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

https://www.pcmag.com/news/starlinks-laser-system-is-beaming-42-million-gb-of-data-per-day

by alden5 • 2 years ago

526 402 2 years ago

scohesc• 2 years ago

The article mentions that they were able to stream video from a starlink satellite as it was de-orbiting - it would be neat to see the video of that, even if it cuts off as the laser link losing connection (or the satellite burns up)

SushiHippie• 2 years ago

[dupe] https://news.ycombinator.com/item?id=39199368

dang• 2 years ago

OP was posted earliest so I guess we'll merge the other threads hither. Thanks!

advisedwang• 2 years ago

42M GB Per day = 3.9tbps

progbits• 2 years ago

M GB

I can hear the SI crying.

ble3• 2 years ago

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 that are ahead or behind themselves in ~ the same orbit.

Cross-plane optical links would have a trickier tracking problem.

While there's no explicit mention of same-plane vs cross-plane optical links, I assume that the first time people have a public cross-plane optical link, they will make a big deal out of it. :)

The article also mentions that SpaceX would need to do further study before using laser links between satellites and ground stations-- this kind of optical link would require both more angular tracking and probably atmospheric correction as well.

sandworm101• 2 years ago

Tracking is an issue, but doppler can also be a thing. At orbital speed (actually up to 2x orbital speeds) the doppler effect between two satellites can change the frequency enough to cause interference. Moving a scope to track a moving target is one problem, allowing the algorithms to adapt at the frequency shifts on the fly another.

Scoundreller6• 2 years ago

Indeed Iridium had to deal with the same thing (or I guess, didn’t):

“ Cross-seam inter-satellite link hand-offs would have to happen very rapidly and cope with large Doppler shifts; therefore, Iridium supports inter-satellite links only between satellites orbiting in the same direction.”

https://en.m.wikipedia.org/wiki/Iridium_satellite_constellat...

ble3• 2 years ago

Links between satellites closing range near 2x orbital speed have two problems: - bigger doppler - the lifetime of the link is much shorter

dreamcompiler• 2 years ago

Doppler is not a big problem with lasers because the carrier frequency is so much higher than RF that it doesn't matter; it's bang-bang AM modulated.

I'm assuming two things: That something like Manchester coding is being used so that some clock skew is tolerable, and that the laser carrier is not in fact being frequency or phase modulated. Last I checked FM and PM of optical frequencies was not yet practical outside of laboratories, but I'm happy to be corrected.

ortusdux3• 2 years ago

“Another really fun fact is that we held a link all the way down to 122 kilometers while we were de-orbiting a satellite,” he said. “And we were able to downstream the video.”
For the future, SpaceX plans on expanding its laser system so that it can be ported and installed on third-party satellites. The company has also explored beaming the satellite lasers directly to terminals on the Earth’s surface to deliver data.

FpUser• 2 years ago

So what happens to the laser beam when there are clouds?

Symmetry• 2 years ago

Right. The Iridium network had communication between satellites in different orbital planes passing each other but that was a pretty unusual capability.

Scoundreller6• 2 years ago

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.

akira2501• 2 years ago

They do have counter rotating planes though, so there are places where two satellite tracks next to each other moving in opposite directions, and these pairs of satellites cannot use the cross plane communication mode.

Additionally, their inter satellite links use regular Ka band radio.

sephamorr2• 2 years ago

Take a look at the slides from the presentation, I think the geometry clearly shows cross-plane links in the mesh. Having worked on these types of systems, I've had more difficulty with the lookahead angles (rx from where the target was, tx to where it will be due to speed of light) than the tracking -- fine tracking performance was required for all modes, and it largely became a GNC and acquisition time issue (since they're ephemeral) for the cross-plane links.

stcredzero3• 2 years ago

GNC?

ble3• 2 years ago

The "routing in the mesh" slide? Definitely given where the satellites are in that picture some of the links would have to be cross-plane, it's just the whole thing looked so messy (even with it being geo-referenced on a globe) that I didn't know whether to consider it a "real routing example" vs a "notional routing example that we overlaid on the globe".

Sounds very cool that cross-plane links are doable, even if they have predictable complications compared to in-plane.

I would have thought that someone would make a big deal (have a press release, e.g.) out of successfully establishing cross-plane links, but maybe it just doesn't seem that impressive to people who already have good enough precise predictive ephemerides or satellite states to make those links in the first place.

nomel• 2 years ago

In general, how is the initial alignment performed?

Is there rough pointing, followed by some rastering, until the sensor gets a hit? Maybe with some slight beam widening first? My assumption is that you would want exactly one laser, one sensor module, and probably a fixed lens on each? Is the sensor something like a 2x2 array, or pie with three pieces, to allow alignment? Or is it one big sensor that uses perturb and observe type approach to find the middle?

Also, is there anything special about the wavelengths selected? Are the lasers fit to one of the Fraunhofer lines? 760nm seems like a good choice?

_0ffh2• 2 years ago

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.)

calrain• 2 years ago

I'll assume there is a lot of double/triple (or higher) accounting going on here as data is sent through multiple relay hops to get the intended target.

londons_explore6• 2 years ago

With 266,000 acquisitions per day, I suggest they are regularly doing links across orbital planes.

