Author Topic: Starlink : General Discussion - Thread 2  (Read 1273138 times)

Offline speedevil

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Re: Starlink : General Discussion - Thread 2
« Reply #240 on: 09/03/2019 04:24 pm »
I note wikipedias page on the satellite in question https://en.wikipedia.org/wiki/ADM-Aeolus#cite_note-%E2%80%9D2019-06-27_Spectrum%E2%80%9D-13 states that it is already doing weekly manoevers to maintain orbit.
It would be interesting to know the magnitude of the previous burns, and this one.
Also if SpaceX bird has manoevered recently - if not - burning to a conjunction in the weeks prior pretty much puts the fault on one side.

Offline Lar

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Re: Starlink : General Discussion - Thread 2
« Reply #241 on: 09/03/2019 04:24 pm »
Seems clear to me that some overall coordination is needed. What is not clear is that it has to be done via "regulation" (what international body has regulatory authority??).

Take further discussion of that idea here I think

https://forum.nasaspaceflight.com/index.php?topic=48954
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Offline Marci

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Re: Starlink : General Discussion - Thread 2
« Reply #242 on: 09/03/2019 04:26 pm »
So the main problem I see is a lot of miscommunication and a lack of cooperation between SpaceX and ESA.

If SpaceX wants Starlink to be successfull they should really start to consider the concerns of the other players. There will be new rules in the future, just because the amount of new satellites is too big. And if you want these regulations be in favour of your plans, you need the others to trust you.

So it should be in SpaceX own interest to have a better relation with ESA (and the scientific community in general) in the future.

Offline envy887

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Re: Starlink : General Discussion - Thread 2
« Reply #243 on: 09/03/2019 04:30 pm »
So the main problem I see is a lot of miscommunication and a lack of cooperation between SpaceX and ESA.

If SpaceX wants Starlink to be successfull they should really start to consider the concerns of the other players. There will be new rules in the future, just because the amount of new satellites is too big. And if you want these regulations be in favour of your plans, you need the others to trust you.

So it should be in SpaceX own interest to have a better relation with ESA (and the scientific community in general) in the future.

I'll note that according to both ESA and reporters in direct contact with ESA sources, ESA never ASKED SpaceX to move. ESA simply "informed" SpaceX of ESA's calculated collision risk (which incorporated ESA internal positioning data not available to SpaceX), and SpaceX "who replied and said that they do not plan to take action”.

ESA might simply have been asking "our data shows a 1:1000 risk, are you planning to maneuver?", to which SpaceX replied "No". This was all the information ESA needed to make the decision to execute their own maneuver which they did.

Offline Lar

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Re: Starlink : General Discussion - Thread 2
« Reply #244 on: 09/03/2019 04:40 pm »
So the main problem I see is a lot of miscommunication and a lack of cooperation between SpaceX and ESA.

If SpaceX wants Starlink to be successfull they should really start to consider the concerns of the other players. There will be new rules in the future, just because the amount of new satellites is too big. And if you want these regulations be in favour of your plans, you need the others to trust you.

So it should be in SpaceX own interest to have a better relation with ESA (and the scientific community in general) in the future.
This is not the spin I'd give this. There seems to be a conflict between ESA saying "SpaceX never communicates with us" and SpaceX saying "we exchanged emails about this and jointly decided no action was warranted, and we're sorry we botched comms when there was an update to the probability"  (both paraphrases)

There may be elements in ESA that would like to make SpaceX look bad, since there is some connection between ESA-ArianeSpace-OneWeb (a direct competitor to Starlink)

Let's not ourselves also play that game ok?
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"We're a little bit like the dog who caught the bus" - Musk after CRS-8 S1 successfully landed on ASDS OCISLY

Offline Draggendrop

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Re: Starlink : General Discussion - Thread 2
« Reply #245 on: 09/03/2019 04:42 pm »
So the main problem I see is a lot of miscommunication and a lack of cooperation between SpaceX and ESA.

If SpaceX wants Starlink to be successfull they should really start to consider the concerns of the other players. There will be new rules in the future, just because the amount of new satellites is too big. And if you want these regulations be in favour of your plans, you need the others to trust you.

