MOSCOW, Feb. 12 (Xinhua) -- Scientists are keeping a close eye on debris generated from Tuesday's collision between a U.S. commercial satellite and a defunct Russian military satellite about 800 km over Siberia.
The accident, the first-ever crash of two intact spaceships in orbit, involves one of the 66 satellites privately owned by Iridium, a U.S. telecoms company and a Russian satellite launched in 1993 but ceased to function two years later.
Space collisions are rare events and normally involve parts of spent rockets or mini-satellites. Prior to Tuesday's incident, only three major collisions were confirmed between spacecraft and space junk in history.
Alexander Vorobyov, press secretary of the Russian Federal Space Agency (Roscosmos), said the debris generated in the collision does not pose a threat to the International Space Station (ISS) in an interview with Russian TV station.
Valery Lyndin, spokesman for the agency's flight control center, told Xinhua that the ISS is operating well and Roscosmos is collecting and processing relevant data.
"The fragments may descend to the ISS orbit over several years, although I do not rule out the possibility that some fragments may go down within several days," said Mikhail Martirosov from the navigation and ballistic support service of the Russian Mission Control Center.
The real threat will be clear next week when there is enough information for calculating the trajectory of the fragments descent, he added.
U.S. and Russian experts are monitoring the ISS environment so that they will be able to take preventive measures once a possible danger approaches, Martirosov said.
Alexander Yakushin, first deputy commander of the Russian Space Forces, said their cosmic space monitoring equipment is following the debris generated by the collision at an altitude of 500 km to 1,300 km.
The ISS has managed to avoid collisions with space junk several times throughout the decade of its existence.
However, an unnamed Russian expert warned that the debris generated in the collision could threaten the defunct Soviet-era satellites with nuclear reactors.
The debris is scattered in different directions and might collide with old satellites drifting at similar altitude, thus forming belts of radioactive debris, the expert said.
Nuclear reactors on these satellites, which served the navy of the former Soviet Union, were used to provide reliable, durable and comparatively low-cost energy for the satellites, he said, adding that the debris could also smash into other satellites of the Strela series, resulting in more debris.
However, the U.S. space agency NASA believes that risks to the ISS caused by the satellite collision is low.
The conclusion was drawn from the fact that the space station orbits at a lower altitude than the satellites.
The collision occurred at roughly 800 km, an altitude used by satellites that monitor weather and carry telephone communications among other things.
There are about 17,000 man-made objects orbiting Earth, and the tally is constantly increasing. Intact satellites share Earth's orbit with everything from spent rocket stages and spacecraft wreckage to paint flakes and dust.
Analysts believe the collision highlights the growing importance for monitoring events taking place in space.
