Russia's military said Wednesday that an old Soviet-built nuclear-powered satellite has spewed fragments in orbit, but insisted they do not threaten the international space station or people on Earth.
The military's Space Forces said the decommissioned Cosmos-1818 satellite "partially fragmented" in July.
Space Forces chief of staff Gen. Alexander Yakushin said in Wednesday's statement that the satellite's fragments remained on a high orbit far above that of the international space station. Yakushin added that the fragments do not pose any threat of radioactive contamination on Earth.
The fragmentation was first reported earlier this month in NASA's newsletter Orbital Debris Quarterly News.
The U.S. space agency's publication said the satellite released a cloud of dozens of small particles in the July 4 incident. It said the particles could be droplets of sodium-potassium coolant of the satellite's nuclear reactor, possibly released because of a breach in a coolant tube.
Space Forces spokesman Lt.-Col. Alexei Zolotukhin said the satellite's fragmentation was minor. Its cause remained unclear and it was impossible to determine what exactly broke off, he said in a telephone interview.
Zolotukhin voiced skepticism about NASA's analysis of the debris, saying it appeared speculative.
He said the satellite is orbiting at around 500 miles above Earth, compared with the international space station's orbit of 200 miles. He said Space Forces has been checking the satellite's orbit daily.
Zolotukhin said that other satellites orbiting Earth were not in danger because the Cosmos-1818's orbit had been chosen in such a way as to keep it away from other spacecraft.
Zolotukhin said the Cosmos-1818 is expected to come down in 2045. He insisted the satellite would not cause radioactive contamination on Earth because it was designed to burn on re-entry.
In 1978, the Soviet Cosmos-954 nuclear-powered satellite scattered radioactive debris over a lightly populated area of Northern Canada on its fiery re-entry, but caused no injuries.
The Cosmos-1818 was launched into orbit in 1987 on a mission to track ships using a powerful radar scanning the ocean surface. It functioned for several months after the launch before going out of service.
Its sister craft, Cosmos-1867, so far has circled Earth without incident, Zolotukhin said.