On January 21, 1968, a cabin fire forced the seven-man crew of a U. S. Air Force B-52 Stratofortress to eject over North Star Bay, Greenland.
The pilotless bomber, carrying four B28FI thermonuclear weapons as part of the Cold War's continuous airborne alert mission Operation Chrome Dome, slammed into the sea ice near Thule Air Base. The impact detonated the conventional high explosives inside the bombs, shattering the nuclear weapons and scattering deadly plutonium, uranium, and tritium across a three-mile crash zone. The disaster triggered Project Crested Ice, a massive, desperate cleanup effort carried out by American and Danish personnel in total polar darkness and temperatures dropping below minus 50 degrees Fahrenheit.
Over eight months, workers scraped up thousands of tons of radioactively contaminated snow, ice, and plane wreckage, packing it into steel drums to be shipped back to the United States. Officially, the Pentagon announced that the site was completely remediated and all four nuclear weapons were destroyed. However, declassified documents released decades later told a vastly different story.
While three of the weapons were accounted for through collected fragments, the secondary stage of weapon serial number 78252—a high-yield uranium nuclear core—was nowhere to be found. Military experts concluded that the intense heat from the burning jet fuel had melted through the thick ice sheet, sending the heavy secondary core sinking into the pitch-black waters of Baffin Bay. A secret oceanographic expedition using the submersible Star III attempted to locate the missing core later that year, but dense ice and technical limitations aborted the hunt.
Today, the active thermonuclear component remains undisturbed on the Arctic seabed.