Here is my attempt at estimating actual coverage, based on a 25 degree angle from the horizon https://i.imgur.com/poj8cae.png
I've included a screenshot of the code I modified so people can play with it themselves. I made a slight simplification in my math (explained in the comments in the screenshot), but I think it should be close enough. Edit: Pictorial explanation of simplification https://i.imgur.com/XtADkmh.png
Such as if you had a theoretical, nonexistant ground terminal that was capable of communicating with a satellite at only 1 degree look angle elevation above the horizon.
Of course in reality this is not the case and most systems that communicate with LEO satellites will have minimum elevation look angles of 15-20 degrees above the horizon.
The circles do, however, provide a useful approximate scale of how much ground area is visible at any given time from the point of view of a satellite. It's not intended to be perfect.
No, no, that is not even close to true. Measure the big circles. They have a radius roughly the same as satellite altitude. From an altitude of 550km, the area the satellite can see all the way down to the horizon is wider than the contiguous united states, east to west.
The big circles seem to be satellites that are at final altitude, showing range equal to altitude, so slightly lower than 45 degrees. The small circles are satellites that aren't there yet, and the size is meaningless.
From the about section:
> Dashed lines show the approximate coverage with very conservative viewing slant (approx 60 degrees above horizon, where 90 means vertically overhead).
Author doesn't seem to have any love for Starlink. I wonder why the built the site.
Starlink isn't designed to offer lower latency or lower prices than existing terrestrial wired or wireless ISPs (at least, decent ones). Instead it's designed to offer a low latency wireless service in places where that has never been available at all. Which is most of the land area of the Earth, and all of the ocean. It may also be cheaper and/or faster than some very bad terrestrial ISPs, because there are a lot of those out there, but that's not what it's designed for.
Impact on earth-based telescopes has been discussed endlessly, to the point where it seems like there's a law that you can't mention Starlink on the Internet without talking about it. And SpaceX responded by talking to the astronomers most affected by Starlink and adding a sunshade that should prevent the satellites from ruining their images. Which is more than any other satellite operator has ever done, AFAIK, and there are many satellites much brighter than Starlink in the sky today.
The Pentagon is certainly interested in Starlink, but commercial service has much higher revenue potential. There are several competitors planning to do roughly the same thing as Starlink, so the business plan is at least plausible.
It is widely believed that a huge chunk of Starlink’s revenue, if not ~all of it, will come from leasing faster-than-currently-available low latency links to HFT companies for nyc-lon and such. This is why their first orbital planes being launched are for the north atlantic and CONUS.
Providing internet to the underserved areas is secondary; the cash will come from beating terrestrial fiber links (even idealized great circle ones) between markets that are already extremely well connected.
One such private low latency link between Seacaucus and LSEG will probably pay 2-5x what everyone else on the planet combined pays for internet access in underserved areas.
This is speculation. Without inter-satellite links the latency between New York and London on Starlink would be quite disappointing.
> This is why their first orbital planes being launched are for the north atlantic and CONUS.
A LEO constellation can only be targeted at specific latitudes (not longitudes). They're just targeting mid-latitudes because that's where potential customers live.
It does seem pretty convenient that the inclination they've chosen lines the satellites up nearly in a straight path from New York to London, but I imagine this would be relevant to many transatlantic communications.
You can't have efficient coverage of the whole planet without launching all of your satellites at fairly high inclination (>45°). There will be more satellites per area near the poles and so that's why Starlink will be available at very high (and very low) latitude before it's available at the equator.
True? I'd heard that the initial target market was passenger planes over the ocean, cruise ships, and similar maritime and aerial activity that has to use geosynchronous satellites at present.
Covid-19 has thrown a spanner into the works of that plan, for a while. I'm sure people with money won't be turned away.
Longer term, remembering that Musk hails from South Africa, I thought the plan was to bring internet to failed states or barely functional areas in Africa (outback Namibia/Zimbabwe/Tanzania etc) and possibly also the Americas and the Middle East).
While for airplanes I think the latency might not be that problematic (I think VoIP in plane package full of people would not be very welcome) you indeed want low latency connection on a cruise ship.
source: I know some of the people who built several of the Chicago-NYC links.
All that vs. laying down some concrete and a telescope in a remote location.
