Starlink's laser system is beaming 42 petabytes of data per day
pcmag.com
pcmag.com
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).
But that’s me.
300+ minutes a day for TV + vMOD (streaming services). Since no one actually watches TV anymore, at least not through traditional TV, I summed them.
I don't think that breaks net neutrality either, which the FCC seems to be reimplementing
Edit: see https://openconnect.netflix.com/en/
I think a few hundred GB for a typical cord-cut household is about right.
T-Mobile absolutely counts all data used over the network, my voice lines go QCI 9 (they are normally QCI 6) when over 50GB of any kind of data usage each month, the home internet lines are always QCI 9. I don't have congestion in my area so it does not affect my speeds. This is QoS prioritization that happens at physical sector level on the tower(s).
Imagine they put 10TB of flash memory on the satellites and run virtual machines for the big CDN companies (cloudflare, Google, Netflix etc).
I reckon that 10TB is still big enough to service a good little chunk of internet traffic.
You have to share that 10 TB with everything on that satellite's orbit.
Most ISPs have CND appliances in their racks to save on uplink bandwidth. And from a satellite perspective the uplink (in this scenario: the downlink from the satellite to the gateway) definitely is the expensive bottleneck.
You want to avoid congestion and every bit of caching could be helpful.
Then it comes down to the mass and power budget (and the reliability of flash drives in space) - but that doesn't seem too terrible.
Maybe I just grew up in a quiet place.
We're outnumbered.
Personally I need almost complete silence in order to get anything done, his abilities in this regard always fascinated me.
It's useful for some people to have recognisable sounds going on while they work, so they have something to latch their focus if they lose it for a second. Whether that be music, or every seinfeld episode on a shuffled loop on the TV.
I have found it useful in the past to listen through every song I have on shuffle while I read, which was nice when I took a few-seconds break every couple of pages and came across a song I wouldn't have picked out otherwise. Alt-tabbing out of a podcast or something completely wrecks my focus on both for some reason though.
If it's dead quiet, I become hyper-alert to noises, to the point I can't concentrate on working.
For some it is just the illusion of having more people around them, though.
I would kill for some decent high res wide fov AR glasses.
kids these days mostly use youtube or twitch for background noise i think
Even back to 1950, for per household data, it was above 4 hours.
[1] https://www.nielsen.com/insights/2009/average-tv-viewing-for...
They didn't have per person for the 1950 to 1990 data, only household (pdf in the link).
Men spent 3 hours a day watching TV, and women 2.5 hours. But TV time is lower (around 2 hrs/day) from ages 20-44, then increases again after 45 and peaks at 75 years old at nearly 5 hours a day.
Households without kids watch more TV, which surprised me.
I'm not sure that's saying household time. For example, when they survey a household it wasn't clear to me if they survey everyone in the household or just one person. If it's one person then it sounds like they collect how that one person (age 15+) spent their own time and if there were kids in their household.
So then it'd be accurate to say that individuals in households without kids watch more TV as a singular activity (the survey doesn't allow simultaneous activities).
In comparison Nielsen used TV viewing diaries and automated data collection meters. You could have the TV on in the background while doing chores and it would still count.
It's interesting that the 2009 ATUS survey [3] had a 2.82 hour/person average because that's fairly different from the Nielsen data (4 hours 49 minutes/person).
I wonder if this difference is people underreporting in ATUS or Nielsen overreporting or a factor of differences in limitations in ATUS (no simultaneous activities allowed, 15+ age limitation) or Nielsen.
[1] https://www.bls.gov/opub/hom/atus/data.htm
[2] https://www.bls.gov/tus/questionnaires/tuquestionnaire.pdf
[3] https://www.bls.gov/news.release/archives/atus_06222010.pdf
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
It should. At some point you are beyond any difference a human eye can detect on a tv or monitor you’re sitting less than 10ft away from.
It probably won’t though because capitalism means there has to be a reason to sell you a new widget and 3D was an utter failure.
not for awhile. apple vision / oculus will stream (4k/8k) 3d movies.
There's of course a limit. The "native" bitrate equivalent of your retina isn't infinite.
Next step though is going to be lightfield displays (each "pixel" is actually a tiny display with a lens that produces "real" 3D images) and I assume that will be a thing, we shall see if it does better than the last generation of 3D TVs/movies/etc. That's a big bump in bitrate.
There's also bitrate for things like game/general computing screen streaming where you need lots of overhead to make the latency work, you can't buffer several seconds of that.
