4 ms·

An order of magnitude lower launch costs to LEO (about $1K/kg now for Falcon 9) and another two magnitudes with Starship.. is a blocking advantage. Constellati

An order of magnitude lower launch costs to LEO (about $1K/kg now for Falcon 9) and another two magnitudes with Starship.. is a blocking advantage. Constellations don't make sense otherwise, see history: https://wikipedia.org/wiki/Starlink#Background https://wikipedia.org/wiki/Starlink#Background Keep in mind lasers don't work to the ground unless there are no clouds and stable atmosphere. RF 10-30 GHz work fine to ground and are directional enough that spectrum can be reused and multiple beams formed with one phased array. The real limitation is ITU regulation on total power flux density on the ground for all constellations in these frequencies.

mikepurvis 4y ago
Also, conventional radio can be steered with multiple transmitters, right? Is there a way to steer laser beams in a solid state way?
- JumpCrisscross 4y ago
  > way to steer laser beams in a solid state way? Yes, MEMs and waveguides.
  - georgeg23 4y ago
    Unfortunately not ready for prime time yet, optical beamforming today is only a few degrees steerable angle and single beam. Also low power and poorly focused.
    - JumpCrisscross 4y ago
      > not ready for prime time yet Totally agree. But the frontier is advancing thanks to LiDAR. And in the meantime, the advantages of laser relay and downlink are vast enough to make mechanical actuation worth it. Particularly for unboosted birds in LEO.
      - georgeg23 4y ago
        Curious how LiDAR tech could be used for high speed communication? At best that is time-multiplexing, not multiple parallel beams of information?
        JumpCrisscross 4y ago
        > Curious how LiDAR tech could be used for high speed communication? Lasers don’t care if they’re carrying data out or on return. The same optics being pursued for LiDAR have applications in communications. Solid-state waveguides and MEMS being examples.
JumpCrisscross 4y ago
> order of magnitude lower launch costs to LEO (about $1K/kg now for Falcon 9) and another two magnitudes with Starship.. is a blocking advantage If they used it to block, sure. Starlink’s advantage is SpaceX’s margin. > lasers don't work to the ground unless there are no clouds and stable atmosphere Relay.
- marcusverus 4y ago
  > If they used it to block, sure. Starlink’s advantage is SpaceX’s margin. As long as Starlink competitors use SpaceX to reach orbit, the advantage is realized on both Starlink launches (as savings) AND on competitors’ launches (as profit). Doesn’t that make SpaceX’s advantage 2x their margin?
  - JumpCrisscross 4y ago
    > the advantage is realized on both Starlink launches (as savings) AND on competitors’ launches (as profit). Doesn’t that make SpaceX’s advantage 2x their margin? Sort of. Every dollar of competitors’ launch margin doesn’t go to Starlink. SpaceX’s near-infinite fundraising capacity, and thus low cost of capital, is far more significant. (There are also orbital trade-offs between imaging and comms.)
    - wpietri 4y ago
      > SpaceX’s near-infinite fundraising capacity I have to wonder how sustainable this is. From the perspective of an investor, I would not be excited by Tesla being down 70% off peak and Twitter becoming the most notable corporate clusterfuck of the year. Investing in SpaceX these days seems like a bet that the CEO will be so distracted by his other problems that he won't have time to mess with the people actually running it.
      - bboygravity 4y ago
        Do you have ANY substantiation for Twitter being a coorporate failure or are you just parotting the biggest Twitter competitors (newspapers)?
techdragon 4y ago
Lasers work to the ground better than your implying. , Modern laser communication ground stations are designed or bring designed incorporating adaptive optics to significantly improve their resilience to atmospheric turbulence. Clouds remain an issue but most laser communications networks are designed with multiple ground stations to ensure sufficient good weather to provide continuous communications. Also several laser communications providers are designing their systems using relay satellites either MEO or GEO to serve as the space to ground really, centralising the higher power space to ground laser link and more expensive optics, and simultaneously placing them higher up enabling better ability to switch between multiple ground stations in the event of cloud disruption. The laser communication industry is very small still but it’s growing as ground stations get more standard and economical, with commercial units available for both space and ground sides, for a couple of years now.
- toomuchtodo 4y ago
  https://news.mit.edu/2022/communications-system-achieves-fastest-laser-link-space-yet-1130 https://news.mit.edu/2022/communications-system-achieves-fas...
- tpc3 4y ago
  Recent (12/21/22) article on the subject: Laser links are great for satellite relay, but challenges abound for taking it to ground https://spacenews.com/walking-a-narrow-beam-laser-links-are-great-for-satellite-relay-but-challenges-abound-for-taking-it-to-ground/ https://spacenews.com/walking-a-narrow-beam-laser-links-are-...
nine_k 4y ago
Do efficient 30 GHz masers exist? If not, how narrow can be made a beam by using a beam-forming phased array 10-20 m wide? The diffraction limit at 30 GHz (10 cm) should be reasonably small.

mikepurvis 4y ago

Also, conventional radio can be steered with multiple transmitters, right? Is there a way to steer laser beams in a solid state way?

