Satellite collision highlights space-junk threat

The collision between a US and Russian satellite some 500 miles above Siberia has raised concerns about the threat posed by orbital garbage.

By , Blogger for The Christian Science Monitor

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    NASA’s Orbital Debris Program Office has counted about 17,000 objects larger than 10 centimeters, and it estimates that there are more than 200,000 particles between one and 10 centimeters. The debris objects shown here are an artist's impression based on actual density data. The objects are shown at an exaggerated size to make them visible at the scale shown.
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The collision between a US and Russian satellite some 500 miles above Siberia has raised concerns about the threat posed by orbital garbage.

A few minutes before 5 a.m. GMT on Wednesday, a US Iridium communications satellite and a defunct Russian military communications satellite smashed into each other, creating at least 600 pieces of debris that each could strike other satellites. It was the first time that two intact orbiting spacecraft have crashed into each other, say officials.

For its part, Iridium, whose network of 66 satellites – make that 65 – provides global coverage for handheld phones, denies that the collision is their fault, and says that any disruption in service will be brief and should be completely remedied by the end of the week.

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The Associated Press quotes Russian space journalist Igor Lisov, who wondered why Iridium, whose satellite was perfectly functional and could maneuver, didn't try to move their bird out of the way.

According to the Voice of America, the official external broadcasting service of the US government, Russian officials say that debris from the collision pose no threat to the International Space Station or its three crewmembers, who are orbiting about 270 miles below the crash. The Pentagon says that it has not yet identified any threats to its own satellites, but added that tracking small objects in space is very difficult.

Reuters quotes Gen. James Cartwright, the vice chairman of the Joint Chiefs of Staff and former head of the Pentagon's space operations, who warns that those with satellites will "have to play a little bit of dodgeball for many tens of years to come" to avoid debris from this collision. General Cartwright says that the good news is that the orbit of this debris will be predictable, eventually; the bad news is that the fragments of the satellites cover a large area.

In the half century since the launch of Sputnik, so-called space junk – including defunct satellites and fragments from exploded ones, spent rocket boosters, engine effluents and coolants, paint flakes, and other small particles, all traveling at about 15,000 miles per hour – has come to surround the earth for thousands of miles in every direction.

NASA’s Orbital Debris Program Office has counted about 17,000 objects larger than 10 centimeters (about 4 inches), and it estimates that there are more than 200,000 particles between one and 10 centimeters. The number of particles smaller than a centimeter (about 3/8ths of an inch) probably exceeds tens of millions. NASA says that debris shields can protect a spacecraft from particles as large as one centimeter.

The problem is particularly insidious because collisions with orbital debris tend to create more debris, thus increasing the risk of future impacts, which in turn create more debris. In theory, a single collision could create a runaway feedback loop known as the Kessler Syndrome, named for NASA consultant Donald Kessler, in which the area around the earth becomes so crowded with orbital detrietus that it becomes impracticable to launch anything into space.

Another Reuters story warns that the growing likelihood of orbital collisions could strain international relations. The news agency quotes Andrew Brookes, an aerospace analyst at the International Institute for Strategic Studies:

"In the longer term, there are geopolitical implications to this because people are going to start wondering, 'was that crash deliberate?' " said Brookes.
"The international community needs to get a grip of space and become much more transparent about what's going on, otherwise we're going to end up in a situation where there are serious diplomatic incidents as a result."

Reuters noted that on Thursday the European Union called for nations to adopt "a code of conduct for civil and military activities in space" to prevent such incidents.

Such calls are not new. The Monitor's Pete Spotts reported in March 2008 that many in the space community are calling for increased international cooperation to create a sort of air traffic control system for low Earth orbit.

The topic is likely to come up at the meeting of the scientific and technical subcommittee of the United Nations Committee on the Peaceful Uses of Outer Space, now under way in Vienna.

Space junk also poses hazards to those of us on Earth. In 2006, a Chilean airliner carrying 270 passengers came within 35 seconds of colliding with a derelict Russian satellite that was plummeting into the Pacific faster than the speed of sound.

The most famous instance of falling space garbage occurred in July 1979, when the US space station Skylab fell back to Earth. The 100-ton space station broke up, and  large chunks of it crashed near the town of Esperance, Australia. Local authorities fined the US government $400 for littering. To this day, the fine remains unpaid.

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