If they could only do in-plane links, they would have barely any acquisitions per day, because most links would stay up for long periods of time.

mschuster912• 2 years ago

The lasers, which can sustain a 100Gbps connection per link
Brashears also said Starlink’s laser system was able to connect two satellites over 5,400 kilometers (3,355 miles) apart. The link was so long “it cut down through the atmosphere, all the way down to 30 kilometers above the surface of the Earth,” he said, before the connection broke.

How do these tiny satellites achieve this kind of accuracy and link quality when they're shooting around Earth with 17.000 miles an hour?

(Meanwhile, me on Earth, has link quality issues due to a speck of dust on a fiber connector)

ugjka• 2 years ago

Given this is Gen3 and Gen4 now being launched, it took some figuring out

sumtechguy• 2 years ago

Relative to the origin satellite I would assume the others are in a fairly fixed position to it. Remember they try to keep them spaced out and even coverage. That means the things are not moving around wildly relative to each other. But to us they are wizzing by. For example I know I am relatively moving fairly quickly to the earths core and pretty fast around the center of the sun. But from my PoV everything around me looks stationary. Also there is not a lot of dirt up there.

diggan• 2 years ago

(Meanwhile, me on Earth, has link quality issues due to a speck of dust on a fiber connector)

It's incredible really. I remember when I was a kid living with my mom on an island, we got broadband relatively late (compared to the rest of the country), as the island required antennas for getting mainland and the island linked, instead of cables. I think it was set up that way because of costs or something, remember it being expensive...

Regardless, the antennas were setup and we finally got broadband, but every time it got a bit windy and/or rainy, the links started to have huge issues, especially if the lake got lots of waves, then the connection simply disappeared.

And now it seems almost like magic to me how the same setup is literally done but way above our heads, in a really hostile environment like space.

dkasper• 2 years ago

In some important ways space is actually the least hostile environment. But yeah, it’s still amazing and has its own challenges.

polishdude20• 2 years ago

Phased array antennas probably have a lot to do with this. You can aim the signal more accurately and faster than any mechanical system ever could.

Tuna-Fish2• 2 years ago

Laser links are not using phased array antennas. It's a physically moving "turret" with a laser and another with a receiver. And they need to be separate units, because the speeds and distances involved are long enough that you are not receiving from the same direction as you are sending.

yencabulator2• 2 years ago

Surely the lasers aren't phased arrays.

ianburrell2• 2 years ago

The current Starlinks satellites aren't small. They are almost a ton and 13ft by 9ft.

Even the original ones weren't that small weighing 570lb.

stefan_• 2 years ago

Their exact position in space can be calculated very precisely. The Starlink terminals do this as well.

mytailorisrich• 2 years ago

The rate of change of their relative positions is what matters. At 5400km distance this is likely slowish so that tracking is not a big issue as long as position is well known, which it is.

Re. Link quality: laser, line of sight, most of the trip is in vacuum and the rest in very sparse atmosphere. So interferences are likely quite low.

mensetmanusman4• 2 years ago

3M just invented a new fiber interconnect thing to mitigate the dust issue: https://www.3m.com/3M/en_US/data-center-us/applications/inte...

Maybe the future of usb in 10 years :)

themeiguoren2• 2 years ago

This says more about the link budget than anything else, it's much harder to keep tracking when satellites are close to each other moving at high relative velocities. At the distances in your example, movement of the laser link optical head is very slow, on the order of 0.01 - 0.1 deg/s. Optical heads also have a control loop which actively corrects for pointing errors once a positive link is established. Check out: https://www.sda.mil/wp-content/uploads/2022/04/SDA-OCT-Stand...

lupusreal• 2 years ago

"We actually serve over lasers all of our users on Starlink at a given time in like a two-hour window"

I can't figure out what this sentence means.

mschuster912• 2 years ago

That any SpaceX user who has a connection established for >2h will have their data sent not via the classic path "ground - satellite - ground" at least once during the connection, but via "ground - satellite 1 - satellite 2 - ground".

NelsonMinar2• 2 years ago

I think it means pretty much all Starlink users have at least some data go over laser links every two hours. Which is a bit of surprise to me, if true. I have a year or so of fine-grained latency detail taken with IRTT on a Starlink connection, I should sit down and see if I can see times I'm using a satellite. Latency is highly variable in Starlink though so it's pretty noisy data.

gibspaulding• 2 years ago

Have you posted that data anywhere? I'm currently on a 10mbps DSL connection and considering StarLink, but have so far been scared away by the cost and concerns about latency, so I'm always on the lookout for real world data.

quailfarmer2• 2 years ago

Hey, I’m very curious if you’ve seen any improvement in latency over the past month.

7e4• 2 years ago

Global internet traffic is estimated to be 3 yottabytes per day. So Starlink is now carrying one of out every 77 million parts of worldwide traffic. Wow, that's small.

EDIT: there's some confusion information out there. With a more conservative estimate of 150.7 exabytes per month, Starlink gets 1 part of 119, which is more impressive.

uoaei• 2 years ago

The quoted number is only for inter-satellite laser links, not for other methods of information transmission.

bagels• 2 years ago

Most of the traffic is probably just bounced off the satellite down to the nearby ground station still.

jlmorton• 2 years ago

Where do you get 3 yottabytes? That is difficult to believe. I see 150 exabytes per month [1], about a thousand times less.

https://gitnux.org/internet-traffic-statistics/ [1]

7e4• 2 years ago

https://www.statista.com/statistics/216335/data-usage-per-mo...

sys_64738• 2 years ago

Is that a lot?

heeton2• 2 years ago

Don’t you mean 42million Gigabytes?

