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Old November 19th 18, 03:31 PM posted to sci.space.policy
Fred J. McCall[_3_]
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Default SpaceX gets FCC approval to deploy thousands more internet satellites

JF Mezei wrote on Mon, 19 Nov 2018
02:49:18 -0500:

On 2018-11-18 21:38, Jeff Findley wrote:

The cargo version of BFS will have a large payload bay .


ok, so there will be a cargo version. Wasn't aware of that. Had only
seen the draw2ings for the cruise shop with hundred+ passengers to Mars.


You are frequently 'not aware' of things. Just how did you think that
"cruise shop [sic]" got to Mars if there was no tanker version to
refuel it in Earth orbit so that it could make the trip?

Actually I'm not sure that's still current information, either.
Original plan was for three versions; a 'passenger' version, a 'cargo'
version, and a tanker version. One of the three went away. I thought
they combined the 'passenger' and 'cargo' versions into a single more
versatile vehicle.


the payload bay door(s) will open and the satellites will be released in
sequence just like Iridium satellites are released from a Falcon 9 upper
stage.


So the payload bay will be fitted with the satellite release mechanism
specific to those stalellites, right? Sort of like the Shuttle payload
being fitted with multiple PAM launchers ?


Which part of "just like a Falcon 9 upper stage" is it that you're
having trouble wrapping your head around?


I don't understand your point. Since it's a global satellite network,
you put the ground terminals exactly where they're needed.


In Canada, unlike the USA, the vast majority of the area where services
are needed do not have any fibre ANYWHERE near, so you can't place the
ground stations where they are needed and need to aggregate traffic to a
satteline that is over a ground station.


Huh? With 7500 or so birds in orbit, a lot of them are going to be
visible at once from any given point, even though they're only 350
miles or so up.


So to serve a town like Resolute Bay at 73° latitude, the satellite that
passes overhead may have to pass the signals down to another and then
another to reach one that is over a ground station. The thing is that
ground station will end up service a verty large area of northern Canada
and thus aggregate a lot fo traffic and this is where the uplink
capacity matters.


Yes, the 7500 orbiting satellites are nodes in a single large network.
What's your point?


These aren't really huge "ground stations".


This issue isn't their size (although you want a huge antenna to paliate
rain/snow fade effect on the uplink since that will affect a lot of users.


Again, huh?

Again, this is a global LEO satellite network. SpaceX could put their
ground stations closest to where the major data sources are in order to
minimize latency and dependence on the existing Internet backbones.


Again, it has to do with spectrum/bandwidth available for the uplink
between one ground station and the staellite currently passing over it
and how many end users end up being connected to that ground station.


With 7500 satellites in the constellation, how many are visible from a
given ground station? Nothing says you have to use the one directly
overhead.


Consider an extreme example of SpaceX having 1 antenna over Musk's home
as the single ground station for the world. All satellites will be
connected and data will flow from the internet to musk's home , on the
uplink to a satellite and then relayed from satellite to satellite until
i reacches the satelite over Gabon where it pushes the data down to the
home of someone in Gabon.

This all works and looks great. The problem is that that one uplink over
Musk's home will be limited in capacity by how much spectrum the ITU/FCC
will have given it and the capacity of the satellite passing over Musk's
house at anty point in time.

If you want to serve the world from 1 ground station, you will need many
many terabits/second capacity on that uplink, and need all your
satellites to be able to process all of the world's data demands since
anyone satellite eventually becomes the one passing over Musk's home and
acts as the main relay to the ground for all of Starlink's end users.


Poppycock! What do you think the bandwidth of the internet backbone
is? Hint: The biggest pipes are around 100 Gbs, over an order of
magnitude smaller than your figure. Most of it is even smaller than
that.


So, it comes down to determining how many ground stations you can have
and how many are needed in order to provide the complete system with
uplink cxapacity that matches the demand from end users.

The more ground stations you have, the more caopaciuty you have and the
better the service end users will have. But the more ground statiosn you
have, the costlier your system becomes. And then you start dealing with
national regulators. Selling service to a Canadian will require the
service abide by CRTC rules, notably net neutrality. But if the groudn
station is in the USA where the Internet no longer exists as a telecom
service, then the "information service" rules (or lack thereof() will
apply.


You still seem confused about how networks work.


Same with a user in Taiwan who might end upo using a ground station
located in China with all of the Chinese firewalls in place.


An end user won't 'use a ground station' unless they're talking to a
business local to that ground station.


Again, you have no idea what Starlink's pricing will be.


If you think it will be radically lower than existing services you are
mistaken. Especially since Musk has stated it needs to generate revenue
to find BFR/BFS, and once they realise how much gorund infrastructure
they will need to support users worldwide, you'll find the costs go way up.


While they haven't established how they're going to charge, they have
said that by the mid-2020's they expect to have 40 million users
generating $30 billion in revenue. That provides a guestimate of what
the 'average' user will pay and it's just not all that high.


The price of the launch is one thing. But if you have demand for X
capaxity, but your system only provides for half of that, then you price
service high and/or impose usage limits or lower speeds to limit demand
for capacity which you don't have. If you oversell the service (as
Xplornet does), then you get a terrible image and people hate you.


Costs and speeds are expected to be commensurate with current wired
internet.

reusability. Starlink will get those launches at cost too. They'll be
far cheaper than launches for any other LEO network.


Getting launches at cost doesn't matter. It's all book keeping. What
matters how how much will be oeration costs, groudn station costs and
how much revenues they will get. (and factor in need to lauhch X
satellites per year to replace falling ones in the longer term)


The satellites are good for around 5.5 years. It costs less than $40
thousand to launch a new one (plus the cost of hardware). I think
you're handwaving problems into existence that don't exist.


--
"The reasonable man adapts himself to the world; the unreasonable
man persists in trying to adapt the world to himself. Therefore,
all progress depends on the unreasonable man."
--George Bernard Shaw