[HN Gopher] Starlink's laser system is beaming 42 petabytes of d...
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Starlink's laser system is beaming 42 petabytes of data per day
Author : alden5
Score : 103 points
Date : 2024-01-31 05:31 UTC (1 days ago)
(HTM) web link (www.pcmag.com)
(TXT) w3m dump (www.pcmag.com)
| scohesc wrote:
| 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 wrote:
| [dupe] https://news.ycombinator.com/item?id=39199368
| dang wrote:
| OP was posted earliest so I guess we'll merge the other threads
| hither. Thanks!
| advisedwang wrote:
| 42M GB Per day = 3.9tbps
| ble wrote:
| 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 wrote:
| 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.
| Scoundreller wrote:
| 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.
| ..
| moffkalast wrote:
| Don't all satellites orbit in the same direction? Launching
| retrograde is just throwing away free velocity.
| nightpool wrote:
| In the context of the full article (https://en.wikipedia.
| org/wiki/Iridium_satellite_constellatio...), it's clear
| they're talking about the polar orbits used by the
| Iridium constellation, which have "seams" around the
| Atlantic and the Pacific as the "first" set of satellites
| passing north-to-south overlap with the "last" set of
| satellites coming back south-to-north on the other side
| of their orbits. So of the 6 orbital planes used by the
| Iridium satellites, each plane covers 1/12th of the globe
| for each "half" of its over-the-poles orbit. So there are
| two "seams" where handoff is not supported, one off the
| eastern seaboard and one roughly over Japan.
|
| There's an animation on linked article that explains this
| pretty well: https://upload.wikimedia.org/wikipedia/commo
| ns/thumb/9/90/Ir...
| moffkalast wrote:
| Ah I didn't realize they have all of their stats in polar
| orbits, that's interesting. Starlink is mostly equatorial
| afaik, the higher latitudes aren't very well covered.
| lxgr wrote:
| Most of Starlink's orbits have an inclination of 53
| degrees, which I wouldn't really call equatorial anymore.
| amlozano wrote:
| The Iridium satellites are in what you might call
| "parallel" orbits, if you stretch the meaning of the word
| a little bit.
|
| 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.
| amlozano wrote:
| There were some experiments with communicating over Iridium
| to small cube-like sats back in the day, but we couldn't
| make the system on a chip beefy enough to do the Doppler
| shift calculations on the fly and survive a launch; it was
| close though. I think its possible to do now.
| ble wrote:
| Links between satellites closing range near 2x orbital speed
| have two problems: - bigger doppler - the lifetime of the
| link is much shorter
| ortusdux wrote:
| > "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.
| Symmetry wrote:
| Right. The Iridium network had communication between satellites
| in different orbital planes passing each other but that was a
| pretty unusual capability.
| Scoundreller wrote:
| 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.
| lxgr wrote:
| Supposedly they use steering, since the horizontal azimuth
| to adjacent-plane satellites varies from 0 to 65 degrees
| across an orbit:
| https://apps.dtic.mil/sti/tr/pdf/ADA348174.pdf
| akira2501 wrote:
| 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.
| sephamorr wrote:
| 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.
| stcredzero wrote:
| GNC?
| Rebelgecko wrote:
| Guidance navigation and/or control
| nightpool wrote:
| Guidance, navigation and control
| malablaster wrote:
| geostationary nanometer circuit
| ble wrote:
| 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.
| _0ffh wrote:
| Nah, I once did a job for a guy and they did LEO to GEO alright
| iirc. (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 expensive.)
| mschuster91 wrote:
| > 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 wrote:
| Given this is Gen3 and Gen4 now being launched, it took some
| figuring out
| sumtechguy wrote:
| 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 wrote:
| > (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 wrote:
| In some important ways space is actually the least hostile
| environment. But yeah, it's still amazing and has its own
| challenges.
| polishdude20 wrote:
| 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-Fish wrote:
| 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.
| topspin wrote:
| > that you are not receiving from the same direction as you
| are sending
|
| That makes my skin crawl in an enjoyable way. Wow. 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 speeds, 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 this is all
| bidirectional.
| yencabulator wrote:
| Surely the lasers aren't phased arrays.
| ianburrell wrote:
| 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_ wrote:
| Their exact position in space can be calculated very precisely.
| The Starlink terminals do this as well.
| mytailorisrich wrote:
| 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.
| mensetmanusman wrote:
| 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 :)
| lupusreal wrote:
| > _" 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.
| mschuster91 wrote:
| 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".
| NelsonMinar wrote:
| 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.
| 7e wrote:
| 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 wrote:
| The quoted number is only for inter-satellite laser links, not
| for other methods of information transmission.
| bagels wrote:
| Most of the traffic is probably just bounced off the
| satellite down to the nearby ground station still.
| jlmorton wrote:
| 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]
| 7e wrote:
| https://www.statista.com/statistics/216335/data-usage-per-
| mo...
| sys_64738 wrote:
| Is that a lot?
