Intelsat loses control of Galaxy 15 again

[ChrisC]

Hey y'all, there's been a public FCC filing that indicates that Intelsat has lost control of the Galazy 15 satellite:
https://licensing.fcc.gov/cgi-bin/ws.exe/prod/ib/forms/reports/swr031b.hts?q_set=V_SITE_ANTENNA_FREQ.file_numberC/File+Number/%3D/SATSTA2022081800087&prepare=&column=V_SITE_ANTENNA_FREQ.file_numberC/File+Number

First mentioned on NSF here, in the thread about the future satellite that's supposed to eventually replace it:
https://forum.nasaspaceflight.com/index.php?topic=51966.msg2397996#msg2397996

August 18, 2022
...
Galaxy 15 is currently authorized to operate at the 133.0° W.L. orbital location.  On August 10, 2022, Galaxy 15 experienced an anomaly, which was likely triggered by space weather. Due to this anomaly, Intelsat lost the telemetry and commanding links. Intelsat was able to regain commanding of the satellite via an alternative path on August 14th; due to an issue of unknown origin, subsequent commands on August 15th were not conveyed to the satellite. Intelsat is diligently working to regain commanding of the satellite. If unsuccessful, the Galaxy 15 satellite is anticipated to drift outside of its authorized +/- 0.05° East/West station-keeping box late this evening.
...

(attn @GWR64 : I'm not see that text you quoted in the FCC filing.  Where did you get it?)

I'm hearing this confirmed from industry insiders.  Typically in this scenario we are frantically moving our traffic to other satellites, and Intelsat is frantically moving a spare satellite into position ...

For context, here's the NSF thread about the 2010 failure:
https://forum.nasaspaceflight.com/index.php?topic=21483

[ChrisC]

SpaceNews picked it up:

High space weather activity likely knocked out onboard electronics needed to communicate with the satellite, Intelsat said, and keep it locked in its geostationary orbit slot at 133 degrees West.  “The satellite is otherwise operating nominally, keeping earth pointing with all payload operations nominal,” Intelsat spokesperson Melissa Longo said.

To me, that statement of "operating normally" does not align with the satellite leaving its stationkeeping box, forcing ground stations to repoint, or worse, go into active tracking.

https://spacenews.com/intelsat-working-to-regain-control-of-galaxy-15-satellite/

[Lee Jay]

In this scenario do other sats have to avoid the drifting object?

[GWR64]

August 18, 2022
...
Galaxy 15 is currently authorized to operate at the 133.0° W.L. orbital location.  On August 10, 2022, Galaxy 15 experienced an anomaly, which was likely triggered by space weather. Due to this anomaly, Intelsat lost the telemetry and commanding links. Intelsat was able to regain commanding of the satellite via an alternative path on August 14th; due to an issue of unknown origin, subsequent commands on August 15th were not conveyed to the satellite. Intelsat is diligently working to regain commanding of the satellite. If unsuccessful, the Galaxy 15 satellite is anticipated to drift outside of its authorized +/- 0.05° East/West station-keeping box late this evening.
...

(attn @GWR64 : I'm not see that text you quoted in the FCC filing.  Where did you get it?)

From the attachment Narrative.pdf in the FCC filing.

[Hog]

In this scenario do other sats have to avoid the drifting object?

Great question.

Having to expend your own satellite's propellant to avoid an on orbit collision with a neighbouring satellite simply because it can't hold its own station, sounds like grounds for litigation, esp if such avoidance maneuvers decrease your own satellites lifespan.  Or are propellant margins on these more modern birds so large as to not matter?
IIRC Satellite that are launched always budget enough propellant so that they can be delivered to a "disposal" orbit as to not affect the specific GTO Geostationary orbits (GEO). I believe its part of the launch approval process.

Edit: GTO/GEO correction.

[DanClemmensen]

In this scenario do other sats have to avoid the drifting object?

GEO is really, really big: about 264924 km in circumference. There are relatively few satellites, and they move very slowly with respect to each other. If collision avoidance were ever needed, it would require only very tiny delta V. They are nominally assigned to slots that are 2 degrees apart (1471 km) for RF separation. Each slot has at most one satellite using any particular RF frequency band. by comparison to LEO these satellites are very far apart and relative motion is slower than highway speeds. In LEO, satellites are much closer together and relative motion is faster than the fastest artillery shells.

The big problem is RF interference. If an uncontrolled satellite with an active transponder in my frequency drifts close to my satellite, then when I try to use my satellite, the rogue will receive and retransmit my signal. I am forced to quit using the frequency until the rogue drifts out of my assigned slot.

[russianhalo117]

SpaceNews picked it up:

High space weather activity likely knocked out onboard electronics needed to communicate with the satellite, Intelsat said, and keep it locked in its geostationary orbit slot at 133 degrees West.  “The satellite is otherwise operating nominally, keeping earth pointing with all payload operations nominal,” Intelsat spokesperson Melissa Longo said.

To me, that statement of "operating normally" does not align with the satellite leaving its stationkeeping box, forcing ground stations to repoint, or worse, go into active tracking.

https://spacenews.com/intelsat-working-to-regain-control-of-galaxy-15-satellite/

The payload is operating nominally along with most bus systems is my read.

[ChrisC]

From the attachment Narrative.pdf in the FCC filing.

Thanks!  I thought I looked at them all.

From that PDF:

The communications payload was unaffected and is currently transmitting. However, if the
satellite does not receive a command by August 31, 2022, the payload is programed to shut off
automatically.

