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Application for Fixed Satellite Service by SpaceX

91 points by lgats 8y ago

hindsightbias 8y ago
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."
- sctb 8y ago
  We've reverted the title from the submitted “SpaceX Files to Introduce Starlink with just 116 Satellites 550 km”.
- gpm 8y ago
  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.
- varjag 8y ago
  Still can't quite wrap my mind around the fact that the world's largest space/satellite programme is about to be run by an LLC.
electricwater 8y ago
Do you know why are they doing this? Lower orbit is probably cheaper?
- deleted 8y ago
  [deleted]
- regnerba 8y ago
  Cheaper how? I would assume with a lower orbit they experience more drag and deorbit faster meaning they need to be replaced more often. Maybe using the ones in lower orbit to cover more densely populated locations?
  - Rebelgecko 8y ago
    The original orbits would take ~100 years to decay, which is way longer than the life of the satellite. The new orbit is around 5 years (not taking into account maneuvers from the fuel on board). Makes a lot of sense, especially since it looks like they'll be iterating the design as they go (two that jumped out at me: initially not all satellites will be taking advantage of both Ku and Ka bands, and not all satellites will have phased array antennas)
    - regnerba 8y ago
      That's really interesting, than you for sharing.
- crunchlibrarian 8y ago
  Geosynchronous satellite latency in best case: 250ms LEO latency best case: 6ms I've used those Hughes satellite connections before, I never got anything close to 250ms. More like 400ms.
  - Diederich 8y ago
    > LEO latency best case: 6ms Light travels about 1800km in 6ms, but that's just one way. Straight up and straight down at 550km is 3.6ms.
gpm 8y ago
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)
- msmithstubbs 8y ago
  > They expect that the smaller amount of lifting will increase satellite lifetime by 50% even after accounting for atmospheric drag. I'm curious: why will this provide a longer life? Is it the lift burn itself that affects the lifetime (so reduced lift burn is better for the satellite)?
  - CarVac 8y ago
    You can use fuel for station-keeping instead of orbit lifting.
    - msmithstubbs 8y ago
      Ah! Thanks.
    - oh_sigh 8y ago
      Wouldn't burning all station-keeping fuel immediately be better than riding through thicker atmosphere for a while, and burning fuel bit by bit?
xt00 8y ago
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..
- gpm 8y ago
  In my opinion even if this was a huge problem for ground base telescopes it wouldn't matter, that negative externality would be tiny compared to the potential benefits. That said, this project will approximately double the number of man made satellites. I believe these satellites will be smaller than normal, but also closer than normal. I'm not an expert, but I think number of satellites is actually a really bad predictor for impact. In particular there was one set of satellites that had really bad effects for some reason. See more here [0]. [0] https://en.wikipedia.org/wiki/Satellite_flare https://en.wikipedia.org/wiki/Satellite_flare
  - xt00 8y ago
    Yea I wonder if with modern telescopes that they do digital integration so effectively they just delete the errant frames from the recorded captures and carry on from there. In the old days with film capture the entire exposure would be toast if a satellite flew through the frame..
- aerophilic 8y ago
  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.
ssvss 8y ago
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 8y ago
  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 8y ago
    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_faq/ https://www.reddit.com/r/Starlink/comments/7zqm2c/starlink_f...
    - zaroth 8y ago
      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 8y ago
        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.
jonplackett 8y ago
Are SpaceX going to put a bunch of their previous satellite operator customers out of business?
- the8472 8y ago
  Not just that, they will even compete on latency with transoceanic fiber operators.
  - Tuna-Fish 8y ago
    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 8y ago
      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 8y ago
        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
jonplackett 8y ago
how can they prevent these satellites being hacked? If they were they would be hard to recover I’d guess?
- adwn 8y ago
  How do you prevent any communication satellite from being hacked? What makes you think that those satellites are easier to hack than others?
idoescompooters 8y ago
10.7GHz... right on the edge of a radio astronomy protected band. Having a downlink here is not very good...

91 points by lgats 8y ago

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."

sctb 8y ago
We've reverted the title from the submitted “SpaceX Files to Introduce Starlink with just 116 Satellites 550 km”.
gpm 8y ago
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.
varjag 8y ago
Still can't quite wrap my mind around the fact that the world's largest space/satellite programme is about to be run by an LLC.

electricwater 8y ago

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

deleted 8y ago
[deleted]
regnerba 8y ago
Cheaper how? I would assume with a lower orbit they experience more drag and deorbit faster meaning they need to be replaced more often. Maybe using the ones in lower orbit to cover more densely populated locations?
- Rebelgecko 8y ago
  The original orbits would take ~100 years to decay, which is way longer than the life of the satellite. The new orbit is around 5 years (not taking into account maneuvers from the fuel on board). Makes a lot of sense, especially since it looks like they'll be iterating the design as they go (two that jumped out at me: initially not all satellites will be taking advantage of both Ku and Ka bands, and not all satellites will have phased array antennas)
  - regnerba 8y ago
    That's really interesting, than you for sharing.
crunchlibrarian 8y ago
Geosynchronous satellite latency in best case: 250ms LEO latency best case: 6ms I've used those Hughes satellite connections before, I never got anything close to 250ms. More like 400ms.
- Diederich 8y ago
  > LEO latency best case: 6ms Light travels about 1800km in 6ms, but that's just one way. Straight up and straight down at 550km is 3.6ms.

gpm 8y ago

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)

msmithstubbs 8y ago
> They expect that the smaller amount of lifting will increase satellite lifetime by 50% even after accounting for atmospheric drag. I'm curious: why will this provide a longer life? Is it the lift burn itself that affects the lifetime (so reduced lift burn is better for the satellite)?
- CarVac 8y ago
  You can use fuel for station-keeping instead of orbit lifting.
  - msmithstubbs 8y ago
    Ah! Thanks.
  - oh_sigh 8y ago
    Wouldn't burning all station-keeping fuel immediately be better than riding through thicker atmosphere for a while, and burning fuel bit by bit?

xt00 8y ago

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..

gpm 8y ago
In my opinion even if this was a huge problem for ground base telescopes it wouldn't matter, that negative externality would be tiny compared to the potential benefits. That said, this project will approximately double the number of man made satellites. I believe these satellites will be smaller than normal, but also closer than normal. I'm not an expert, but I think number of satellites is actually a really bad predictor for impact. In particular there was one set of satellites that had really bad effects for some reason. See more here [0]. [0] https://en.wikipedia.org/wiki/Satellite_flare https://en.wikipedia.org/wiki/Satellite_flare
- xt00 8y ago
  Yea I wonder if with modern telescopes that they do digital integration so effectively they just delete the errant frames from the recorded captures and carry on from there. In the old days with film capture the entire exposure would be toast if a satellite flew through the frame..
aerophilic 8y ago
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.

ssvss 8y ago

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 8y ago
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 8y ago
  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_faq/ https://www.reddit.com/r/Starlink/comments/7zqm2c/starlink_f...
  - zaroth 8y ago
    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 8y ago
      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.

jonplackett 8y ago

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

the8472 8y ago
Not just that, they will even compete on latency with transoceanic fiber operators.
- Tuna-Fish 8y ago
  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 8y ago
    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 8y ago
      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

jonplackett 8y ago

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

adwn 8y ago
How do you prevent any communication satellite from being hacked? What makes you think that those satellites are easier to hack than others?

idoescompooters 8y ago

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