The next gen sci-fi of more integrated sensory experiences is certainly going to be a thing eventually too. Who knows how much information that will need.
When more bandwidth becomes available, new things become possible, sometimes that are hard to imagine before somebody gets bored and tries to figure it out.
When I'm futzing around with ML models, I'm loading tens of gigabytes from disk into memory. Eventually something like that and things orders of magnitude larger will probably be streamed over the network like nothing. PCIe 4.0 x16 is, what 32 GBps? Why not that over a network link for every device in the house in 10 years?
Resolution is always determined by angular resolution at viewing distance, even for analog TVs(they were smaller and further away), and also,
Videos on Internet is always heavily compressed - the "resolution" is just the output size passed to the decoder and inverse of minimal pattern size recorded within, technically not related to data size. Raw video is h * v * bpp and have always been like low to dozen Gbps.
Just my bets, the bandiwth may peak or see a plateau, but resolution could continue to grow as needed for e.g. digital signage video walls that wraps around buildings.
Dead internet theory (alive and well!)
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"
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?
I believe Starlink (like Iridium) doesn't even try to establish connections "across the seam," ie the one place the satellites in the adjacent plane are coming head on at orbital speed.
This make side-linking easier because the relative velocity is comparatively low, but in general you unavoidably still need to switch side-link satellites (on one side) twice per orbit. Hence 49 minutes: this average must be calculated per connection not per second, so the front/back links (plus random noise) count less, so it only drags the average from 45 minutes up to 49 minutes.
The slide showing the multiple possible paths traffic can take seems to disagree with this statement?
However looking at other sources, it seems Starlink (having more satellites) actually wraps the orbital planes 360° around the Earth (vs Iridium's minimalist 180° configuration), overlapping both North-moving and South-moving satellites in the same sky simultaneously. This means the Iridium seam disappears entirely. Neat! TIL.
Another problem that vanishes simply by being "hardware rich."
So actually this Iridium-type "seam" disappears, meaning that every satellite should always have co-orbiting "neighbors" on both sides. Cool!
[0] https://en.wikipedia.org/wiki/Right_ascension_of_the_ascendi...
I'd be interested in what the sustained power/thermal budget of the satellites is.
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.
You can't freely blast radio waves into a country without falling subject to its varying regulations, but the regulations for "pre Starlink" satellite broadband/phones/etc are fairly well established.
So it's hard to sustain the theoretical 100GPS connection for hours let alone days across 2 end points which are in constant motion.
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".
I should probably see if my router can bandwidth limit their mac addresses...
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.
I don't believe the AF spent anything more than 100m for whatever R&D program. And the money was post development.
Was it a black budget thing?
1tb feels reasonable to push that much video.
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.
“ 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...
There's an animation on linked article that explains this pretty well: https://upload.wikimedia.org/wikipedia/commons/thumb/9/90/Ir...
The wikipedia link above explains it well:
""" Orbital velocity of the satellites is approximately 27,000 km/h (17,000 mph). Satellites communicate with neighboring satellites via Ka band inter-satellite links. Each satellite can have four inter-satellite links: one each to neighbors fore and aft in the same orbital plane, and one each to satellites in neighboring planes to either side. The satellites orbit from pole to same pole with an orbital period of roughly 100 minutes.[8] This design means that there is excellent satellite visibility and service coverage especially at the North and South poles. The over-the-pole orbital design produces "seams" where satellites in counter-rotating planes next to one another are traveling in opposite directions. 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. """
The 'seams' have interesting implications for latency when I was working on Global Data Broadcast.
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.
> 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.
The customer terminals will likely never connect through lasers (because a laser can only point in one direction at a time), but moving the ground station uplink to a laser link sounds very beneficial.
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.
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.
Apparently it only happens above/below 68 degrees latitude, so the next satellite with a working inter-orbital-plane connection is at most one hop ahead or behind.
https://spaceflight101.com/spacecraft/iridium-next/ has some more photos and diagrams; seems like they're really mechanically steered even on the NEXT constellation.
Additionally, their inter satellite links use regular Ka band radio.
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.
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?
On wavelengths, if you're trying to hit 100gbit+, you're probably having to use coherent optics, and there aren't many technology options or wavelengths on the market.
You'd normally achieve this by transmitting a well-known pseudorandom sequence. You also need clock stability into the ppb range.