Alifatisk• 2 years ago

Isn’t that equivalent? What does it help to use GB instead of PB?

heeton2• 2 years ago

https://news.ycombinator.com/item?id=39199368

ortusdux3• 2 years ago

I was going to put 336,000,000,000,000,000 bits/day, but it seamed a bit overkill.

MeImCounting4• 2 years ago

*seemed

I dont think theres anything having to do with seams or fabric in this conversation

Scoundreller6• 2 years ago

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.

edgyquant2• 2 years ago

Why would we expect faster than fibre?

Cu3PO422• 2 years ago

The speed of light in a vacuum is roughly 50% higher than the speed of light in fiber.

stcredzero3• 2 years ago

Also, as pointed out elsewhere, the number of hops is the biggest contributor to latency.

oger2• 2 years ago

That could already be the case. Round trip time to the ~500km orbit is about 4 milliseconds (+ all other network elements before, after and in between). They claim to have a >5000km link running for significant time. Now think of a fibre link of that length and how many repeaters / routers will be needed due to attenuation and physical constraints. I can clearly see a path where Starlink laser links could be a viable option to subsea cables - at least for some priority traffic...

baq• 2 years ago

a few random outages which happened near places some oligarch's yacht has visited recently and it'll become the priority backhaul.

I see folks in the Pentagon doing a collective /phew that this project is online in the next decade, multiple times.

ggreer• 2 years ago

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 lower depending on the location of the satellites.

My guess is the real latency depends mostly on the latency of relay nodes (either satellites or routers on earth), not the medium through which signals travel.

minhazm• 2 years ago

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 station that's likely already at an IXP or very close to one.

oh_sigh2• 2 years ago

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?

Scoundreller6• 2 years ago

True, it would be bouncing around between ground and the atmosphere (when it works at all).

ianburrell2• 2 years ago

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.

7e4• 2 years ago

Starlink adds a latency penalty of tens of milliseconds going through the atmosphere. Each round trip is four hops through the clouds. I expect most of this delay is forward error correction, combined with lower bandwidth of the radios.

On top of that, you may have queuing in each satellite.

Finally, the satellite laser links aren’t pointing exactly in the direction you want to your packets to travel. They’re at some diagonal, and the packets need to tack back and forth, which wastes distance. Think the streets of Manhattan.

mlindner11• 2 years ago

This is just incorrect. The speed of light through atmosphere is almost identical to speed of light in a vacuum. There's no latency penalty for traveling through the atmosphere. The one-way time delay to a Starlink satellite is about 2 milliseconds.

bilinguliar• 2 years ago

Are they using Mynaric technology?

axus• 2 years ago

Internet says no: https://www.cnbc.com/2021/11/19/german-space-lasers-company-...

jstummbillig3• 2 years ago

I have absolutely no idea how that number relates to any comparable operation. Can anyone add a banana for scale?

adgjlsfhk1• 2 years ago

10 minutes of 4k video is ~30GB.

jstummbillig3• 2 years ago

Knowing the size of a video file is exactly not the information, that would help me put this number in a meaningful perspective with any comparable operation.

How do I think of 42 petabytes in terms of an ISP? Is that a lot? How does it compare to other satellite providers? How does it compare to 4G capacities? Is this a small country worth of traffic or just any ol' data center? I have no intuition about traffic at this scale.

SirMaster• 2 years ago

I feel like this is a bad example.

Most people's experience with 4K video is through a streaming service, and 10 minutes of 4K video on a streaming service is more like 1-1.5 GB.

Or a UHD Disc perhaps where 10 minutes is 3.5-7 GB.

zetsurin• 2 years ago

Based on 2160p movies i've seen around the very largest max out at around 100, and 40 is more common, so this seems wrong.

colordrops3• 2 years ago

If you've got a laptop with a terrabyte drive, it would be 42,000 full laptops worth of data.

lizhang• 2 years ago

If you've got a server farm with a petabyte of storage, it would be 42 server farms

bee_rider• 2 years ago

Implementing a “comparable operation” to this satellite network using laptops instead is going to be really expensive fuel-wise, I think.

madeofpalk• 2 years ago

If you have a laptop with a petabyte drive, it would be 42 full laptops worth of data!

whycome• 2 years ago

If you took a petabyte's worth of 1GB flash drives and lined them up end to end, they would stretch over 92 football fields.

https://info.cobaltiron.com/blog/petabyte-how-much-informati...

organsnyder• 2 years ago

That's actually a somewhat useful visual.

permalac• 2 years ago

EMBL-EBI’s open transfer systems provide ~5PB of data each month.

ftp.ebi.ac.uk for example.

stcredzero3• 2 years ago

Better yet, a work in a 35 foot long Twinkie.

new_user_final• 2 years ago

Bangladesh, the whole country, usage 2,300Gbps as of 2021. So 1 Petabyte per hour?

