Author Topic: Starlink : General Discussion - Thread 1  (Read 1116083 times)

Online gongora

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Re: SpaceX - now a satellite manufacturer (Starlink)
« Reply #2400 on: 11/18/2018 01:07 pm »
Problem with that thinking as I understand it is that there will be no V band at all until the VLEO 7000 satellite constellation. FCC filings only include V band for those, not the early satellites.

That is not correct.  The FCC approved a modification to the original constellation at the same time they approved the VLEO sats.  They can all use V-band.

Offline oldAtlas_Eguy

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Re: SpaceX - now a satellite manufacturer (Starlink)
« Reply #2401 on: 11/18/2018 03:31 pm »
Problem with that thinking as I understand it is that there will be no V band at all until the VLEO 7000 satellite constellation. FCC filings only include V band for those, not the early satellites.

That is not correct.  The FCC approved a modification to the original constellation at the same time they approved the VLEO sats.  They can all use V-band.
In that case the requirement is 2,200 sats with a Ka and Ku band transmitter by April 2024 and with 3,500 sats with a V band transmitter by November 2024 such that only as few as 3,500 sats fulfill the license requirement.

Then the driving requirement for satellite manufacture and launch rate is the 3,500 by November 2024 and not a value of nearly 6,000.

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Re: SpaceX - now a satellite manufacturer (Starlink)
« Reply #2402 on: 11/18/2018 03:49 pm »
In that case the requirement is 2,200 sats with a Ka and Ku band transmitter by April 2024 and with 3,500 sats with a V band transmitter by November 2024 such that only as few as 3,500 sats fulfill the license requirement.

Then the driving requirement for satellite manufacture and launch rate is the 3,500 by November 2024 and not a value of nearly 6,000.

I don't think that is correct either.  I think the 4000 and 7000 sat constellations will still have different deployment milestones.  I found the order a little vague on that point.  When they get around to posting the final paperwork I'll look again.

Offline oldAtlas_Eguy

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Re: SpaceX - now a satellite manufacturer (Starlink)
« Reply #2403 on: 11/18/2018 04:59 pm »
In that case the requirement is 2,200 sats with a Ka and Ku band transmitter by April 2024 and with 3,500 sats with a V band transmitter by November 2024 such that only as few as 3,500 sats fulfill the license requirement.

Then the driving requirement for satellite manufacture and launch rate is the 3,500 by November 2024 and not a value of nearly 6,000.

I don't think that is correct either.  I think the 4000 and 7000 sat constellations will still have different deployment milestones.  I found the order a little vague on that point.  When they get around to posting the final paperwork I'll look again.
Thanks.

The capability to have or not have V band and Ka/Ku band on same satellite has a huge impact on manufacture rates and launch rates.

Offline Lar

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Re: SpaceX - now a satellite manufacturer (Starlink)
« Reply #2404 on: 11/18/2018 08:20 pm »
Lower than operating altitude, they have minimal time on orbit (few weeks to decay) for check-out, so orbit raising becomes a time-critical maneuver.
That may be viewed as a feature, not a bug.  If dead-on-arrival satellites self-scuttle promptly, one is less guilty of space trash trouble-making, and one may be in better odor with authorities and critics.

How often would a bird be too sick to make the planned ascent, yet still economically salvageable?
The first Dragon that went to ISS had some problems that took some time to sort out, IIRC. It took a bit of time. So I think it's not a zero percent chance of it happening.
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Offline meberbs

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Re: SpaceX - now a satellite manufacturer (Starlink)
« Reply #2405 on: 11/18/2018 10:32 pm »
Problem with that thinking as I understand it is that there will be no V band at all until the VLEO 7000 satellite constellation. FCC filings only include V band for those, not the early satellites.

That is not correct.  The FCC approved a modification to the original constellation at the same time they approved the VLEO sats.  They can all use V-band.
My mistake then, I missed that. It is hard to keep up with all of the details for these interlinked approvals.

That is interesting since the recent filling to modify the orbit mentions that initial satellites will be Ku only (including intersatellite links), with Ka and other technologies getting added later. Presumably that would apply to V band as well.