A path loss of 110 decibels is huge. It can easily account for your lenses being hugely off axis.
https://en.wikipedia.org/wiki/Shannon%E2%80%93Hartley_theore...
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.
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.
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.
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
The things he's _purchased_ are amazing.
The man has a lot of flaws and since covid drifted into ideologies I don't agree with. I also wouldn't buy a Tesla. But there is no denying that both Tesla and SpaceX revolutionized their respective industries. And it seems safe to say that neither would have managed to do this without Musk. And at least SpaceX manages to sustain a substantial lead over the competition and continues revolutionizing industries.
I would venture a guess that the bulk of Elon animosity started exactly at twitter acquisition time, when the people selling the narratives lost their merchanting channel and so they made sure to poison the well beforehand.
He is also a founder at Tesla, as when he entered the round A financing Tesla was just three guys, some networking, and nothing more. Even the "Tesla" trademark and logo registration was made by SpaceX people. He didn't found his own car company with just J. B. Straubel (another Tesla founder who was being paid by him to develop electric car batteries at the time) because he thought it would be better to cooperate with that other group that was was inspired by the same idea and he though he would be able to concentrate more on SpaceX that way. He was wrong and had to take the CEO position on Tesla later to avoid bankrupcy, move the Model S design headquarters to SpaceX, etc. And it's now nothing like what it was when he first put money on it.
If you have enough real-world data, and learned the patterns of history, along with fundamental principles that seem to be precursors or prerequisites to change, then a prophet is more or less someone with a honed and an extended-expanded open mind neural network compared to most.
P.S. It's why it's a really good idea to allow immigrants fleeing from communist countries, as they'll be best and perhaps first to detect and sound the alarm bells if fascism patterns begin to emerge in their new country.
This is such a baseless and almost comically wrong heuristic I'm curious how it's one you landed on. I'm earnestly curious, do you use the same heuristic in other areas of your life?
If you were in the market for a car, would you let the past performance of other vehicles you've owned influence that decision? It seems to me to be such a simple and fundamental part of decision making, I'm fascinated you've gotten along thus far without it.
Really?
It's my understanding Elon isn't popular anymore (I could care less), but this point does not help whatever it is you're trying to say. I deal a lot with statistics and making predictions from past performance, and you most definitely can determine future performance with a high amount of accuracy. This shouldn't really need said.
You are probably right about him smelling too many of his farts, but you really hurt your main thesis right off the bat with that first claim.
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.
Per day?
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.
-- Andrew Tannenbaum
https://info.cobaltiron.com/blog/petabyte-how-much-informati...
1GB flash drives are still 1GB today.
>256 GB is now common, which would make that petabyte less than 1 football field. (It's only 4096 such drives.)
If we're completely changing what we're using for scale, you can fit a petabyte on ~10 100TB drives, which is like 3% the length of an olympic swimming pool.
is it supposed to be actual football one or the field for handegg?
As a side-note Canadian Gridiron football uses a longer field than American Gridiron football, though (measuring between the goal lines) still slightly shorter than a typical Association Football pitch.
Australian Rules Football is on a field typically longer even than an Association Football pitch, though I don't believe there is a regulation limiting the size.
ftp.ebi.ac.uk for example.
Edit: It's international traffic. YouTube, Facebook video has local cache server by ISP.
- 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
Which also makes me wonder how many of the shooting stars I've seen recently are just old starlinks burning up.
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!
I don’t remember the details anymore, but it was one of the coolest practical experiments we did.
And of course, if it is 3am, and there is no sunlight at any altitude because the sun is on the other side of the world, no satellites are visible.
I could be wrong.
I don’t know how you would know that. People are very bad at seeing distances at these scales.
If they were indeed satelites they could be starlink satelites. They are put into orbit as a bunch together and then they spread along their orbital path as they take up their position.
This article has a picture, maybe you can check if it is similar to what you have seen? https://earthsky.org/space/spacex-starlink-satellites-explai...
If you could recall more details then maybe we can figure out more exactly what this might have been. (Such as where you were, which direction you were looking at, when did this happen, how fast did they cross the sky and how far the dots were from each other. Were the line spread in the direction they were moving or sideways?)
You should try to find one once, with the help of an app. It's not that difficult.
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.
ISS is often visible in the middle of the day even in bright midday Southwest sun, if you know where & when to look.
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.
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.
https://www.timeanddate.com/astronomy/different-types-twilig...