Edit: It's international traffic. YouTube, Facebook video has local cache server by ISP.

MeImCounting4• 2 years ago

This is a useful scale of comparison and what I think OP was after

theteapot• 2 years ago

486GB/s

nharada• 2 years ago

Assuming it's a constant data transfer rate, this is 3,889 Gbps. This is

- About 4,000 customers worth of maxed out Gigabit internet

- ~243,000 simultaneous Netflix 4K streams

- 1.6% the capacity of the latest BlueMed undersea fiber cable

danbruc• 2 years ago

According to a quick search the average US household is closing in on 600 GB of traffic per month, that makes 42 PB per day the internet traffic of 2.1 million households. Incidentally the second picture in the article says 2.3M+ customers. With an US average of 2.5 people per household that is the traffic of 5 million people or 1.5 % of the US population.

latchkey5• 2 years ago

I sit in my hot tub at night and see 1-2+ satellites go over every single time I'm out there.

Which also makes me wonder how many of the shooting stars I've seen recently are just old starlinks burning up.

gnrlst• 2 years ago

How do you spot a satellite? I've never seen one.

kirubakaran• 2 years ago

The Starlink ones look like Santa's sleigh https://i.imgur.com/4S0vbfY.gif

giancarlostoro• 2 years ago

Probably out in a rural area far enough away from a major city its easier to see them.

TheAlchemist• 2 years ago

It depends where you live certainly - if you live close to a big city you will probably never see them. But there are places - like New Zealand - where you can see them fairly often. There are some online trackers you can use.

latchkey5• 2 years ago

To me, they look like little white dots moving across the sky. Brightness can change as they move too. It'll start off bright and then as it goes away it eventually disappears entirely. Since I usually sit in the same position in the hot tub, I've come to notice that I usually see one of them cross a pretty specific path from north to south, so I've gotten used to looking in that part of the sky as I'm sitting there. It happens so frequently, I get a little disappointed if I don't see one!

Planes are similar, but tend to have flashing or colored lights and obviously aren't as far away.

I'm in a big city, but close to the ocean so I have a bit less light pollution. The city is also heavy military, so that could be part of the frequency.

Update: if you're near any of the spacex launches, you can watch the rocket too. I'm house sitting in Irvine, CA and saw the Monday launch go right near the house. Amazing to watch the plume from the rocket!

qayxc5• 2 years ago

If the seeing is good it's actually possible to spot up hundred satellites with the unaided eye. Due to light pollution, it's unlikely to spot one in most places, though. The ISS at least should be easily visible due to its size, even in places that aren't particularly dark.

flir• 2 years ago

Even in a city you stand a chance if you've got high walls around you. A courtyard garden for example. Just lie back and stare up.

qwertox• 2 years ago

It's usually a somewhat like a fast moving little but visible star. Fast as in it would usually cross 1/4 of the visible sky within 20 seconds or so.

You should try to find one once, with the help of an app. It's not that difficult.

embedded_hiker• 2 years ago

The easiest satellite to see is the ISS. NASA provides times when it can be seen from any given place. I subscribe to the SpotTheStation mailing list.

In general, you can see a satellite when it is overhead and illuminated by the sun. In the evening, it will appear in the west, moving towards the east ( almost all satellites go this way, not just ISS ). As it goes farther east, heading towards darkness, it will fade away. The ISS is bright enough to see a reddish tinge as it passes through sunset light.

Shooting stars go much faster than satellites.

drynewton• 2 years ago

https://james.darpinian.com/satellites/ Put in your location and it will tell you when and where to look at the sky to see one. Works great for me and hopefully it will work for you.

HPsquared2• 2 years ago

1. The satellite needs to be passing overhead at an angle where you can see it, and clear skies etc.

2. The sky needs to be dark enough to see it (so twilight or night)

3. The satellite needs to be illuminated by the sun.

4. The satellite needs to reflect enough light that you can see it.

Basically this happens just before sunrise, and just after sunset. So the ground and sky are dark (allowing you to see through the atmosphere), and the satellite - being at high altitude - is still illuminated.

As they pass overhead, you can often see them suddenly vanish as they pass into the Earth's shadow.

The International Space Station is a good one to find, as it's quite bright (very large).

There are various websites and apps; some phone apps use the GPS and magnetometer to show you what direction and time to look, and a search tool to look for visible objects at your location. It used to be really good with the old Iridium satellites, which gave a bright flash due to their large flat antennas.

pxeger1• 2 years ago

My tip is that the very central part of your field of view has worse night vision than the rest (trading off for higher resolution instead), so if you spot something moving in your peripheral vision, don’t try to look straight at it or it’ll disappear; instead, look slightly to the side, and it’ll be easier to see (although maybe blurrier).

nativeit• 2 years ago

It takes several minutes for your eyesight to adjust enough to spot them with the naked eye. You can use websites to know when one is likely to pass overhead. Choose a suitable time (see: everyone else, basically right after dusk), and then lie down and stare up about 15-minutes ahead. Mushrooms are optional, they increase the chances of seeing something but decrease the chance that what you saw was real.

wkat42422• 2 years ago

I can guarantee you you have.

