Falling satellite debris doesn't have to be huge to be dangerous

A few days ago, an aging European satellite harmlessly burned up in the Earth's atmosphere, pretty much as predicted and pretty much as occurs all the time, given the large amount of space debris that's up there. As the average artificial satellite is tiny (about the size of the average office desk up to an SUV - which is still pretty small if you think about it) it's truly astronomical that a large enough piece of debris is likely to cause damage. But that's not to say that debris, even when minuscule, can't be dangerous.

The above image (courtesy US Department of Energy via Historic Wings) is an illustration of an object commonly referred to as "Kosmos 954" (it's actual designation, as far as I can tell, is still classified). It was one of a series of satellites called "Upravlyaemy Sputnik Aktivnyj" or as we in the West call it, RORSAT (Radar Ocean Reconnaissance SATellite). As the name implies, they were meant to spy on NATO fleet movements. And, oh yeah, they were nuclear powered too.

On January 24, 1978, it re-entered Earth's atmosphere, and in the process, dumped radioactive particles over huge swaths of Canada.

Needless to say it was a bit of a thorn in everybody's side at a time when the end of the world was a few keyturns and button pushes away. Our northern neighbors and the Soviets went back and forth as to who should pay for the clean-up (apparently the Russians only footed about half the bill) and there's still a question as to how effective the clean-up was, with some estimates claiming as little as 1% of the radioactive material recovered.