If only there were launch platforms that could put up smaller telescopes (optical and radio).
I mean you can do a lot with telescopes that are much smaller than Hubble Class or JSW. A lot of people are doing work with telescopes that are much smaller. Also, as long as frequencies and locations are published, much of this noise (not all!) can be removed. Sure, the VLA is going to have a major headache, but LIGO wouldn't exist if we didn't know how to remove noise (LIGO had to deal with noise from cars many miles away and all kinds of vibrations because it is ridiculously sensitive).
Arrays like Starlink are a persistent foreground for the big radio telescopes. SKA and the like are in the Outback for a reason, but for this there is no escape.
I'm not saying it is easy, but it is definitely possible.
If only there was a space launch company bringing orders of magnitude reduction in cost.
JWST is 6500kg. Quick googling shows SpaceX costs about $3k per kg, so the launch cost is about $20M.
The total project cost for JWST is $10bn according to wikipedia.
Look at how, say, Planetary Resources was putting together their much smaller telescopes and you'd get an idea of how it could be done on the cheap. Then to scale up you'd focus on cost effectiveness instead of maximizing capability at all cost. Do multiple cheap launches ($100m each) instead of spending billions on a complicated automated unfurling mechanism, etc.
NASA is first and foremost our nation's science program. Everything from the network card driver your AWS instance is using to the planes flying into hurricanes to determine how strong they will hit was built with major contributions from NASA engineers.
LASIK eye surgery, the nutritional supplements in baby formula, solar panels affordable for consumers, OpenStack, even the BowFlex were all developed by NASA or under NASA funding programs.
You could at best say NASA is a jobs program for HN readers. :)
If suddenly launches only cost $50m then you might build a cheaper and slightly less reliable satellite as you know you can always launch another for only $50m
Starlink used that study to come up with the night shade idea to mitigate those impacts.
In that survey, radio telescopes were in the "minorly affected" list.
The severity of the noise for radio was not graded in the slightest, and the word "minorly" is never used.
It's really baffling how someone motivated and talented enough to make such a tracking site would have such an odd opinion section.
Obviously, Starlink is not the best choice in all situations, but it is so compelling on some dimensions that such a flatly negative opinion is bizarre for anyone with even a cursory understanding of what's going on.
For existing GEO satellites, the equivalent measurement is 600ms. That's the relevant comparison. With just 20ms added on top of regular internet latency it would still be usable for competitive gaming at all but the highest levels, as the tweet says.
Those are very easy numbers to beat. Yes it might not beat prices and latencies for a super competitive city with true competition, but those are honestly rare and few between. The majority of north american cities have shitty internet at high prices and high latency.
Also, slap this router on a Tesla car, allowing it to have connection anywhere it drives, and you're golden.
So if they can do better just on COST then this it would be wonderful.
It might work a few hundred miles offshore, but not further than that. So it'll be a while before you can have video calls from the middle of an Atlantic crossing.
At an altitude of 340 miles a starlink satellite has line of site up to 1800 miles so conceivably a ship at sea could be 3600 miles from the nearest land station and still be able to bounce off Starlink. Of course that's ideal conditions, but it wouldn't take too many ground stations to ensure 99% of oceangoing traffic is covered.
Of course even with line of site, the antenna may not be oriented in such a way as to cover more than a couple hundred miles of surface even if there is line of site.
If it's not able to cover more than a couple hundred miles, I don't think it's a line of site issue.
When I put 550km into a horizon calculator I get a distance of 2700km.
Edit: Okay, I want an explanation for the downvotes. If you're upset that I didn't say "the user terminal is horizontal at max range", I thought it was clear from context.
> Just take a look to see how many handoffs there are over CONUS alone
That's just a simulation picking angles he thought looked good, in an area where there are plenty of options. It doesn't tell you anything about the limits of beam size, especially when there is no other sat in range.
We're talking about receiving internet on ships, right? You need one per ship that wants internet. And it doesn't have to be 'extremely' expensive, it could be a moderate multiple of the normal user terminal.
In case you forgot the context, this is not a conversation about using relays. This is a conversation about how far offshore you can go in a single bounce.
> I'm not sure what you are arguing about the simulation. Are you saying it's inaccurate and there's a better one?