You probably just thought it was a star or a plane. They move but relatively slowly (even a fast LEO sat will cover the sky in about 5 minutes). They look just like a star apart from moving slowly. Depending on angles they can look pretty dim, especially the latest SpaceX sats. But the ISS is usually really bright because it's so huge and technically it's also a satellite.

You can tell them apart from a plane because they don't flash.

Edit: But yes there are several conditions that need to be met to see them like the other posters have mentioned. But every clear night near dusk or dawn you will see sats for sure. There are just so damn many in LEO now.

qayxc5• 2 years ago

Which also makes me wonder how many of the shooting stars I've seen recently are just old starlinks burning up.

Probably close to none. The lifetime of the satellites is about 5 years give or take. According to this page [1], a total of 355 satellites have deorbited over the past roughly 5 years. That's an average of about 71 per year or about one every 5 days.

Since planned disposals are done over uninhabited areas (e.g. the pacific ocean), the likelihood of spotting one is very low.

Hope that helps answer your question, even it wasn't necessarily meant seriously :)

    [1] https://starlinkinsider.com/starlink-launch-statistics/

latchkey5• 2 years ago

No, I love this data! Thank you.

aetherspawn• 2 years ago

If someone makes a mistake and the satellite deorbits in the wrong place, am I likely to be impaled by a satellite screw or something travelling at terminal velocity?

macspoofing• 2 years ago

The lifetime of the satellites is about 5 years give or take. According to this page [1], a total of 355 satellites have deorbited over the past roughly 5 years.

Wow ... is it economical to replace the entire constellation every 5 years? How does the business side work? Or is it just a great money-burning party?

steve_adams_862• 2 years ago

There are so many that I spot them with my telescope while watching the sky with some frequency. In the last year I've probably caught 6 or so. It's just a spot of light passing through the view, nothing spectacular, but I think it would have been virtually impossible 20 years ago.

whalesalad• 2 years ago

The first time I saw the long line of starlink satellites in a dark rural area it was unreal. Straight up looked like aliens invading.

meroes• 2 years ago

As someone who also spends a decent amount of time outside at night, do you also see a ton of shooting stars?

I see them 1/3 of the time in outside for 30 minutes or more I’d say. Thought they were much rarer. Only seems a Starlinkn train once.

Animats3• 2 years ago

But how do they beam copies of the space to space links down for wiretapping, as Iridium does?

supertrope2• 2 years ago

At the ground stations

inemesitaffia4• 2 years ago

GS is layer 2. It's done at the POP's like every other company

Animats3• 2 years ago

Starlink is rolling out "direct to cell" connections, where the satellites connect directly to GSM cell phones. Is any ground station involved in a cell to cell call?

7e4• 2 years ago

If I send one byte and it hops through ten satellites, is SpaceX counting that as ten bytes of data?

why_at• 2 years ago

Random thought I just had: What are the odds of a rocket launch crossing through one of these laser links on its way to a higher orbit and disrupting traffic for a fraction of a second?

I know space is really big and so the odds of a rocket hitting a satellite on its way up are incredibly low, but now we're talking about lots of lines between each satellite rather than just the satellites themselves. Are the odds still tiny?

Not that it would be a big deal if it happened, just curiosity.

elevatedastalt• 2 years ago

I think they are still tiny. Also don't networking systems routinely deal with temporary link disruption?

burnished3• 2 years ago

What does that have to do with the odds of rocket induced dropped packets?

versteegen2• 2 years ago

the odds of a rocket hitting a satellite on its way up are incredibly low

Aside, but it's not left to chance. They only launch when there's a gap in the space traffic.

bdamm• 2 years ago

Fair, but they don't compute and probably can't know the laser paths between Starlink nodes.

ra• 2 years ago

It doesn't matter what the odds are; loss of connectivity is going to happen. Packet loss is common across the internet, fortunately we have protocols that can deal with this.

burnished3• 2 years ago

Interesting question. It used to be zero, before the satellites and before the rockets, but now is probably not zero.

I think you could take the time a rocket would be in the way and compare it to the time it would take any given satellite link pair to make an orbit to form an estimate of the chance of a single interference. Then multiply by rockets and satellite pairs to form an overall estimate.

MadnessASAP• 2 years ago

I've done some research, I don't have a probability but from what I've found. A Falcon 9 shortly before stage 1 separation is around 50km altitude[0] doing ~2000 m/s. Preseperation the F9 is 70m tall, add 130m for plume[1] so 200m total. At 2000 m/s it'll cover it's own length and plume in 100ms. If the laser link is running at 100 Gbps that's 10Gb of data lost.

Which is actually a lot more then I estimated when I started this math, kinda puts into perspective more then 1 of the scales at play here.

Tl;dr Rockets are fast, data is apparently faster.

[0] Apparently on its longest distance link Starlink intersected 30km altitude

[1] Ref: my ass

andy_ppp3• 2 years ago

It's absolutely incredibly small, think of how large the surface area of a sphere of LEO and the surface area of these lasers linking the vertices of the 5,289 satellites. The gaps between them are probably hundreds of kilometres. I would imagine that each link has multiple routes so if there was a failure traffic can still be routed in the same way the Internet has many routes.

https://satellitemap.space is pretty amazing but a Starlink satellite looks massive on there, really at the scales we are talking they wouldn't even be a pixel. Do we know how many of the satellites are actually interlinked by lasers?

hinkley2• 2 years ago

There’s no friction in space. So the question is not how wide the plume of a rocket engine gets, but how spread out does the vapor trail need to be before it stops being an optical impediment?

therealmarv• 2 years ago

I hate that PCMag ignores browser preferred language lists. It switches the language on my geo IP address which is a language I cannot read.

shoelessone• 2 years ago

This is a serious annoyance for me all day long, across the internet. Have you found most sites respect your preferred languages list?

