The time in 1978 when a Soviet nuclear-powered satellite crashed into Canada and scattered radioactive debris everywhere

• In 1978, a Soviet nuclear-powered satellite malfunctioned and crashed into northern Canada. 
• Kosmos 954 spread radioactive debris across hundreds of miles, leading to an extensive cleanup.
• Reactions by the US, Soviet Union, and their respective allies marked a major moment in the Cold War.

Almost 50 years ago, a Soviet nuclear-powered satellite experienced a malfunction, fell out of the sky, and exploded over North America, scattering dangerous debris.

The initial crash, cleanup effort, and reactions from across the world were major moments, heightening Cold War tensions and leading to questions about the future of nuclear energy.

In September 1977, the Soviet Union launched Kosmos 954, a reconnaissance satellite, part of a larger program designed to monitor NATO and commercial vessels at sea. These Soviet satellites were powered by nuclear reactors, the majority of which were fueled by uranium, and designed for long-term orbit observation, giving the Soviets an effective way to spy on the US and its allies.

These types of satellites, US intelligence surmised, use a small nuclear reactor to power their radar and the onboard equipment needed to communicate with ground control. But this wasn't confirmed, and the Soviets were unsurprisingly tight-lipped about the operation.

Just a few months after the launch, Kosmos 954 wasn't looking like a success mission.

In November, the Soviets began having trouble tracking it and found that the satellite had deviated from its orbit and was moving at unpredictable speeds and in irregular directions. US intelligence was closely monitoring the situation, too, and had clocked that this satellite was operating differently than other Soviet spacecraft.

By December, the US and some allies were in full crisis management mode. They were sure the Soviets were going to lose control of the satellite, which they did a month later in January 1978, and the rogue Kosmos 954 was likely going to reenter the atmosphere.

Part of the problem, the US later determined, was that the Soviet satellite didn't eject its spent reactor core into an orbit far from Earth — a graveyard orbit — and was instead going to crash land with its nuclear reactor still attached. Depending on where it landed, this could either be benign — an ocean landing, for instance, would have little impact — or, were it to crash near a highly populated area, disastrous.

But regardless of where or how it landed, the crash of the Kosmos 954 would still be, as Gus W. Weiss, a White House policy adviser, wrote in an assessment on "The Life and Death of Cosmos 954," "a no-win situation."

"A colleague suggested the outcome of 954 would be akin to determining the winner of a train wreck," Weiss said.

In the early days of 1978, the US and the Soviet Union had a frank conversation — er, a lively back-and-forth "in the spirit of cooperation," Weiss added.

American officials said they'd determined Kosmos 954 would crash "any time within the next month" and were concerned that it was powered by a nuclear reactor and "reentry into the atmosphere thus may represent a potential for nuclear contamination."

"If the debris falls on or near a populated area, there is the obvious possibility of a serious hazard to the public," they added.

The Soviets responded rather curtly, according to a paraphrased answer, saying the satellite was "explosive-proof" and would burn up in the atmosphere.

But, the Soviets added, "it cannot be ruled out that some destroyed parts of the plant still would reach the surface of the Earth. In that case an insignificant local contamination may occur in the places of impact with Earth which would require limited usual measures of cleaning up," according to Weiss' report.

Nothing to worry about, the Soviet response indicated. But that wasn't quite right, the parties involved would later learn.

By mid-January, US intelligence had determined that the satellite Kosmos 954 was going to crash somewhere in North America. In cooperation with Canada, the US deployed a variety of forces as part of Operation Morning Light — from radioactivity detectors to special nuclear accident support teams — across the areas where the satellite would potentially reenter the atmosphere.

The goal was to be ready for collection and cleanup as quickly as possible, wherever it landed and whenever.

On January 24, it was go time. Kosmos 954 fell through the atmosphere, quickly flying across northwestern Canada. Soviet officials were certain that it had burned up completely upon reentry, but the US and Canadian teams recovered plenty of debris from the satellite across an area of hundreds of square miles.

"The search for radiative debris was quickly put into action," Hsieh Ch'u of the Foreign Technology Division, a former name for the US Air Force National Air and Space Intelligence Center unit, wrote in a 1979 report. "More than one hundred nuclear scientists and technicians and the emergency team were sent to the area where the satellite crash had taken place."

A U-2 reconnaissance jet, a WC-135 weather observation plane with radiation detecting instruments, and several of Canada's C-130 planes were deployed. Teams wore heavy anti-radiation suits, ultimately recovering 12 large pieces, 10 of which were highly radioactive.

Despite the potential hazardous effects of nuclear debris spreading across the environment, the US and Canada were especially interested in recovering as much of the wreckage as possible. For one thing, they wanted to prevent the debris from harming the inhabitants.

But this is the Cold War we're talking about. They also wanted information. The Kosmos 954 crash was a unique opportunity for the US and its allies to collect data on what reconnaissance technology the Soviets were using, as well as what information the Soviets had collected with the satellite.

As Ch'u wrote, "the crash of this Soviet satellite was indeed an unexpected opportunity for the intelligent organizations of the United States and its allies in the Western World."

The Soviets wanted in on the search and rescue, too, but the US wasn't having that. When the Soviets asked, the US simply declined and left it at that.

In the aftermath of the multi-million-dollar, two-month operation, there were plenty of questions about who was and wasn't informed about the Kosmos 954 disaster. The general public certainly wasn't, in part because all informed NATO allies were told to keep the information private.

"A reversal" at the last minute, Weiss wrote, "would have been, at best, awkward."

Speaking of informed NATO allies, it became quite clear that the US had trouble figuring out which of its partners to tell and which to not. This sparked some tension, notably from South Korea and Spain, who, afterwards, were "questioning the advantages of their ties with the US," US officials said when reporting on reactions to the accident.

Close allies, like UK and France, were informed, as were others that the US had "special relationships" with, Weiss said.

"What were our responsibilities to our allies and to the world for a problem which was not of our making but about which we know? Skipping pros and cons, lists of countries, and the imponderable factor that the more nations informed, the greater chance of a leak, the notification problem was surely disturbing," he questioned.

"Mortals, with notorious shortcomings, should not have to make these judgements," Weiss surmised.

News of the satellite crash did eventually break, and while the general media reaction towards the relevant efforts was favorable, there was some criticism of the US over how long it took to tell Canada about the potential for Kosmos 954 to reenter the atmosphere over its territory.

The Kosmos 954 accident came at what would become a turning point in the Cold War. After the general easing of relations between the US and Soviet Union during President Richard Nixon's term, the late 1970s saw tensions enter a new phase with the Soviet-Afghan War and, going into the 1980s, President Ronald Reagan's confrontational policies.

"The climax of the drama of Soviet satellite crash was over," Ch'u wrote. "But the event once again made peoples over the world aware of the fact the armament race between the two superpowers of the United States and the Soviets could bring threat and disasters to the life of common people."

More recently, a relatively new podcast called "Operation Morning Light" has delved into the history of the Kosmos 954 incident, as well as the long-term consequences of the spread of radioactive debris on the Dene indigenous people near Great Slave Lake. Their communities still live with the effects, including radiation in soil and high cancer rates, today.