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Engineers back in contact with Galaxy 15

BY STEPHEN CLARK

SPACEFLIGHT NOW

Posted: December 31, 2010



Engineers have regained communications with a rogue Intelsat broadcasting satellite that spent nearly nine months traversing the populated arc of geosynchronous satellites responsible for television services for the Americas.





Galaxy 15 under construction before launch in 2005. Credit: Orbital Sciences Corp.



Its threat to other satellites now diminished, Galaxy 15 is responding to commands and ground controllers are receiving telemetry to the spacecraft, Intelsat announced this week. "The situation evolved favorably over the holidays, with a reset completed and telemetry now regularly being received from the satellite," said Nick Mitsis, an Intelsat spokesperson. "The satellite no longer poses any threat to other operators or satellite users." Galaxy 15 stopped communicating with engineers in April, but the craft continued blaring powerful C-band television signals as it drifted uncontrollably through geosynchronous orbit 22,300 miles above the equator. A solar storm may have crippled the satellite, but officials are still investigating the root cause of the anomaly. Between April and December, Galaxy 15 passed by more than a dozen operational C-band communications satellites owned by Intelsat, SES, Telesat of Canada and Satmex of Mexico. Satellite operators reported no significant disruptions in communications. Officials were concerned Galaxy 15's television broadcast signals would interfere with transmissions coming from operational satellites. Engineers devised novel avoidance maneuvers as Galaxy 15 slowly moved east along the equator. Intelsat and Orbital Sciences Corp., Galaxy 15's manufacturer, had difficulty predicting when the spacecraft would lose Earth lock and reset its electronics. Engineers expected the craft's orientation-controlling reaction wheels would become saturated with momentum, causing the satellite to lose attitude lock on Earth and drain its batteries of electricity. The electronics reset was initially anticipated in August, but Galaxy 15 continued functioning for months longer until finally succumbing to the loss of attitude control in mid-December. According to Intelsat, Galaxy 15's electronics suite reset Dec. 23. The satellite soon began accepting commands and controllers got their first look at the craft's health since April. "Over the next many weeks, we'll complete some diagnostics, update software, and ultimately move it to one of our orbital locations to complete the extensive testing necessary to determine the functionality of the satellite," Mitsis told Spaceflight Now. The satellite continues drifting, but Intelsat expects to stabilize the craft's orbit within weeks. Intelsat hopes to recover full functionality of Galaxy 15 and return it to commercial service, according to a posting on the company's website.