Symbiote• 2 years ago

For Google, I found setting my browser to "Accept-Language: en,sv" when I live in Denmark was sufficient — just English and they seem to assume I can't configure the browser and want the local language.

PCMag serves me English, with "en-GB,en", though I don't know if they would support Danish anyway.

joshspankit• 2 years ago

I’m waiting for two things:

1. Full-circumference world round-trip latency sat to sat (yes it has to go to ground to “count” but I just want to know what the number is)

2. Deployed LEO servers running with laser communication to the Starlink satellites. Preferably gaming or CDN since either is a great way to verifiably test the limits.

mrb3• 2 years ago

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 probably achievable in ideal situations (eg. 2 satellites very close to each other), so 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 and no longer are within line of sight of each other.

And with 2.3M customers, that's an average 1.7 Mbit/s per customer, or 550 GB per customer per month, which is kinda high. The average American internet user probably consumes less than 100 GB/month. (HN readers are probably outliers; I consume about 1 TB/month).

garciasn2• 2 years ago

Netflix uses 3-7GB an hour. The average person is spending 4-5hrs a day watching TV. I’d say most are above 100GB/month.

But that’s me.

kuchenbecker• 2 years ago

Do you have a source on the 4-5 hrs?

lillecarl• 2 years ago

Yep, but that data originates from the providers network and never leave the providers network, so they probably don't count it towards your usage the same way.

I don't think that breaks net neutrality either, which the FCC seems to be reimplementing

Edit: see https://openconnect.netflix.com/en/

seemaze• 2 years ago

Who has 4-5 hrs a day to watch television? ..or am I completely out of touch?

tonetegeatinst• 2 years ago

Yeah 1TB seems average for anyone in IT who is really into data.

I'm kinda pissed their is no local ISP competition in my area....and iv tried reaching out to companies with little success...or they say were expanding to your area soon but will not say when.

10GB symmetric fiber isn't hard. Hell I'd use more bandwidth if I could but I'm stuck with no fiber atm

londons_explore6• 2 years ago

Data might get counted multiple times as it takes many laser hops to reach its destination.

mrb3• 2 years ago

Good point.

yosito• 2 years ago

I think the average Instagram or TikTok user must be using more than 100GB/month. And if you count YouTube and Netflix, it's probably more than that.

calvinmorrison• 2 years ago

Is resolution going to peak? Like speeding on a highway are there diminishing returns? On the other hand, bandwidth availability seems to also drive demand...

bluedino• 2 years ago

This is being downvoted but it's probably about right.

bhdlr• 2 years ago

My smart TV used 483 GB in the last 30 days

jgalt212• 2 years ago

And with 2.3M customers, that's an average 1.7 Mbit/s per customer, or 550 GB per customer per month, which is kinda high. The average American internet user probably consumes less than 100 GB/month.

Dead internet theory (alive and well!)

StanislavPetrov• 2 years ago

"Customer" may refer to households, not individuals, in which case it could be numerous internet users soaking up data per customer.

schiffern4• 2 years ago

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 maintained for weeks at a time"

mrb3• 2 years ago

FTA: "in some cases, the links can also be maintained for weeks at a time"

I think there is a lot of variance. The article also states about 266,141 “laser acquisitions” per day, which, if every laser link stayed up for the exact same amount of time, with 9000 lasers, means the average link remains established for a little less than an hour: 9000 (lasers) / 266141 (daily acquisitions) * 24 * 60 = 49 minutes

So some links may stay established for weeks, but some only for a few minutes?

Gravityloss• 2 years ago

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

gleenn• 2 years ago

Just because they seem grossly underused, there are probably plenty of other non-ideal constraints like power usage for instance.

dredmorbius2• 2 years ago

Thermal management is also a tremendous problem in space. All power generated must be radiated away, and satellites effectively sit inside a vacuum insulator.

I'd be interested in what the sustained power/thermal budget of the satellites is.

robomartin• 2 years ago

That means each laser is grossly underused on average, at 0.432% of its maximum capacity.

Don't forget that every communication protocol has fixed and variable overhead.

The first is a function of the packet structure. It can be calculated by simply dividing the payload capacity of a packet by the total number of bits transmitted for that same packet.

Variable overhead is more complex. It has to do with transactions, negotiations, retries, etc.

