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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

#451

Post by mlindner »

robbiep wrote: post #386
mlindner wrote: post #324

Earlier quoted context omitted.

This is something commonly misunderstood. Kessler syndrome is a statistical process that happens over many years. It is not a sudden cascade like is seen in movies like Gravity. Statistical processes are not what militaries are interested in. It's actually thought that Kessler syndrome is kind of already happening right now, which is why there's a lot of push right now to try to de-orbit the very large pieces of debr…

Why can’t every satellite have a small rocket/firework like thing on the back pointing out to the expanse and if the power goes out or it doesn’t receive a signal from the dead man’s switch for long enough then it ignites? Even with a big mass you don’t need to give it much of a shove downwards in a zero friction environment to speed the de-orbit period up. I’m sure I’m missing something but it just seems like a no b…

1. Most significant satellites already have propulsion, only the smallest do not (which is a side problem). The problem is that when satellites fail, the guidance will often fail too.

2. Engines and fuel are heavy. Including one on the smallest satellites may take up the entire mass availability that would go to the instruments, leaving the satellite with nothing to do. There are people working on this, one idea is including a small air canister and a balloon. At end of mission the balloon can be inflated which greatly increases the drag of the satellite causing it to de-orbit relatively soon.

3. As a side note, you don't want to fire "out to the expanse" as that won't de-orbit your satellite. It'll just "twist" the orbit, lowering the perigee and raising the apogee. Primarily it'd just waste fuel. To de-orbit you want to slow down, so you need aim "backwards" along your orbit's path.

4. With a big mass you need an equally large amount of fuel as what determines your ability to de-orbit is the satellite mass, your engine's propulsion efficiency, and the amount of fuel you have.

5. The problem isn't existing satellites. The problem is very old defunct satellites and rocket bodies and existing small debris. Many rockets used to (and still do to some extent) leave large pieces of themselves in orbit.

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

#452

Post by lannisterstark »

bell-cot wrote: post #367
lannisterstark wrote: post #274

Earlier quoted context omitted.

Like all other US defense companies, why not? Do you think US Navy produces their own ships?

Note that, historically , the US Navy had plenty of its own shipyards, and did produce many of its own ships. https://en.wikipedia.org/wiki/Category:United_States_Navy_sh... But that's mostly been "optimized away" in more-recent times, in the name of Capitalism and Campaign Donations.

>did produce many of its own ships.

Problem is that we're talking about how it works currently. US also used to send its own specifically owned spacecrafts into space. But it hasn't in ages.

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

#453

Post by qayxc »

mlindner wrote: post #449
qayxc wrote: post #424

Earlier quoted context omitted.

> Actually the person you replied to somewhat incorrectly. They're not targeted re-entries because the on-board propulsion of Starlink is too low to precisely control the re-entry location. SpaceX says otherwise, see [1] SpaceX spokesman James Gleeson, when asked about the 10 satellites, said SpaceX is “performing a controlled de-orbit of several first iteration Starlink satellites,” using onboard propulsion. There's…

And I'm telling you that the statement is incorrect. Starlink is not equipped with propulsion capable of doing that. They use electric propulsion, which means they can't target a re-entry. They can de-orbit it on a time scale, but they cannot do what is conventionally described as a controlled de-orbit. Meaning they cannot precisely target a general area of the Earth. They can target re-entry within a couple hours to…

I think there's a major misunderstanding on what "precision" and controlled de-orbit means here. Precision doesn't mean a targeted landing. It simply means aiming for a certain latitude by adjusting the orbit accordingly, which is sufficient to make the difference between deorbiting over a desert or ocean and potentially densely populated coastlines or other population centres (central Europe comes to mind). Controlled means that it's the operator who decides how exactly and when that happens, i.e. they remain in control of the spacecraft and its orbital parameters throughout the process.

So if you control the orbit, you control the zone of re-entry. It's not a point or an oval in this case, but a "strip" a couple of kilometres wide. This is all that's required if the goal is to avoid major population centres.

This also means that the target is not "all over the world" as you put it - it's a very narrow, well defined stripe/trace (remember the scale we're talking about here!) and that's exactly what a controlled de-orbit is about.

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

#454

Post by Gravityloss »

schiffern wrote: post #269
mrb wrote: post #225

So that is "432 Mbit/s per laser, and 9000 lasers total". I don't know you guys but I find that statement much more relatable than "42 PB/day". Interestingly, they also say each laser "can sustain a 100Gbps connection per link" (although another part of the article even claims 200 Gbit/s). That means each laser is grossly underused on average, at 0.432% of its maximum capacity. Which makes sense since 100 Gbit/s is p…

>these laser links are used in bursts and the link stays established only for a few tens of seconds or minutes, until the satellites move away The way Starlink satellites are in orbit, the same satellites will remain "ahead" and "behind" you in the orbital plane. Those laser links (specifically!) will remain relatively persistent. This arrangement is similar to Iridium FYI. FTA: "in some cases, the links can also be…

Partially! There are also ascending and descending satellites meeting. Ascending and descending doesn't mean altitude but in a "2D view" sense. See https://www.heavens-above.com/StarLink.aspx

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

#455

Post by mlindner »

qayxc wrote: post #453
mlindner wrote: post #449

Earlier quoted context omitted.