So it should be in SpaceX own interest to have a better relation with ESA (and the scientific community in general) in the future.

In this instance I believe ESA could have handled this in a more professional manner.  Twitter is not the venue to use for a general avoidance maneuver or to use this situation for other means without direct dialogue with those in a conflicting situation.

oops...been ninja'd

Offline guckyfan

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Re: Starlink : General Discussion - Thread 2
« Reply #246 on: 09/03/2019 04:44 pm »
Seems there are contradicting statements. This ESA statement sounds more positive on SpaceX than the SpaceX statement.

An ESA comment on n-tv a german news channel.

https://www.n-tv.de/wissen/Esa-Satellit-umfliegt-SpaceX-Satelliten-article21248848.html

Quote
Zuvor hatte die ESA SpaceX kontaktiert. Zusammen wurde entschieden, dass "Aeolus" ausweicht. Die Absprache sei wichtig, sagte Holger Krag, der Leiter des Esa-Büros für Raumfahrtrückstände. Ansonsten könnte es im schlimmsten Fall sein, dass beide Satelliten in die gleiche Richtung ausweichen und so weiter aufeinanderzusteuern. Die Absprache mit SpaceX funktionierte laut dem Experten gut. Das sei nicht immer so: "Es gibt Satellitenbetreiber, die reagieren gar nicht, wenn man sie anschreibt."

Before (ESA did the course correction) ESA had contacted SpaceX. Together they decided that "Aeolus" makes the avoidance maneuver. Agreement is important, said Holger Krag, head of ESA office for Space flight (not sure how to translate Rückstande - which means remnants). Otherwise worst case both satellites maneuver in the same direction and stay on collision course. Communication with SpaceX worked well according to the expert. That's not always the case. "There are satellite operators that don't react at all if contacted."

Offline envy887

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Re: Starlink : General Discussion - Thread 2
« Reply #247 on: 09/03/2019 04:45 pm »
So the main problem I see is a lot of miscommunication and a lack of cooperation between SpaceX and ESA.

If SpaceX wants Starlink to be successfull they should really start to consider the concerns of the other players. There will be new rules in the future, just because the amount of new satellites is too big. And if you want these regulations be in favour of your plans, you need the others to trust you.

So it should be in SpaceX own interest to have a better relation with ESA (and the scientific community in general) in the future.

In this instance I believe ESA could have handled this in a more professional manner.  Twitter is not the venue to use for a general avoidance maneuver or to use this situation for other means without direct dialogue with those in a conflicting situation.

oops...been ninja'd
ESA went to twitter long after the maneuver had been performed. And they did have a direct dialog with SpaceX, per their statements to Forbes and SpaceNews.

Offline Draggendrop

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Re: Starlink : General Discussion - Thread 2
« Reply #248 on: 09/03/2019 04:57 pm »
The SpaceNews article was updated to say ESA received notification 5 days before the close approach, presumably SpaceNews run SOCRATES after the ESA tweet which is yesterday, so the data used by SpaceNews' SOCRATES run should be only 2 days before the close approach at maximal, which is 3 days after the 5 days notification.

Did you really read that article?  Maybe you should read it again.  It doesn't say anything about Space News running SOCRATES.  It does say that ESA monitored the situation from the time they were informed of it and then made the decision to adjust the orbit the day before the potential conjuction.  The idea that Space News somehow ran a better analysis of the situation than ESA is ridiculous.

Of course I read it, twice, once before they did the update, once after they did the update. If SpaceNews didn't run SOCRATES, where did this comes from?

Quote
According to a list of conjunctions called the Satellite Orbital Conjunction Reports Assessing Threatening Encounters in Space (SOCRATES), maintained by the Center for Space Standards & Innovation, Aeolus was predicted to have a close approach shortly after 7 a.m. Eastern Sept. 2 with a satellite identified as “Starlink AV” for its international designation, 2019-029AV. The two satellites were predicted to come within about four kilometers of each other, at a relative velocity of 14.4 kilometers per second. However, the SOCRATES data predicted a very low probability of collision — less than one in one million — which ordinarily would be far below the threshold for an avoidance maneuver.

