Quote:On the afternoon of March 11, 1958, Ella Hudson was nine years old and visiting her cousins' home in Mars Bluff, South Carolina. After an otherwise normal school day wrapped up, Ella had the bizarre pleasure of witnessing firsthand the United States Air Force accidentally drop a nuclear weapon — with its fissile material fortunately removed — on the woods near her cousins' house. Hudson spoke with io9 about that fateful day and how she thought the Cold War had heated up an hour outside of Myrtle Beach.

This happened in March. After school, I had gone to play at my cousin's house, the unfortunate location where this happened. It had been a really wet March. That was the reason everybody lived. When the bomb hit, instead of exploding — which it should have done the minute it hit the ground — it went down into the ground and exploded. We were basically protected from the all of the shrapnel. Nobody was killed, which was a miracle.
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We were then all in the front of the house. We were running, and some guys had seen the mushroom cloud from the highway and gave us a ride to the hospital. I remember thinking, "We had been bombed by the Soviets, and the Americans were too stupid to let us know!"

Quote:Mars Bluff: Aftermath by Charles Glassmire

A SAC B-47 Stratojet bomber crew, on a simulated combat mission out of Hunter Air Force Base Georgia, accidentally dropped a 30-kiloton Mark 6 atomic weapon from its bomb bay. The date was March 11, 1958 over the peaceful town of Mars Bluff, South Carolina, when suddenly a tremendous explosion destroyed the home of railroad conductor Walter Gregg. As described in our last entry, family members were wounded and treated in hospital, and one 9 year old required surgery. The Gregg house was destroyed along with two of his automobiles and a small truck. Ironically, there was no radiation spread from the weapon detonation, since the Plutonium core of the bomb was not inserted. Thus the detonation was only from chemical explosive, but for months afterward the Air Force periodically checked the family and the surrounding land for radiation contamination – and found none.

When the B-47 crew returned to base and landed that day, they found a strange reception. The aircraft parking area was surrounded by Air Police with weapons pointed. The aircrew was required by regulations to carry loaded sidearms; they were immediately disarmed of these and then were taken to, and locked into, a room in the Operations Center of the base. It was suspected that espionage had taken place in a deliberate weapon release. The crew was forbidden to contact anyone, including their families, and was informed they were to remain locked in until further notice. Later that evening, no less a senior staff than General Curtis Lemay, then Vice Chief of Staff of the United States Air Force, telephoned and talked personally with the air crew. Satisfied the incident was purely accidental, he ordered their immediate release. They were charged to speak to no one about the event (and later they were all transferred to overseas assignments.)



Cub reporter Thom Anderson had ignored the advice of his preoccupied editors at the Florence Morning News to “check on it in the morning” and had arrived at the farm with a photographer. He diagnosed the event, including pictures, and the following morning the News headlined the story of an atomic bomb destroying the Gregg household. His paper contained four stories on the event, and carried much more coverage than the New York Times, which had to telephone Thom at the paper to try to get some details of the explosion for its New York edition. Thom also fielded inquiry’s from multiple foreign newspapers. He later was to become the Managing Editor of the News. Strangely, coverage of the story by the national press was to virtually vanish after three days, in stark contrast to the media hysteria typical of today’s nuclear coverage.

The Air Force announced they would make a fair settlement with the Greggs. They sent an officer who accessed the house Gregg had built with his own hands at a nominal value. They got no allowance for housing since they had moved in with their relatives. Their belongings were virtually destroyed in the wreckage, and were estimated at their depreciated value instead of their replacement cost. The officer insisted they provide a list of every item lost, together with its purchase date and original purchase price. The Air Force compensated them for a loss of between “6 to 14” chickens which roamed freely over the yard; lacking a body count, some of them were vaporized in the blast. Since Gregg’s vehicles were destroyed by the blast, the officer provided them a rental car for one week – claiming this was sufficient time to process their insurance claim and purchase another vehicle. Overall the Air Force offered them compensation of $44,000, for loss of property and personal injury.

The Greggs declined the offer and asked their congressman for permission to sue the Air Force. The request went to President Eisenhower, who signed his approval and allowed the lawsuit to proceed. Three years later they received $55,000, from which they had to pay their legal bills. The Greggs abandoned farming and moved into Florence- living there in a modest bungalow.

Immediately after the blast, the Air Force sent a special crew to control access to the site and search for any parts of the weapon which were spread over a wide area. After a week they turned over control back to the State Police and announced all bomb parts were the property of the United States government. A nephew of Walter Gregg, Clyde Gregg, allegedly found a piece of the weapon in a nearby field – he never admitted to the location of the piece, but rumor says it was offered for sale on eBay in 2005. Rumor also says Clyde turned down an offer of $6,000 and has stored the piece under a stuffed beaver in his home. It’s also noted the Florence Historical Society Museum contains several pieces on display for the curious to view and perhaps remember.

