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Starlink Thread (split from SpaceX)


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Just now, tater said:

They are launching 2 tomorrow morning as tests.

I was aware of that, however many will have to be launched before it makes sense to switch (need to have line of sight at all times, there needs to be enough in sight so one sat isn't bogged down, etc.). As far as I know, there hasn't been any public announcement of timeframes (or anything Starlink in general).

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The OneWeb constellation is being built by Airbus, who have had to revolutionize the way they build satellites.

We don't really know how advanced the SpaceX project is, but if they were contracting another company, it would have to be one of the traditional aerospace companies (LM, NG, Boeing, Orbital, etc...). Mass production of spacecraft is a whole new industry. Since none of the traditional contractors have experience with it anyway, it makes sense that SpaceX would do it themselves.

 

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53 minutes ago, Nibb31 said:

The OneWeb constellation is being built by Airbus, who have had to revolutionize the way they build satellites.

We don't really know how advanced the SpaceX project is, but if they were contracting another company, it would have to be one of the traditional aerospace companies (LM, NG, Boeing, Orbital, etc...). Mass production of spacecraft is a whole new industry. Since none of the traditional contractors have experience with it anyway, it makes sense that SpaceX would do it themselves.

 

As far as I know, SpaceX are building the satellites themselves, in their Seattle facility if I'm remembering correctly.

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Afaik, the last declared number was 12 000?

Spoiler

U R here:

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18 hours ago, kerbiloid said:

Afaik, the last declared number was 12 000?

  Reveal hidden contents

U R here:

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They can launch a hundred at once.  

Also, can the satelites be named after characters in Tintin?

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10 hours ago, kerbiloid said:

I'm afraid for 12 000 sats you need Chinese ABC.

Or just use Captain Haddock's curses, that should cover a thousand or so...

Quote

Captain Haddock's colourful insults [included] "bashi-bazouk", "visigoths", "kleptomaniac", "sea gherkin", "anacoluthon", "pockmark", "nincompoop", "abominable snowman", "nitwits", "scoundrels", "steam rollers", "parasites", "vegetarians", "floundering oath", "carpet seller", "blundering Bazookas", "Popinjay", "bragger", "pinheads", "miserable slugs", "ectomorph", "maniacs", "pickled herring"; "freshwater swabs", "miserable molecule of mildew","Logarithm", "bandits", "orang-outangs", "cercopithecuses", "Polynesians", "iconoclasts", "ruffians", "fancy-dress freebooter", "ignoramus", "sycophant", "pickled herring", "dizzard", "black-beetle", "pyrographer", "slave-trader" and "Fuzzy Wuzzy"

And of course, there's "Billions of blue blistering barnacles," so you could have (Blue?) Barnacle 1A, 1B, 2A, 2B, etc...

Edited by StrandedonEarth
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  • 1 year later...

From wiki.

Phase Orbit shells (km) Number of satellites Inclination

(degrees)

Half size contractual completion time Full size contractual completion time Current completion (23 May 2019)
1
550 1,584 53 March 2024 March 2027 62[43]
1,110 1,600 53.8 0
1,130 400 74 0
1,275 375 81 0
1,325 450 70 0
2
335.9 2,493 42 November 2024 November 2027 0
340.8 2,478 48 0
345.6 2,547 53 0

So, they distinguish 335, 340, and 345 km orbit, and as well 1110 and 1130.
They also distinguish 53° and 53.8°, i.e. 0.2° = 12' ~= 12 nm ~= 22 km.
So, this gives us a mesh step ~= 5..20 km in their sat pattern.

Total area of a sphere of radius:
330 km = 4 * pi * (6370+330)2 ~= 564 mln km2
1330 km = 4 * pi * (6370+1330)2 ~= 745 mln km2

So,
564*106 * ((345+5) - (335-5)) / 7500 = 1.5 mln km3/sat in 340 km orbits.
745*106 * 20 / 4400 = 3.4 mln km3/sat in higher than ISS orbits.

A 340 km orbit length = 2 * pi * (6730 + 340) ~= 44 400 km.
A 480 km orbit length (ISS) = 2 * pi * (6730 + 480) ~= 45 300 km.
So, say, our orbit is ~45 000 km long.

Say, our cross-section area is 20 x 20 m ~400 m2 = 4*10-4 km2. (A large sat, a spaceship + upper stage, or else).
Total volume of the orbital torus = 45 000 * 4 * 10-4 ~= 18 km3.
So, the probability of a sat crossing our way is roughly:
~18 / 1.5*106 ~=1.2 * 10-5, 1 chance per ~80 000 orbital turns in LEO.
~18 / 3*106 ~= 0.6 * 10-5, 1 chance per ~160 000 orbital turns in typical OS 480 km orbit (ISS, Mir), when the sats orbit get significantly decayed.

