Scientists are keeping a close eye on orbital debris created when two communications satellites — one American, the other Russian — smashed into each other hundreds of kilometers above the Earth.
NASA said it would take weeks to determine the full magnitude of the unprecedented crash and whether any other satellites or even the Hubble Space Telescope are threatened.
The collision, which occurred nearly 800km over Siberia on Tuesday, was the first high-speed impact between two intact spacecraft, NASA officials said.
“We knew this was going to happen eventually,” said Mark Matney, an orbital debris scientist at Johnson Space Center in Houston, Texas.
NASA believes any risk to the international space station and its three astronauts is low. It orbits about 435km below the collision course.
A spokesman for the Russian civilian space agency Roscosmos, Alexander Vorobyev, said on state-controlled Channel I television that “for the international space station, at this time and in the near future, there’s no threat.”
There also should be no danger to the space shuttle set to launch with seven astronauts on Feb. 22, officials said, but that will be re-evaluated in the coming days.
Nicholas Johnson, an orbital debris expert at the Houston space center, said the risk of damage from Tuesday’s collision is greater for the Hubble Space Telescope and Earth-observing satellites, which are in higher orbit and nearer the debris field.
The collision involved an Iridium commercial satellite, which was launched in 1997, and a Russian satellite launched in 1993 and believed to be nonfunctioning.
The Russian satellite was out of control, Matney said.
The Iridium craft weighed 560kg, and the Russian craft nearly 1 tonne. No one has any idea yet how many pieces were generated or how big they might be.
“Right now, they’re definitely counting dozens,” Matney said. “I would suspect that they’ll be counting hundreds when the counting is done.”
There have been four other cases in which space objects have collided accidentally in orbit, NASA said. But those were considered minor and involved parts of spent rockets or small satellites.
Litter in orbit has increased in recent years, in part because of the deliberate breakups of old satellites. It’s gotten so bad that orbital debris is now the biggest threat to a space shuttle in flight, surpassing the dangers of liftoff and return to Earth. NASA is in regular touch with the Space Surveillance Network, to keep the space station a safe distance from any encroaching objects, and shuttles, too, when they’re flying.
Iridium Holdings has a system of 65 active satellites that relay calls from portable phones that are about twice the size of a regular mobile phone. It has more than 300,000 subscribers, including the US Department of Defense.
Iridium said the loss of the satellite was causing brief, occasional outages in its service and that it expected to have the problem fixed by today.