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Zombiesat has three more satellites in its crosshairs

Posted: July 25, 2010

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The out-of-control Galaxy 15 spacecraft will pass near three more orbiting broadcast platforms before it loses power in late August or early September, putting an end to the zombie satellite's menacing tour of the geostationary arc.

Galaxy 15 under construction by Orbital Sciences. Credit: Orbital Sciences
Galaxy 15 stopped responding to commands from ground controllers in April, most likely due to a solar flare that zapped the satellite's electronics. But engineers are still analyzing the cause, according to David Thompson, chairman and CEO of Orbital Sciences Corp.

Orbital manufactured Galaxy 15 for Intelsat.

"We still have not been able to isolate the problem with the satellite to a single root cause," Thompson told investment analysts last week. "We've certainly narrowed down the list of suspects very substantially, but there are a handful of possible causes that cannot at this point be eliminated. We have a leading theory."

Galaxy 15 started drifting east out of its operating location after the anomaly, moving toward several other satellite in geostationary orbit 22,300 miles above Earth.

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

After attempts to regain control of the craft failed, Intelsat and rival satellite operator SES World Skies planned a complex maneuver to ensure Galaxy 15's powerful C-band signals did not interfere with the AMC 11 craft's mission of broadcasting high-definition television to North America.

SES ordered AMC 11 to drift ahead of Galaxy 15, then slid a newly-launched satellite behind the wandering spacecraft to ensure continuity of its broadcasting mission.

Since navigating around AMC 11 without incident, Galaxy 15 approached a cluster of four Intelsat-owned satellites. The wayward craft passed by Galaxy 13 with no problems earlier this month.

In an update posted on Intelsat's website, officials said Galaxy 15 is expected to fly close to another of the company's satellites this week. Its closest approach to the Galaxy 14 craft is expected Friday.

Galaxy 14's C-band communications payload provides video services to the continental United States.

Intelsat will employ a large ground antenna to isolate Galaxy 14 and keep Galaxy 15's blaring C-band transmissions from cutting off broadcasts from the operational craft.

"This plan offers turnaround services via Intelsat's 19-meter antenna located at the Clarksburg Teleport to provide a very high level of uplink isolation on Galaxy 14 as Galaxy 15 is in close proximity to it," Intelsat said in an update. "We will also offer dual illumination options on other satellites, as necessary and work with customers that plan to ride out the fly-by event."

Intelsat's Galaxy 18 and Galaxy 23 satellites will be in the crosshairs of Galaxy 15 in August as the stray craft continues its march east.

Officials expect Galaxy 15's orientation-controlling reaction wheels will become saturated by late August or early September, causing the satellite to lose its lock on the sun and stop generating electricity.

Thompson said controllers will try to capture control of the satellite after the power reset.

J.R. Thompson, Orbital's president and chief operating officer, said the company has developed modifications and software patches for its Star-series satellites under construction to protect against another anomaly like Galaxy 15.

Orbital's bottom line was hit with $2.5 million in unexpected costs from the Galaxy 15 mishap, and the company expects to spend another $1 million on the issue in the next three months, according to Garrett Pierce, vice chairman and chief financial officer.