And where did I suggest SpaceNews' analysis is better? What I'd like to know is the cause of the different results, is it because 18SPCS public TLE data is not accurate? Or something else.

And if public TLE data is not accurate, is it because 18SPCS is holding back more accurate dataset, or is it because ESA is not sharing up to date orbital data with 18SPCS? Both are concerning, especially given a few pages back some people are concerned the public TLE age is too old, but if 18SPCS has a secret dataset which it only shares with operators, then the age of the public TLE doesn't matter. It's all tied together, you can't argue both ways.

The TLE data set issued is for general consumption. The accuracy is reasonable and it is up to the end user how to present, modify or tease accuracy from various elements.

There is no "more accurate" TLE set for general consumption.

Several billions of dollars of equipment are in use and/or available for general tracking and for refined operations.

Radar, laser and GPS equipment, to name a few, have levels of accuracy and abilities to modify beam patterns and apply mathematical modifications to extract increased accuracy.

There is no way that this increased accuracy will be let out in the wild...for obvious reasons.

Entities can engage in agreements for increased accuracy pertaining to their payloads. This data can again be modified as the user deems to their desired standard.

There is no universal standard that everyone uses to tease data...but the methods can be verified mathematically.

Offline Draggendrop

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Re: Starlink : General Discussion - Thread 2
« Reply #249 on: 09/03/2019 05:05 pm »
So the main problem I see is a lot of miscommunication and a lack of cooperation between SpaceX and ESA.

If SpaceX wants Starlink to be successfull they should really start to consider the concerns of the other players. There will be new rules in the future, just because the amount of new satellites is too big. And if you want these regulations be in favour of your plans, you need the others to trust you.

So it should be in SpaceX own interest to have a better relation with ESA (and the scientific community in general) in the future.

In this instance I believe ESA could have handled this in a more professional manner.  Twitter is not the venue to use for a general avoidance maneuver or to use this situation for other means without direct dialogue with those in a conflicting situation.

oops...been ninja'd
ESA went to twitter long after the maneuver had been performed. And they did have a direct dialog with SpaceX, per their statements to Forbes and SpaceNews.

True but a certain twitter handle was stating inside information from someone in ESA , probably not sanctioned, that started and continued this mess. I followed this "drama" during the early part...not pretty. Some of it ended in a Forbes article and not as it is presented now.

It appears to be handled now and hopefully kept off twitter in the future.

Offline aameise9

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Re: Starlink : General Discussion - Thread 2
« Reply #250 on: 09/03/2019 06:54 pm »
Interview on "space safety" with ESA expert Holger Krag was just published by German quality daily (Frankfurter Allgemeine Zeitung):

https://www.faz.net/aktuell/wissen/weltraum/esa-satellit-muss-musks-starlink-satellit-ausweichen-16366503.html

IMHO, his statements are balanced and reasonable.  No bashing that I can perceive.  He argues that new procedures -- largely automated and autonomous -- need to be discussed and agreed upon, because such incidents are bound to become increasingly frequent.

Offline Lar

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Re: Starlink : General Discussion - Thread 2
« Reply #251 on: 09/03/2019 07:22 pm »
Interview on "space safety" with ESA expert Holger Krag was just published by German quality daily (Frankfurter Allgemeine Zeitung):

https://www.faz.net/aktuell/wissen/weltraum/esa-satellit-muss-musks-starlink-satellit-ausweichen-16366503.html

IMHO, his statements are balanced and reasonable.  No bashing that I can perceive.  He argues that new procedures -- largely automated and autonomous -- need to be discussed and agreed upon, because such incidents are bound to become increasingly frequent.
Did he discuss that ESA is seeking funding for just such a system?
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"We're a little bit like the dog who caught the bus" - Musk after CRS-8 S1 successfully landed on ASDS OCISLY

Offline alexterrell

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Re: Starlink : General Discussion - Thread 2
« Reply #252 on: 09/03/2019 07:39 pm »
So the main problem I see is a lot of miscommunication and a lack of cooperation between SpaceX and ESA.

If SpaceX wants Starlink to be successfull they should really start to consider the concerns of the other players. There will be new rules in the future, just because the amount of new satellites is too big. And if you want these regulations be in favour of your plans, you need the others to trust you.

