Do yourself a favor and read this article about high-altitude cloak and dagger operations in India in the 1960s.

In 1965, Schaller was part of an American spy team that tried to place a nuclear-powered surveillance device on top of Nanda Devi, one of the highest mountains in the world.

That mission was a spectacular failure. The device and its nuclear core vanished along with, or so the CIA hoped, any news about it.

The specifics of the loss of the plutonium-powered surveillance device are worthy of Homer Simpson:

The generator, which weighed about 40 pounds, held at least a half-dozen cells -- each about the size of a cigar -- containing an alloy of plutonium 238 and plutonium 239.

It was the potent combination of the two that made the device both hardy and heat-generating, so warm that the Sherpas would cozy up to it at night, Schaller said.

Just as the team reached Camp 1V, the last camp before the peak, however, a blizzard blew up and forced them to abandon the summit ascent. With no choice but to turn back, Kohli made a fateful decision -- to lash the contraption to a ledge of rocks and leave it behind to avoid having to carry it a second time up the mountain.

The plan was to return in the spring climbing season to finish the job, Schaller said.

Throughout his training, Schaller had tried not to think about potential radiation damage in personal terms, though handling the warm cells made him nervous. With the equipment now at the mercy of the mountain, he remembers having qualms on a larger scale.

"I was very much against leaving the device," he said.

[Snip]

But if the fuel cells burned their way to bedrock, could the massive tonnage of the glacier, grinding away for decades, or centuries, destroy the core and release the plutonium to the environment?

No one can say.

This month, however, a potential clue emerged. In 2005, Takeda took a sample of sediment from waters in the Sanctuary. Recent tests on that coarse sample show the likely presence of plutonium 239, an isotope that does not occur in nature.

Very interesting stuff. The article also has a worthwhile photo gallery, and links to remarkably many published books on Himalayan espionage.