Author Topic: Starlink : General Discussion - Thread 3  (Read 346181 times)

Offline theinternetftw

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Re: Starlink : General Discussion - Thread 3
« Reply #620 on: 10/05/2022 08:14 pm »
Another Gen2 filing https://licensing.fcc.gov/myibfs/download.do?attachment_key=17429628

Quote
SATELLITE DIMENSIONS
The tables below present information for the current form factors of SpaceX Gen2
satellites: two of which will be launched initially on Falcon 9 rockets and one that will be launched
on Starship. For convenience, these satellites are labeled satellites F9-1, F9-2, and Starship,
respectively.


A quick visual aid for the scale of the sat variants.

Offline freddo411

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Re: Starlink : General Discussion - Thread 3
« Reply #621 on: 10/05/2022 08:34 pm »
I've heard that starlinks are getting brighter again (instead of dimmer).
They no longer have visors, because they might interfere with laser links. As a result, all the newer birds will be brighter.

Source?
https://skyandtelescope.org/astronomy-news/newest-starlink-satellites-have-gotten-brighter-again/
0.6 magnitude brighter than visorsats, but still dimmer than original Starlinks.
So starlinks are getting brighter again. They will also start getting even brighter with the larger sized ones.

This "dimmer than original" covers up the elephant in the room that is always ignored. They are only at the smaller magnitude when they reach final orbit. However, there are always hundreds of satellites on their way up to orbit (which takes several months. Starship is gonna change this to possibly thousands). In a couple years, there will also start to be many hundreds (or thousands) constantly on their way DOWN from orbit to be removed as they hit their 5yr lifespan or whatever and are replaced. So while some starlink satellites are at their minimum magnitude, there will always be a large number of satellites that are much brighter. The constellation will never be finished, there will always be many hundreds on their way up or down.

Good points.   Agreed, starlink sats are visible in the night sky when they are illuminated

However, the world has gained an important new global utility that is significantly changing everyday communication in remote locations.   High speed internet available on any continent, at sea, and in the air.   Remote (anywhere!) emergency messaging from regular phones (coming soon).

Significantly, this business is enabling cheaper access to space for everyone, including those that do astronomy from orbit.   It's worth pointing out that a Hubble servicing mission is possible due to this.

Online oldAtlas_Eguy

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Re: Starlink : General Discussion - Thread 3
« Reply #622 on: 10/05/2022 09:48 pm »
Expect the eventual fallout from all of SpaceX's experimentation with reflectivity and effects to terrestrial observation assets to result in an eventual US and then later an International set of standards for all new sats in Earth orbit. This will be a big gain for the terrestrial astronomical instruments usage. But for even more advanced observations will likely move out into space beyond most of the objects that are in the way such as placed out at Lagrange  Earth-Sun 2 past the Moon's orbit and is permanently facing away from the sun. This is beyond the Lagrange Earth-Moon 2 point.

Offline OceanCat

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Re: Starlink : General Discussion - Thread 3
« Reply #623 on: 10/06/2022 12:36 am »
A quick visual aid for the scale of the sat variants.

Interesting that the brightness mitigation document they posted at the end of July kind of suggests that gen2 satellites will have L shape similar to gen1 satellites. I can imagine how two solar arrays you pictured might work but I would expect the description of "terminator tracking" and the illustration to be more specific about how each array rotates.

Quote

To scatter sunlight hitting the front side of the solar arrays, the second-generation satellites will
point the solar arrays away from the Sun when crossing the terminator (the line on Earth's
surface separating night and day) in a maneuver called "terminator tracking." This maneuver
will point the knife edge of the solar array at the earth limb, which minimizes brightness when
viewed from the ground, as shown in the image below.

Offline su27k

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Re: Starlink : General Discussion - Thread 3
« Reply #624 on: 10/06/2022 01:45 am »
So starlinks are getting brighter again. They will also start getting even brighter with the larger sized ones.