| heeton wrote:
| Don't you mean 42million Gigabytes?
| Alifatisk wrote:
| Isn't that equivalent? What does it help to use GB instead of
| PB?
| heeton wrote:
| https://news.ycombinator.com/item?id=39199368
| ortusdux wrote:
| I was going to put 336,000,000,000,000,000 bits/day, but it
| seamed a bit overkill.
| MeImCounting wrote:
| *seemed
|
| I dont think theres anything having to do with seams or
| fabric in this conversation
| versteegen wrote:
| Been quite a lot of discussion of both of those things in
| this thread!
| Scoundreller wrote:
| 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.
| edgyquant wrote:
| Why would we expect faster than fibre?
| Cu3PO42 wrote:
| The speed of light in a vacuum is roughly 50% higher than the
| speed of light in fiber.
| andrewpolidori wrote:
| Is attenuation in a vacuum also better?
| mensetmanusman wrote:
| yes, glass has a non zero amount of absorption which is
| why Erbium amplification is required.
| edgyquant wrote:
| The area between a starlink receiver on the ground and a
| satellite isn't a vacuum
| gkfasdfasdf wrote:
| That's a great point, I was curious so I looked it up.
| Google offered the following:
|
| "The speed of light in air is about 299,705 kilometers
| per second, or 2.99705 x 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.
| delecti wrote:
| The speed of light in air is 99.97% of that in a vacuum,
| vs about 2/3 of c through fiber.
| ortusdux wrote:
| I will note that this is the case for conventional fiber-
| optic cable. The newer hollow-core fiber cables transmit
| light at nearly c. As far as I know hollow-core has not
| seen wide-spread use, but it will be interesting if trans-
| continental connections switch over.
| stcredzero wrote:
| Also, as pointed out elsewhere, the number of hops is the
| biggest contributor to latency.
| oger wrote:
| 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 wrote:
| 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 wrote:
| 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 wrote:
| 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_sigh wrote:
| 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?
| Scoundreller wrote:
| True, it would be bouncing around between ground and the
| atmosphere (when it works at all).
| 7e wrote:
| 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.
| bilinguliar wrote:
| Are they using Mynaric technology?
| axus wrote:
| Internet says no: https://www.cnbc.com/2021/11/19/german-space-
| lasers-company-...
| jstummbillig wrote:
| I have absolutely no idea how that number relates to any
| comparable operation. Can anyone add a banana for scale?
| adgjlsfhk1 wrote:
| 10 minutes of 4k video is ~30GB.
| jstummbillig wrote:
| 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.
| theropost wrote:
| 42 million gigabytes per day, or if we are working with
| 30GB for 10min of 4k movies - 233,000 hours of ultra HD
| movies per day
| deathanatos wrote:
| It's 42 PB per _day_ , though.
| besnn00 wrote:
| per day*
| e12e wrote:
| > 42 million gigabytes per second
|
| Per day?
| WheatMillington wrote:
| Over estimating by a factor of 86,400.
| MeImCounting wrote:
| I still dont think this is what the OP was asking for.
| This is in the context of an individual-HD video is an
| individual perspective. More helpful would be a
| comparison to say a small town or a major city or state.
| SirMaster wrote:
| 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.
| colordrops wrote:
| If you've got a laptop with a terrabyte drive, it would be
| 42,000 full laptops worth of data.
| bee_rider wrote:
| Implementing a "comparable operation" to this satellite
| network using laptops instead is going to be really expensive
| fuel-wise, I think.
| jonathankoren wrote:
| "Never underestimate the bandwidth of a station wagon full
| of tapes hurtling down the highway."
|
| -- Andrew Tannenbaum
| whycome wrote:
| > 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 wrote:
| That's actually a somewhat useful visual.
| vikingerik wrote:
| Not really unless you're using 1 GB flash drives from
| fifteen years ago. 256 GB is now common, which would make
| that petabyte less than 1 football field. (It's only 4096
| such drives.)
| dtgriscom wrote:
| You can buy a 1TB microSD card for $150 now.
| danparsonson wrote:
| What a time to be alive! Even those of us without a
| football field can lay out huge amounts of data in a
| straight line.
| tempmac wrote:
| dang I can hear the youtube channel voice
| permalac wrote:
| EMBL-EBI's open transfer systems provide ~5PB of data each
| month.
|
| ftp.ebi.ac.uk for example.
| stcredzero wrote:
| Better yet, a work in a 35 foot long Twinkie.
| new_user_final wrote:
| 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.
| MeImCounting wrote:
| This is a useful scale of comparison and what I think OP was
| after
| jstummbillig wrote:
| OP agrees
| theteapot wrote:
| 486GB/s
| nharada wrote:
| 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
| latchkey wrote:
| 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 wrote:
| How do you spot a satellite? I've never seen one.
| kirubakaran wrote:
| The Starlink ones look like Santa's sleigh
| https://i.imgur.com/4S0vbfY.gif
| qayxc wrote:
| Only directly after deployment, though.
