The Day We Lost the H-Bomb: Cold War, Hot Nukes, and the Worst Nuclear Weapons Disaster in History

The bar was connected to a twenty-five-foot length of line with a snap hook at its end. The Aluminaut grasped the snap hook in one of its claws, carried it to a ring at the end of the lift line, and snapped it in. Mizar raised Alvin and towed the crippled sub to a fishing ground off Martha's Vineyard, where a crane lifted Alvin

onto a barge. Alvin, it turned out, was in remarkably good condition. Scientists and engineers flushed and cleaned every system, replaced the broken parts, and, by 1971, had her back on the job.

But just as Alvin got back to work, government funding for deep-sea exploration dried to a trickle.

Aluminaut, despite its great success recovering Alvin

, grew desperate for work, accepting projects that embarrassed the crew. The most famous, and perhaps the one for which Aluminaut is best remembered, was a television commercial for Simoniz Wax. Producers coated one side of a Ford Falcon with Simoniz, the other with Brand X, then tied the car to Aluminaut and submerged it under water. (“I don't even like to think about it,” said one crew member.) But such exploits failed to cover Aluminaut's operating costs, and in 1971 Reynolds canceled the Aluminaut

program and put the sub into storage. It planned to put it back into the water when it would prove profitable. That day never came.

Alvin, on the other hand, managed to survive the lean years despite its saltwater dunking and went on to a long and prosperous career of scientific discovery. The sub is probably best known for exploring the wreck of the Titanic in 1986 and aiding the discovery of “black smokers,” hydrothermal vents off the Galápagos Islands teeming with bizarre marine life. Over the years, WHOI has replaced individual parts of the sub in piecemeal fashion. All that remains of the original Alvin is three metal plates circling the entry hatch. The sub will retire by 2015, after nearly fifty years of service.

Palomares was not the last major nuclear weapons accident.

On January 21, 1968, almost exactly two years after the accident over Palomares, a SAC B-52 on airborne alert was circling 33,000 feet above Thule Air Base, Greenland. At around 3:30 p.m., the copilot, feeling chilly, cranked the cabin heater up to maximum. Shortly afterward, when other crew members complained about the heat, the copilot started to turn it down. A few minutes later, one crew member smelled burning rubber. As the fumes grew stronger, the aircraft commander told the crew to put on oxygen masks. The crew searched the plane and discovered a small fire in the lower cabin. The navigator fought the fire with two extinguishers, but the flames grew out of control, filling the plane with dense smoke. The pilot reported the fire to the ground, requested an emergency landing at Thule Air Base, and began his descent. Soon afterward, the electrical power on the plane blinked out. The pilot gave the order to eject. Six of the crew members bailed out into the darkness and landed safely in the snow. The seventh was killed.

The pilotless B-52, carrying four Mark 28 hydrogen bombs, continued its descent. The plane glided over the air base, banked left, then crashed into the ice seven miles away. When it hit, the plane was flying more than five hundred miles per hour. The jet fuel on board exploded into a massive fireball, detonating the high explosive in all four hydrogen bombs and spreading radioactive debris over miles of ice. U.S. personnel took four months to clean up the contamination, eventually removing 237,000 cubic feet of ice, snow, and aircraft parts.

By the time of the Thule accident, Secretary of Defense Robert McNamara had concluded that airborne alert was not necessary for national security. In 1966, using the Palomares accident for leverage, McNamara had proposed canceling the program. The Joint Chiefs of Staff and SAC objected to McNamara's plan. Eventually, the two sides compromised. In June 1966, President Johnson approved a curtailed program, allowing only four nuclear-armed bombers on airborne alert each day. It was one of these bombers that crashed in Greenland.

After the Thule accident, McNamara had had enough. He ordered SAC to stop carrying nuclear weapons on airborne alert. Within a day, the weapons had been removed. SAC continued to fly the missions with unarmed bombers, buying time as it continued to lobby for airborne alert. Its arguments, however, failed to persuade civilian authorities, who were tired of cleaning up diplomatic messes left by SAC's accidents. The program was canceled by the end of 1968.