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A Traffic Cop for Satellites

/ Source: Discovery Channel

Collisions in space don't happen very often, but when they do the impact is long-lasting. A coalition of satellite traffic cops, however, aims to prevent these episodes from occurring at all.

In orbit, chunks and fragments from a crash won't settle down. They'll keep moving -- extremely rapidly -- upping the odds of additional crashes.

"You don't just sweep up the debris and haul it away on a tow truck. That's why we're having to take all these precautions," said Tobias Nassif, vice president of satellite operations and engineering for Intelsat and a director of the newly formed Space Data Association.

The group, which began operations in July, provides advance notice of potential collisions so satellite operators can reposition their spacecraft before it's too late.

Washington, D.C.-based Intelsat partnered with London-based Inmarsat and SES of Luxembourg to develop and launch Space Data Association, which currently runs interference for the group's combined 120 satellites.

In 16 years of work in the field, Nassif says he's had to maneuver spacecraft perhaps twice to avoid coming too close to another satellite. But as more and more spacecraft are put into orbit, the chance of a collision increases as well, he added.

The prospect of an orbital crash seemed pretty remote until Feb. 10, 2009, when an obsolete Soviet-era satellite called Cosmos 2251 plowed into a working commercial telecommunications satellite owned by Iridium.

Striking at a relative speed of 7.2 miles per second, the crash, which occurred 491 miles above Earth, generated more than 1,700 pieces of debris that were large enough to be tracked by radars on Earth. Ninety-six percent of the junk remains in orbit today.

The Iridium-Cosmos 2251 crash isn't even the largest source of space debris. That dubious distinction belongs to the Fengyun-1C spacecraft, which was the target of a Chinese anti-satellite test in 2007. NASA's Orbital Debris Program Office says there's still more than 2,700 pieces of orbital space junk from Fenyun-1C's destruction.

"We saw a need to operators to work better to share information in order to protect our operations in space," Nassif told Discovery News. "Just having the contact information among the operators might help mitigate the possibilities of collisions in space."

The group, which is a non-profit based in the Isle of Man, expects to be fully operationally by January, issuing not just warnings of potential collisions, but also ways to mitigate radio interference.

"Our objective is to attract any and all that are interested," Nassif said.

Currently, there are about 350 commercial satellites in orbit 22,300 miles above Earth, and hundreds more in lower orbits.

"The system really isn't limited in the number of spacecraft that it can handle. We're outreaching to all the operators and civil agencies," he said.

Details of the U.S. military's collision avoidance programs will be discussed at the American Institute of Aeronautics and Astronautics Space 2010 conference in Anaheim, Calif., this week.