Intelsat Re-establishes Contact with Rogue WAAS GEO Satellite
January 5, 2011 By: Eric GakstatterJanuary 5, 2011, Update:
The FAA reported that the satellite operator, Intelsat, determined that static electricity charge caused the initial failure that sent Galaxy 15 (WAAS PRN 135) drifting uncontrolled for more than nine months. According to the FAA, Intelsat has uploaded new software to prevent the event from occurring again. Intelsat will test it for approximately 30 days and then move it back into its original orbit to resume WAAS service.
Intelsat reported that they are shifting Galaxy 15 to 93°W for further testing and that it should arrive at that destination on or around January 15th, 2011.
Intelsat has reported that it has re-established control over its geostationary satellite Galaxy 15 (known as FAA WAAS satellite CRW - Central Region West - which operated as PRN 135). The satellite had been uncontrollable since April 5 and has drifted from its assigned orbital slot at 133°W longitude to about 98°W.
Intelsat announced that on December 23 the power from the Galaxy 15 battery completely drained during its loss of earth lock and the Baseband Equipment (BBE) command unit reset, as it was designed to do. Shortly thereafter Galaxy 15 began accepting commands and Intelsat engineers began receiving telemetry in their Satellite Operations center.
According to the announcement, Intelsat has placed Galaxy 15 in safe mode and reported that it no longer poses any threat of satellite interference to either neighboring satellites or customer services. After completing initial diagnostic tests, Intelsat will load updated commanding software to the satellite. It expects to relocate the satellite to an Intelsat orbital location where engineers at their Satellite Operations Control Center will initiate extensive in-orbit testing to determine the functionality of every aspect of the spacecraft.
Galaxy 15 contained one of two WAAS GEO transponders leased by the Federal Aviation Administration (FAA) to transmit GPS integrity and correction data to aviation and ground users.
On April 5, Intelsat reported it had lost communications with Galaxy 15. Shortly thereafter, the FAA announced that Galaxy 15 (PRN 135) would discontinue transmitting WAAS GPS integrity and correction information within a few weeks. Surprisingly, the uncontrolled Galaxy 15 ended up staying on track well enough to continue broadcasting WAAS integrity and correction data until December 16, when broadcasts ceased. During that period it had drifted from 133°W longitude to 98°W longitude.
On December 29, the FAA confirmed that they are considering bringing Galaxy 15 back into WAAS service, but that it depends on how long it takes to move it back to its intended orbit location. The FAA said It also depends on the results of the testing efforts in pinpointing the initial failure.
"We don't want to use it again if it is just going to fail again," said Leo Eldridge, FAA GNSS Group Manager.
A complete FAQ on the Galaxy 15 status is available on Intelsat website here.
About the Author: Eric Gakstatter
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