It's perfectly fine, but the goal of that simulation is to show a way of doing long distance high speed relays. The goal is not to show you maximum range if you don't relay.
For the non-relay case, we've already established that due to beam size you can't get very far off shore before it won't work. The goal of the simulation was also to show beam size. If the beam sizes are arbitrarily large then obviously the simulation would have shown a single hop.
I figured that out, but that's not really what the conversation was about. If you add those gateways then you don't have the range problems, and this was a conversation about range problems.
> Those terminals do have to be expensive, just like the gateway ones, because the antenna performance is much higher than the user terminal's, and the radome is very large (see other pictures from reddit on here).
The video you linked talks about using normal user terminals as relays. A couple of those won't be full bandwidth, but your mid-ocean service wouldn't need to be full bandwidth.
If you're actually making a dedicated relay ship you'd probably want a full radome link, but only if it's cheaper than the ship you're putting it on. The limiting factor is the cost of the ships.
> The goal of the simulation was also to show beam size.
I strongly disagree. Beam size is modeled in a very simple way, because it's not the goal of the simulation. The goal is to show how links work in different ways, using normal-scope full-bandwidth service beams.
I strongly doubt that an almost-idle sat is unable to aim even a few degrees wider if they wanted to.
But the person making that sim would have no way to model that, and it's not really worth it to get an extra fraction of a millisecond. Better to make the simulation based on confirmed capability.
But for ships at sea it's not a fraction of a millisecond, it's the difference between connectivity and no connectivity. If ships at sea were starlink's primary customers then I bet they could and would get better range even with zero hardware changes.
If you see my comment and others, using user terminals as relays is going to be very difficult, if not impossible. The EIRP/GT of those terminals will likely be very low, and that single relay will cut the bandwidth significantly. They also have much lower availability than a gateway, which makes the routing decisions harder.
> I strongly disagree.
What beam size do you think they're using? It's not really a question of IF they want to. Doing so on a cheap terminal can easily break FCC interference guidelines due to sidelobes, thus making it not their decision. That's the reason why these systems design for a very specific elevation limit from the user side, because anything else would either have too poor performance at the detriment of the entire satellite, or it's illegal if you're transmitting where you shouldn't. The performance degradation is very serious as well. It can be as bad as a single user consuming 10x more satellite resources than a nominal user, just because they're outside of the coverage of the beam.
So I realize where you're coming from in that they can do it, but I guarantee given the link budgets and cost-benefit tradeoff, it's simply not worth it to cover that far off boresight.
Look at a picture like this:
This is clearly not representative of starlink, but rather a GEO constellation. But the same concept applies: they will have tiny 0dB contours, and it rapidly falls after that. Serving users outside of the main contours, while it might be feasible given their antennas, is a massive hit to capacity on the entire constellation.
By the way, I think this dialogue is good and neither of us are going to convince each other. I think we will have to wait and see a year from now and revisit these comments.
And for what it's worth I looked up one of the licensing sheets earlier and it talked about the allowed signal strength below 25 degrees tapering off by 15dB. That's not enough to stop you from having a signal.
> too poor performance at the detriment of the entire satellite
> Serving users outside of the main contours, while it might be feasible given their antennas, is a massive hit to capacity on the entire constellation.
I think you're agreeing with me here.
It might cost a lot of the satellite's performance, which is why you wouldn't do it over land, and why it would be even less reasonable to include it in the simple simulation you linked.
But satellites over the ocean have nothing better to do with most of their capacity.
> By the way, I think this dialogue is good and neither of us are going to convince each other. I think we will have to wait and see a year from now and revisit these comments.
I'm fine stopping here, but revisiting in a year probably wouldn't help. There is a huge difference between what they can do, and what they care enough to do. Servicing ships that are more than 300 miles offshore, but not too much more, is definitely not a priority.
Yes, there is no satellite crosslinks in V1.
But you can bounce it off "ground" stations sitting in the ocean. For instance on barges and islands, or just on other customers ships. It doesn't take that many ground stations to be able to be routed to land. Or from land on one side of the ocean to the other.
Is v2 just a software update? Does it require sending a whole new set of satellite or it something they are planning to patch into existing satellites someday and have inter-sat support?
But that's not a big stumbling block -- SpaceX plans on replacing 1/5th of their constellation every year.
