NORAD analysts had been tracking Cosmos 954 since it launched, on September 18, 1977, Annie Jacobsen explains (in Area 51), but after three months, the movements of the spy satellite were causing NORAD ever-increasing alarm:
The Russian satellite had been designed to track U.S. submarines running deep beneath the surface of the sea, and what NORAD knew about the satellite was that it was forty-six feet long and weighed 4.4 tons. To get that much payload into orbit required phenomenal power, most likely nuclear.
She misunderstood. The Kosmos 954 required the phenomenal power of a small nuclear reactor (containing 50 kg of uranium) for its naval reconnaissance radar, and the heavy satellite required a powerful booster to get into orbit:
Because a return signal from an ordinary target illuminated by a radar transmitter diminishes as the inverse of the fourth power of the distance, for the surveillance radar to work effectively, US-A satellites had to be placed in low Earth orbit. Had they used large solar panels for power, the orbit would have rapidly decayed due to drag through the upper atmosphere. Further, the satellite would have been useless in the shadow of Earth. Hence the majority of the satellites carried type BES-5 nuclear reactors fueled by uranium-235.
Why was NORAD alarmed?
In December of 1977, analysts determined that the Russian satellite was slipping out of orbit, dropping closer and closer to Earth on each ninety-minute rotation of the globe. Calculations indicated that unless the Russians could get control of their satellite, Cosmos would, in all probability, reenter the atmosphere and crash somewhere in North America within a month.
President Carter’s national security adviser Zbigniew Brzezinski pressed Moscow for information about what exactly was on board the crashing satellite. The Russians told Brzezinski that Cosmos 954 carried 110 pounds of highly enriched uranium 235.
[…]
According to a secret CIA report declassified in 1997, a decision was made not to inform the public. Trying to predict the public’s reaction to a nuclear satellite crash was like “playing night baseball with the lights out,” wrote CIA analyst Gus Weiss, because “the outcome of [Cosmos] 954 would be akin to determining the winner of a train wreck.” The CIA knew exactly what would happen, and that was that “the satellite was coming down carrying a live reactor.” The CIA also believed that “a sensationalized leak would disturb the public in unforeseeable ways.” This information has never been made public before.
[…]
“The satellite was still pretty high up, there was no radioactive danger until it actually hit the ground. But imagine the panic if people, or say a mayor of a city, started calling for cities to evacuate based on where they thought the satellite was going to crash down on the next ninety-minute rotation?” Mingus says the feeling at the command center was that if that were to happen, it would be panic like in The War of the Worlds.
When Cosmos 954 finally crashed, it hit the earth across a large swath of ice in the middle of the frozen Canadian tundra, one thousand miles north of Montana on Great Slave Lake. At McCarran Airport a fleet of unmarked NEST vans—meant to look like bakery vans but really loaded with banks of gamma-and neutron-detection equipment inside—drove into the belly of a giant C-130 transport plane and prepared to head north. NEST personnel included the usual players in the nuclear military-industrial complex: scientists and engineers from Los Alamos, Livermore, Sandia, and EG& G. Troy Wade was the lead federal official dispatched to the crash site. Looking back, he explains, “It was the radioactive fuel we were most concerned about. If a piece comes down that weighs a ton, you can’t predict how far and wide the debris, including all that fuel, will go.”
[…]
After several long months, 90 percent of the debris from Cosmos 954 had been recovered. In the postaccident analysis, officials at NORAD determined that if the satellite had made one last orbit before crashing, its trajectory would have put it down somewhere on America’s East Coast.
Betraying the West German center-right over the neutron bomb, trying to sneak US troops out of South Korea, hiding the danger of a Soviet nuclear satellite crashing on America- D-Carter’s foreign policy was consistent.