This "dimmer than original" covers up the elephant in the room that is always ignored. They are only at the smaller magnitude when they reach final orbit. However, there are always hundreds of satellites on their way up to orbit (which takes several months. Starship is gonna change this to possibly thousands). In a couple years, there will also start to be many hundreds (or thousands) constantly on their way DOWN from orbit to be removed as they hit their 5yr lifespan or whatever and are replaced. So while some starlink satellites are at their minimum magnitude, there will always be a large number of satellites that are much brighter. The constellation will never be finished, there will always be many hundreds on their way up or down.

No and No.

They won't get even brighter with the larger sized ones since the larger sized ones will use better mirror material, it's all laid out in their brightness mitigation document. I would also expect later builds of Gen1 to reduce brightness again due to the use of this new material.

And satellites in transit is not "elephant in the room", SpaceX talks about them in every brightness related documents, there's no effort to try to ignore them. Also their impact should be minimal, i.e. not an "elephant" since:
1. SpaceX expects to use Starship to inject Gen2 satellites directly to their plane, this avoids the drifting to nearby orbital plane and speed up orbital raising from a few months to a few weeks.
2. Since Gen2 is 30,000 satellites, this means replacing 6,000 satellites every years assuming 5 year life span. Assuming orbital raising/deorbit takes 4 weeks, this means at any time there're only 461 x 2 = 922 satellites in transit, a very small number comparing to the entire constellation and inconsequential to astronomy (multiple astronomers have said the initial constellation does not have big impact to astronomy, 900 satellites is much smaller the Gen1)
3. The satellites in transit would be grouped together in a few satellite trains (probably less than 10), this means they're easier to avoid for astronomers
4. When the satellites are in lower orbit, they appear more briefly during twilight, thus further reduce their impact
5. In addition, SpaceX is also refining the attitude control and solar array pointing during these two phases to reduce brightness, they can do this because when raising orbit or deborit, satellite doesn't need to provide service thus doesn't need to keep a fixed orientation wrt ground, and can live with less power.

Offline kevin-rf

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Re: Starlink : General Discussion - Thread 3
« Reply #625 on: 10/06/2022 01:31 pm »
With the micro Gen 2 Falcon 9 compatible satellites just around the corner, will they even continue building v1.5 satellites and take advantage of the new materials? One has to wonder if they have built all the v1.5's they are going to build and it's just a matter of launching the backlog.
« Last Edit: 10/06/2022 01:31 pm by kevin-rf »
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Online mn

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Re: Starlink : General Discussion - Thread 3
« Reply #626 on: 10/06/2022 04:16 pm »
....
5. In addition, SpaceX is also refining the attitude control and solar array pointing during these two phases to reduce brightness, they can do this because when raising orbit or deborit, satellite doesn't need to provide service thus doesn't need to keep a fixed orientation wrt ground, and can live with less power.

Curious about the last part.

At first glance it makes sense that the power requirement for orbit raising is less than for transmitting data, but did anyone do any math on that, or is it just an assumption?

Online FutureSpaceTourist

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Re: Starlink : General Discussion - Thread 3
« Reply #627 on: 10/06/2022 05:24 pm »
twitter.com/elonmusk/status/1578055594573004800

Quote
Starlink view of 2nd stage deorbit burn

https://twitter.com/joroulette/status/1578056421647831040

Quote
Pretty sure this is the first time we’ve ever seen imagery taken by a Starlink satellite

twitter.com/joroulette/status/1578062876627144704

Quote
SpaceX had a NOAA license in 2015 for a low-res panchromatic video camera on MicroSat 1A and 1B - two early prototype satellites that ended up never flying to space.

https://twitter.com/joroulette/status/1578063054327189510

Quote
Per the license, they were installed to capture pics and vids of Earth and the satellites themselves, and "potentially be used for general educational purposes, such as through the release of inspiring public Earth images"

Offline kevin-rf

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Re: Starlink : General Discussion - Thread 3
« Reply #628 on: 10/06/2022 05:54 pm »
Can't help but think about a Luna 3 quote some 43 years ago, so that one had a camera...
If you're happy and you know it,
It's your med's!

Online Bob Shaw

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Re: Starlink : General Discussion - Thread 3
« Reply #629 on: 10/06/2022 06:07 pm »
twitter.com/elonmusk/status/1578055594573004800

Quote
Starlink view of 2nd stage deorbit burn


Can anyone interpret this image please?

