Author Topic: Starlink : General Discussion - Thread 1  (Read 1217443 times)

Offline guckyfan

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Re: SpaceX - now a satellite manufacturer (Starlink)
« Reply #1340 on: 07/12/2017 09:15 am »
China may prefer to build their own Internet constellation, anyway.

Sure, but that capability may take a decade or more to aquire. Also such a constellation should be used worldwide to amortize. Unlike GEO sats they are not local by their nature. Though they would not need to cover polar regions unless they want to use it on their ships.

Offline jpo234

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« Last Edit: 07/17/2017 07:06 pm by jpo234 »
You want to be inspired by things. You want to wake up in the morning and think the future is going to be great. That's what being a spacefaring civilization is all about. It's about believing in the future and believing the future will be better than the past. And I can't think of anything more exciting than being out there among the stars.

Offline jpo234

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Re: SpaceX - now a satellite manufacturer (Starlink)
« Reply #1342 on: 07/18/2017 06:52 am »
https://www.spaceintelreport.com/spacex-satellite-mega-constellation-attracts-competitors-fire/

Did anybody read this? There is good stuff in here:

* They "only" expect to launch 1600 satellites within the first 6 years after getting the license ("We can’t launch 4,425 satellites – 1.7 million kilograms’ worth – in 72 months")
* public interference-mitigation plan filed on 07/12
* concerns regarding collision risk

You want to be inspired by things. You want to wake up in the morning and think the future is going to be great. That's what being a spacefaring civilization is all about. It's about believing in the future and believing the future will be better than the past. And I can't think of anything more exciting than being out there among the stars.

Offline AncientU

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Re: SpaceX - now a satellite manufacturer (Starlink)
« Reply #1343 on: 07/18/2017 10:15 am »
https://www.spaceintelreport.com/spacex-satellite-mega-constellation-attracts-competitors-fire/

Did anybody read this? There is good stuff in here:

* They "only" expect to launch 1600 satellites within the first 6 years after getting the license ("We can’t launch 4,425 satellites – 1.7 million kilograms’ worth – in 72 months")
* public interference-mitigation plan filed on 07/12
* concerns regarding collision risk

I would think orbital check-out and constellation ops would be limiting, but this directly addresses launch limitations.  Mass-wise, we've been assuming 20 per launch (7,720kg), which would be 'only' 80 launches in those six years -- seems easily doable at 12-14 per year; for 4,425 sats, 36-38 dedicated launches per year... not impossible, but much more of a stretch.  If volume limited to say 10-12 sats per launch, the doubled number of launches (plus existing backlog/commitments) might be making the challenge unattainable or at least un-guarantee-able. 

Possibly only negotiating for a moderate minimum requirement as an alternative to a 4,425 in six years guarantee.
« Last Edit: 07/18/2017 10:21 am by AncientU »
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Offline Jcc

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Re: SpaceX - now a satellite manufacturer (Starlink)
« Reply #1344 on: 07/18/2017 11:09 am »
If SpaceX can't launch 4000 sats in 6 years nobody else can either, so I don't think the need to worry too much about a competitor beating them to it. It would be absurd for the FCC to withhold a license from them because they provide a realistic schedule to provide partial service initially.

Offline envy887

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Re: SpaceX - now a satellite manufacturer (Starlink)
« Reply #1345 on: 07/18/2017 11:50 am »
That 6 years is from getting the license, not from start of launches. They still have to finish the design, test the prototype satellites, then ramp up manufacturing, and build/rebuild a pair of launch sites. That only gives them 4 or so years to launch everything.

Offline AncientU

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Re: SpaceX - now a satellite manufacturer (Starlink)
« Reply #1346 on: 07/18/2017 01:41 pm »
That 6 years is from getting the license, not from start of launches. They still have to finish the design, test the prototype satellites, then ramp up manufacturing, and build/rebuild a pair of launch sites. That only gives them 4 or so years to launch everything.

Good point.

Early constellation may (will) also demonstrate weaknesses in the initial spacecraft build -- time to correct these weaknesses may also eat into the 4 or so years.
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Online meekGee

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Re: SpaceX - now a satellite manufacturer (Starlink)
« Reply #1347 on: 07/18/2017 02:14 pm »
But now we have a semi-official mass number.. ~400 kg.

I believe 25/launch (10 tons), with a dedicated reusable s2/dispenser - as long as F9 based, and that's 60 launches for the first 1600.

