From SPACE.com:
posted: 11 February 2009 6:00 p.m. ET
By Becky Iannotta and Tariq Malik

WASHINGTON - Iridium Satellite LLC confirmed today that one of its satellites was destroyed Tuesday in an unprecedented collision with a spent Russian satellite and that the incident could result in limited disruptions of service.

According to an e-mail alert issued by NASA today, Russia's Cosmos 2251 satellite slammed into the Iridium craft at 11:55 a.m. EST (0455 GMT) over Siberia at an altitude of 490 miles (790 km). The incident was observed by the U.S. Defense Department's Space Surveillance Network, which later was tracking two large clouds of debris.

"This is the first time we've ever had two intact spacecraft accidentally run into each other," said Nicholas Johnson, chief scientist of NASA's Orbital Debris Program Office at the Johnson Space Center in Houston. "It was a bad day for both of them."

The collision appears to be the worst space debris event since China intentionally destroyed one of its aging weather satellites during a 2007 anti-satellite test, Johnson told SPACE.com. That 2007 event has since left about 2,500 pieces of debris in Earth orbit, but more time is needed to pin down the extent of Tuesday's satellite collision, he added.

"We're tracking more than 500 pieces of debris which pose an additional risk to satellites," said U.S. Navy Lt. Charlie Drey, a spokesperson for the U.S. Strategic Command which oversees the U.S. Space Surveillance Network.

In a prepared statement, the Bethesda, Md.-based Iridium characterized the incident as a "very low probability event" and said it was taking immediate action to minimize any loss of service. Iridium, which operates a constellation of 66 low Earth orbiting satellites providing mobile voice and data communications globally, said its system remains healthy and that it would implement a "network solution" by Friday.

"Within the next 30 days, Iridium expects to move one of its in-orbit spare satellites into the network constellation to permanently replace the lost satellite," the statement said.

The 1,234-pound (560-kg) Iridium 33 satellite involved in the collision was launched in 1997; the 1,984-pound (900-kg) Russian satellite was launched in 1993 and presumed non-operational. It did not have a maneuvering system, NASA said.

Iridium's spacecraft circle the Earth along a near-polar orbit once every 100 minutes and fly at a speed of about 16,832 mph (27,088 kph), the company states on its Web site.

An unprecedented crash

Johnson said outdated spacecraft, rocket stages and other components break apart in space every year, but there have only been three relatively minor collisions between such objects in the last 20 years. Never before have two intact satellites crashed into one another by accident, he added.

The debris created in Tuesday's collision is being tracked to assess its risk of damaging other satellites and the International Space Station, which is currently home to two American astronauts and one Russian cosmonaut.

The space station flies at an altitude of about 220 miles (354 km), well below the impact point between the Russian and U.S. satellites 490 miles (790 km) up. Johnson said that only a very minor portion of debris from the two clouds is expected to descend across the space station's orbital path.

"We believe that the increased risk above the normal every day background risk is very, very small," Johnson said

NASA's orbital debris experts are also assessing the threat to other spacecraft. The agency's Earth Observing System satellites, which orbit at 438 miles (705 km), "are of highest interest for immediate consideration," NASA said in its e-mail alert, a copy of which was forwarded to Space News, a sister publication to SPACE.com.

Drey told SPACE.com that the first hint of the collision came when Iridium officials contacted a U.S. Strategic Command support office to report that they had lost contact with one of their satellites.

"Shortly after, our space surveillance center reported that they had observed multiple new objects in low orbit," Drey said. The U.S. Space Surveillance Network continuously tracks more than 18,000 separate man-made objects and debris at any given time, he added.

Tuesday's collision is the latest in a series of satellite woes in recent weeks.

Last month, the nascent Eutelsat W2M telecommunications satellite failed in orbit just five weeks after it launched into space. Another communications satellite, ASTRA 5A owned by SES Luxemburg, also failed and was adrift in orbit. The loss forced its operators to warn the owners of neighboring satellites to be prepared for the remote possibility of having to maneuver their spacecraft to avoid a collision with Astra 5A.

NASA's Orbital Debris Program Office also released an update last month on Russia's Soviet-era satellite Cosmos 1818 stating that the spacecraft appeared to spew a cloud of debris on July 4, 2008 that may be the result of leaking reactor coolant from a debris strike or fragmentation.