It's been awhile, but I'm pretty sure I've seen these much later than that. I'm talking about lying in a sleeping bag, looking up at the amazing starfields of pitch-black wilderness nights (tip: never use a tent except in extremis - look what you're missing!).
I would guess, reflected moonlight (moon over the horizon) would be enough to light up the dot well enough to see unaided.
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.
Yup 5-10 minutes is right. It depends on the orbit altitude and the height of the pass.
You can use sat tracker apps to identify which one you're seeing. I do this sometimes because I'm a ham radio operator and I track the one I want to use sometimes with a directional antenna.
> No way a star is moving that fast relative to other stars
No star moves relative to other stars when viewed from earth. They are all so far away they appear static. The starscape rotates as a whole (well it doesn't, the earth does, but to the observer it seems that way), but relative to each other they absolutely don't move.
If they do move, it is definitely a sign to stop drinking :) :)
> Asteroid? That seems hard to believe, due to size and illumination.
Also asteroids move way faster across the sky than a satellite. And they're rare except during that time of the year when they're really common.
> Comet? Are there lots of tiny ones? I never see tails.
Comets are incredibly rare in this galactic neighbourhood.
> 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.
And the distance - most asteroids pass by much further out than even the moon, so their motion would be hard to detect.
Higher orbits are visible for longer, due to the angles involved: because they're so high, such satellites can remain illuminated with the Sun further below the horizon. The Moon is the most extreme example: it's almost never in Earth's shadow.
Very good point.
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.
The flashing of satellites will generally be gentler than the short burst strobing of an aircraft.
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/...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.
Put another way, every kilogram of Starlink spacecraft has as much energy "stored" in it's motion as around 4-5 tons of TNT.
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.
[1] https://spacenews.com/spacex-launches-fourth-batch-of-starli...
Now, none of this is an actual problem as they're entirely demisable, but the statement that they can achieve controlled de-orbit is false.
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.
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.
Starlink satellites are pretty well aerodynamically balanced when in their "ducked" orientation, but are not going to be able to overcome aerodynamic torques below 200 km or so, meaning they will be unable to point their thrusters in target directions. At that point, there are still 1-2 days before reentry will occur. Hour-to-hour variability in tropospheric atmospheric density due to solar flux levels and geomagnetic activity means that the precise reentry time will be unpredictable to within a few hours (which equates to anywhere along the ground track of a few orbits).
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?
They also want to make Starlink satellites bigger, which also requires Starship's much larger diameter.
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.
> 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)
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.
It's a thrill to think about that. Starlink is really out there.
I bet this is lost on a lot of people. Not to patronize anyone, but what Tuna-Fish is pointing out is that due to the speed of light, the distance between satellites and their relatives velocities, when one satellite is beaming data to another satellite it must aim where the receiving satellite will be, as opposed to where it is now, when the light arrives. Further, the receiver must be looking at where the transmitter was back when the signal was sent, as opposed to where the transmitter is now. And because this is all bidirectional, each satellite must send and receive in different, continuously changing directions at the same time.
Assuming the lenses are about 2 inches across (from photos) and they are 1310nm IR lasers:
https://www.wolframalpha.com/input?i=single+slit+diffraction...
So we have a minimum beam width of 0.0014 degrees.
And the speed of light round trip distance is say 3.3 milliseconds.
So the question is, does the angle between the satellites change faster than 0.0014/0.0033 = 0.42 degrees/second?
Well the worst case is one satellite heading north at 7.4 Km/s and another heading south at 7.4 km/s. Lets assume the satellites are 550 km apart (the distance between planes at the equator), and use the small angle approximation... Comes out as 1.4 degrees per second.
So yes, these satellites do need the ability to aim transmit and receive in different directions! (although they might be able to just defocus the beam a little when angles are changing fast to trade off throughput for design complexity)
Even the original ones weren't that small weighing 570lb.
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.
Maybe the future of usb in 10 years :)
Also, if it is that strategically important, the government can just buy SpaceX.
https://en.wikipedia.org/wiki/Defense_Production_Act_of_1950
American vehicle manufacturing was a strategic advantage during WWII because they swiftly pivoted to selling tanks to the government instead of cars to civilians.
Which isn't unprecedented. But it's also far from the equivalence your comment suggests.
and commercial cargo transport.
And lots of other stuff.
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.
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.
And you can't just wave around "hacking the control plane". Russia's been trying to interfere with Starlink for a while and they haven't had any long term success. And finally, even if the did somehow get access to the control systems at SpaceX, the satellites can't de-orbit quickly. It takes weeks to de-orbit, over which time they could be commanded to reverse course.