25 satellites is ~half an orbital plane, so they can start by quarter-populating the constellation (50% per plane, 50% of planes, very roughly) and work up from there.

Afterwards, I agree with those that think that a future craft will take over.

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Offline envy887

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Re: SpaceX - now a satellite manufacturer (Starlink)
« Reply #1348 on: 07/18/2017 02:45 pm »
But now we have a semi-official mass number.. ~400 kg.

I believe 25/launch (10 tons), with a dedicated reusable s2/dispenser - as long as F9 based, and that's 60 launches for the first 1600.

25 satellites is ~half an orbital plane, so they can start by quarter-populating the constellation (50% per plane, 50% of planes, very roughly) and work up from there.

Afterwards, I agree with those that think that a future craft will take over.

I have some doubts that even Block 5 will be able to put an integrated dispenser/reusable upper stage plus 9,600 kg of payload into 1100 km circular and return the booster and upper stage. However, they might dispense to a lower orbit (maybe ~600 km like Iridium) and raise the birds individually.

I'm also wondering if they can fit 25 into the fairing. Iridium fits 10 that are almost exactly twice as heavy and thus about twice as big. Perhaps 4 or maybe even 5 stacked rings of 5 roughly cube-shaped satellites each? Or 2 rings of 10 or 12 longer, slender satellites?

Using an Iridium-style dispenser would simplify integration and dispensing over a "payload bay". But how would they return the dispenser and stage? I can imagine a Dragon-style heatshield upside down atop the dispenser, and a ballistic entry, avoiding lifting entry with its heat load on the sides of the dispenser or stage.


Offline Semmel

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Re: SpaceX - now a satellite manufacturer (Starlink)
« Reply #1349 on: 07/18/2017 03:20 pm »
But now we have a semi-official mass number.. ~400 kg.

I believe 25/launch (10 tons), with a dedicated reusable s2/dispenser - as long as F9 based, and that's 60 launches for the first 1600.

25 satellites is ~half an orbital plane, so they can start by quarter-populating the constellation (50% per plane, 50% of planes, very roughly) and work up from there.

Afterwards, I agree with those that think that a future craft will take over.

What if they don't spend time and money into redesigning a reusable second stage of F9 but instead invest that time, talent and money into the next vehicle that should have a reusable second stage / spacecraft by design? Especially when that rocket obsoletes F9 altogether? What is more economical?

Offline Lar

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Re: SpaceX - now a satellite manufacturer (Starlink)
« Reply #1350 on: 07/18/2017 03:43 pm »
If the dispenser has a rotation mechanism (think of a lazy susan inside a cabinet) then a payload bay door approach would work. Just rotate the birds to a position where they can be dispensed...

LOL "just" means there is another thing to test, another failure mode, another thing that adds weight, etc.
« Last Edit: 07/18/2017 04:01 pm by Lar »
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Offline envy887

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Re: SpaceX - now a satellite manufacturer (Starlink)
« Reply #1351 on: 07/18/2017 03:56 pm »
But now we have a semi-official mass number.. ~400 kg.

I believe 25/launch (10 tons), with a dedicated reusable s2/dispenser - as long as F9 based, and that's 60 launches for the first 1600.

25 satellites is ~half an orbital plane, so they can start by quarter-populating the constellation (50% per plane, 50% of planes, very roughly) and work up from there.

Afterwards, I agree with those that think that a future craft will take over.

What if they don't spend time and money into redesigning a reusable second stage of F9 but instead invest that time, talent and money into the next vehicle that should have a reusable second stage / spacecraft by design? Especially when that rocket obsoletes F9 altogether? What is more economical?

That depends how many second stages they throw away per year, how many years it takes before a reusable alternative is available, and how much development costs to add reuse to the second stage and how much operating cost it saves, and whether the new vehicle can reduce costs for other launches (i.e. the opportunity cost of delaying it).

Say there are 15 constellation launches per year for the next 4 years, on average - that's 60 upper stages, at ~$10M each is ~$600M. A reuse solution based on existing hardware (fairing parachute/bouncy castle, Dragon heat shield) should cost less then ~$150M to develop and cut operating costs by ~70%. So the opportunity cost of the delay would have to be ~$270M to make reuse not worthwhile.

Other estimates will obviously yield different results, but the constellation is inherently high flight rate which tends to make reuse a immediate priority.