For example, while the theoretical overhead of TCP/IP is in the order of 5%, actual overhead could be as high as 20% under certain circumstances. In other words, 20% of the bits transmitted are not data payload but rather the cost of doing business.

feedsmgmt• 2 years ago

Where did you get that 100GB/mo number from? 4K streaming eats up data transfer quickly. Comcrap & friends knew what they were doing making arbitrary data caps that sounded like a big number at the time. Wireline data caps should be illegal.

bottlepalm• 2 years ago

Most customers aren't served by lasers, their data goes up to the satellite and down to the nearest gateway. Lasers serve customers out of range of a downlink gateway, and the traffic probably travels the minimum hops needed to get to one.

whazor• 2 years ago

But with lasers, it makes sense to route your packets via space. For example traffic to a different continent would be faster (and cheaper) through space. Furthermore, I assume lasers have more capacity than gateways, so they could increase capacity of one satellite by bundling with more gateways.

janalsncm• 2 years ago

There’s probably redundancy in the links. In other words, A sends a MB to B which sends it to C, that’s 1 MB of information transmitted to customers but 2 MB of laser transmission.

cranberryturkey• 2 years ago

if you stream you use a lot more than 100gb/month. I use around 1tb with a family of 3.

Hadriel• 2 years ago

i think even more relatable is how many customers they can handle at say 200 mbps

p1mrx• 2 years ago

The first slide says "9000+", suggesting that the number of space lasers is slightly over 9000. I feel like that's an important distinction.

Tade0• 2 years ago

Most likely it's a reference to the "it's over 9000!" meme.

deepGem• 2 years ago

There is one key issue of keeping lasers aligned for long durations between satellites and even between a satellite to a ground station. There are vibrations in satellites and even a tiny bit of that vibration translates to beam misalignment. Am not an expert though. That could explain the bursts.

So it's hard to sustain the theoretical 100GPS connection for hours let alone days across 2 end points which are in constant motion.

hnaccount_rng• 2 years ago

I’d have guessed they count “delivered bytes” not “transmitted bytes” and then you need to take into account each leg of the transfer. Which for starlink is at least two (for the simple bend pipe situation) and up to potentially something like ?20? (for a “halfway around the globe, totally starlink” connection). The latter is probably statistically negligible, but even the factor two would give ~2% utility. Which, taking into account, that at least 2/3 of the orbit time is spend out of reach of anywhere useful, this would give something like 1 in 10 possible bytes being transmitted. Which is much better than I’d have guessed if asked blindly

try_the_bass3• 2 years ago

That means each laser is grossly underused on average, at 0.432% of its maximum capacity. Which makes sense since 100 Gbit/s is probably achievable in ideal situations (eg. 2 satellites very close to each other), so 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 and no longer are within line of sight of each other.

I think I agree that each laser is grossly underused on average, but if you read the article, there's quotes about the uptime of these links. They're definitely not just "used in bursts [of] a few tens of seconds or minutes".

mensetmanusman4• 2 years ago

My parents moved in and, being old, stream TV all day (instead of cable) and end up using about 40 GB per day with 1080p. We keep hitting our max of 1.2 TB set by our cable company (because there are others in the home!).

I should probably see if my router can bandwidth limit their mac addresses...

bcrl• 2 years ago

I'm seeing about 6Mbps per customer during peak hour on my own network, so 1.7Mbps over a longer period of time sounds like it's in the right ballpark.

p_l2• 2 years ago

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.

inemesitaffia4• 2 years ago

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

edmundsauto• 2 years ago

The average household probably watches significantly more tv than HN users. That is almost all streamed - something like 6 hours per day times multiple TVs.

1tb feels reasonable to push that much video.

Havoc2• 2 years ago

In the long run that could become a massive strategic advantage for the US. A 2nd layer of resilience over undersea cables

bagful• 2 years ago

A privately-held strategic advantage?

supriyo-biswas• 2 years ago

Offloading the risk on private players, reduces the amount of government investment required, and shields them from any criticism, should the project fail.

Also, if it is that strategically important, the government can just buy SpaceX.

roywiggins2• 2 years ago

It doesn't really matter who owns it as long as it can be bent towards national goals when it matters.

American vehicle manufacturing was a strategic advantage during WWII because they swiftly pivoted to selling tanks to the government instead of cars to civilians.

dotnet00• 2 years ago

Plenty of US strategic advantages are privately held or otherwise very dependent on the private sector. It's fine because the company can't really leave the US.

Havoc2• 2 years ago

At that level of strategic usefulness ownership stops mattering if shit hits the fan. It'll simply get commandeered.

lannisterstark2• 2 years ago

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

le-mark• 2 years ago

Real time video and telemetry for military drones that’s nearly immune to electronic warfare counter measures is the real end game. The fpv drone carnage in Ukraine is currently limited to the contact lines plus or minus a few kilometers. Satellite comms change that drastically. Yes it’s available now but highly restricted.

techopoly• 2 years ago

But not immune to missiles. Russia's already threatened to target Starlink satellites. Maybe they're bluffing, or not, but it does offer a reminder that these are just floating computers in the sky.

usrbinbash• 2 years ago

A strategic advantage depending on the whims of a single provate company.

Sounds great, what could possibly go wrong?

itomato• 2 years ago

Assuming imminent domain and pursuant seizure.

throwaway2037• 2 years ago

Somewhat tangential: I assume that Starlink is not yet profitable. How many customers do they need to become profitable?

BluSyn• 2 years ago

I recall reading they were profitable on a quarterly basis at end of 2023.

mmaunder• 2 years ago

The amount of bleeding edge innovation that is rapidly developed and deployed into production in Musks companies is incredible.

itsoktocry2• 2 years ago

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.

misiti37802• 2 years ago

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 ?

hk1337• 2 years ago

Isn’t the user experience with starlink pretty abysmal for the average user? Both the service and the customer service?

inemesitaffia4• 2 years ago

It's pretty average ish.