So it should be in SpaceX own interest to have a better relation with ESA (and the scientific community in general) in the future.

In this instance I believe ESA could have handled this in a more professional manner.  Twitter is not the venue to use for a general avoidance maneuver or to use this situation for other means without direct dialogue with those in a conflicting situation.

oops...been ninja'd
Twitter was used to report the news after the event.

SpaceX have admitted that they were partly at fault:
Quote
A SpaceX spokesperson said a bug in its on-call operating system prevented the team from seeing that the risk of a collision with the ESA craft may have increased.

“Had the Starlink operator seen the correspondence, we would have coordinated with ESA to determine best approach with their continuing with their manoeuvre or our performing a manoeuvre,” the spokesperson said.

This is a bit like pulling out of a junction without seeing another car, with both having equal priority, but the other driver has plenty of time to avoid you, and does so. A quick "sorry" is the end of the problem.

Except in this case .... some sort of procedures will be needed to support 10s of thousands of satellites in orbit. For everyone's sake. 

By the way, who is responsible for warning SpaceX about collision threats? Is this the USAF? Do they provide this as a service to all satellite operators?

Offline envy887

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Re: Starlink : General Discussion - Thread 2
« Reply #253 on: 09/03/2019 07:44 pm »
By the way, who is responsible for warning SpaceX about collision threats? Is this the USAF? Do they provide this as a service to all satellite operators?

Yes and yes.

Offline alexterrell

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Re: Starlink : General Discussion - Thread 2
« Reply #254 on: 09/03/2019 07:44 pm »
Interview on "space safety" with ESA expert Holger Krag was just published by German quality daily (Frankfurter Allgemeine Zeitung):

https://www.faz.net/aktuell/wissen/weltraum/esa-satellit-muss-musks-starlink-satellit-ausweichen-16366503.html

IMHO, his statements are balanced and reasonable.  No bashing that I can perceive.  He argues that new procedures -- largely automated and autonomous -- need to be discussed and agreed upon, because such incidents are bound to become increasingly frequent.
Did he discuss that ESA is seeking funding for just such a system?
No he wasn't asked and it wasn't relevant.

I've used DeepL to provide a translation of the final paragraph:
Quote
I think that in the next two to three years we should have technical solutions that make our work much easier. Communication protocols, automatic decisions based on machine learning. Perhaps also the possibility of reaching the satellite at any time and not just when it is flying over a ground station, so that we can react more flexibly. Our proposal is to demonstrate by 2023 that a satellite makes a decision after a collision warning, votes and then evades autonomously. Autonomous does not mean that it does everything on board, which of course requires contact with the ground. But at the moment we are not in a position to do so. Many experts are paid to stay awake around the clock and assess the situation. And that is no longer manageable when we soon have five times the number of satellites.

Translated with www.DeepL.com/Translator

Seems all sensible stuff.

Offline Draggendrop

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Re: Starlink : General Discussion - Thread 2
« Reply #255 on: 09/03/2019 07:56 pm »
So the main problem I see is a lot of miscommunication and a lack of cooperation between SpaceX and ESA.

If SpaceX wants Starlink to be successfull they should really start to consider the concerns of the other players. There will be new rules in the future, just because the amount of new satellites is too big. And if you want these regulations be in favour of your plans, you need the others to trust you.

So it should be in SpaceX own interest to have a better relation with ESA (and the scientific community in general) in the future.

In this instance I believe ESA could have handled this in a more professional manner.  Twitter is not the venue to use for a general avoidance maneuver or to use this situation for other means without direct dialogue with those in a conflicting situation.

oops...been ninja'd
Twitter was used to report the news after the event.

SpaceX have admitted that they were partly at fault:
Quote
A SpaceX spokesperson said a bug in its on-call operating system prevented the team from seeing that the risk of a collision with the ESA craft may have increased.

“Had the Starlink operator seen the correspondence, we would have coordinated with ESA to determine best approach with their continuing with their manoeuvre or our performing a manoeuvre,” the spokesperson said.

