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Starlink's laser system is beaming 42 petabytes of data per day

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Re: Starlink's laser system is beaming 42 petabytes of data per day

#191

Post by iamgopal »

scottlamb wrote: post #159
oconnor663 wrote: post #155

Earlier quoted context omitted.

No, they burn up. You can think of how much work goes into the heat shields on spacecraft that are supposed to survive reentry. Satellites have none of that.

I also think a screw at terminal velocity might not be particularly dangerous, similar to the popular "will a penny dropped off the empire skyscraper kill you?" question. ...which I suppose is closely related. The deorbiting satellite burns up because all that potential energy goes into heat because of the ~friction~ [edit: compression, thanks for the correction] that limits it to that low terminal velocity.

Heat is Not because of friction but compression of air

Re: Starlink's laser system is beaming 42 petabytes of data per day

#192

Post by ianburrell »

oh_sigh wrote: post #108
Scoundreller wrote: post #23

So which points are getting “faster than fibre” latency because of this? Extra distance up and down, but make up for it on the long-haul. Won’t beat HF radio though.

It's possible for starlink to beat radio, because radio can't always go straight to the target. If I wanted a radio link from NY->Tokyo, what would that path look like?

It would look like the HF radio bouncing off the ionosphere. I have contacted someone in Japan from Oregon. The downside of HF is that the bandwidth is low with 30MHz across the entire band.

There was company recently wanting to do high-frequency trading on HF because of the quickest path.

Re: Starlink's laser system is beaming 42 petabytes of data per day

#193

Post by Scoundreller »

lxgr wrote: post #160
Scoundreller wrote: post #26

Earlier quoted context omitted.

I wonder how iridium actually handles the tracking (or if it’s just slow enough and lack of attenuation in free space just lets them blast it). And if they have zones where they don’t go to adjacent orbits, but instead go up or down within their orbit for the handover between orbits.

Supposedly they use steering, since the horizontal azimuth to adjacent-plane satellites varies from 0 to 65 degrees across an orbit: https://apps.dtic.mil/sti/tr/pdf/ADA348174.pdf

It doesn’t get into it too much on pages 14 and 15, but it indeed suggests that they probably exclusively use the “intra-orbital” links closer to the poles to get data to a satellite where the inter-orbital links are more practical.

I believe Iridium had way more downlinks than they used to pre-bankruptcy. I guess volume constraints were less of an issue, so ok to hop around more in space.

Re: Starlink's laser system is beaming 42 petabytes of data per day

#194

Post by mort96 »

AtlasBarfed wrote: post #184
mort96 wrote: post #167

Earlier quoted context omitted.

I guess I just wish the HN timeline wasn't so full of his garbage.

I use starlink, it works pretty well, as good as cable. Not garbage. I've ridden in Teslas. Some likes, but holy shit that drivetrain. Not garbage. You however, have been consuming garbage media. Hint: if every other day (ahem Gawker sites) there is an outrageous anti-Musk headline or "crazy thing Musk said" headline, your media source is total garbage. Is he a "good guy"? No. Is he "the worse thing ever?" No. What d…

Agree to disagree I guess. The fact that it's his project makes it uninteresting even if the tech would have been alright in the hands of someone less harmful.

If you aren't catching things like his signal boosting of literal nazis on Twitter, your media sources are garbage. (Also is Gawker even still a thing?)

Re: Starlink's laser system is beaming 42 petabytes of data per day

#195

Post by theultdev »

mort96 wrote: post #179
theultdev wrote: post #177

Earlier quoted context omitted.

You were clear on the opinion, not the reasoning. I was just curious as to why you didn't care for the projects.

I don't really see an individual asshole's ownership of such a large part of the world's internet access as "humans advancing". Nor do I see his attempt at shifting the conversation away from actual solutions (e.g public transport, walkable cities, etc) over to "buy slightly more efficient and very expensive cars from him" as "humans advancing". His efforts to signal-boost the far right is certainly not "humans advan…

that internet access didn't exist before this project.

it's not like he took over an existing share of the internet, he connected more people together that weren't previously.

btw you'll still need vehicles, whether you make your city/town walkable or not, stores need trucks, people have emergencies.

and it's up to your local government to handle public transportation properly, not Elon...

Re: Starlink's laser system is beaming 42 petabytes of data per day

#196

Post by Scoundreller »

minhazm wrote: post #56
ggreer wrote: post #42

Earlier quoted context omitted.