To be clear, I am saying their plan is so have the links up before the consolation is finished. These early launches are going to be in a higher orbit which will allow them to offer the service on land before the full constellation is finished as well as provide redundancy.
Presumably this setup would also help with the cloud coverage issue due to the shorter travel distance and higher likelihood of redundant satellites to connect to.
But that requires the inter-satellite links be viable, which they aren't yet: the required lasers would survive reentry and they want the satellites to burn up completely on de-orbit so current versions of the satellites don't have them.
And yes, there are significant capacity limitations. Only the truly rural will get good data rates.
In theory a LEO satellite network could also beat transoceanic fiber connections since the high refractive index causes the speed of light in fiber to be only ~2/3rds the vacuum speed of light. But that would require satellite-to-satellite optical links which the first generation of starlink doesn't have.
Actually it is due to their distances.
Speed of light delays is something that exists everywhere, like fiber internet. In fact, speed of light is faster in space than it is in optical fiber. The problem is distance.
Your weird pedantic distinction doesn't make a difference. They're synonyms in this context. Obviously the difference is how much you have, everyone knows that.
from the site
>Impact on earth based telescopes has not been discussed
I am guessing the author wanted to show how they fill up the sky.
> No evidence a working starlink network can offer lower latency
This is weird. Even if we pretend that these satellites are directly competing with terrestrial based systems, their orbits put them in range for a latency that is at least competitive with terrestrial systems. It's unproven that they get those latencies, but there's clear evidence.
Note: we're talking about like 50ms (IIRC 20ms - 100ms depending on which constellation). Geostationary satellites (which is what they are competing with) are like 250ms (these numbers are off the top of my head so correct me if I'm off). Starlink is competing with geostationary internet satellites AND places that have no internet at all.
> lower prices
Seems to me they can service a lot more people. Isn't this "scale?" Aren't they targeting something like a billion+ users? I know plenty of people with boats and RVs that are excited about this because the terrestrial solutions just suck (and generally aren't terrestrial based solutions).
> Impact on earth based telescopes has not been discussed
What? You're literally discussing it. It is pretty easy to find articles from astronomers getting upset . I can tell you that everyone in my community (which includes astronomers and astrophysicists) is aware of this issue. The fact is that most people just don't care. They see greater utility so it is worth the cost. Of course, there are also plenty of people that disagree.
> Starlink is a play for pentagon funding to keep SpaceX launch schedule busy?
Little bit of this, little bit of that. Having worked at a rocket company I can definitely tell you that, like every other manufactured product in the existence of products, flights are cheaper the more you do (especially true for reusable rockets!). Sometimes this is called the "launch chasm." I'm not sure why you're mad at SpaceX here. If you have an issue with this, it is with Pentagon funding.
Look, I'm not the biggest fan of Musk or SpaceX either, but these aren't great arguments. The things to dislike are a little more nuanced whereas this just comes off as hating SpaceX to hate on SpaceX.
> What? You're literally discussing it. It is pretty easy to find articles from astronomers getting upset. I can tell you that everyone in my community (which includes astronomers and astrophysicists) is aware of this issue. The fact is that most people just don't care.
SpaceX plans modifications to reduce the impact on optical astronomy: https://www.spacex.com/updates/starlink-update-04-28-2020/
The cost will need to be very expensive, relatively speaking. See this quick math for why: https://mobile.twitter.com/quirkyllama/status/12727488943806...
Your link's math says that SpaceX is marginally profitable selling 220GB of internet at $50 per month using 2016 bandwidth levels, which is pretty impressive.
Those numbers are from the original 2016 FCC filing, they've got a lot more bandwidth out of the satellites now because 4 years is a long time in technology. Musk says 3Tbps per set of 60 satellites. That's 50gigabits per satellite, not 20. Shotwell has indicated a price of $80 a month, not $50. And you know that's going to be the low price, not the high one. So let's assume that includes a 100 gigabyte cap, which is still about 10X as much as you get with the base plans from the geostationary satellite providers.
Those new numbers increase the subscribers per satellite from 7000 to 38000. Revenue per satellite per month jumps from $35K to $300K. At 60 satellites per launch over a lifetime of 5 years, that's gross revenue of $1.1B per launch.
