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Space junk flies as satellites collide
Source: Agencies |
February 13, 2009, Friday
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Print Edition
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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 Earth.
The US National Aeronautics and Space Administration said it will 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 800 kilometers over Siberia early Wednesday, 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.
NASA believes any risk to the international space station and its three astronauts is low. It orbits about 435 kilometers below the collision course. A spokesman for the Russian civilian space agency Roscosmos, Alexander Vorobyev, said in a televised interview 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 February 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 the 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 non-functioning. The Russian satellite was out of control, Matney said.
The Iridium craft weighed 560 kilograms, and the Russian craft nearly a ton. 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."
At the beginning of this year there were roughly 17,000 pieces of man-made debris orbiting Earth, Johnson said. The items, at least 10 centimeters in size, are being tracked by the US Space Surveillance Network, which is operated by the military. The network detected the two debris clouds created on Wednesday.
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.
"The collisions are going to be becoming more and more important in the coming decades," Matney said.
Iridium Holdings LLC 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. The US Department of Defense is one of its largest customers.
The company 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.
Iridium also said it expected to replace the lost satellite with one of its eight in-orbit spares within 30 days. Initially launched by Motorola Inc in the 1990s,
Iridium plunged into bankruptcy in 1999. Private investors relaunched the service in 2001.
Iridium satellites are unusual because their orbit is so low and they move so fast.
Most communications satellites are in much higher orbits and don't move relative to each other, which means collisions are rare.
The US National Aeronautics and Space Administration said it will 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 800 kilometers over Siberia early Wednesday, 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.
NASA believes any risk to the international space station and its three astronauts is low. It orbits about 435 kilometers below the collision course. A spokesman for the Russian civilian space agency Roscosmos, Alexander Vorobyev, said in a televised interview 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 February 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 the 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 non-functioning. The Russian satellite was out of control, Matney said.
The Iridium craft weighed 560 kilograms, and the Russian craft nearly a ton. 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."
At the beginning of this year there were roughly 17,000 pieces of man-made debris orbiting Earth, Johnson said. The items, at least 10 centimeters in size, are being tracked by the US Space Surveillance Network, which is operated by the military. The network detected the two debris clouds created on Wednesday.
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.
"The collisions are going to be becoming more and more important in the coming decades," Matney said.
Iridium Holdings LLC 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. The US Department of Defense is one of its largest customers.
The company 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.
Iridium also said it expected to replace the lost satellite with one of its eight in-orbit spares within 30 days. Initially launched by Motorola Inc in the 1990s,
Iridium plunged into bankruptcy in 1999. Private investors relaunched the service in 2001.
Iridium satellites are unusual because their orbit is so low and they move so fast.
Most communications satellites are in much higher orbits and don't move relative to each other, which means collisions are rare.
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