Now Days nobody talks much about the event in Mars Bluff. If one drives East out of Florence on U.S. 76 to the intersection of East Palmetto Street and University Road, there on the roadside one sees a historical marker titled “Atomic Bomb Accident at Mars Bluff…”.



Asking local teenagers for directions to the atomic bombing site evokes a puzzled stare. There were some directional signs to the “Atomic Bomb Crater Site” but most have been stolen by students from the local college. Walter Gregg was in his 90’s in 2012, and he’s reluctant to discuss the matter anymore. He says the aircrew flying the bomber have all written to the family with their deepest apologies for the event, and some have even visited and stayed over a few days to become good friends of the family.

The Air Force took some preventive measures after the fact. It is said a multimillion dollar upgrade to the nuclear arsenal explosives now surrounding nuclear weapons insures they no longer can detonate from impact, but require a special electrical signal. Flying procedures now require that the safety pin securing the weapons into the aircraft must remain in place throughout the flight until approaching the target area.

Perhaps the citizens of Mars Bluff will sleep a little more securely tonight…

Quote:What is EMP?

In the early 1960’s, after the Soviets abrogated a test moratorium,  the United States began  high altitude nuclear testing (one of which was code named Starfish Prime) to attempt to destroy any incoming ICBM’s. Some of these tests were unique for the detonation altitudes, being above 200 miles, and essentially triggering in space far above any existing atmosphere. The Starfish Prime test, surprisingly produced serious electrical blackouts in cities some 900 miles distant from the explosion. Luckily, in places like Hawaii, the rugged technology of the electric grid was rather ancient, thus subject to less damage, and was eventually repaired and restored to working order.

Scientists running the test were surprised by this consequence, and also noted many of their electrical test instruments were destroyed. The culprit was a large Electromagnetic Pulse (EMP) from the burst. This effect had been predicted early on by Enrico Fermi at the 1945 Alamogordo test, but awareness of the effect seemed to fade over the years, mostly because few tests were at high enough altitude to initiate an EMP. Additional high altitude tests were, later on, to shed light on the mechanisms generating this seldom seen effect.



What causes this extremely damaging event? When a nuclear weapon is detonated at altitudes above the existing atmosphere, there is an immense burst of gamma radiation released at the moment of detonation.

Gamma rays are electromagnetic waves similar to radio waves or visible light radiation, but more energetic. After burst, this wave of radiation hits the upper atmosphere with a huge impact, and has energy sufficient to knock off electrons from the air molecules, thus causing charged electrons to separate from the now positive atoms. This effect is simple ionization, but with an enormous energy content.



Now a large wave of negative electrons begins to follow the magnetic field lines of the earth, moving over the Earth’s surface while spiraling around the lines of the Earth magnetic field. This action generates an electromagnetic pulse (EMP) of very high intensity, headed for the surface and expanding outwards in a rapidly broadening wave.

Ninety percent of the energy of this wave is contained in high frequencies, up to about 1 GigaHertz. This very short wavelength allows the pulse to couple easily with electrical systems, including computers, power supplies, semiconductors, alarm systems, banking computers and ATM circuits, intercom systems, life-support system controls, transistorized receivers and transmitters, power system controls, radio and communication links, microwave towers, long electrical lines used for power transmission, etc.

When this pulse hits one of the above, it arrives with a very sharp rise time of only a few nanoseconds! This arrival time is so short that there is not time for any safeguard circuitry to close before the pulse couples in. It is likely that this arriving pulse will destroy any surge suppressors, opening the way for later stages of the pulse to couple into the now unprotected circuitry. E.g. this means that your PC surge suppressor cannot close quickly enough to provide any protection to your computer from an EMP attack.

The EMP propagates towards the Earth’s surface in a radially spreading wave, acting along a line of sight from the burst. Therefore, the higher the burst the greater land mass will be impacted and damaged. “The greatest threat is from a high-altitude EMP detonated at 25 to 250 miles above the Earth’s surface… if even a small 1 megaton weapon was detonated at 250 miles above [Kansas for instance] the resultant pulse could disrupt, disable, and damage electronics across most, if not all, of the continental United States”.

But what about the backup generators? When electric power is lost, critical systems are often designed to automatically switch to local generators for their electric power. This will work as long as the generators are supplied with fuel, such as gasoline or diesel. However, these fuels ultimately must be supplied through the national network of supply trucks. These vehicles also deliver critical items such as food to the local supermarkets. The EMP will shut down most modern engines. They simply stop functioning. Older trucks, with sturdier ignition systems may continue to run but evidence is slim on this point. So – when the trucks stop the generators stop. And the food stops...

(To be continued…)

A monochrome YouTube video of the Starfish Prime event created by Joint Task Force Eight and DSWA, and some other shots in the Operation Fish Bowl series, is available.  Note the interesting color effects which appear near the end of the sequence: http://youtube.com/watch?v=KZoic9vg1fw