Hacker News new | ask | show | jobs
by ncmncm 1871 days ago
Yes, the useful unit is light-milliseconds:

  $ units
  You have: 340 mi
  You want: light ms 
          * 1.8251859
          / 0.5478894
So, 3.6 ms round-trip. In practice, the route will be slanted, so could just exceed 5 ms.

  $ sudo apt install units
Once the constellation is mature, certain very-high-paying subscribers will get the packets forwarded from one satellite to the next via laser links, across oceans, before being downlinked, and get there a few ms before packets dawdling along on fiber links below 0.7c, to trigger securities trades ahead of the crowd acting on now-ancient information. The time by fiber from Singapore to New York is on the order of 90 ms, where Starlink ought to get them there in well under 70 ms, leaving a good 20 ms to arbitrage. In investment banking, they say "a microsecond is an eon, a millisecond is an eternity".

Even just between New York and London, they can gain a few ms headway, enough to dominate.

It would not be surprising if the US military, and maybe some others, will have access to satellite-to-satellite routing. (They have their own WGS, "Wideband Global SATCOM", but it is GEO, thus high-latency.)

AFAIK, only the polar-orbit nodes have inter-satellite laser links, thus far, so this is a phenomenon of the near future, not the present. Other things to expect in the near future are lofting them with a few TB of storage, to minimize uplink bandwidth by edge-serving Disney and Netflix blockbusters; and multicast downlinks for real-time soccer games and maybe even time-binned shows.

3 comments

Military already has this: https://en.wikipedia.org/wiki/Wideband_Global_SATCOM

The SpaceX edge here is making this kind of thing cheaper and scalable to the point that a global community of hundreds of millions of users can multiplex signals on it, but for a sufficiently well-funded organization with fewer users, it was already possible.

The military system is orbiting at 32,000km, the latency is much higher than Starlink.
Why was this downvoted though?
This one guy watches and downvotes everything I post, lately.
And continues to, welp. Someone apparently has time today.
You forgot about the latency of going through the atmosphere, and the Manhattan distance between the satellites.
I cited the latency going through the atmosphere, 1.8 to 2.5 ms, in the very post you clicked "reply" on, very evidently without, you know, reading it. (Not reading saves time, but you know what else does? Not posting.)

And there is no "manhattan distance". Satellites (will) have a laser pointing to the next one in their orbit, and one pointing back. That's all.