SES Details Plan To Avert Interference by Failed Intelsat Craft


PARIS — Satellite fleet operator SES on May 17 said it would reroute a just-launched satellite as part of a plan to protect customers from the signal-interference threat posed by an uncontrolled Intelsat spacecraft expected to drift into an SES satellite’s orbital neighborhood, with its electronics payload still active, starting May 25.

Luxembourg-based SES, which has been coordinating an interference-mitigation procedure with Intelsat since Intelsat’s Galaxy 15 satellite stopped responding to commands April 5, said it hopes to minimize interference to its AMC-11 satellite’s cable television customers by maneuvering the SES-1 satellite into the same orbital station as AMC-11.

SES will also make use of a high-power, 19-meter-diameter antenna operated by Intelsat’s Clarksburg, Md., teleport during the period between May 25 and June 7, when Galaxy 15 is expected to be inside the SES orbital slot.

SES spokesman Yves Feltes described the maneuver this way: As Galaxy 15 moves eastward through the orbital “box” occupied by SES’s AMC-11, the AMC-11 will be placed to the far upper-right-hand corner of the box, to maximize its distance from Galaxy 15.

Meanwhile, SES-1, which was launched April 24, will be arriving from the west and will be stationed on the box’s western end. If needed, cable traffic will be transferred from AMC-11 to SES-1.

Using the Intelsat antenna to maintain links between AMC-11 and its cable head-end customers, SES will wait until the dead of night in the United States, when broadcast traffic is lowest, to perform what the company called a “leapfrog” maneuver as AMC-11 is rushed westward, back toward the center of the box.

Feltes said May 17 that SES and Intelsat, who together have been addressing what for both is an unprecedented situation, have concluded that, at worst, some AMC-11 programming could be interrupted for a few hours late in the night of the leapfrog maneuver. The interference would occur when AMC-11, heading west, passes “over” the Galaxy 15 satellite as the uncontrolled satellite continues its eastward drift.

SES said it will begin moving AMC-11 eastward May 25. The risk from Galaxy 15 is expected to last until June 7.

The interference threat is due to the fact that Galaxy 15, like AMC-11, is a C-band satellite. As Galaxy 15 moves through the geostationary orbital arc, its still-active electronics payload is ready to pick up and amplify any C-band signals it encounters. SES-1 is also a C-band satellite and can take over AMC-11 traffic as needed.

“A team of our best engineers and scientists is working around the clock to ensure the success of this unprecedented mission,” SES World Skies Chief Technology Officer Alan Young said in a May 17 statement. He said SES is in regular close contact with its customers in order to brief them on the operation and prepare them for the necessary maneuvers.