I wonder exactly how the FCC defines the 50% level for this case, if SpaceX launched 50% of satellites by 2024, but they were all Ku only (not actually a probable situation) Would SpaceX be allowed to continue deployment, but lose its Ka allocation? That seems consistent with the intent of preventing sitting on spectrum, but the FCC is basically making up rules as they go to deal with this new situation. (Not complaining about that, what they are doing is much better than the expected stopping of everything just for not fitting in a nice box.)

Also, I assume which orbits they put satellites into will be the primary decider of whether satellites count towards the number to be launched for the 4000 satellite or the 7000 satellite constellation, regardless of what frequencies they actually have equipped. I will be surprised if they are able to make the deadline for both simultaneously, and expect they will have to ask for an extension for the VLEO deployment deadlines, pointing to their other deployments as evidence that they aren't just sitting on the spectrum.

Offline envy887

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Re: SpaceX - now a satellite manufacturer (Starlink)
« Reply #2406 on: 11/19/2018 01:31 am »
Lower than operating altitude, they have minimal time on orbit (few weeks to decay) for check-out, so orbit raising becomes a time-critical maneuver.
That may be viewed as a feature, not a bug.  If dead-on-arrival satellites self-scuttle promptly, one is less guilty of space trash trouble-making, and one may be in better odor with authorities and critics.

How often would a bird be too sick to make the planned ascent, yet still economically salvageable?
The first Dragon that went to ISS had some problems that took some time to sort out, IIRC. It took a bit of time. So I think it's not a zero percent chance of it happening.

At 330 km you have several weeks, if not more, to sort things out. If you can't get it operational in that time you probably never will.

That's higher than the orbit where Falcon drops Dragon off.
« Last Edit: 11/19/2018 01:33 am by envy887 »

Offline Lar

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Re: SpaceX - now a satellite manufacturer (Starlink)
« Reply #2407 on: 11/19/2018 02:35 am »
Lower than operating altitude, they have minimal time on orbit (few weeks to decay) for check-out, so orbit raising becomes a time-critical maneuver.
That may be viewed as a feature, not a bug.  If dead-on-arrival satellites self-scuttle promptly, one is less guilty of space trash trouble-making, and one may be in better odor with authorities and critics.

How often would a bird be too sick to make the planned ascent, yet still economically salvageable?
The first Dragon that went to ISS had some problems that took some time to sort out, IIRC. It took a bit of time. So I think it's not a zero percent chance of it happening.

At 330 km you have several weeks, if not more, to sort things out. If you can't get it operational in that time you probably never will.

That's higher than the orbit where Falcon drops Dragon off.
Yup

my point was merely that there are some situations in which things don't work but that with some time, they can be made to work.

I agree that if you have had several weeks and can't get it working you probably never will.
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Offline meekGee

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Re: SpaceX - now a satellite manufacturer (Starlink)
« Reply #2408 on: 11/19/2018 12:47 pm »
Lower than operating altitude, they have minimal time on orbit (few weeks to decay) for check-out, so orbit raising becomes a time-critical maneuver.
That may be viewed as a feature, not a bug.  If dead-on-arrival satellites self-scuttle promptly, one is less guilty of space trash trouble-making, and one may be in better odor with authorities and critics.

How often would a bird be too sick to make the planned ascent, yet still economically salvageable?
The first Dragon that went to ISS had some problems that took some time to sort out, IIRC. It took a bit of time. So I think it's not a zero percent chance of it happening.

At 330 km you have several weeks, if not more, to sort things out. If you can't get it operational in that time you probably never will.

That's higher than the orbit where Falcon drops Dragon off.
Yup

my point was merely that there are some situations in which things don't work but that with some time, they can be made to work.

I agree that if you have had several weeks and can't get it working you probably never will.

Also, with >10,000 satellites, even with 1% failure rate, you simply don't have enough missions control centers to deal with broken satellites on an individual basis.  I'd wager that if the automated start-up sequence fails (and this sequence may have some contingency planning in it) then nobody will bother with one-off failures.

