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SpaceX just got FCC approval to launch 7,518 satellites

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Re: SpaceX just got FCC approval to launch 7,518 satellites

#151

Post by stcredzero »

jandrese wrote: post #147
bargl wrote: post #33

This is such a cool problem. We already have a ton of Geo sat which can do this kind of communication but they are super expensive and have a limited bandwidth. These satellites will actually have a ton of limitations in how much data they can send around and how they'll have to balance out their signals. Geo are easier to point to because, well they don't move. But these are going to be moving and changing all the t…

Motorola solved this problem with its Iridium constellation back in the 90s. Handoff between satellites isn't really that hard. Your phone knows where it is and what birds are overhead (and which are about to appear/disappear) so they can adjust automatically. Routing through the satellite constellation gets kind of hairy, but is also solvable via orbital mapping and some arcane routing algorithms. The real trick is…

The real trick is getting enough link margin with omni antennas to get good bandwidth.

What about phased arrays?

Also, why not have a completely different scale of ISPs? How about something the size of a soda vending machine or something the size of a suitcase which contains all the hardware for a very small scale internet service provider?

Re: SpaceX just got FCC approval to launch 7,518 satellites

#152

Post by axus »

bargl wrote: post #33

This is such a cool problem. We already have a ton of Geo sat which can do this kind of communication but they are super expensive and have a limited bandwidth. These satellites will actually have a ton of limitations in how much data they can send around and how they'll have to balance out their signals. Geo are easier to point to because, well they don't move. But these are going to be moving and changing all the t…

A GPS receiver is constantly switching between the satellites in the GPS constellation. This sounds like that, on a bigger scale.

Re: SpaceX just got FCC approval to launch 7,518 satellites

#153

Post by stcredzero »

nickik wrote: post #142
porscheburnaby wrote: post #104

goodbye, great firewall of china...

Why. China can just force SpaceX to turn off over China. Unless this is part of a political 'Radio Free Europe' style operation China will control this as much as everything else.

Why. China can just force SpaceX to turn off over China.

How? By shooting down satellites?

Re: SpaceX just got FCC approval to launch 7,518 satellites

#154

Post by Scoundreller »

bargl wrote: post #33

This is such a cool problem. We already have a ton of Geo sat which can do this kind of communication but they are super expensive and have a limited bandwidth. These satellites will actually have a ton of limitations in how much data they can send around and how they'll have to balance out their signals. Geo are easier to point to because, well they don't move. But these are going to be moving and changing all the t…

The bandwidth of geosats can be vastly improved with spotbeams:

https://www.montanasatellite.com/support/satellite-footprint...

Re: SpaceX just got FCC approval to launch 7,518 satellites

#155

Post by stcredzero »

Rebelgecko wrote: post #126
craftyguy wrote: post #49

Earlier quoted context omitted.

You need more than just any satellites to provide GPS. Each of them needs a very precise atomic clock (among other things I'm sure I'm not aware of).

You can build GPS (well, a GNSS would be more accurate) system without atomic clocks. One way to do so requires user equipment that can transmit back to the satellites, but that will already be the case for SpaceX's customers. You can also use Doppler measurements to get your location, although this tends to be less accurate, especially if you're moving quickly

You can also use Doppler measurements to get your location, although this tends to be less accurate, especially if you're moving quickly

There would still be a market for lower cost lower resolution location.

Re: SpaceX just got FCC approval to launch 7,518 satellites

#156

Post by ubercore »

Rooster61 wrote: post #149
throwahey wrote: post #124

Earlier quoted context omitted.

You won't find an answer to your question because you don't seem willing to drop your alarmist attitude. There is just far too much space for 100k objects, let alone 10k to ever run the risk of collission. These satellites are all meant to be in line-of-sight. They will communicate with optics as opposed or in conjunction to radio. You fear unforseen space particles destroying one and causing a chain reaction. Why do…

> There is just far too much space for 100k objects, let alone 10k to ever run the risk of collission. No, there isn't. Satellites can and do collide despite the vast amount of space in a given orbit. It is improbable, but likely enough to warrant at least some concern. > Why don't you hold that same fear for existing satelittes which typically operate at an orbit with far lower decay rate? I do, as does the FCC. Thi…

> Satellites can and do collide despite the vast amount of space in a given orbit.

Excluding planned collisions, or collisions during failed docking, I found 4 instances of collisions between satellites and space debris. Ever. Now, a couple of things:

* Yes this larger constellation will increase those odds in the future.

* No, a catastrophic doomsday scenario did not occur when those happened.

* SpaceX will have complete control of these satellites through their operational lifespan (excluding collisions or malfunctions).

* Orbital decay for debris at the altitude they're operating at is ~10 years.