[GWR64]

From the attachment Narrative.pdf in the FCC filing.

Thanks!  I thought I looked at them all.

From that PDF:

The communications payload was unaffected and is currently transmitting. However, if the
satellite does not receive a command by August 31, 2022, the payload is programed to shut off
automatically.

To my shame, I have not read these footnotes.
This is perhaps a safety timer that was programmed after the first blackout in 2010.
Galaxy 15 is slowly drifting east, until August 31 it will not reach its neighbors at 131°W. (AMC-11 and later SES-21)

[GWR64]

one of two more filings, more power 

Galaxy 15 recently experienced an anomaly which resulted in the loss of commanding. Intelsat is utilizing KA275 as it diligently works to regain satellite commanding on Galaxy 15; as part of this effort, Intelsat requires the use of the antenna at a power higher than the maximum licensed power. The operations will be performed in the following uplink frequencies: 6025.0 MHz, 6165.0 MHz, and 6420.5 MHz in the uplink.

[GWR64]

According to this post, Intelsat has already informed its customers on August 18 that the services will move to Galaxy 23 (121°W).
I don't know how reliable this source is, the memo looks official to me.

https://rickcaylor.websitetoolbox.com/post/memo-says-intelsat-has-lost-control-of-galaxy-15-133-west-12427006?trail=45

[Sam Ho]

Intelsat confirmed that the payload muted as expected August 31.  All customers moved to Galaxy 23 for now, and will eventually move to Galaxy 33.

https://spacenews.com/intelsats-galaxy-15-mutes-payload-as-its-drifts-into-other-satellite-paths/

[Vultur]

The big problem is RF interference. If an uncontrolled satellite with an active transponder in my frequency drifts close to my satellite, then when I try to use my satellite, the rogue will receive and retransmit my signal. I am forced to quit using the frequency until the rogue drifts out of my assigned slot.

Thank you for explaining this. I'd never really understood why GEO slots had to be limited/assigned given how huge the GEO orbit is and given there aren't millions of satellites there. But if it's not about physical room at all, that makes sense.

[DanClemmensen]

The big problem is RF interference. If an uncontrolled satellite with an active transponder in my frequency drifts close to my satellite, then when I try to use my satellite, the rogue will receive and retransmit my signal. I am forced to quit using the frequency until the rogue drifts out of my assigned slot.

Thank you for explaining this. I'd never really understood why GEO slots had to be limited/assigned given how huge the GEO orbit is and given there aren't millions of satellites there. But if it's not about physical room at all, that makes sense.

The slots need to be far enough apart that a simple affordable dish user antenna on Earth can point to one of them and exclude the adjacent ones. In the early days of consumer usage of GEO, this ended up being standardized by ITU, and that's where the two-degree longitude spacing came from. Remember, higher directivity requires a bigger (more expensive) dish. You cannot use closer spacing in GEO unless you require tens of millions of users to switch to larger dishes. The first big wave of consumer-class user equipment used 4-meter C-band dishes: big but fairly cheap, with reasonably cheap electronics. The move to Ku band was enable when the cost of Ku-band electronics came down. Higher frequencies allow smaller dishes with the same directivity (laws of physics at work) but the dishes must be smoother C-band dishes were wire mesh. Ku dishes are solid plastic with a metal coating. 2-meter dishes.   ITU could have required 4-meter Ku and reduced increased the number of Ku slots, but ITU consensus was that cheaper terminals were a lot more important. The number of potential users goes up by a factor of 10 or more when the dish size is reduced from 4 meters to 2 meters, simply due to siting constraints in residential areas.

[russianhalo117]

The big problem is RF interference. If an uncontrolled satellite with an active transponder in my frequency drifts close to my satellite, then when I try to use my satellite, the rogue will receive and retransmit my signal. I am forced to quit using the frequency until the rogue drifts out of my assigned slot.

Thank you for explaining this. I'd never really understood why GEO slots had to be limited/assigned given how huge the GEO orbit is and given there aren't millions of satellites there. But if it's not about physical room at all, that makes sense.

The slots need to be far enough apart that a simple affordable dish user antenna on Earth can point to one of them and exclude the adjacent ones. In the early days of consumer usage of GEO, this ended up being standardized by ITU, and that's where the two-degree longitude spacing came from. Remember, higher directivity requires a bigger (more expensive) dish. You cannot use closer spacing in GEO unless you require tens of millions of users to switch to larger dishes. The first big wave of consumer-class user equipment used 4-meter C-band dishes: big but fairly cheap, with reasonably cheap electronics. The move to Ku band was enable when the cost of Ku-band electronics came down. Higher frequencies allow smaller dishes with the same directivity (laws of physics at work) but the dishes must be smoother C-band dishes were wire mesh. Ku dishes are solid plastic with a metal coating. 2-meter dishes.   ITU could have required 4-meter Ku and reduced increased the number of Ku slots, but ITU consensus was that cheaper terminals were a lot more important. The number of potential users goes up by a factor of 10 or more when the dish size is reduced from 4 meters to 2 meters, simply due to siting constraints in residential areas.

Some of my properties have both albeit abandoned or inactive.

[GWR64]

Intelsat regained control of Galaxy 15 on March 7th. The satellite is currently at 108.9° W.L.
From April 10, the orbit will initially be raised by 150 km, after further tests then to a graveyard orbit and there Galaxy 15 will be decommissioned.

SAT-STA-20230310-00052
SAT-STA-20230330-00068