The level of involvement for humans would be fleet-wide or type-wide issues and how to solve them for the next manufacturing batch (or with fleet-wide software updates)
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Offline Joffan

Re: SpaceX - now a satellite manufacturer (Starlink)
« Reply #2409 on: 11/19/2018 01:39 pm »

Also, with >10,000 satellites, even with 1% failure rate, you simply don't have enough missions control centers to deal with broken satellites on an individual basis.  I'd wager that if the automated start-up sequence fails (and this sequence may have some contingency planning in it) then nobody will bother with one-off failures.

The level of involvement for humans would be fleet-wide or type-wide issues and how to solve them for the next manufacturing batch (or with fleet-wide software updates)

I would expect that a satellite reporting serious problems would get a little bit of focussed attention, before mission control hit the "splash" button - if only to confirm that there was enough control to splash reliably. And maybe to check that there isn't a less final response available. But I agree that splashing a satellite from a large constellation shouldn't be a step that is avoided at all costs; a problem satellite will have a very limited budget of response time. With good diagnostics data, you can spot trends betraying systemic issues later - you don't need to keep the satellite itself on hand.

The satellites that would get less attention, but regularly over time, would be the ones reporting healthy and doing their job.
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Offline envy887

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Re: SpaceX - now a satellite manufacturer (Starlink)
« Reply #2410 on: 11/19/2018 01:48 pm »

Also, with >10,000 satellites, even with 1% failure rate, you simply don't have enough missions control centers to deal with broken satellites on an individual basis.  I'd wager that if the automated start-up sequence fails (and this sequence may have some contingency planning in it) then nobody will bother with one-off failures.

The level of involvement for humans would be fleet-wide or type-wide issues and how to solve them for the next manufacturing batch (or with fleet-wide software updates)

I would expect that a satellite reporting serious problems would get a little bit of focussed attention, before mission control hit the "splash" button - if only to confirm that there was enough control to splash reliably. And maybe to check that there isn't a less final response available. But I agree that splashing a satellite from a large constellation shouldn't be a step that is avoided at all costs; a problem satellite will have a very limited budget of response time. With good diagnostics data, you can spot trends betraying systemic issues later - you don't need to keep the satellite itself on hand.

The satellites that would get less attention, but regularly over time, would be the ones reporting healthy and doing their job.

The discussion started with those deployed so so that they will splash in a matter of week regardless of attention of functionality.

I imagine the higher ones will get more attention, but if a VLEO bird malfunctions that badly they will almost certainly just let it go down.

Offline biosehnsucht

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Re: SpaceX - now a satellite manufacturer (Starlink)
« Reply #2411 on: 11/28/2018 06:30 pm »
Rumors from someone who claims to know a guy at SpaceX in the Starlink group over at TMC

Quote from: ZeApelido
Previous leads of the program got axed because - surprise! - they told Elon something couldn't be done in time. People in charge now are from a rocket engineering background, not wireless comms.

Quote from: ZeApelido
They closed Irvine office, then opened it back up because shockingly people didn't want to do a horrific commute to Hawthorne. Some concern that Seattle office might not stay open long term.

Quote from: ZeApelido
satellites will launch at 55 or 50 deg latitude (can't remember which) but orbit with different trajectories and oscillate between those latitudes N/S. So no coverage above 55 degrees latitude N/S.

Quote from: ZeApelido
Goal is to deploy "tens" of satellites early next year. Then hundreds by end of year. Best coverage will be at 50 degrees latitude. Worst coverage will be near the equator, as satellites are more spread out at the widest point. Equator will improve when a lot more satellites are deployed.

Quote from: ZeApelido
Satellites are like 3'x3' in size. Each trip they will dump them all out at the same time, then use internal controls to get them separated onto different trajectories.

Quote from: ZeApelido
Antenaes are like 18"x18". Interestingly this seems to be an area they have not spent much time on or optimized, not clear how compact it could get. First applications will be for big companies / governments then rural coverage.
« Last Edit: 11/28/2018 06:31 pm by biosehnsucht »

Offline Slarty1080

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Re: SpaceX - now a satellite manufacturer (Starlink)
« Reply #2412 on: 11/28/2018 06:46 pm »
Rumors from someone who claims to know a guy at SpaceX in the Starlink group over at TMC

Quote from: ZeApelido
Previous leads of the program got axed because - surprise! - they told Elon something couldn't be done in time. People in charge now are from a rocket engineering background, not wireless comms.

