> > 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.

SpaceX plans modifications to reduce the impact on optical astronomy: https://www.spacex.com/updates/starlink-update-04-28-2020/

Their latencies are not at least as competitive as anything if they're not proven. With low orbits, they need multiple hops to get to most destinations, along with queuing and network delays. Propagation delay may not even be the dominant factor.

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 does calculations on $50 a month. That's crazy cheap, not expensive.

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.

I think you're going to need to explain how a satellite at 550km in the sky with a low elevation covers the US without any hops. That's contradictory to what every technical piece of information about Starlink says. You have to hop between base stations. That's a hop, regardless of whether it's through networking equipment or a gateway.

They'll use the internet backbones for communications between their base stations rather than satellites.

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.

And therein lies the problem. Fiber latency from coast to coast in CONUS is 20ms in the very best case. But that will never happen, and you instead of many hops, where the latency is typically upwards of 40ms just for the fiber. Elon is saying the latency will be around 20ms. How? Because he's quoting a single path up and down in the same beam in the best case. Nominally, it will be much, much higher.

When people quote you their ping times, they quote it to the nearest AWS or Google CDN, not to servers on the other side of the country. They type "ping google.com". If the Starlink base station is co-located with a Google CDN, best case is an 8ms ping time. (There might not be a google CDN but there definitely will be a Netflix cache in each base station) 550km one way at the speed of light is 2ms. Up & down for the ping and then up & down for the pong gives 8. Normal case is probably about triple that because the satellite won't be straight up and the CDN won't be co-located. But lots of base stations will be in the same metro as a CDN.

I've never heard of people quoting their ping time based on the closed DC to them. Let's say you're playing a game (fortnite, for example). You have a ping time based on where that server is. It may be across the country from you, and there's nothing you can do about that to make it better. Their ping time will not be anywhere near 20ms as that tweet alluded to. I'm pinging google.com on a fiber connection right now, which would go to one of their load-balanced DNS entries. I get 30ms. When people say you have 30ms of latency, they expect that latency for the normal things they do, not in some artificial test of path delay. Otherwise traditional satellite is 480ms and not 600ms, and fiber is 15ms and not 30-40ms.

The ranges are big. It doesn't take many base stations with fiber backhauls to cover the entire country. No need for multiple hops if that would be slow for some reason.