Rogue Russian satellite collides with US military (Iridium) satellite - accident?

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Rogue Russian satellite collides with US military (Iridium) satellite - accident?

Two big communications satellites collided in the first-ever crash of two intact spacecraft in orbit, shooting out a pair of massive debris clouds. One was a malfunctioning Russian satellite, the other an Iridium commercial satellite. The odds of it happening were considered remote, the Russian craft changed orbit 'randomly' to exactly hit the Iridium craft. Its like a bullet hitting a bullet.

The Iridium satellite is used primarily by the U.S. Department of Defense and the accident with the 'malfunctioning' Russian satellite happened over Siberia.

Accidental or a first shot in a form of space war? The Pentagon knew where the Russian satellite was, and they could move the Iridium satellite, yet inexplicably a fluke happened and it hit. Did the orbit change and they missed it?

Fortunately there are seven spare satellites in orbit that can be boosted to the correct orbit to replace the destroyed one, assuming the orbit is cleared of debris.

The Russian craft was being monitored by Pentagon organizations that keep track of space debris in order to prevent in-orbit collisions from damaging or destroying both commercial and government satellites.

Pentagon officials will face a barrage of questions about how they missed such an impending collision with an intact satellite, according to Tim Farrar, a satellite consultant familiar with Iridium. Commercial satellites are "routinely repositioned to avoid potential collision with smaller pieces of debris," said Mr. Farrar.

Pentagon brass, satellite industry executives and NASA leaders for years have publicly expressed concern about the dangers of orbital debris. But the odds of a direct hit between satellites were considered so small as to be basically unthinkable. The ground-based and space-based reconnaissance tools available to the Pentagon generally were considered adequate to keep close track of larger objects.

NASA said it will take weeks to determine the full magnitude of the crash, which occurred nearly 500 miles over Siberia on Tuesday.

"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 space station and its three astronauts is low. It orbits about 270 miles below the collision course. 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.

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 1,235 pounds, 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."

As for pieces the size of micrometers, the count will likely be in the thousands, he added.

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.

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.

At the beginning of this year there were roughly 17,000 pieces of manmade debris orbiting Earth, Johnson said. The items, at least 4 inches in size, are being tracked by the U.S. Space Surveillance Network, which is operated by the military. The network detected the two debris clouds created Tuesday.

Iridium Holdings LLC has a system of 65 active satellites which relay calls from portable phones that are about twice the size of a regular mobile phone. It has more than 300,000 subscribers. The U.S. Department of Defense is one of its largest customers.

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.

By netchicken: posted on 12-2-2009

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