read, “It Was High Noon at 11:00 PM Today.”
Soon after it was determined the THOR was launched in a successful manner a barrage of NIKE missiles were launched to gather additional data. The trajectory and splash down points of these rockets and associated recording pods could not be predicted as precisely as the pods from the THOR rockets. One atomic veteran who was stationed on board another ship wrote. “The major danger, we were told, would not be from the nuclear explosion, but from the barrage of instrumented Nike missiles which would be launched to take readings on the detonation. The impact points for these missiles were unpredictable (I shot a Nike in the air, and where it fell…). Heavy steel I-beams were stacked on top of the instrumented vans to minimize damage should one or more of these unguided missiles land on us.” This observation was reinforced by the fact that none of the recording devices of the NIKES were ever located by squadron flight crews pilots even though extensive search patterns were flown attempting to recover them.
On the other hand, the THOR’s recording devices splash down points were more predictable and the four sections assigned to retrieve them had much better luck. When such a pod was located one aircraft would approach it at an altitude of 10 to 12 feet and hover over it while the crew chief, using a grappling hook and line, would snare the parachute to prevent it from blowing up into the rotor system which would have certainly ruined the crew’s day, especially over water. Next the crew chief, using another tool which resembled a “shepherds crook”, would use the hook to latch the free end of a 50 foot long sling to an attaching point on the pod. The other end of the sling was fastened securely to the helicopter. Once the hookup was made the pod was hauled back to Johnson Island trailing below the aircraft.
Bluegill Prime, the second attempt to launch the payload which failed on 3 June was scheduled for 23:15 (local) on 25 July. It too was a genuine disaster. The THOR missile was carrying one pod, two re-entry vehicles (all heavily instrumented) and the warhead. The missile engine malfunctioned immediately after ignition, and the range safety officer fired the destruct system while the missile was still on the launch pad. Dale K. Olson aboard the U.S.S. John S. McCain, DL-3 remembers the night, “I got a real sick feeling knowing that there was a fully active A-bomb on the rocket. It gave a new meaning to ‘Put your head between your legs and kiss your ass good-bye.’ I monitored the count down and opened the outside hatch (against orders – but what the hell, if it blew who would know) when we heard the abort code. Hell of a fire ball!” The Johnston Island launch complex was demolished. This proved the wisdom of evacuating all non-essential personnel from the island. According to the Los Angeles Times, “There was no release of radiation and no personnel were injured.” True the warhead did not detonate but when the rocket was destroyed, the warhead was also destroyed and plutonium was scattered all over Johnston Island. There was speculation that the tests would be canceled. In any event the USS Princeton would not be required in the area until the island was cleaned up and another launch pad built so she departed for San Diego with an interim stop in Hawaii.
A third attempt was made to launch the Bluegill device which had now twice been unsuccessful. This launch, named Bluegill Double Prime, was rocketed aloft at 21:14 (local time) on 15 October 1962. Between 86 to 90 seconds into the flight the THOR again failed and the missile began tumbling. It was destroyed by remote control 156 seconds after launch and some of its radioactive debris fell back onto Johnston Island.
Bluegill Triple Prime, on 26 Oct ’62, was the fourth and finally successful launch of this high altitude test using the W-50 warhead in a Mk 4 RV. The 1000 kt warhead detonated at an altitude of 31 miles, approximately 19 miles south-southwest of Johnston Island. This burst occurred low enough in the atmosphere for fireball formation to occur, and observers saw a brilliant white flash and noticeable heat pulse on bare skin. A slightly distorted bright moon-like sphere was seen, yellow at first, then gradually showing green, pink, and violet hues. Blue-purple streamers were formed. A bright glow persisted for 30 minutes, at times bright enough to read a watch face in the dark. The fireball was seen in Hawaii also.
At dawn the following morning the search for the three recording devices which had been attached to the THOR was underway. The pods, which floated only a few inches out of the water, were equipped with a radio transmitter that emitted a signal which was received by two directional antennas attached to each main gear of the helicopter and connected to an oscilloscope next to the crew chief. The crew chief could tell if they were flying toward, or away from, the pod by viewing the strength of the signal. The signal would create a bar on the scope and by keeping the bar centered, with verbal instructions to the pilot, the crew chief could direct the helicopter right to the floating pod. As each was found the lead aircraft of the section would hover low while the crew chief, using the “shepherds hook,” attached the loose end of the strap to the device. The crew chief would then verbally direct the pilot to commence lifting straight up, lifting straight up and out of ground effect into the “Dead Man’s Curve.” (Hovering and/or very slow airspeed at low altitude eliminates the possibility of a safe automation in the event of engine failure and operations within this environment is known as the “Dead Man’s Curve.”) At approximately 50 feet above the water all the slack was out of the lifting strap. Then with a jolt the helicopter would abruptly stop ascending as if it was anchored to the bottom of the ocean for the pod alone, without all the sea water it had accumulated, weighed approximately 2,000 pounds. The pilot would raise the collective a bit more as he twisted the motorcycle type throttle clockwise to wind the Pratt and Whitney R-1820 engine up to its red line of 2,850 RPM and 54″ of manifold pressure which developed the maximum rated 1,525 shaft horsepower. Then, so very slowly the helicopter with its remaining fuel load and crew of four began ascending again lifting the water laden pod from the sea with streams of water pouring from it. Once the pod was out of the sea and the water drained, the cyclic stick was moved unreceptively forward to produce the slight forward component of lift which eased the aircraft forward, allowed it to gain translational lift, and accelerate to 60 knots which finally placed the aircraft in a safe operating environment outside of the “Dead Man’s Curve.” The pod was hauled to Johnston Island at this relatively slow speed of approximately 60 knots because, with the total weight of aircraft and the pod, the engine was not capable of greater airspeed while at the same time maintaining an altitude of approximately 100 feet. Upon reaching Johnston Island the pods were placed in protective mounds which were lined with lead. Each of the other two pods were recovered in the same fashion. The crews searching for the Nikes and their recordings were not so lucky again.