And I'm telling you that the statement is incorrect. Starlink is not equipped with propulsion capable of doing that. They use electric propulsion, which means they can't target a re-entry. They can de-orbit it on a time scale, but they cannot do what is conventionally described as a controlled de-orbit. Meaning they cannot precisely target a general area of the Earth. They can target re-entry within a couple hours to…

I think there's a major misunderstanding on what "precision" and controlled de-orbit means here. Precision doesn't mean a targeted landing. It simply means aiming for a certain latitude by adjusting the orbit accordingly, which is sufficient to make the difference between deorbiting over a desert or ocean and potentially densely populated coastlines or other population centres (central Europe comes to mind). Controll…

Here's a blog post by ESA that talks about what controlled reentry means. https://blogs.esa.int/cleanspace/2018/11/16/basics-about-con... Controlled requires precise aiming towards a targeted location. Not just the operator deciding to do something. By ESA's definition Starlink de-orbits aren't even "semi-controlled".

This generally involves landing at a precise location of the Earth. It goes by a nickname, Point Nemo. A patch of ocean in the south pacific farthest away from any land. It's also far from standard shipping lanes. If you can't achieve this type of targeting it, definitionally, is not a controlled re-entry.

> It simply means aiming for a certain latitude by adjusting the orbit accordingly

You cannot aim a satellite for a "certain latitude" as orbits cannot follow lines of latitude. That's not how orbital dynamics work. I'm not quite sure what you meant to convey here.

> This also means that the target is not "all over the world" as you put it - it's a very narrow, well defined stripe/trace (remember the scale we're talking about here!) and that's exactly what a controlled de-orbit is about.

No it's all over the world, definitionally, because low earth orbits cross the entire planet as the Earth rotates. The possible locations the satellite can re-enter span a large portion of the globe from the negative to the positive latitude equivalent to the spacecraft's inclination.

I think you have a major misunderstanding yourself. If there's some term I'm using that you don't understand please let me know so I can help you.

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

#457

Post by p_l »

mrb wrote: post #225

So that is "432 Mbit/s per laser, and 9000 lasers total". I don't know you guys but I find that statement much more relatable than "42 PB/day". Interestingly, they also say each laser "can sustain a 100Gbps connection per link" (although another part of the article even claims 200 Gbit/s). That means each laser is grossly underused on average, at 0.432% of its maximum capacity. Which makes sense since 100 Gbit/s is p…

Starlink's big investor and launch customer was US Air Force.DoD had long complained about lack of fast sat comms, it's also why they effectively own Iridium.

So in addition to households add foreign bases and possibly drone command networks to possible sources of traffic going fast enough to warrant sat-to-sat connection.

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

#458

Post by misiti3780 »

misiti3780 wrote: post #415
itsoktocry wrote: post #394

Earlier quoted context omitted.

> The amount of bleeding edge innovation that is rapidly developed and deployed into production in Musks companies is incredible. SpaceX for sure. Hard to argue that Tesla is "bleeding edge" anymore; they maintain some advantages, but have fallen behind in other domains.

What are you talking about - weather you think it will work or not, no other company is collecting training data and attempting to solve FSD in the same order of magnitude as Tesla. (last is saw, TSLA collects more video data in 1.5 years then Waymo does in 1 year) FSD12 is end-to-end neural nets and the videos are pretty impressive. Who else is doing that ?

1.5 days**

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

#459

Post by inemesitaffia »

p_l wrote: post #457
mrb wrote: post #225

So that is "432 Mbit/s per laser, and 9000 lasers total". I don't know you guys but I find that statement much more relatable than "42 PB/day". Interestingly, they also say each laser "can sustain a 100Gbps connection per link" (although another part of the article even claims 200 Gbit/s). That means each laser is grossly underused on average, at 0.432% of its maximum capacity. Which makes sense since 100 Gbit/s is p…

Starlink's big investor and launch customer was US Air Force.DoD had long complained about lack of fast sat comms, it's also why they effectively own Iridium. So in addition to households add foreign bases and possibly drone command networks to possible sources of traffic going fast enough to warrant sat-to-sat connection.

Launch customer yes. Investor no. That's Google and Fidelity Paying above the regular rate. Definitely

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

#460

Post by p_l »

inemesitaffia wrote: post #459
p_l wrote: post #457

Earlier quoted context omitted.

Starlink's big investor and launch customer was US Air Force.DoD had long complained about lack of fast sat comms, it's also why they effectively own Iridium. So in addition to households add foreign bases and possibly drone command networks to possible sources of traffic going fast enough to warrant sat-to-sat connection.

Launch customer yes. Investor no. That's Google and Fidelity Paying above the regular rate. Definitely

USAF fronted significant (40%? Those kinds of numbers were floating around) of initial operational capability costs.
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