I just watched a program that talked about all the stuff, trash, satellites and otherwise, that is in orbit around Earth. It is amazing that this does not happen more often! Literally thousands of objects spinning around in something that you could only equate to a ballet of orbits.

Somehow, they actually manage to track most of it too!

_________________
"Too Soon from the Cave, Too Far from the Stars"

Speaking of which (tracking space objects), I found a good wiki on the Space Surveillance Network, which is part of he United States Strategic Command's (USSTRATCOM) mission and involves detecting, tracking, cataloging and identifying man-made objects orbiting Earth, i.e. active/inactive satellites, spent rocket bodies, or fragmentation debris.

Details:
http://en.wikipedia.org/wiki/United_States_Space_Surveillance_Network

And be sure to check out this link:
http://science.nasa.gov/RealTime/JTrack/3D/JTrack3D.html

...which shows the current location of about 900 objects, out of thousands, swarming about our earth. You can clearly see the communications satellites that are in geostationary orbit.

An update from SPACE.com:
posted: 12 February 2009 10:17 am ET
By Tariq Malik, Senior Editor

Scientists at NASA are keeping close tabs on two clouds of debris from Tuesday collision between U.S. and Russian satellites to determine how much of a risk they pose to the agency's Earth-watching spacecraft and, possibly, the Hubble Space Telescope.

The rare collision between a U.S. Iridium 33 communications satellite and the defunct Russian military communications satellite Cosmos 2251 is unprecedented, marking the first time two intact satellites orbiting Earth have accidentally crashed into and obliterated one another, NASA officials said. Their smash-up created two large clouds of space debris that are currently being tracked by the U.S. Space Surveillance Network.

The debris poses a greater risk to science satellites than to the International Space Station, which is currently home to two American astronauts and a Russian cosmonaut, since the collision occurred 490 miles (790 km) above Siberia. The space station flies in an orbit about 220 miles (354 km) above Earth.

"This is like over 400 kilometers above the station, so we do believe that some of the debris is going down through station altitude. But it's a very, very small minority of the debris clouds," said Nicholas Johnson, chief scientist of NASA's Orbital Debris Program Office at the Johnson Space Center in Houston. "For robotic spacecraft at higher altitudes, the answer's a little bit different. So one by one we'll be looking at those."

Earth observations satellites, such as NASA's Aqua and Aura spacecraft in orbit 438 miles (705 km) above Earth, are particularly vulnerable - though the risk of an impact is still low - and there's another satellite in a 497-mile (800-km) orbit just above the impact level, Johnson told SPACE.com late Wednesday. The Hubble Space Telescope orbits the Earth at about 372 miles (600 km), Johnson said.

"That's a little bit farther away, but it's a lot bigger too. All that matters," Johnson said of Hubble. "It's about how close you are to the debris cloud and how big you are."

It will be weeks before the U.S. Space Surveillance Network pins down an accurate count of the number of individual debris pieces created in the event, but unofficial estimates put the damage somewhere in the 500 count. The U.S. Space Surveillance Network is currently tracking more than 18,000 separate man-made objects and debris at any given time, officials with the U.S. Strategic Command said Wednesday.

"This is the first time we've had two intact spacecraft collide, so it is a big deal," Johnson said. "But you know, it's not unexpected."

Johnson said that some satellites fly within a few hundred meters of each other every day. Each year, there are about six instances in which old satellites and satellite parts break apart in what scientists call "fragmentation events." Satellite components or spent rocket stages have accidentally collided three times before in the last 20 years.

In June 1997, an unmanned Russian Progress cargo ship slammed into Russia's Mir Space Station, damaging a solar array and radiator, and punching a hole in the ship's hull that depressurized one of its modules. Unlike Tuesday's collision, that Progress spacecraft was deliberately heading for Mir, where it was expected to dock in a rendezvous system test.

"This was going to happen," Johnson said of Tuesday's accidental collision. "There was no doubt that it was going to happen."

Johnson said the chances of a satellite being damaged by the debris from Tuesday's collision are admittedly low, but as the collision itself proved, such things can happen. He does not expect to see reports of many secondary impacts from the event.

He pointed out that when China intentionally destroyed one of its aging weather satellites during a 2007 anti-satellite test, the impact created a cloud of more 2,500 pieces of debris.

"We don't know if any of them have hit any other satellite, alive or dead," Johnson said of the Chinese test debris. "So the odds are still very small, but they're bigger today than they were two days ago."