This is a bit like pulling out of a junction without seeing another car, with both having equal priority, but the other driver has plenty of time to avoid you, and does so. A quick "sorry" is the end of the problem.

Except in this case .... some sort of procedures will be needed to support 10s of thousands of satellites in orbit. For everyone's sake. 

By the way, who is responsible for warning SpaceX about collision threats? Is this the USAF? Do they provide this as a service to all satellite operators?

Yes twitter was used to report the news after the event. That is not the issue when one has hindsight.

This issue erupted in an incoherent manner with false assumptions by a twitter handle with information from a probably unauthorized individual. This then spread to a few articles. This went on for approximately 12 hours.

Only later did the dust settle but the point being...twitter was not the venue to use for an avoidance maneuver.

That is my opinion and others are welcome to theirs...we don't need this thread derailed so I am done with this until the next adventure occurs.

Thanks for your input though.

Offline AC in NC

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Re: Starlink : General Discussion - Thread 2
« Reply #256 on: 09/03/2019 08:01 pm »
I'm a little surprised this problem isn't far more tractable than it seems on the surface based on how the principals are behaving.  Is there something that makes this anything other than a mathematics problem, even if that mathmatics problem requires an excessive number of FLOPS from the CPU hamsters?

It almost feels like they are calculating 1in1000 because they are arbitrarily introducing an artificial "sphere of uncertainty" which turns something they know is a non-collision intersection into one that might have some marginal chance of collision.

Seems strange.  Curious if knowledgeable folk know differently.

Offline envy887

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Re: Starlink : General Discussion - Thread 2
« Reply #257 on: 09/03/2019 08:07 pm »
I'm a little surprised this problem isn't far more tractable than it seems on the surface based on how the principals are behaving.  Is there something that makes this anything other than a mathematics problem, even if that mathmatics problem requires an excessive number of FLOPS from the CPU hamsters?

It almost feels like they are calculating 1in1000 because they are arbitrarily introducing an artificial "sphere of uncertainty" which turns something they know is a non-collision intersection into one that might have some marginal chance of collision.

Seems strange.  Curious if knowledgeable folk know differently.

I don't think computation is the issue. If every satellite had a GPS position feeding realtime data, the assessments could probably be done in short order on a typical workstation-class computer with very high accuracy.

The problem is getting that data from many operators at once, sending it to a central location in a reasonable time, then disseminating to all the operators. And also that debris isn't going to give you GPS locations, and debris is fy far the biggest share of objects and will be even if SpaceX launches 12,000 Starlinks.

Offline whitelancer64

Re: Starlink : General Discussion - Thread 2
« Reply #258 on: 09/03/2019 08:15 pm »
I'm a little surprised this problem isn't far more tractable than it seems on the surface based on how the principals are behaving.  Is there something that makes this anything other than a mathematics problem, even if that mathmatics problem requires an excessive number of FLOPS from the CPU hamsters?

It almost feels like they are calculating 1in1000 because they are arbitrarily introducing an artificial "sphere of uncertainty" which turns something they know is a non-collision intersection into one that might have some marginal chance of collision.

Seems strange.  Curious if knowledgeable folk know differently.

Orbits can be somewhat chaotic. Drag is a very big factor and it's not a constant, it's a variable. The very high upper atmosphere of the Earth can be more or less dense by a considerable amount, depending largely on solar activity. So you can't make precise orbital predictions very far out. This is more true the lower the altitude of the satellite (the more it is influenced by Earth's atmosphere).

So you have to work with probability, and 1-in-1000 is not a bad threshold to work with. As mentioned, there is some uncertainty in orbital tracking, in the time delay to get that information out, and variability in the orbit itself.
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Offline OTV Booster

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Re: Starlink : General Discussion - Thread 2
« Reply #259 on: 09/03/2019 08:31 pm »
Looking at the orbital parameters of Aeolus, the satellite it intercepted was 44278 aka 2019-029AV, currently in a 346km by 311km orbit (as of the last TLE), the only satellite with the perigee lower than the Aeolus mean orbital altitude, that currently is in a 314km by 308 km orbit.

Is it still settling into its final orbit? I’d assume so if it has a unique perigee. Last one or are others still raising perigee?

Phil
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