Optical fiber has an index of refraction of around 1.6, so signals travel at around 0.6c. For a perfectly straight cross-continental link (5,000km) with no delays from amplification/retransmission, that's about 26 milliseconds. Assuming the satellites are directly overhead, Starlink adds another 500km up and down, making the minimum possible latency around 20 milliseconds. The real number might be slightly higher or…

Number of hops definitely matters more usually. For example I'm about 150 miles from Azure East US 2 (richmond, va), and at the speed of light that should be sub 2ms round trip, but actual latency to it is ~30ms. But I'm sure I'm going through dozens of switches/routers to get there. What Starlink buys you is that you get to go straight to a satellite, then a laser in a vacuum to other satellite(s) and then a ground…

Could also be shit routing.

Some big ISPs here refused to locally peer with some cheaper providers, so some packets to a local data centre (5 miles away) in Toronto would round trip through Chicago and back.

If they wanted a direct connection; they wanted them to pay for transit.

Re: Starlink's laser system is beaming 42 petabytes of data per day

#197

Post by mort96 »

theultdev wrote: post #195
mort96 wrote: post #179

Earlier quoted context omitted.

I don't really see an individual asshole's ownership of such a large part of the world's internet access as "humans advancing". Nor do I see his attempt at shifting the conversation away from actual solutions (e.g public transport, walkable cities, etc) over to "buy slightly more efficient and very expensive cars from him" as "humans advancing". His efforts to signal-boost the far right is certainly not "humans advan…

that internet access didn't exist before this project. it's not like he took over an existing share of the internet, he connected more people together that weren't previously. btw you'll still need vehicles, whether you make your city/town walkable or not, stores need trucks, people have emergencies. and it's up to your local government to handle public transportation properly, not Elon...

None of that has anything to do with what I wrote, cool.

Re: Starlink's laser system is beaming 42 petabytes of data per day

#198

Post by theultdev »

mort96 wrote: post #197
theultdev wrote: post #195

Earlier quoted context omitted.

that internet access didn't exist before this project. it's not like he took over an existing share of the internet, he connected more people together that weren't previously. btw you'll still need vehicles, whether you make your city/town walkable or not, stores need trucks, people have emergencies. and it's up to your local government to handle public transportation properly, not Elon...

None of that has anything to do with what I wrote, cool.

Smart choice to deflect.

See you on the next Elon article you crave.

Re: Starlink's laser system is beaming 42 petabytes of data per day

#199

Post by wolverine876 »

burnished wrote: post #176
wolverine876 wrote: post #162

Earlier quoted context omitted.

> Basically this happens just before sunrise, and just after sunset. I've seen plenty of satellites in the middle of the night, from very dark areas (wilderness). They look like stars, only they move more quickly. These observations go back a decade, at least.

That doesn't seem right, why would they be bright?

That's a very good question. I'm sure of what I've seen, many times over years:

I can tell you that they look like stars - so much that I need a reference point, an actual star or planet, to verify they are moving and not a 'stationary' star (judging movement being otherwise very difficult at that distance). They move very steadily, horizon to horizon, or as far as I can track them. A wild guess, based on memory, is one might take 5 or 10 minutes to cross between my horizons (usually I'm not on a plain - trees, hills, mountains may elevate my 'horizons' and reduce the distance).

Natural celestial object? No way a star is moving that fast relative to other stars and Earth's horizons. Asteroid? That seems hard to believe, due to size and illumination. Comet? Are there lots of tiny ones? I never see tails. Maybe a meteorite entering the atmosphere that doesn't yet have a tail?

Other human-made objects? Airplanes would look bigger and have colored, blinking lights - I've seen plenty of airplanes at night. Maybe there are higher flying airplanes without the colored and blinking lights? Are they illuminated whitish, and so far away they'd look like stars?

I've seen them so many times, I'm confident that I could take anyone to a wilderness area on a clear night and find one within 15-20 minutes, probably less.

Re: Starlink's laser system is beaming 42 petabytes of data per day

#200

Post by _0ffh »

ble wrote: post #5

My understanding of the state of the art of inter-satellite optical links is that they have only been used between satellites that are basically in the same orbital plane and in more or less the same orbit. That is, the angle from one satellite to the other changes very very slowly, so that the optics don't have to do much tracking -- and consequently satellites can only form an optical link with other satellites tha…

Nah, I once did a job for a guy and they did LEO-GEO distances alright iirc and LEO-Earth in the mid-end 2000s, which has to deal with some pretty high angular velocities, if not as potentially high as LEO-LEO when they don't happen to be relatively nicely aligned. (In case that sounds strange, the guy was one of the two owners of a small, very specialized company that in turn was subcontracted by a rather bigger company. These laser terminals were quite the beasts and not really cheap.)
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