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 debris, so they can't act to form further debris.
The reason it's a scary outcome is because it's an exponential. It can look like an isolated incident or incidents, then the next day be not practically stoppable.
And I'm telling you, your "image" of what this looks like is just incorrect. The kessler syndrome is likely already occurring. Yes creating more debris will make it happen more, but it's not like lighting a match to a pile of tinder.
And it's not in fact exponential in the sense that people commonly imagine when they hear that. It's an exponential that's very close to flat, i.e. an exponential with an exponent barely above one. Given enough time, yes it can destroy all satellites in Starlink's orbit, but it's not on time scales that's relevant to a war.
I’m sure I’m missing something but it just seems like a no brainer to make the deorbit process speed up with something relatively failsafe, as opposed to hopefully/maybe saving a bit of fuel to push it that way eventually
Satellites do have deorbit thrusters, but they're a lot more deliberate. I think Starlink have a whole separate remote controllable system just for deorbit control.
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.
The effort of getting a ballistic trajectory that peaks at 500km is a lot smaller than reaching a stable orbit of that height. And just like WWII aircraft you don't need to hit them, just produce enough shrapnel in their vague vicinity.
The biggest hurdle is the universal international condemnation you would receive for such an act
I should add that anti-satellite missiles are _large_ missiles. The missiles of this size in the US arsenal are SM-3 missiles (or larger). The number even the US has is only in the high hundreds to possibly low thousands. That's completely out of the ability of Russia. It's maybe possible for China but not in their current stockpiles.
Laser beams are also the replacement for ASAT.
Sounds great, what could possibly go wrong?
I can't figure out what this sentence means.
SpaceX for sure.
Hard to argue that Tesla is "bleeding edge" anymore; they maintain some advantages, but have fallen behind in other domains.
FSD12 is end-to-end neural nets and the videos are pretty impressive. Who else is doing that ?
Won’t beat HF radio though.
"The speed of light in air is about 299,705 kilometers per second, or 2.99705 × 10^8 meters per second. This is almost as fast as light travels in a vacuum, slowing down by only three ten-thousandths of the speed of light."
So seems like the speed of light in atmosphere is still a lot faster than fiber.
This would be huge for realtime gaming across continents.
You say sans routing latencies, but these are very much significant for intercontinental communication:
I get 6ms ping to AWS eu-central, which is less than 100km by air from me. I get 114ms to AWS us-east-1, which is roughly 6500km. Now 6500km / (2/3 * c) = ~32ms. So if there were a fibre running in a straight line, time in the fibre would be 32ms. Of course it isn't running in a straight line, so let's say 50ms are pure "light traveling through fibre". Switching all of that to hollow-core would cut that to 33ms, so that's a savings of 17ms or roughly 15% of my total latency.
This is still a very nice savings, but very far off from cutting latency in half.
(Also, it's a single hop from my company network to DE-CIX, one of the largest internet exchanges in the world, so I feel confident saying my results aren't skewed by a bad uplink.)
I see folks in the Pentagon doing a collective /phew that this project is online in the next decade, multiple times.
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.
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.
There was company recently wanting to do high-frequency trading on HF because of the quickest path.
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.
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.
Lets not forget about clouds, birds, airplanes, hot hair balloons and tons of other things that separate the ground from space.
We have protocols and networks already designed today that deal with this exact problem.
Aside, but it's not left to chance. They only launch when there's a gap in the space traffic.
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.
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
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?
If you’re in low earth orbit you’re traveling through rocket exhaust. That doesn’t mean you’re seeing enough to affect optical transmission gain. Or orbital decay. But the notion that you’re going to miss because there’s 100’s of kilometers between fast moving satellites? That’s the part of this conversation that deserves condescension, if anything.
But practically what happens is the phone connects to a sat, the sat connects to a local ground station, then across conventional fiber to another ground station, up to a sat and then down to the other phones.
The are likely doing that because regulation and so on. But the do what you suggest.
PCMag serves me English, with "en-GB,en", though I don't know if they would support Danish anyway.
I can hear the SI crying.
https://www.sda.mil/wp-content/uploads/2023/06/SDA_OCT_Stand...
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.
They’ve also nearly halved the price since I signed up.
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.
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.
Might be an issue for Antarctica and major seas.
I dont think theres anything having to do with seams or fabric in this conversation
You can try it out for 30 days and form your own opinion.
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.