Quote from: ZeApelido
They closed Irvine office, then opened it back up because shockingly people didn't want to do a horrific commute to Hawthorne. Some concern that Seattle office might not stay open long term.

Quote from: ZeApelido
satellites will launch at 55 or 50 deg latitude (can't remember which) but orbit with different trajectories and oscillate between those latitudes N/S. So no coverage above 55 degrees latitude N/S.

Quote from: ZeApelido
Goal is to deploy "tens" of satellites early next year. Then hundreds by end of year. Best coverage will be at 50 degrees latitude. Worst coverage will be near the equator, as satellites are more spread out at the widest point. Equator will improve when a lot more satellites are deployed.

Quote from: ZeApelido
Satellites are like 3'x3' in size. Each trip they will dump them all out at the same time, then use internal controls to get them separated onto different trajectories.

Quote from: ZeApelido
Antenaes are like 18"x18". Interestingly this seems to be an area they have not spent much time on or optimized, not clear how compact it could get. First applications will be for big companies / governments then rural coverage.
Would have thought that some of the first customers would be the banks / high frequency traders. Trimmimg a few microseconds off of the communication time between London and New York would be very very valuable.
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Offline Bananas_on_Mars

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Re: SpaceX - now a satellite manufacturer (Starlink)
« Reply #2413 on: 11/28/2018 06:48 pm »
Sounds like they might focus on backhaul services first. That could simply mean they are further along with the optical links then with the beam-forming antennas. Since there is a market for low latency communication links around the world that might not require immense bandwidth, they might simply go for that market segment first. They could fly a lot of iterations/versions in parallel in their constellation.

Offline envy887

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Re: SpaceX - now a satellite manufacturer (Starlink)
« Reply #2414 on: 11/28/2018 07:49 pm »
Rumors from someone who claims to know a guy at SpaceX in the Starlink group over at TMC
Quote from: ZeApelido
satellites will launch at 55 or 50 deg latitude (can't remember which) but orbit with different trajectories and oscillate between those latitudes N/S. So no coverage above 55 degrees latitude N/S.

If launched to 50 deg inclination at 550 km, it would still have coverage up to 55 deg latitude with the new 25 deg above horizon angle from the updated FAA application. If launched to 55 deg inclination, it will cover up to 60+ latitude or a little higher.

The 1100 km sats could cover even higher latitudes from the same inclinations.

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Re: SpaceX - now a satellite manufacturer (Starlink)
« Reply #2415 on: 11/28/2018 09:28 pm »
Their recent modification request seemed to imply the early models won't have the laser interconnects.

Offline copper8

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Re: SpaceX - now a satellite manufacturer (Starlink)
« Reply #2416 on: 11/29/2018 01:06 am »
Get something up quickly.  Get some experience.  Get some revenue. Iterate.

Online gongora

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Re: SpaceX - now a satellite manufacturer (Starlink)
« Reply #2417 on: 11/29/2018 01:08 am »
Get something up quickly.  Get some experience.  Get some revenue. Iterate.

That seems to be the plan.  Hopefully they can get that modification to the orbits approved next year.

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Re: SpaceX - now a satellite manufacturer (Starlink)
« Reply #2418 on: 11/29/2018 03:02 am »
Get something up quickly.  Get some experience.  Get some revenue. Iterate.

You reminded me of how different SpaceX' position is relative to competitors because of steadily lowering launch costs. In most cases launch price is not the same as launch cost, as NSF members constantly remind each other. But in this case they are exactly the same. So in an era when prices may not be dropping as fast as costs, Starlink gets to exploit the difference. They also have a much better understanding of their likely launch costs 2, 3, and 5 years from now than anyone else does.

Offline Asteroza

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Re: SpaceX - now a satellite manufacturer (Starlink)
« Reply #2419 on: 11/29/2018 04:49 am »
Their recent modification request seemed to imply the early models won't have the laser interconnects.

Do they even need FCC clearance/mods for lasercomm? Or is it ancillary evidence, like telescope parts surviving reentry in the debris declaration that would give away that they were still installed?

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