Starlink and the future of communication at sea

[GordMay]

Originally Posted by Paul L

... His title was mission phenomenologist. Never really figured out what he did...

Phenomenology is commonly understood in either of two ways: as a disciplinary field in philosophy, or as a movement in the history of philosophy.

The discipline of phenomenology may be defined initially as the study of structures of experience, or consciousness. Literally, phenomenology is the study of “phenomena”: appearances of things, or things as they appear in our experience, or the ways we experience things, thus the meanings things have in our experience. Phenomenology studies conscious experience as experienced from the subjective or first person point of view...

From ➥ https://plato.stanford.edu/entries/phenomenology/

Interesting, but still a bit opaque, to me.

[Paul L]

Originally Posted by GordMay

Phenomenology is commonly understood in either of two ways: as a disciplinary field in philosophy, or as a movement in the history of philosophy.

The discipline of phenomenology may be defined initially as the study of structures of experience, or consciousness. Literally, phenomenology is the study of “phenomena”: appearances of things, or things as they appear in our experience, or the ways we experience things, thus the meanings things have in our experience. Phenomenology studies conscious experience as experienced from the subjective or first person point of view...

From ➥ https://plato.stanford.edu/entries/phenomenology/

Interesting, but still a bit opaque, to me.

Opaque to me. This was on a classified spook satellite being developed. I had to ask the phenomologist for modeling data. Of course the data I needed was above my need-to-know level, making my job a bit dubious. The satellite ended up launching close to a decade late.

[Jon Hacking]

Originally Posted by hellosailor

...I don't think you're aware of how these satellite systems work. Musk is putting up two kinds of satellites. A small number of high orbit (20,000 miles high) geostationary satellites, that always sit on top of one place on the earth. And then a much larger number (7600?) of low earth orbit (LEO) satellites, which typically are spaced out in rings, along the lines of latitude. So there may be 50 of these LEO satellites on the equator, and 25 or them at latitude 60 (north as well as south) and just like the international space station, they rip over the entire surface of the earth in about 90 minutes. Every 90 minutes or so, every one of them circles the entire planet. They don't give a damn if Durban or Paris or Detroit happens to pass under them, or if 3000 miles of empty ocean pass under them, they still CIRCLE THE EARTH at high speed, all day and all night.
So if there is ANY LAND receiving any coverage at a particular latitude, all of the barren places and all of the empty water or ice at that same latitude will get equally good coverage...

Hello (may I call you just Hello?) you're absolutely correct that the birds don't care what's under them, & if any part of the world is covered, so is everything else at that latitude. But there are several things that need more explanation here:

1. There will be NO geosynchronous satellites. The Speed of Light (SoL) delay in going up that high adds way too much latency (1/3 sec) to each packet of data. This is why undersea cables are used for data & phone whenever possible. One of the later phases will add birds in higher (& lower) orbits than the original 800, but they'll still be technically LEO.
2. One of SpaceX's goals it to provide *faster* service than terrestrial (international) fiber, if you listen to the coverage video. That's why the birds can't be too high, to limit SoL delays.
3. While you're correct that the orbits will be in rings, they aren't along lines of latitude. Orbits *have* to be great circles. They go over the same orbit every time, but the earth spins underneath them, giving the illusion that the orbits precess around the world. This is why the coverage video twitches now & then, as new optimum communications paths have to be worked out. (Cell systems do this all the time while you're driving)
4. The angle of those orbits define the areas covered. When the birds are put into orbit, that angle is defined & doesn't usually change. It looks like SpaceX will limit the initial angle to cover the continental US (48deg). Still, those of us in the tropics should be well covered, wherever we are.
5. I think that part of the FCC regs state that Alaska has to be covered at some point, which effectively means the whole world. However, SpaceX plans to do that later, after the original 800-bird constellation is up & working (& presumably making enough money to justify the expansion).

[Dsanduril]

Originally Posted by Thalas

I... They use overlapping orbits and laser handoff between them to share data. As such, you WILL have high speed internet ANYWHERE in the world ...

The current crop of satellites have NO capability for inter-satellite communications/handoff. Yes, that is part of the dream, but for the time being, with the current design, only satellites in view of a ground station will be able to provide internet service. And with low orbits that means they won't provide service at long distance from land (and specifically land where SpaceX has decided to place a ground terminal).

The Starlink website is now estimating coverage to northern North America at the end of this year (presuming they get 6 more launches in).

The telling thing, from this article is that Musk/SpaceX estimate that they can cover the "entire populated world" with 1500 satellites, while a final constellation that will provide additional bandwidth and coverage of the "unpopulated world" will be more like 12,000 satellites. It will be interesting to see if they get the 1500 up and then slow down, as there is not a lot of money to be made from users on the wide blue sea. Launching an extra 7x satellites to be able to say they have global coverage may be a dream that reality (business use case/money) erases. Time will tell.