Also, have to ask... is all this concern a result of reading Seveneves? :)

Re: SpaceX just got FCC approval to launch 7,518 satellites

#157

Post by Scoundreller »

dzhiurgis wrote: post #121
aportnoy wrote: post #30

Earlier quoted context omitted.

Iridium already employs SpaceX for their launches.

What's perplexing is why Iridium is not doing way more. They are essentially just letting SpaceX to cannibalise them. Sure, they don't have fancy rockets, but still can scale their satellite net before Elon catches up with sat tech or outsource launches to even cheaper Indian launch provider. p.s. the story of Iridium and how they recovered is quite amazing.

I think the more amazing part of Iridium’s story is that they got the money to launch their constellation in the first place. It’s crushing debt and inevitable bankruptcy with the assets being acquired for something like 1/20th of a cent on the dollar was to be expected really.

Re: SpaceX just got FCC approval to launch 7,518 satellites

#158

Post by Denzel »

test6554 wrote: post #146
zaroth wrote: post #11

Too bad the public markets have given Elon such a lashing with Tesla, because I would love to buy into SpaceX. But then, I’m not the only one; “There is an unlimited amount of funding that the company could probably access globally in private markets," Hilmer said, adding that he has personally met many of "a diverse group" interested in SpaceX. Everywhere I travel around the world, investors of all types — individua…

Anybody who sees a ceo who plans to spend a large chunk of company profits on colonizing mars for the sake of humanity might think to themselves, "I wonder if I can start a similar company, avoid the mars colonization expenses and undercut them on price."

You misunderstand just slightly, and through no fault of your own I might add since SpaceX’s messaging is deliberately murky here.

SpaceX has no plans right now to colonize Mars. In fact, they keep saying, “Look! We want other companies or nations to step up and plan for how to establish a colony. We’re only going to do it if we absolutely have no other choice.”

SpaceX is truly establishing a financially viable solar transport system that may eventually extend beyond our solar system. This is analogous to the birth of the U.S. railroad system. We don’t know yet what what don’t know is possible.

SpaceX is poised to own space transport outright. That’s major!

Now what does Mars have to do with this? It’s just a helpful organizing goal. People love a good milestone. Something to reach for with meaning. I mean if you’ve been following SpaceX’s 15-year history you’d see that they’re nothing if not methodical in their planning and attainment of milestones.

SpaceX is one of the most well-run companies in the world. And right now they have the best prices, the best technology, the best pace, the best outlook, the best...

They have no competition. Literally. I’d invest the entirety of my lifetime earnings in SpaceX if I could. We’re witnessing historic achievements in the making.

Re: SpaceX just got FCC approval to launch 7,518 satellites

#159

Post by PeterisP »

Rooster61 wrote: post #149
throwahey wrote: post #124

Earlier quoted context omitted.

You won't find an answer to your question because you don't seem willing to drop your alarmist attitude. There is just far too much space for 100k objects, let alone 10k to ever run the risk of collission. These satellites are all meant to be in line-of-sight. They will communicate with optics as opposed or in conjunction to radio. You fear unforseen space particles destroying one and causing a chain reaction. Why do…

> There is just far too much space for 100k objects, let alone 10k to ever run the risk of collission. No, there isn't. Satellites can and do collide despite the vast amount of space in a given orbit. It is improbable, but likely enough to warrant at least some concern. > Why don't you hold that same fear for existing satelittes which typically operate at an orbit with far lower decay rate? I do, as does the FCC. Thi…

Satellites don't just cross their paths by magic. If their orbits don't intersect, they can't collide. Satellites don't collide with each other, it has never happened.

Satellites do collide with debris, but that's a different issue. Furthermore, they don't need a guarantee that they can be put into a graveyard orbit - the proposed satellites (and even any debris, if they'd explode for whatever reason) will be in a graveyard orbit from day one until they stop being pushed up and deorbit.

Re: SpaceX just got FCC approval to launch 7,518 satellites

#160

Post by soperj »

toomuchtodo wrote: post #112
Rebelgecko wrote: post #105

Earlier quoted context omitted.

I would be surprised if they launch many of the satellites on customer launches. They have some very specific orbits, and are planning on dropping the satellites off in orbits much lower than where they will actually be operating. It would probably be more fuel efficient to drop off a bunch of them in the right inclination all at once, then boost them up into spaced out orbits.

It's possible that they will use reflown Falcon 9s that have exceeded their reuse capability (~10 launches) to deliver these satellites. You're only paying for the propellant, the oxidizer, the second stage, and your fixed operations cost; the rest of the vehicle has been amortized through paying customer flights.

They only reuse the first stage at this point, so still a lot of cost there.
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