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'Zombie' satellite runs amok in Earth's orbit

The out-of-control communications satellite Galaxy 15 is drifting into orbits occupied by other spacecraft.

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"Intelsat fully coordinated with neighboring operators the timing and the effects of this testing to neighboring spacecraft. It is our current understanding that no SES AMC-11 customers were affected by the disabling attempt," Intelsat said.

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Intelsat and Luxembourg-based SES have been closely coordinating interference-avoidance options since the initial Galaxy 15 failure, knowing that at predicted drift speeds the satellite will enter AMC-11's 131 degrees west slot to within 0.5 degrees of AMC-11 on or about May 23.

SES officials say they are devising an elaborate series of maneuvers to create a maximum distance between Galaxy 15 and AMC-11 during the period of maximum threat. While they cannot guarantee that there will be no interference to media customers using AMC-11, the SES officials believe they have the resources, including teleport facilities to reroute traffic, required to minimize the problem during this two-week period.

Continuing its eastward drift, Galaxy 15 will exit the AMC-11 orbital slot starting around June 7, when it is expected to have moved to 0.5 degrees to the east of the satellite.

At that point, a new opportunity will be open to Intelsat as there is no C-band satellite at the next orbital station of 129 degrees west.

What Intelsat might do to precipitate a shutdown remains unclear. Industry officials say the Galaxy 15 problem — a satellite operating at full payload power that is no longer under control — is unprecedented. Intelsat has said it is seeking advice from satellite operators and manufacturers — not just the Galaxy 15 builder, Orbital Sciences of Dulles, Va., but also other companies with more experience with in-orbit problems — on possible options to force a shutdown.

Current estimates are that Galaxy 15 will lose Earth orientation sometime in late July or early August. The exact date cannot be known. But when it loses Earth pointing, its solar arrays will lose their lock on the sun, draining the satellite's batteries and causing the satellite to shut down on its own.

Once the satellite leaves the vicinity of the AMC-11 and passes through the relatively safe neighborhood of 129 degrees west, it will enter a new neighborhood where it poses an interference threat similar to what AMC-11 now faces. But this time, it is only Intelsat-owned satellites and their customers at risk.

Galaxy 15 will be moving through the operating areas of Intelsat's Galaxy 13 in mid-July, and is expected to arrive at the Galaxy 14 neighborhood in late July. By mid-August, it will be at the orbital slot of Intelsat's Galaxy 18.

IN PICTURES: 'In orbit'