[zboss]

Originally Posted by Dsanduril

The current crop of satellites have NO capability for inter-satellite communications/handoff. Yes, that is part of the dream, but for the time being, with the current design, only satellites in view of a ground station will be able to provide internet service. And with low orbits that means they won't provide service at long distance from land (and specifically land where SpaceX has decided to place a ground terminal).

The Starlink website is now estimating coverage to northern North America at the end of this year (presuming they get 6 more launches in).

The telling thing, from this article is that Musk/SpaceX estimate that they can cover the "entire populated world" with 1500 satellites, while a final constellation that will provide additional bandwidth and coverage of the "unpopulated world" will be more like 12,000 satellites. It will be interesting to see if they get the 1500 up and then slow down, as there is not a lot of money to be made from users on the wide blue sea. Launching an extra 7x satellites to be able to say they have global coverage may be a dream that reality (business use case/money) erases. Time will tell.

This is correct although ground stations will also be deployed on cruise and cargo ships [first] with the intention that other stations will be able to use them as bridges until such time better antennas for smaller vessels are developed, probably by third parties. I would expect speeds on smaller vessels to be in line with what a practical transceiver size may be.

I read yesterday that the satellites will be deployed at two altitudes, they will decay orbit so quickly that they will need to launch 200 new satellites -every- month, and that they are designed such that 90% of the satellite burns up on reentry.

[denverd0n]

Originally Posted by zboss

...they are designed such that 90% of the satellite burns up on reentry.

And the other 10% rains down on our heads?

[zboss]

Originally Posted by denverd0n

And the other 10% rains down on our heads?

I was thinking the same thing!

[Dave_S]

Me three at 200 per month.

[thrill]

Originally Posted by GordMay

Phenomenology is commonly understood in either of two ways: as a disciplinary field in philosophy, or as a movement in the history of philosophy...

Phenomenology in the science ("real" physics) side of the world, as opposed to the philosophical ("meta" physics) of things deals usually with coming up with a phenomenological model, that is a way of estimating what might happen next. A Phenomenological model differs from a theoretical model in that it is derived from observation, rather than from extrapolation from theory.

So, when something is too complex to manage with theory as presently understood, it may still be useful, such as in orbital mechanics, to have a model to say where things will probably be based on all the (or as many as can be found) things that will affect it.

Orbital mechanics is particularly a good fit for this kind of modeling because when there's more than 2 (two!) celestial bodies involved, except for a very few restricted cases of 3, but especially when there's "over 9000" bodies involved, the only way to come up with solutions (estimates really) of movement due to gravity, and other factors, such as reflection of light, temperature differences, atmospheric drag, and well, everything else, is to make a model that makes estimates based on observation, vice theory - hence its own fancy name.

[Sos]

Originally Posted by thrill

Phenomenology in the science ("real" physics) side of the world, as opposed to the philosophical ("meta" physics) of things deals usually with coming up with a phenomenological model, that is a way of estimating what might happen next. A Phenomenological model differs from a theoretical model in that it is derived from observation, rather than from extrapolation from theory.

So, when something is too complex to manage with theory as presently understood, it may still be useful, such as in orbital mechanics, to have a model to say where things will probably be based on all the (or as many as can be found) things that will affect it.

Orbital mechanics is particularly a good fit for this kind of modeling because when there's more than 2 (two!) celestial bodies involved, except for a very few restricted cases of 3, but especially when there's "over 9000" bodies involved, the only way to come up with solutions (estimates really) of movement due to gravity, and other factors, such as reflection of light, temperature differences, atmospheric drag, and well, everything else, is to make a model that makes estimates based on observation, vice theory - hence its own fancy name.

What a great explanation!

[Dsanduril]

Starlink has now filed with the FCC for testing of 10 boat-based terminals on their rocket recovery vessels:

https://www.cnbc.com/2020/09/16/spac...-of-boats.html

The ground terminals seen in the wild for testing are small (~16"/400mm):

[B23iL23]

and the beta testers are starting to get good results - 100mb down and 40mb up with a latency of around 20ms!

Current coverage is still limited to northern U.S. but that's changing quickly.

[CaptTom]

Interesting to read the timeline of this thread. Especially this one from 2018 which laid out the schedule. Elon time indeed!

Cool to see they're already in beta testing. I actually signed up for it but wasn't called. I'm in the Northeastern US, but I think they are looking for people in specific cities. Not us out in the hinterlands.

[Dsanduril]

Wouldn’t want to do the beta testing with the advertised use case I’ve offered a truly remote testing site but no response.

[CarlF]

Wow! Is there any word as to whether the ship antennas they want to use would be motorized to actively track satellites like satellite TV on a boat or be fixed like a sat phone antenna ?

If the latter, we'll all have these in a couple of years.