Kingfish was the last THOR launched device which was detonated on 1 November. The detonation occurred at an altitude of 60 miles. The dramatic visual (and other) effects were observed over much of the central Pacific. The explosion appeared as a bright yellow glow, at first circular, but elongating along a south-to-northwest axis. The long axis reached 125 miles after 30 minutes, and eventually reached 185 miles. The glow persisted for at least 1.5 hours. On Johnston Island a yellow-white luminous circle with intense purple streamers was visible for the first minute. Brilliant streamers (beta particle auroras) were seen going north and south from Maui. At Oahu a bright flash was seen, and after about ten seconds a great white ball was seen rising slowly out of the sea and remained visible for several minutes. Another major effect of this shot was the widespread disturbance of the ionosphere and the consequent disruption of radio communications over the central Pacific, which lasted at least three hours.”
Program 437 – Thor Anti-Satellite System based on Johnston Island
In 1964, the US Air Force tested and deployed several Thor rockets which were modified for the anti-satellite mission. This capability grew out of the Operation Dominic series of high altitude nuclear tests, conducted in 1962. These nuclear-tipped ASATs became operational on Johnston Island in the Pacific in 1964 and could intercept a target at much greater range than the Nike-Zeus. The system consisted of “a thrust-augmented Thor-Delta with three strap-on solid rockets, a combination giving the high acceleration needed to intercept satellites in near earth orbit.” The Program 437 Thor system was tested at least 16 times from 1964 to 1970, prior to its retirement in 1976. This system could be restored to operational status on 6 months notice, since the booster components are stored as part of the American capability to resume nuclear testing in the event of the demise of the Limited Test Ban Treaty.
It has been claimed that “Program 437….laid the technological groundwork for the Sentinel, Spartan, Sprint and Safeguard.” Both the Nike Zeus and Thor anti-satellite systems would have utilized nuclear warheads to destroy their targets. This, coupled with the complexity of their launch procedures, amounted to a limited capability with severe operational constraints. “The respective advantages of the two systems were that the Nike Zeus could react more quickly due to its solid propellant, while the Thor missile could be fired against targets at higher altitudes.” Following the retirement of the Thor program, the US emphasis shifted to non-nuclear kinetic kill mechanisms.
Program 437 was America’s second operational anti-satellite system. It was launched on sub-orbital trajectories by Thor LV-2D’s operated by the U.S. Air Force from Johnson Atoll. Perhaps not coincidentally, Thor had been used for space nuclear tests from the same launch site in the early 1960’s. These tests that inadvertently led to discovery of the extreme damage to electronics that could be caused by EMP (electromagnetic pulse) from a high altitude nuclear detonation. The Program 437 Thor could hit satellites up to 700 km altitude using a Mk. 49 nuclear warhead with an 8 km kill radius. The first flight was February 1964, and the system was declared operational in June 1964. The system had a two week reaction time – the missiles and warheads were stored in kits at Vandenberg and had to be deployed to the atoll.
The limitations of a nuclear-tipped ASAT system are apparent – using nuclear warheads just to get a satellite would be destabilizing in a non-nuclear war scenario. Furthermore the EMP effect could damage a large number of your own satellites. The Program 437 system was put ‘on standby’ in 1970 and canceled in 1972 when a hurricane damaged the guidance computers on the atoll beyond economic repair.
In 1965-1966 four Program 437 Thors were launched with ‘Alternate Payloads’ for satellite inspection. This was evidently an elaboration of the system to allow visual verification of the target before destroying it. These flights may have been related to the late 1960’s Program 922, a non-nuclear version of Thor with infrared homing and a high explosive warhead.
The SALT-1 Treaty of May 1972 prohibited ‘interference with national means of verification’ which meant that ASAT’s were not allowed, by treaty, to attack Russian spy satellites. While this did not explicitly prohibit development of ASAT’s, further development would be met by Soviet protests and opposition by certain political groups in the US.
After the loss of Program 437 capability, the USAF moved on to air-launched conventional warhead ASAT’s, first with project SPIKE for launch from an F-106, culminating in the F-15 ASAT missile of the 1980’s.