1 day = 24 / 1.5 = 16 turns.
Chances to hit a sat spending in 340 km orbit
a day = 1-(1 - 1.2*10-5)16 = 0.0002 = 1:5000
a week = 1-(1 - 0.0002)7 = 0.0014 = 1:700
a month = 1-(1 - 0.0002)30 = 0.006 = 1:160
a year = 1-(1 - 0.006)12 = 0.07 = 1:14

Chances to hit a decaying orbit sat spending in 480 km orbit
a year = 1-(1 - 0.6*10-5)16*365 = 0.034 = 1:30

***

Say, a sat lifespan is ~15 years.
This means that every year they should deliver ~1/15 of total sats amount = ~800 sats/year.
Probably they are going to deorbit the failed sats, so ~800 sats are going to deorbit.

But as a launch vehicles are ~0.98 reliable, and the sats to be deorbited are by definition out of service,
we can presume that ~20% of sats will stay in orbit as garbage.
So, +160 sats every year.

Twenty years later there will be ~3000 additional dead sats plus to the initial amount.

***

Plus kesslerization of this

Say that 15 years long Starlink sat.
Say, its cross-section is ~5 m2 (including the solar panel)

Its orbital torus volume ~ 45 000 * 5*10-6 ~= 0.2 km3.
At 1.5 mln km3/sat around, the probability to hit another Starlink sat is ~ 0.2/1.5*106 ~= 1.3*10-7 per turn.
Per year = 1-(1-1.3*10-7)16*365 ~= 0.00076 = 1:1300.
So, we can expect ~5..10 Starlink collisions per year.

Every collision creates, say, 10 debris, so +several hundred objects per year.

Of course, most of them will deorbit, but while deorbiting they can hit a Starlink sat in a lower shell.

***

So, if the Starlink had been raised, 30-40 years later there will be no safe orbit below the radiation belts for anything bigger than a Starlink sat.

Spoiler

Chances to hit a sat spending in 340 km orbit
a day = 1-(1 - 1.2*10-5)16 = 0.0002 = 1:5000
a week = 1-(1 - 0.0002)7 = 0.0014 = 1:700
a month = 1-(1 - 0.0002)30 = 0.006 = 1:160
a year = 1-(1 - 0.006)12 = 0.07 = 1:14

Chances to hit a decaying orbit sat spending in 480 km orbit
a year = 1-(1 - 0.6*10-5)16*365 = 0.034 = 1:30

Edited by kerbiloid
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Also the Starlink idea itself is an antithesis to the reusable rocket idea itself.
They are just opposite to each other.

Currently For decades there are just small rockets, up to ~20 t.
They launch small sats, up to ~15 t, or even 2..3 t in high orbits.

The sats are tiny, the place onboard is overexpensive. And there is no way to replace, support, or resupply damaged equipment.
Thus, the satellite equipment manufacturers are forced to make electronics as compact and durable as possible, and this makes the satellites cost like they are made of brilliants.

Can a reusable rocket solve this problem?

If it has 20 t of payload like Falcon - definitely, no. Because a sat anyway costs like several reusable rockets at once.

Say, a reusable rocket gets 100-200 t capable.
The things wouldn't change, as it would be silly to change sat making technology just to put twice as more sats than now.

But if the annual lifted mass starts being counted in thousands tonnes, the things should dramatically change.
In this case you don't need a 15 years living individual sat. You build a big orbital data-center full of standard cheap equipment, and instead of miniaturization and making the equipmentt live for 15 years, you just fill it with cheap electronic garbage from online shops and replace 10% of your equipment per year.

Instead of puny 1 m antennas you use 10 m wide ones.
Instead of high-tech radiators you bring moar water for cooler.
And by using thick hull made of steel you protect your cheap electronic rubbish from radiation and vacuum.

Then you lease it for low price, and nobody needs overexpensive, overdurable, overreliable vacuum rad-protected electronics. Arduino and Raspberry is enough.

The sats get much cheaper, several huge orbbital platforms are serviced and resupplied easily, just send a brigade of engineers once per month.
On Dragon. No. On a big reusable shuttle launched by the big reusable rocket. Puny Dragons are just for ISS (until the first collision with Starlink cloud, lol).

As we can see, the situation when sats get cheap and widely available, and reusable rockets start being self-supported:
1) absolutely opposite to Starlink
2) makes sense when reusable rockets are not second-hand cigarettes like Falcon, but proper large things like Nexus.

Size matters.