| giancarlostoro wrote:
| Probably out in a rural area far enough away from a major
| city its easier to see them.
| TheAlchemist wrote:
| 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.
| dmd wrote:
| I live 10 miles from Boston and I've seen them a whole
| bunch. I've used
| https://james.darpinian.com/satellites/?special=starlink
| latchkey wrote:
| 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!
| aqfamnzc wrote:
| I guess they disappear as they approach the horizon because
| the light is spread/absorbed too much by going through more
| atmosphere?
| latchkey wrote:
| I actually see them disappear long before they get to the
| horizon. My guess is just less reflected light on
| whatever is shiny on the satellite.
| m2fkxy wrote:
| that and/or entering the Earth penumbra.
| krisoft wrote:
| In higschool we did an experiment with one of our science
| teachers based on this fact. We measured the duratuon of
| the iridum flares and could use some basic geometry to
| estimate how high their orbit is based on where the
| shadow of the earth is.
|
| I don't remember the details anymore, but it was one of
| the coolest practical experiments we did.
| PaulDavisThe1st wrote:
| My impression was that you can only see them as they
| reflect sunlight in your direction. As the angle formed
| between you, the satellite and the sun changes, you will
| first not see the satellite, then see, then not see it
| again.
|
| 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.
| streb-lo wrote:
| Just throwing this out there, but has anyone else seen
| 'formations' of satellites? I've only seen them once but
| there were about 5 to 10 (it was a while ago) of what I'm
| assuming are satellites moving in a line formation at high
| speeds across the night sky. They're too distant and too
| fast to be planes so I'm assuming they are some sort of
| military formation of satellites?
| unwiredben wrote:
| That's often a recently launched StarLink formation --
| the bunch up in a line when deployed, and have to be
| maneuvered over several weeks to spread out and take
| different orbits.
| krisoft wrote:
| > They're too distant
|
| 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?)
| qayxc wrote:
| 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 wrote:
| 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 wrote:
| 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 wrote:
| 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.
| yencabulator wrote:
| Yeah. With Starlink satellites, you need a lot of luck with
| the conditions to see them. I've seen them a handful of
| times and I'm in a relatively dark sky location.
|
| ISS is often visible in the middle of the day even in
| bright midday Southwest sun, if you know where & when to
| look.
| drynewton wrote:
| 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.
| HPsquared wrote:
| 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.
| WanderPanda wrote:
| I remember chasing one of the iridium flares and it was
| very bright, even during the day
| carlosjobim wrote:
| In short: after sunset.
| wolverine876 wrote:
| > Basically this happens just before sunrise, and just
| after sunset.
|
| I've seen plenty of satellites in the middle of the night,
| from very dark areas (wilderness). They look like stars,
| only they move more quickly. These observations go back a
| decade, at least.
| pxeger1 wrote:
| 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 wrote:
| 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.
| qayxc wrote:
| > 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/
| latchkey wrote:
| No, I love this data! Thank you.
| aetherspawn wrote:
| 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?
| latchkey wrote:
| China is still working on those reusable rockets...
|
| https://www.youtube.com/watch?v=sDufpRp57ok
| oconnor663 wrote:
| No, they burn up. You can think of how much work goes into
| the heat shields on spacecraft that are supposed to survive
| reentry. Satellites have none of that.
| scottlamb wrote:
| I also think a screw at terminal velocity might not be
| particularly dangerous, similar to the popular "will a
| penny dropped off the empire skyscraper kill you?"
| question.
|
| ...which I suppose is closely related. The deorbiting
| satellite burns up because all that potential energy goes
| into heat because of the friction that limits it to that
| low terminal velocity.
| Animats wrote:
| But how do they beam copies of the space to space links down for
| wiretapping, as Iridium does?
| 7e wrote:
| If I send one byte and it hops through ten satellites, is SpaceX
| counting that as ten bytes of data?
| mort96 wrote:
| I'm so immensely disinterested in Musk's little projects.
| theultdev wrote:
| I'm immensely interested in people commenting how they are
| disinterested in X thing.
|
| Please go on! I'd love to know the motivation of posting, it
| makes no sense to me.
|
| Seems to be a self-fulfilled prophecy.
| mort96 wrote:
| I guess I just wish the HN timeline wasn't so full of his
| garbage.
| theultdev wrote:
| Do you have a specific qualms with satellites providing
| internet to remote areas or EVs or space exploration or is
| it purely personal?
|
| In other words, what makes it "garbage" to you?
| mort96 wrote:
| I think I have been pretty clear? I don't care for Musk's
| projects.
| why_at wrote:
| 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 wrote:
| I think they are still tiny. Also don't networking systems
| routinely deal with temporary link disruption?
| burnished wrote:
| What does that have to do with the odds of rocket induced
| dropped packets?
| versteegen wrote:
| > 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 wrote:
| Fair, but they don't compute and probably can't know the
| laser paths between Starlink nodes.
| ra wrote:
| [delayed]
| burnished wrote:
| 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.
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