
Application for Fixed Satellite Service by SpaceX - lgats
https://fcc.report/IBFS/SAT-MOD-20181108-00083
======
gpm
The application lists the following benefits

\- Rapid, passive disposal in the unlikely event of a failed spacecraft

\- Self-cleaning debris environment in general

\- Reduced fuel requirements and thruster wear

\- Benign ionizing radiation environment

\- Fewer NGSO operators affected by the SpaceX constellation

The first two are because there is more atmospheric drag. I believe that
orbital debris in the case of a collision was something that SpaceX was
struggling to mitigate (every struggles, but no one has put up this many
satellites before).

The third is because originally the plan was to launch to a 400km orbit and
then have the satellites lift themselves to a 1150km orbit. Now they intend to
launch to a 300-350km orbit and lift themselves to 550km. They expect that the
smaller amount of lifting will increase satellite lifetime by 50% even after
accounting for atmospheric drag.

The fourth is apparently just "there's less radiation lower, and radiation is
bad for electronics".

The fifth is just "less of the other theoretical internet constellations are
at this height" as far as I can tell.

(All information sourced from the technical information attachment)

~~~
dmurray
Curious that they don't mention lower communications latency as a benefit.

~~~
ckastner
Perhaps because it's only 2ms per direction. I assume that someone that
sensitive to latency wouldn't use satellite communications in the first place.

~~~
gpm
This constellation should have lower latency over long distance than is even
theoretically possible using terrestrial fiber, because the speed of light in
space is substantially better than the speed of light in fiber. [0]

Even over short distance the latency (which the "Legal Narrative" pdf quotes
as 15ms) is negligible for almost all applications.

[0] paper [http://nrg.cs.ucl.ac.uk/mjh/starlink-
draft.pdf](http://nrg.cs.ucl.ac.uk/mjh/starlink-draft.pdf) / video
[https://www.youtube.com/watch?v=AdKNCBrkZQ4](https://www.youtube.com/watch?v=AdKNCBrkZQ4)

~~~
the8472
> than is even theoretically possible using terrestrial fiber,

If we're talking about theoretical limitations then hollow core waveguide
fibers should get you close to vacuum speed.

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ssvss
This animation based on this proposal is good,
[https://m.youtube.com/watch?feature=youtu.be&v=AdKNCBrkZQ4](https://m.youtube.com/watch?feature=youtu.be&v=AdKNCBrkZQ4)

~~~
reaperducer
That animation was great. Just what I needed to wrap my brain around this.

But 4,400+ satellites! How many launches is that going to take?

Also, glad to see that Alaska doesn't get shafted in this. As the computer
voice noted, it's an FCC requirement.

~~~
cagenut
good question so I found this[1] faq which says:

    
    
      Using a Falcon 9 at 25 satellites per launch it would take 177 flights, about 36 flights per year.
      Using a Falcon Heavy with 40 satellites it would take 112 flights, over 5 years that's about 22 flights per year.
      Using a BFR assuming 350 satellites per launch, until someone comes up with a better number, would need 13 flights total.
    

now those are based on the old higher orbit so presumably the numbers move
substantially with this new plan.

[1][https://www.reddit.com/r/Starlink/comments/7zqm2c/starlink_f...](https://www.reddit.com/r/Starlink/comments/7zqm2c/starlink_faq/)

~~~
zaroth
Ehh, give ‘em a few more years, they can do it with one rocket over the course
of a few days.

Only a little </s>.

Imagine a business plan for 4,400 satellites being _sane_. What a world.

~~~
Klathmon
Not only that, but the companies first successful orbital launch was only 10
years ago!

In those 10 years they went from being literally laughed out of rooms, to
being the forefront of the industry. And even now that they are arguably "on
top" in many ways, they keep on trying to do these insane things.

They are currently trying to build a rocket with the largest launch capacity
in history, launch and maintain a satellite network which is the largest in
history (if successful, it won't just be the largest, but will be at or near
half of all satellites in orbit!), and still have a goal of getting humans to
mars.

Say what you will about Elon Musk, the guy knows how to set goals.

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hindsightbias
Not sure where you got 116. Looks like the number is the same but they're
relocating some.

"On March 29, 2018, the Commission authorized Space Exploration Holdings, LLC,
a wholly owned subsidiary of Space Exploration Technologies Corp.
(collectively, “SpaceX”), to construct, deploy, and operate a constellation of
4,425 non-geostationary orbit (“NGSO”)satellites using Ku- and Ka-band
spectrum. With this application, SpaceX seeks to modify its license to reflect
constellation design changes resulting from a rigorous, integrated, and
iterative process that will accelerate the deployment of its satellites and
services. Specifically, SpaceX proposes to relocate 1,584 satellites
previously authorized to operate at an altitude of 1,150 km to an altitude of
550 km, and to make related changes to the operations of the satellites in
this new lower shell of the constellation."

~~~
gpm
I think this quote better summarizes the change.

"Under the modification proposed herein, SpaceX would reduce the number of
satellites and relocate the original shell of 1,600 satellites authorized to
operate at 1,150 km to create a new lower shell of 1,584 satellites operating
at 550 km"

This shell will also now use 24 orbital planes instead of an originally
planned 32. (per a table in the technical information pdf).

The total number of satellites in the constellation goes from 4,425 to 4,409.

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xt00
I wonder if there is any consideration for high quantities of LEO satellites
affecting ground based telescope operations? I guess one question would be
"how many LEO objects are up there that are the size of say more than 1 cubic
meter in size right now?".. if SpaceX would be doubling the total number up
there right now that does sound concerning.. I personally love the idea of the
global internet constellation they are working on.. just worry that there
could be other ramifications..

