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SES will shuffle two satellites to avoid zombie spacecraft

Posted: May 18, 2010

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A wayward out-of-control Intelsat broadcasting satellite is forcing a rival operator to change the position of two spacecraft to ensure U.S. television viewers continue receiving high-definition programming in late May and early June.

Artist's concept of the Galaxy 15 satellite built by Orbital Sciences Corp. Credit: Orbital Sciences
Controllers have been unable to command the Galaxy 15 satellite since a solar storm struck the craft 22,300 miles over the Pacific Ocean in early April.

The anomaly left Galaxy 15's antennas still turned on, and the satellite continues blaring powerful communications signals that could interfere with operational satellites.

"Thus far, neither our attempts to recover nor our attempts to disable the satellite have been successful," said David McGlade, Intelsat's CEO. "In order to minimize interference with other satellites in the cable arc, we are fully cooperating with operators to limit any service issues for satellite customers in North America."

The uncontrolled spacecraft started drifting east along the equator in the arc of geostationary communications satellites that provide multimedia services, television programming and networking solutions to millions of customers in the Americas.

The events led some media outlets to label Galaxy 15 a zombie satellite, but Intelsat and other industry officials insist there is no threat of a physical collision between Galaxy 15 and other spacecraft in the tightly-jammed geostationary orbit.

Galaxy 15 now has its sights set on AMC 11, another cable television satellite positioned at 131 degrees west longitude serving media markets in the United States, Canada and Mexico.

AMC 11 is one of the top high-definition television broadcasting satellites covering North America.

The stray satellite will pass through the 131 degrees west position around May 31, but AMC 11's operator -- SES World Skies -- says it will order the threatened satellite to drift east ahead of Galaxy 15 and slide a newly-launched spacecraft into position behind the wandering satellite.

"As the stray satellite nears AMC 11's orbital location at 131 degrees west, SES World Skies plans to have AMC 11 match the eastward drift of Galaxy 15 in order to maintain a minimum separation between the two satellites. This synchronized drift is designed to protect AMC 11 services from interference caused by Galaxy 15," the company said in a statement Monday.

Artist's concept of the AMC 11 spacecraft in orbit. Credit: Lockheed Martin
"At the same time, SES World Skies will move its new SES 1 satellite to the opposite side of Galaxy 15, thereby enabling some customers, including cable television networks, to leapfrog their broadcasts over interference caused by the wandering spacecraft. Customers will either be able to maintain services on AMC 11 during its drift, or repoint antennas to SES 1 in order to best protect their services," the SES World Skies press release said.

SES 1 was launched April 24 to replace two aging satellites covering North America from a different location, but officials are tasking the new spacecraft on a temporary new mission in the first chapter of its life.

The maneuvers will begin around May 25, and SES World Skies says the risk of interference will end arond June 7 as Galaxy 15 exits the area to the east.

"This extraordinary technical initiative underscores our commitment to finding innovative solutions to minimize the impact of an unexpected event like this on our customers," said Alan Young, chief technology officer for SES World Skies. "A team of our best engineers and scientists is working around the clock to ensure the success of this unprecedented mission."

SES World Skies says the mitigation effort should alleviate interference for most of North America, but customers in Hawaii, Alaska and the Caribbean could experience more significant disruptions.

Intelsat executives say they have third-party liability insurance to pay for damages to other satellite operators.

"We think we're in very good shape to either minimize or eliminate any interference with SES's customers," McGlade said. "That said, we do have insurance, but we don't anticipate needing to use that."

If Intelsat is unable to retake control of Galaxy 15, or turn off its transmitters, the satellite is expected to pass near three of the company's own satellites in July and August.