JumpCrisscross 4y ago
> way to steer laser beams in a solid state way? Yes, MEMs and waveguides.
- georgeg23 4y ago
  Unfortunately not ready for prime time yet, optical beamforming today is only a few degrees steerable angle and single beam. Also low power and poorly focused.
  - JumpCrisscross 4y ago
    > not ready for prime time yet Totally agree. But the frontier is advancing thanks to LiDAR. And in the meantime, the advantages of laser relay and downlink are vast enough to make mechanical actuation worth it. Particularly for unboosted birds in LEO.
    - georgeg23 4y ago
      Curious how LiDAR tech could be used for high speed communication? At best that is time-multiplexing, not multiple parallel beams of information?
      - JumpCrisscross 4y ago
        > Curious how LiDAR tech could be used for high speed communication? Lasers don’t care if they’re carrying data out or on return. The same optics being pursued for LiDAR have applications in communications. Solid-state waveguides and MEMS being examples.

JumpCrisscross 4y ago

> order of magnitude lower launch costs to LEO (about $1K/kg now for Falcon 9) and another two magnitudes with Starship.. is a blocking advantage If they used it to block, sure. Starlink’s advantage is SpaceX’s margin. > lasers don't work to the ground unless there are no clouds and stable atmosphere Relay.

marcusverus 4y ago
> If they used it to block, sure. Starlink’s advantage is SpaceX’s margin. As long as Starlink competitors use SpaceX to reach orbit, the advantage is realized on both Starlink launches (as savings) AND on competitors’ launches (as profit). Doesn’t that make SpaceX’s advantage 2x their margin?
- JumpCrisscross 4y ago
  > the advantage is realized on both Starlink launches (as savings) AND on competitors’ launches (as profit). Doesn’t that make SpaceX’s advantage 2x their margin? Sort of. Every dollar of competitors’ launch margin doesn’t go to Starlink. SpaceX’s near-infinite fundraising capacity, and thus low cost of capital, is far more significant. (There are also orbital trade-offs between imaging and comms.)
  - wpietri 4y ago
    > SpaceX’s near-infinite fundraising capacity I have to wonder how sustainable this is. From the perspective of an investor, I would not be excited by Tesla being down 70% off peak and Twitter becoming the most notable corporate clusterfuck of the year. Investing in SpaceX these days seems like a bet that the CEO will be so distracted by his other problems that he won't have time to mess with the people actually running it.
    - bboygravity 4y ago
      Do you have ANY substantiation for Twitter being a coorporate failure or are you just parotting the biggest Twitter competitors (newspapers)?

techdragon 4y ago

Lasers work to the ground better than your implying. , Modern laser communication ground stations are designed or bring designed incorporating adaptive optics to significantly improve their resilience to atmospheric turbulence. Clouds remain an issue but most laser communications networks are designed with multiple ground stations to ensure sufficient good weather to provide continuous communications. Also several laser communications providers are designing their systems using relay satellites either MEO or GEO to serve as the space to ground really, centralising the higher power space to ground laser link and more expensive optics, and simultaneously placing them higher up enabling better ability to switch between multiple ground stations in the event of cloud disruption. The laser communication industry is very small still but it’s growing as ground stations get more standard and economical, with commercial units available for both space and ground sides, for a couple of years now.

toomuchtodo 4y ago
https://news.mit.edu/2022/communications-system-achieves-fastest-laser-link-space-yet-1130 https://news.mit.edu/2022/communications-system-achieves-fas...
tpc3 4y ago
Recent (12/21/22) article on the subject: Laser links are great for satellite relay, but challenges abound for taking it to ground https://spacenews.com/walking-a-narrow-beam-laser-links-are-great-for-satellite-relay-but-challenges-abound-for-taking-it-to-ground/ https://spacenews.com/walking-a-narrow-beam-laser-links-are-...

nine_k 4y ago

Do efficient 30 GHz masers exist? If not, how narrow can be made a beam by using a beam-forming phased array 10-20 m wide? The diffraction limit at 30 GHz (10 cm) should be reasonably small.