~~~
aerophilic
I think something that most people don’t comprehend is just how HUGE space is.
For context, at 550km orbit, the “surface area” of the sphere surrounding the
earth is ~601 BILLION square kilometers. Suppose we had 40,000 (double the
number of objects larger than a softball we have been tracking) objects up
there, in that exact orbit, we would still only have one object every 15
MILLION square miles.

So, while it is a valid concern... until we put up “millions” of items, I
think astronomers will be pretty safe. However, orbital debris avoidance...
much bigger issue.

~~~
smueller1234
I agree with your conclusions. Just a nit: the r² increase in surface of a
sphere that makes this so much bigger an area to scatter the satellites across
also applies to the field of view of telescopes and thus cancels out.

Edit: Clarification. The above is only true if having a satellite in the field
of view is enough to be a problem.

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jonplackett
Are SpaceX going to put a bunch of their previous satellite operator customers
out of business?

~~~
the8472
Not just that, they will even compete on latency with transoceanic fiber
operators.

~~~
Tuna-Fish
Also bandwidth. Because there is little other use for the satellites over the
pacific, the instant the first phase of the constellation is up, it is better
than the Southern Cross fiber line at everything it does.

~~~
the8472
I'm a bit skeptical about that. Fiber has mind-boggling bandwidth scaling
compared to beaming radio signals through a hundred kilometers of atmosphere.
Light has a higher bandwidth and you can put more than one fiber into a cable
and there's less interference too.

~~~
Tuna-Fish
Their satellites don't communicate with each other by radio links, but by
laser. Laser works better in vacuum than it does in fiber. Radio is just for
the downlinks.(1)

They have not publicly stated anything about the inter-satellite links, but a
research paper published by independent researchers(2) estimated that based on
other state of the art, they get >100Gbps of bandwidth between two
communicating satellites. The total trans-pacific capacity between NZ and the
US will be better than the SC fiber line because there will be many different
non-sharing paths using different satellites.

(1): Also likely for crossing connections. The paper mentioned below assumed
use of laser for those too, but that is IMHO unlikely because steering would
be too hard. Lasers work great for satellites on the same plane and those that
are on the neighboring ones, because the angular speed that the system needs
to move to track stays very low -- the satellites near them are almost
stationary from their point of view. In contrast, satellites on crossing
planes zip by very fast and have high angular motion, especially when near.

(2): [http://nrg.cs.ucl.ac.uk/mjh/starlink-
draft.pdf](http://nrg.cs.ucl.ac.uk/mjh/starlink-draft.pdf)

~~~
the8472
The up/downlink is the bottleneck if you want to provide backbone-like
connectivity over satellites, and that's still done via radio.

Those speeds may be great for individual endusers, but if you're a datacenter
which needs a lot of bandwidth then starlink would be limited by the shared
radio bandwidth to the sats, which could be quite crowded in an urban
environment, while fiber wouldn't be. That's why I only see them as competing
on latency, not on bandwidth.

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idoescompooters
10.7GHz... right on the edge of a radio astronomy protected band. Having a
downlink here is not very good...

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jonplackett
how can they prevent these satellites being hacked? If they were they would be
hard to recover I’d guess?

~~~
adwn
How do you prevent any communication satellite from being hacked? What makes
you think that those satellites are easier to hack than others?

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electricwater
Do you know why are they doing this? Lower orbit is probably cheaper?

~~~
theptip
Low orbit is cheaper to get a satellite to just considering launch costs (less
fuel, easier to recover the first stage), but as siblings have mentioned, it's
more expensive overall, particularly considering that you need lots more
satellites to provide coverage.

Their plan to launch O(1000) satellites is to get lower latency and higher
bandwidth, which would render the current generation of satellite internet
obsolete.

It's a great example of the sort of business plan that's only possible with
cheap launches that SpaceX's reusable rockets have provided.

Here's a more detailed primer:

[https://arstechnica.com/information-
technology/2016/11/space...](https://arstechnica.com/information-
technology/2016/11/spacex-plans-worldwide-satellite-internet-with-low-latency-
gigabit-speed/)

~~~
RivieraKid
What is O(1000) satellites?

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oh_sigh
It's borrowed from comp sci, but you can read O(x) as "on the order of x", so
maybe 900, maybe 1200, but somewhere around there.

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loeg
In Comp Sci O() notation has a very specific meaning and "on the order of"
does not approximate it. I think it was probably just a misuse of the
notation.

~~~
repsilat
In informal contexts it's also used as a fudge/handwave, purely as a
questionable analogy that nobody is expected to take too seriously. `theptip`
almost certainly knows that O(1000)=O(1), they were just being playful.

~~~
loeg
Exactly.