I can't see the burn mentioned by Musk.
« Last Edit: 10/06/2022 06:08 pm by Bob Shaw »

Offline deadman1204

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Re: Starlink : General Discussion - Thread 3
« Reply #630 on: 10/06/2022 06:08 pm »
Expect the eventual fallout from all of SpaceX's experimentation with reflectivity and effects to terrestrial observation assets to result in an eventual US and then later an International set of standards for all new sats in Earth orbit. This will be a big gain for the terrestrial astronomical instruments usage. But for even more advanced observations will likely move out into space beyond most of the objects that are in the way such as placed out at Lagrange  Earth-Sun 2 past the Moon's orbit and is permanently facing away from the sun. This is beyond the Lagrange Earth-Moon 2 point.
Most observations can't and won't move out into space. The cost of a space based observatory is HUGE compared to an equivalent ground based one. And just for the record, launch cost has no impact on this. Free launch won't change this.

Offline groknull

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Re: Starlink : General Discussion - Thread 3
« Reply #631 on: 10/06/2022 07:00 pm »
Expect the eventual fallout from all of SpaceX's experimentation with reflectivity and effects to terrestrial observation assets to result in an eventual US and then later an International set of standards for all new sats in Earth orbit. This will be a big gain for the terrestrial astronomical instruments usage. But for even more advanced observations will likely move out into space beyond most of the objects that are in the way such as placed out at Lagrange  Earth-Sun 2 past the Moon's orbit and is permanently facing away from the sun. This is beyond the Lagrange Earth-Moon 2 point.
Most observations can't and won't move out into space. The cost of a space based observatory is HUGE compared to an equivalent ground based one. And just for the record, launch cost has no impact on this. Free launch won't change this.

My bold.

Do you have links to actual numbers I can do research on?  Published reports, etc.  Also interested in $/minute of actual observation time for different types and locations of terrestrial observatories.  Thx.

Since this is not really Starlink specific, a PM is probably more appropriate.

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Re: Starlink : General Discussion - Thread 3
« Reply #632 on: 10/06/2022 07:09 pm »
Follow-up on Starlink cameras:

https://twitter.com/joroulette/status/1578095938530328576

Quote
The type of cameras aboard Starlink satellites are primarily for mission assurance purposes - like to monitor separation events and spacecraft health - and therefore don't require a NOAA license, per an agency spokesman pointing to 15 CFR § 960.2 (b).

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Offline deadman1204

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Re: Starlink : General Discussion - Thread 3
« Reply #634 on: 10/06/2022 08:30 pm »
Expect the eventual fallout from all of SpaceX's experimentation with reflectivity and effects to terrestrial observation assets to result in an eventual US and then later an International set of standards for all new sats in Earth orbit. This will be a big gain for the terrestrial astronomical instruments usage. But for even more advanced observations will likely move out into space beyond most of the objects that are in the way such as placed out at Lagrange  Earth-Sun 2 past the Moon's orbit and is permanently facing away from the sun. This is beyond the Lagrange Earth-Moon 2 point.
Most observations can't and won't move out into space. The cost of a space based observatory is HUGE compared to an equivalent ground based one. And just for the record, launch cost has no impact on this. Free launch won't change this.

My bold.

Do you have links to actual numbers I can do research on?  Published reports, etc.  Also interested in $/minute of actual observation time for different types and locations of terrestrial observatories.  Thx.

Since this is not really Starlink specific, a PM is probably more appropriate.


Look up the price of literally ANY space telescope. Also, the price is as much time as it is money.  Look into the years and years of time it takes to build and design one. This is a silly fantasy that free launch is the majority of the solution.

However, to save you the 3 seconds of google time, the ELT (biggest telescope EVER https://en.wikipedia.org/wiki/Extremely_Large_Telescope) has a price tag of 1.5 billion euros. We literally do not have the technology to build this in space, but if we tried, after the tech dev and decades of work, it would easily be 50billion plus. How does the difference of $30million on the launch price change anything? (Again ignoring the decades of time lost by trying to build a space based one).

 Even if there was free launch today for a new telescope, it would easily be a decade to fund, design, build, and test something to take advantage of it. 