Edited by kerbiloid
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2 hours ago, kerbiloid said:

Also the Starlink idea itself is an antithesis to the reusable rocket idea itself.
They are just opposite to each other.

Currently For decades there are just small rockets, up to ~20 t.
They launch small sats, up to ~15 t, or even 2..3 t in high orbits.

The sats are tiny, the place onboard is overexpensive. And there is no way to replace, support, or resupply damaged equipment.
Thus, the satellite equipment manufacturers are forced to make electronics as compact and durable as possible, and this makes the satellites cost like they are made of brilliants.

Can a reusable rocket solve this problem?

If it has 20 t of payload like Falcon - definitely, no. Because a sat anyway costs like several reusable rockets at once.

Say, a reusable rocket gets 100-200 t capable.
The things wouldn't change, as it would be silly to change sat making technology just to put twice as more sats than now.

But if the annual lifted mass starts being counted in thousands tonnes, the things should dramatically change.
In this case you don't need a 15 years living individual sat. You build a big orbital data-center full of standard cheap equipment, and instead of miniaturization and making the equipmentt live for 15 years, you just fill it with cheap electronic garbage from online shops and replace 10% of your equipment per year.

Instead of puny 1 m antennas you use 10 m wide ones.
Instead of high-tech radiators you bring moar water for cooler.
And by using thick hull made of steel you protect your cheap electronic rubbish from radiation and vacuum.

Then you lease it for low price, and nobody needs overexpensive, overdurable, overreliable vacuum rad-protected electronics. Arduino and Raspberry is enough.

The sats get much cheaper, several huge orbbital platforms are serviced and resupplied easily, just send a brigade of engineers once per month.
On Dragon. No. On a big reusable shuttle launched by the big reusable rocket. Puny Dragons are just for ISS (until the first collision with Starlink cloud, lol).

As we can see, the situation when sats get cheap and widely available, and reusable rockets start being self-supported:
1) absolutely opposite to Starlink
2) makes sense when reusable rockets are not second-hand cigarettes like Falcon, but proper large things like Nexus.

Size matters.

The problem is space junk will accumulate over time anyway. You can bash Falcon for being small and puny as much as you want but it's its second stage that actually deorbits itself to keep space as clean as possible.

Now, as I said, space junk will build up anyway. You can either accept it and keep leaving spent second stages in stable orbits (because it's better to boost that extra 200-300kg to its final orbit than deorbit the upper stage), or fight it with big stuff like Starship that could probably act as a space garbage truck collecting all those upper Atlas stages.

Either way, I agree. Size matters.

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Regarding the long @kerbiloid post, I miss the point? Sats cost more than rockets? GEO sats certainly do right now, but smallsats don't. I'd imagine that the total cost of all the 60 launched Starlinks on that one flight exceed the retail cost of F9, but honestly, I'd be surprised if SpaceX wasn't trying to get their actual cost for those down in the "expensive car" range. There's no reason why spacecraft need to cost 100s of millions.

I agree that bigger reusables make a difference, because cheaper launch costs (once there is competition to reduce costs) and/or larger volumes can mean cheaper, and more long lasting spacecraft.

Assume Starship works, and that it is reusable enough that the SpaceX cost of launch is on the order of Falcon 1. SpaceX could retail a Starship launch for what they charge for a F9 right now, 60M$, and they'd profit 54M on that flight. If you launch a single 2019 type sat, you've gained nothing as the customer---but if you made that single sat vastly larger, more survivable, with large prop reserves, etc, ad nauseum, you've gained quite a bit. That's a way SpaceX could transition to SS without leaving money on the table.

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38 minutes ago, tater said:

SpaceX could retail a Starship launch for what they charge for a F9 right now, 60M$

Not the launch cost itself. But maximum total mass which can be delivered into orbit in one piece, inside one hull, without orbital construction works.

Instead of spamming the sky with tens thousands small satellites which cannot be serviced, repaired, upgraded, resupplied, and which raise collision chances up to the enormous values.
And should be made of vacuum-resistant and radiation-protected electronics.
And should contain each its own propulsion system (to deorbit), power source, SAS, cooling system and so on.

When you have several tens heavy platforms with thick pressurized steel hulls, you can place all these sats equipment inside, make it from cheap electronic components from trash can, use single power and cooling system for all of them at once. They are already protected from the radiation and the vacuum. (Yeah, the Soviet school with pressurized command module! Huzzah!)
You can easily repair, replace, upgrade, resupply the equipment, or switch off the currently unused ones until somebody rents it.
You can use nice big antennas of proper shapes and configurations, not just what could be packed into a small sat.
You can make this platform crewless but habitable for engineers visiting it from time to time, and the engineers work in usual clothes, not in spacesuits.