Re: your other point about latency. They've already got 28 base stations in the US. That's enough to cover the continental US without any hops.
To be more explicit, before they sell you service at a location, they will ensure that they have enough base stations close to you that both your terminal and a base station are both always visible to a single satellite. The base station is connected to an internet backbone. So the signal goes from you to the satellite to the base station to the internet backbone. The reply goes in reverse.
So yes, this means that they need to have a similar number of base stations as satellites in a minimal constellation. They've said that a minimal constellation for full US coverage is 1000 - 2000. They have 28 base stations in the continental US, 2% of the globe's area. Yup, 28 is about 2% of 1000 - 2000.
They're probably going after a different market?
Also, only the green circled satellites are in their final orbit, the yellow circled ones were recently launched and are not yet at their final altitude and position. It takes a couple of months for orbit raising.
They could, but I bet they won't. Speculation is fun but permanent floating platforms are expensive, it's easier to just wait until inter-satellite links.
550 km is the altitude for the operational orbits, the satellites are deployed lower and need to raise their orbit. (But I see most are labeled around 550 km, so I'm not sure what you're referring to.)
I do understand that the satellites are deployed into lower orbits, but satellites from launches 1, 2 and 3 (and some of launch 4) are now at 550km:
Those launches are shown way too low in this map. From measuring pixels, I make them to be roughly 200km.
Edit: maybe I'm being pedantic here, but the combination of showing artifically small coverage zones, plus showing satellites much lower than they are so giving a misleading impression of how much area each satellite can see, taken together give the misleading impression that Starlink coverage will be worse than it will actually be.
I find it helpful, anyway. (And to me, at least, it is more helpful than a hypothetical coverage map, since I can't get Starlink internet now.)
* No evidence a working starlink network can offer lower latency, or lower prices, than terrestial
* Impact on earth based telescopes has not been discussed
* Starlink is a play for pentagon funding to keep SpaceX launch schedule busy?
"No evidence a working starlink network can offer lower latency, or lower prices, than terrestial"?
The FCC themselves don't believe the 100ms, and the price nobody in the industry thinks will be affordable since they haven't released any info about their user antenna.
If I recall the FCC filing correctly, the constellation was intended to always have a sat >50deg above horizon.
Here's a version with roughly 25 degrees (as per FCC filings) https://i.imgur.com/poj8cae.png
Here's a version with roughly 60 degrees (as per what the author claims to have done) https://i.imgur.com/TfNoqwt.png
Code is included in screenshots, and you can do this yourself in chrome, ctrl-shift-c to open dev tools, navigate to the area in the code I have open, and modify it. Please check my work.
Edit: And here's an explanation of why my circles are also estimates/not quite right: https://i.imgur.com/XtADkmh.png
Doesn't include coverage yet but I do plan to add that with some kind of heatmap. I think these static circles in the OP are a bit deceptive in indicating 'coverage' as these satellites are constantly moving.
Photos here of a starlink ground station with three small devices that are quite possibly the end-user equipment.
To be pedantic the radomes are only a couple of thousand dollars each, it's what's inside them that's expensive. Spherical radomes up to a couple of meters in size are kind of a commodity item. The Cobham-manufactured, agile, ku-band tracking dish antennas with Rx+Tx RF chains are expensive.
The small white things not in radomes shown in the picture are possibly beta test CPEs.
TL;DR User terminals are RF phased array antennas. Ka-band and Ku-band, plus E-band for ground stations. v1 has no cross satellite links. Plans for v2 include laser cross links.
Interesting, the picture on reddit above--those don't look like phased arrays to me.
There is already some polar coverage from the Iridium network, which uses orbits with higher inclination.
They orbit near them but somehow none go over the south or north poles?
edit: more answers at https://news.ycombinator.com/item?id=23556843
Seeing them move will make it clearer.
Here’s an awesome visual explanation with a ton of other cool info:
Also, nobody wants a figure-8 demolition derby in space...
Added: Because the satellites spend more time at the northern and southern extremes they get denser coverage there. That is likely why they are initially offering coverage near the US/Canada border.
Additionally, the starlink satellites perform active collision avoidance.
Is that currently true, or a planned feature in the future? IIRC the whole Aeolus kerfluffle happened because someone wasn't paying attention to their pager.