You can try it out for 30 days and form your own opinion.

karim79• 2 years ago

Has anyone tried Starlink? I super curious as to whether it's a decent drop in replacement for the ISP have been using at home, and have had trouble with since day one. I won't mention any names (but I will say that it sounds a bit like Smodabone). What is the latency like? The variability of the up/down? Does it do what it says on the tin? Is (non-professional) online gaming a go?

freedomben• 2 years ago

Been using it since it was first available. Latency is fine, speeds are good and steady. Occasional outages of several hours every few months or so, but improving as time goes on.

Only complaint is that their DHCP server is buggy so if you don't use their blessed router, you can expect outages when you get transitioned to a new base station and starlink expects your IP to have changed, but it doesn't, or sometimes when your IP lease expires. Took me months to figure out that was the issue. I run almalinux on my router so I just have a script that checks a heartbeat and if it gets interrupted it will nmcli down the wan interface and back up, which usually gets a new IP. Though sometimes it will give the special IP to my router that is supposed to go to the blessed router.

Overall I do recommend, but have a backup ISP if always up is important.

madaxe_again• 2 years ago

My experience, a year of use - 300Mbps down pretty consistently, 40Mbps up, 40-60ms latency, fine for gaming for the most part, and the drop outs are unnoticeable short when they do infrequently happen. Never had an outage more than 10 seconds.

They’ve also nearly halved the price since I signed up.

itsoktocry2• 2 years ago

Has anyone tried Starlink? I super curious as to whether it's a decent drop in replacement for the ISP have been using at home

I use it when I'm venturing around my rural area, which has spotty (or zero) LTE and broadband. It's awesome for that, literal game-changer.

But it does suffer from downtime, sometimes poor reception, bit of lag, etc. It's the difference between 99% uptime and 99.999999%; you'll notice if you're using it all day, every day. It's also more expensive than my home broadband for lower speeds. I don't think you could replace your ISP, unless your ISP is pretty bad.

mise_en_place• 2 years ago

4 nines uptime is great, but I would think the SNR matters more in a packet switched network like this. There are conditions that may lead to a very low SNR.

mrbonner• 2 years ago

Wait, I thought only Kuiper has laser.

gggggg1• 2 years ago

Kuiper tested 1 laser

hasoleju2• 2 years ago

I just noticed that they were launching their first satellites in 2019. It's impressive that they are now able to casually talk about the different routing options for the data streams to remote areas just 5 years after that.

At first this sounded like an utopian dream but now it looks like common infrastructure that has a place in everyones life.

This must have been the same feeling when the first landlines were installed. The very first lines were a sensation and then after only a few years it becomes normal quickly.

loceng2• 2 years ago

I think it's likely a bad idea at this point to bet against Elon - he seems to make more good decisions than bad decisions, and is able to attract and keep the talent that is enabling his companies to snowball exponentially towards reaching the abundance of the universe.

My deepest hope currently is that the riches of the universe now on the horizon of being relatively easily accessible, in a systematic and efficient way, will lead to the military industrial complex profit seeking to redirect their efforts to mining the riches of the our solar system and beyond, rather than likely mostly inadvertently driving for hell on Earth.

robbiep3• 2 years ago

Past performance is a piss poor indicator of future performance.

You can’t deny (I don’t think) that the things he’s done are amazing. He’s in the zone where he’s smelt too many of his farts though, and believes he can do no wrong, which is historically a very bad place to be. I hope, for all of the awesome things he’s said he’d like to do, that they don’t come agutsa due to that

eterevsky• 2 years ago

That's around 3.9 Tb/s, in case you are wondering.

hypertele-Xii• 2 years ago

Is it possible one of these laser satellites miss and hit you in the eye? Would that blind a man?

hasoleju2• 2 years ago

No. The focus of a laser beam is not constant over these large distances. It is the same effect you get if you use a laser pointer over large distances. The spot becomes large quickly.

Denote6737• 2 years ago

3.65 days of downtime isn't going to be winning any prizes.

vardump2• 2 years ago

If near a ground station, can't the satellites just use their standard radio links to cover that?

Might be an issue for Antarctica and major seas.

gotmedium• 2 years ago

When will we see data centers in space?

ryankrage77• 2 years ago

I think the biggest hurdle would be heat dissipation. Solar power is plentiful, but all that energy then has to be radiated away somehow.

ijhuygft776• 2 years ago

This post currently has 420 points, I bet Musk would like that (wont vote to keep it this way)

testemailfordg2• 2 years ago

My novice view....Laser connections are point to point, so they can be between satellites....But to the end user equipment,having those many point to point laser connections might be too difficult or impractical to achieve...So that's where they use radiowaves, which means any satellite over the horizon can talk to a dish...

sheepybloke• 2 years ago

Just for context, here's SDA's Open Standard on how they expect to do connections over Optical Links. I assume the starlink terminals work in a similar manner:

https://www.sda.mil/wp-content/uploads/2023/06/SDA_OCT_Stand...

sonicanatidae• 2 years ago

But how much of that data is insane right-wing conspiracy theories? lol

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

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