And this is a question of the rocket payload. The rocket should be reusable and big.
Falcons add nothing here, as their payload is tiny compared to, and their landing technologies unlikely can be used in really big rockets.
BFR/Starship brings probably not much more, as the idea of 150 engines in a rocket 2 times smaller than Nexus mostly looks like a dead end in ideas.

Upd.
The same about Bigelow's balloon aerial circus.
When you have a big steel cystern in sky, who needs these inflatable ponies.

Edited by kerbiloid
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The problem is, the whole point of Starlink is the widely distributed physical network. Like the terrestrial internet, this adds redundancy and bandwidth. It also cuts down on lightspeed delays from going all the way out to geostationary orbit.

This is the same reason why Iridium has a fleet of 76 sats (plus spares) rather than one or two.

You can question whether one company should be allowed to profit by simply taking so much of a common resource (orbital space). But saying they should just build a few big satellites ignores what they are trying to do.

53 minutes ago, Wjolcz said:

could probably act as a space garbage truck

Reminds me of:

 

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8 hours ago, Wjolcz said:

Looks to me like the hinge part we've seen before.

I agree, though the better view suggests strongly that it is a movable piece within a larger flaperon, and the landing legs themselves are somehow fixed.

I never liked the idea of a single failure point that takes out both maneuverability and landing capability.

8 hours ago, Technical Ben said:

Seems others are reporting it's one of the dead SpaceX sats. So, "dead".

I guess SpaceX still have some work to iron out with their designs. Also "chance of collision", so it's for safety, and not necessarily and emergency.

SpaceX chose three satellites -- either ones that weren't operating perfectly well, or some other approach -- to test passive decay. Avoidance of Kessler syndrome requires that the satellites will passively decay if left without control. These three sats are being used for this purpose, to show that even if SpaceX completely lost control, they will all fall out of the sky on their own in a controlled fashion.

In this case, SpaceX likely rejected any suggestion that a collision was likely and accordingly declined to move their sat, as doing so would ruin its data. Even an inclination change would alter numerous factors (like insolation, exospheric temperature, etc.) and make the whole thing harder to work out. ESA was free to move its satellite if it was concerned...which, evidently, it was.

6 hours ago, kerbiloid said:

Say, a sat lifespan is ~15 years.
This means that every year they should deliver ~1/15 of total sats amount = ~800 sats/year.
Probably they are going to deorbit the failed sats, so ~800 sats are going to deorbit.

But as a launch vehicles are ~0.98 reliable, and the sats to be deorbited are by definition out of service,
we can presume that ~20% of sats will stay in orbit as garbage.
So, +160 sats every year.

Twenty years later there will be ~3000 additional dead sats plus to the initial amount.

Sats are low enough that they decay on their own without control input within a few years. So, not a problem.

6 hours ago, kerbiloid said:

The sats are tiny, the place onboard is overexpensive. And there is no way to replace, support, or resupply damaged equipment.
Thus, the satellite equipment manufacturers are forced to make electronics as compact and durable as possible, and this makes the satellites cost like they are made of brilliants.

Can a reusable rocket solve this problem?

If it has 20 t of payload like Falcon - definitely, no. Because a sat anyway costs like several reusable rockets at once.

More likely, Falcon 9 or FH drops off a stack of replacement sats with larger propellant reserves directly in an eccentric MEO (perhaps with a slightly higher apogee). The cluster of sats would hang around up there until they were needed, at which point they could use their onboard propellant to adjust inclination at apogee to match plane with the derelict sat's former orbit. This is dV-cheap, since it is done at a high apogee. Then, they lower their perigee just enough to use atmospheric braking to circularize. The replacement sats wouldn't have quite the same lifetime as a brand new one dropped off directly in the desired orbit, but that's fine.

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1 minute ago, Technical Ben said:

*If not controlled*. They have fuel to boost for their assumed useful lifespan.

This.

And as the 12 000 objects constellation is presumed to be permanently existing, the argument of orbit decay is not applicable.
This cloud of floating contact mines will be existing and make low orbits as dangerous as a minefield.

Edited by kerbiloid
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3 hours ago, Technical Ben said:
3 hours ago, kerbiloid said:

So, the whole 12 000 constellation will be lost in several years? Great.

*If not controlled*. They have fuel to boost for their assumed useful lifespan.

Exactly. They carry onboard fuel to adjust trajectory and stay in space, and enough to perform a rapid deorbit if there was a problem. The only time that they will deorbit passively is if they somehow lose electrical power and become junk. They are probably programmed to do a rapid deorbit if they lose comms as well.

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