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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

#281

Post by jandrese »

stcredzero wrote: post #151
jandrese wrote: post #147

Earlier quoted context omitted.

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?

Phased arrays are nice, but have a slight problem with being stupendously expensive. It's going to be hard to convince people to jump on board if the starter hardware pack is $20k.

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

#282

Post by jessriedel »

jonplackett wrote: post #272
russellbeattie wrote: post #145

Earlier quoted context omitted.

That is amazing. Seeing the complexity of the grid is mind blowing - and the realization the blocks representing the satellites are the size of cities makes you realize how big space is. That said, future launches are going to have to run a gauntlet...

It seems like that doesn't it, but space is MASSIVE. Imagine if there were only 7000 people spread out on the face of the earth, would you be worried you'd accidentally run into one of them? These things are up another few hundred miles so are even more spaced out than that.

This is true but not as useful an intuition as it first appears. The major difference for satellites is that everything in low-Earth orbit is traveling at ~8 km/s, so the spatial volume they traverse in any amount of time can be surprisingly large. A cubic-meter satellite traverses 250 cubic kilometers of volume in a year. (If you want to get an order-of-magnitude estimate for collision frequency, you imagine one satellite occupies it's normal volume and the other occupies the traversal volume, and then just ask what the chance is that those volumes overlap, given the amount of space above the Earth within the altitude range of the orbits.)

And indeed, there has already been an accidental satellite-satellite collision (not just satellite-debris collision).

https://en.wikipedia.org/wiki/2009_satellite_collision

The Iridium constellation has about ~80 satellites, and one passes within 5km of another satellite about 50 times/day.

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

#283

Post by jacquesm »

buboard wrote: post #220
jacquesm wrote: post #219

Earlier quoted context omitted.

What is the last time you traveled on an airplane? In flight wifi is pretty routine now, aircraft have lots of infrastructure to enable this. It would definitely be possible to adapt that hardware to connect to the satellite system launched by SpaceX instead, all it would take is a different antenna and radio system that the Sat operator would be happy to provide.

I thought you meant some kind of direct passenger connection. I think airplanes already use satellites for the internet connection, no? In any case , i dont see the huge benefit here: they will still all be sharing the same routers and probably have the same connection speed.

The amount of bandwidth available to a single aircraft would be much larger than it is today with this system.

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

#284

Post by natechols »

nickik wrote: post #273
natechols wrote: post #218

Earlier quoted context omitted.

One of the consequences of the Sputnik launch was that it basically enshrined the principle that overflying another country with an active satellite was not an illegal act. (That is, the US government decided not to protest, because it meant they wouldn't have to apologize for their own future spy satellites.) I doubt China wants to break this precedent.

No. There is a difference between flying over and operating communication satilliets.

As far as international law is concerned, I doubt it. Sputnik was transmitting the entire time it overflew the US.

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

#285

Post by nickik »

natechols wrote: post #284
nickik wrote: post #273

Earlier quoted context omitted.

No. There is a difference between flying over and operating communication satilliets.

As far as international law is concerned, I doubt it. Sputnik was transmitting the entire time it overflew the US.

Its about offering a service in China, not about the technical act of communicating.

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

#286

Post by ceejayoz »

ALurchyBeast wrote: post #139
Rooster61 wrote: post #102

Earlier quoted context omitted.

<10K isn't the problem. It's when that 10K becomes much, much larger because of an unforeseen collision with an unrelated spacecraft/piece of space junk. It only takes one big collision to utterly litter that particular orbit, and thousands of slightly different orbits caused by the new trajectories of the various bits of the original spacecraft.

So whats your solution? Never put a bunch of satellites in space?

There are a variety of potential mitigations. Legal requirements that satellites deorbit or park in a safe orbit before going dark, technology like https://en.wikipedia.org/wiki/E.Deorbit to capture and deorbit large chunks, better tracking of orbital debris, etc.

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

#287

Post by pcr0 »

dv_dt wrote: post #168
IshKebab wrote: post #120

Earlier quoted context omitted.

What do you think investment is exactly?

I think that systemic interest in investment in fundamental economic improvements has declined while systemic investment in financial vehicles (pardon the pun) is rampant. This would be ok if the financial vehicles were connected to economic well being, but that link is increasingly tenuous. It basically takes a crazy, put it all on the line billionaire to assemble technologies, but why doesn't the economic system re…

I think salesmanship and being able to sell a daring vision is key. Why else would anyone invest in risky long term projects like space travel when they could just buy an ETF instead?

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

#288

Post by shaklee3 »

deftnerd wrote: post #262
shaklee3 wrote: post #217

Earlier quoted context omitted.

That's completely wrong. It's 100% not going to compete with DSL. It will be used by enterprise, or people who pay $100+/more to offset equipment costs. The reason satellite internet costs so much is equipment cost.

Someone could have made the same argument against mobile phones, saying that they wouldn't compete with landlines because of the increased handset costs.

Not even close. Mobile phones actually had numerous advantages over landlines. You could travel with them, have apps, long distance was far cheaper, etc. The writing was on the wall for landlines very early on, and everyone saw it coming. It would be like predicting today that streaming won't take over over the air programming for TV. It wasn't that much more expensive than a landline when all was said and done.

SpaceX has very little, if any advantage over decent DSL, especially since mid-range DSL will be $30/month with no equipment to invest in.

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

#289

Post by regnerba »

shaklee3 wrote: post #250
regnerba wrote: post #247

Earlier quoted context omitted.

Isn't the lower orbit even better for them in terms of latency though? So long as the orbit doesn't decay faster than the planned 5 year life span of the sats, it's actually a win.

The lower orbit means the satellite coverage on Earth is smaller now, so they need more satellites to compensate for delivering the same capacity in a given area. It's better in terms of latency, but it's not a significant difference.

Very good point, thanks for responding.

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

#290

Post by kartickv »

Tepix wrote: post #274
kartickv wrote: post #240

Earlier quoted context omitted.

If Starlink didn't route data in space and instead used space only as a last mile, would it be significantly cheaper, or have higher bandwidth, or be feasible to provide without data caps? What are the economic and technical tradeoffs here? I don't mind the latency of today's fiber or cable Internet, and if it's problem, it can be solved by moving servers closer to users. That is, what if, instead of bypassing the fi…

If you're in the middle of the Pacific it won't work unless the satellites talk to each other and route the data to a ground station that may be thousands of miles away.

Sure but most people don't live in the middle of the Pacific, so is an optimised system possible for them?
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