If the dispenser has a rotation mechanism (think of a lazy susan inside a cabinet) then a payload bay door approach would work. Just rotate the birds to a position where they can be dispensed...
True, this is a possible solution, and probably would work well on the next generation of launch vehicle. But this adds the performance penalty of carrying the aero surfaces to orbit, and additional mechanisms for doors and dispensers.

I think constellation reuse could be done in the very near term (1-2 years from now) with the existing fairing 2.0 design, and a modified Iridium dispenser, Dragon heatshield, and fairing landing system.

Offline Semmel

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Re: SpaceX - now a satellite manufacturer (Starlink)
« Reply #1352 on: 07/18/2017 05:21 pm »
Envy. You forgot the fact that it delays the development of the next generation vehicle. You also forgot that a reusable second stage might just not work. I would think it's bad investment. But we are again on the wrong thread for this discussion and should defer to not continuing.

Offline philw1776

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Re: SpaceX - now a satellite manufacturer (Starlink)
« Reply #1353 on: 07/18/2017 05:32 pm »
Delaying the next vehicle goes against Musk's Mars goal.  He has only so many years of life to achieve his colony dream. BIG opportunity cost.
And the opportunity cost analysis does not allow for the loss of payload mass, i.e. number of satellites per launch that a Falcon class re-useable upper stage would penalize.  So the cost of Falcon class re-useability is higher than stated.
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Offline envy887

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Re: SpaceX - now a satellite manufacturer (Starlink)
« Reply #1354 on: 07/18/2017 05:34 pm »
Envy. You forgot the fact that it delays the development of the next generation vehicle. You also forgot that a reusable second stage might just not work. I would think it's bad investment. But we are again on the wrong thread for this discussion and should defer to not continuing.

Replying here: https://forum.nasaspaceflight.com/index.php?topic=42637.msg1703544

Offline Lar

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Re: SpaceX - now a satellite manufacturer (Starlink)
« Reply #1355 on: 07/18/2017 07:04 pm »
How much does a dispenser cost? Ballpark guesses... What if you were making many of them a year?
"I think it would be great to be born on Earth and to die on Mars. Just hopefully not at the point of impact." -Elon Musk
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Offline Norm38

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Re: SpaceX - now a satellite manufacturer (Starlink)
« Reply #1356 on: 07/20/2017 02:22 pm »
I just saw a commercial for Airborne Wireless Network, which is doing an airliner based constellation. There are planes constantly in the sky all over the globe. And they claim they can use these already flying planes as the platform for their service. I didn't see a thread for this, but a model like that could seriously dent the business model for a large satellite constellation.

Offline Ictogan

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Re: SpaceX - now a satellite manufacturer (Starlink)
« Reply #1357 on: 07/20/2017 02:41 pm »
I just saw a commercial for Airborne Wireless Network, which is doing an airliner based constellation. There are planes constantly in the sky all over the globe. And they claim they can use these already flying planes as the platform for their service. I didn't see a thread for this, but a model like that could seriously dent the business model for a large satellite constellation.

A large part of the business case for satellite constellation like the one SpaceX is planning is providing internet to rural regions and ships in the open sea. These regions are far less overflown by planes than cities with big airports, in which ground-based internet can be done much better. So essentially the areas in which they'll have the most coverage are the ones than least need it.

Online meekGee

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Re: SpaceX - now a satellite manufacturer (Starlink)
« Reply #1358 on: 07/21/2017 08:17 am »
I just saw a commercial for Airborne Wireless Network, which is doing an airliner based constellation. There are planes constantly in the sky all over the globe. And they claim they can use these already flying planes as the platform for their service. I didn't see a thread for this, but a model like that could seriously dent the business model for a large satellite constellation.

A lot fewer planes at night.  FlightRadar24 will show you a snap shot at any given time.

They fly 6-7 miles high, but are often separated by a lot more than that, more like 100 miles.

I'm not sure how it's going to work.

--

And besides before they route internet traffic, they should figure out how to route luggage, no?   :)
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Re: SpaceX - now a satellite manufacturer (Starlink)
« Reply #1359 on: 07/21/2017 02:59 pm »
Quote
Operator @INTELSAT wants @FCC to delay approval of @SpaceX sat constellation pending review of interference risk.
https://twitter.com/pbdes/status/888410507010551808

https://www.spaceintelreport.com/intelsat-joins-group-urging-u-s-regulator-delay-approval-spacex-constellation/

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