Craven, meanwhile, was increasingly on call as the Navy's resident deep-ocean expert. But there was one call that stood out from all the rest. It came on a Saturday morning in January 1966.
"This is Jack Howard," said an assistant secretary of Defense in charge of nuclear matters. "I've lost an H-bomb."
"Why are you calling me?" Craven asked.
"This one I've lost in the water, and I want you to find it." Craven was being assigned to work with a team hastily assembled by an admiral in the Pentagon. Another group was going to the site.
A B-52 bomber had collided with an air tanker during a refueling operation 30,000 feet in the air off the coast of Palomares, Spain, losing its atomic payload. Three of four bombs were recovered almost immediately. But a fourth was lost and had presumably fallen to the bottom of the Mediterranean. President Lyndon Johnson knew the Soviets were looking for the bomb, and he refused to believe the Navy's assurances that there was a good probability that it would never be recovered by either side. Indeed, that was the belief of most of the people assigned to find the bomb — but not Craven.
Craven called in a group of mathematicians and set them to work constructing a map of the sea bottom outside Palomares. That sounded reasonable enough, but Craven intended to use that map for an analysis that seemed more reminiscent of racetrack betting than of anything ever put down in a Navy search and salvage manual.
Once the map was completed, Craven asked a group of submarine and salvage experts to place Las Vegas-style bets on the probability of each of the different scenarios that might describe the bomb's loss being considered by the search team in Spain. Each scenario left the weapon in a different location.
Then, each possible location was run through a formula that was based on the odds created by the betting round. The locations were then replotted, yards or miles away from where logic and acoustic science alone would place them.
To the uninitiated, all this sounded like the old joke about a man who loses his wallet in a dark alley. Instead of searching the alley, the man chooses to search for his wallet yards away under a street lamp because the light there is better. But as far as Craven was concerned, there was good science behind his apparent madness.
He was relying on Bayes' theorem of subjective probability, an algebraic formula crafted by Thomas Bayes, a mathematician born in 1760. Essentially, the theorem was supposed to quantify the value of the hunch, factor in the knowledge that exists in people beyond their conscious minds.
Craven applied that doctrine to the search. The bomb had been hitched to two parachutes. He took bets on whether both had opened, or one, or none. He went through the same exercise over each possible detail of the crash. His team of mathematicians wrote out possible endings to the crash story and took bets on which ending they believed most. After the betting rounds were over, they used the odds they created to assign probability quotients to several possible locations. Then they mapped those probabilities and came up with the most probable site and several other possible ones.
Without ever having gone to sea, the team now believed they knew where the bomb was. According to their calculations, the most probable site lay far from where the other three bombs had been recovered and far from where most of the plane's debris had hit the water. Worse, if Craven's calculations were correct, the bomb lay in a deep ravine and was all but unreachable.
The Navy had come across a Spaniard who was reputed to be the very best fisherman in Palomares, Francisco Simo-Orts. Simo-Orts claimed to have seen the bomb fall into the water, and he pinpointed its location right over the same ravine. With no other leads, the team in the Med had no choice but to arrange a serious search of the ravine and began contacting the companies that had tried to interest the Navy in their deep-diving submersibles.
The Bureau of Ships agreed to pay to fly two submersibles to Palomares, Reynolds's Aluminaut and Woods Hole's Alvin. After several weeks and no success, President Johnson was furious. He demanded to know where the bomb was, and he demanded to know just when it would be recovered.
In answer, a copy of Craven's latest probability hill — altered to take the weeks of failures into account — was sent to the president.
Johnson blew up at the sight of Craven's curves and graphs. If the search teams couldn't give him instant answers, the president would find scientists who could. He insisted that another group of scientists be hired from Cornell and the Massachusetts Institute of Technology. They met in an all-day session. In the end they agreed that Craven's plan was the best anyone had.
Johnson didn't have much time to react. For that same day, the crew of the Alvin, on its tenth dive, sighted a parachute enshrouding a cylindrical object. It was 2,550 feet underwater wedged into a 70-degree slope. The Alvin had found the missing H-bomb right where Craven's latest calculations put it.
1