This is a "starlink" problem, and it HAS already been one problem for years. Will there eventually be other mega constellations? Probably. Does that change the fact that starlink is already causing these problems? Nope.
« Last Edit: 10/06/2022 08:41 pm by deadman1204 »

Offline kevin-rf

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Re: Starlink : General Discussion - Thread 3
« Reply #635 on: 10/06/2022 08:41 pm »

Can anyone interpret this image please?

I can't see the burn mentioned by Musk.


You can see it a little better in the video Elon Musk posted. What you see is the stack of Starlinks separating and to the right you see a sudden flare that one would assume is the second stage suddenly moving to the right.
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Offline groknull

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Re: Starlink : General Discussion - Thread 3
« Reply #636 on: 10/06/2022 08:47 pm »
Expect the eventual fallout from all of SpaceX's experimentation with reflectivity and effects to terrestrial observation assets to result in an eventual US and then later an International set of standards for all new sats in Earth orbit. This will be a big gain for the terrestrial astronomical instruments usage. But for even more advanced observations will likely move out into space beyond most of the objects that are in the way such as placed out at Lagrange  Earth-Sun 2 past the Moon's orbit and is permanently facing away from the sun. This is beyond the Lagrange Earth-Moon 2 point.
Most observations can't and won't move out into space. The cost of a space based observatory is HUGE compared to an equivalent ground based one. And just for the record, launch cost has no impact on this. Free launch won't change this.

My bold.

Do you have links to actual numbers I can do research on?  Published reports, etc.  Also interested in $/minute of actual observation time for different types and locations of terrestrial observatories.  Thx.

Since this is not really Starlink specific, a PM is probably more appropriate.


Look up the price of literally ANY space telescope. Also, the price is as much time as it is money.  Look into the years and years of time it takes to build and design one. This is a silly fantasy that free launch matters is the majority of the solution.

However, to save you the 3 seconds of google time, the ELT (biggest telescope EVER https://en.wikipedia.org/wiki/Extremely_Large_Telescope) has a price tag of 1.5 billion euros. We literally do not have the technology to build this in space, but if we tried, after the tech dev and decades of work, it would easily be 50billion plus. How does the difference of $30million on the launch price change anything?

 Even if there was free launch today, it would easily be a decade to fund, design, build, and test something to take advantage of it.

I was actually asking about the development, construction and operation costs of terrestrial observatories as a baseline.  No reply necessary.  I'll find that info myself.

Now back to discussions directly related to Starlink...

Offline OceanCat

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Re: Starlink : General Discussion - Thread 3
« Reply #637 on: 10/07/2022 03:21 am »
....
5. In addition, SpaceX is also refining the attitude control and solar array pointing during these two phases to reduce brightness, they can do this because when raising orbit or deborit, satellite doesn't need to provide service thus doesn't need to keep a fixed orientation wrt ground, and can live with less power.

Curious about the last part.

At first glance it makes sense that the power requirement for orbit raising is less than for transmitting data, but did anyone do any math on that, or is it just an assumption?

Just a wrong assumption.

Quote
During orbit raise from the insertion orbit to the operational orbit, the
satellites need to maximize power generation and minimize drag at low altitudes and
aren't able to perform solar array off-pointing.

Just like during orbit raise, satellites will be brighter at the end of their life while
lowering their orbits until they burn up on reentry.

From the brightness mitigation document SpaceX published.

Offline Robotbeat

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Re: Starlink : General Discussion - Thread 3
« Reply #638 on: 10/07/2022 03:30 am »
This is a problem solvable with more mass. Chemical or even cold gas thrusters would allow high thrust orbit insertion and deorbit. Expensive with F9. Eventually cheap when Starship is fully and rapidly reusable.
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Offline Kaputnik

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Re: Starlink : General Discussion - Thread 3
« Reply #639 on: 10/07/2022 11:54 am »

Can anyone interpret this image please?

I can't see the burn mentioned by Musk.


You can see it a little better in the video Elon Musk posted. What you see is the stack of Starlinks separating and to the right you see a sudden flare that one would assume is the second stage suddenly moving to the right.

What sort of acceleration are we seeing here? Looks pretty... sporty.
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