While tracking news of Galaxy 15's path across the geostationary arc, I came across "Zombie" satellite shuts down critical NOAA NWS systems overnight in Anthony Watts commentary, "Watts Up With That?".
While Intelsat reported Galaxy 15 Completes Fly-by of SES' AMC-1 Spacecraft, Watts said this weekend he was dealing with a problem that affected National Weather Service (NWS) offices nationwide, in addition to his business's weather data feed. The problem began Dec. 4, the day Intelsat said Galaxy 15 had successfully completed the AMC-1 satellite fly-by. The lack of data caused the Advanced Weather Interactive Processing System (AWIPS) to fail. That system is used to issue severe weather bulletins.
I don't think Galaxy 15 was the problem. The confusing thing about this report is that NOAAPORT uses SES-1, not AMC-1. Intelsat's Ephemeris Data for Galaxy Fleet showed Galaxy 15 was at 257.339 degrees west longitude at 0000 UTC on Dec. 7, and moving east about a tenth of a degree every 15 hours. I don't see how it could have caused problems for SES-1 at this location.
What may have caused some of the confusion is DM11-10.05 SBN/NOAAPORT Potential Satellite Interference – Notice 1 concerning changes due to Galaxy 15 passing by SES-1 from Dec. 12 to Dec. 18.
There is little additional information on last weekend's outage, but I wonder if something else could have been the problem.
According to Watts, "NWS Wallops Island uplink boosted the signal strength on the transponder and the problem was solved...or so they thought." "Yesterday, all hell broke loose."
He also quoted a service data outage message: "The Family of Service at NSOF is down and has affected the above products to be unavailable until further notice. Tech. control in Silver Spring reports, the problem is due to the NOAAPORT Satellite at NCF AWIPS having poor signal quality. The problem is being investigated."
My guess is the Galaxy 15 itself had no role to play in this, but in the complicated dance of satellites and shifting of uplinks to minimize interference during the AMC-1 fly-by, perhaps a mistake by an uplink operator on the ground caused the problems observed on the NOAAPORT SES-1 transponder.
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