4 ms·

It's all about latency. Having broadband with 200+ms of latency to reach geostationary satellites is to slow for modern networks. https://www.satsig.net/latenc

It's all about latency. Having broadband with 200+ms of latency to reach geostationary satellites is to slow for modern networks. https://www.satsig.net/latency.htm https://www.satsig.net/latency.htm You have to move the satellites closer to Earth to reduce latency - hence low earth orbit (LEO). You can achieve much better latencies, <20ms, and support modern networking applications. https://arstechnica.com/information-technology/2020/03/musk-says-starlink-isnt-for-big-cities-wont-be-huge-threat-to-telcos/ https://arstechnica.com/information-technology/2020/03/musk-... But when you reduce the height to LEO, not only are the satellites no longer geostationary, they also have a much smaller coverage area. So you need more satellites to cover the same area, and fancy networking to handle the constant hand-off between satellites.

tachyonbeam 6y ago
Bandwidth as well. Starlink can reach 100Mbps, and they're talking about 200Mbps. They can do that in part because they have more satellites.
- mbreese 6y ago
  > because they have more satellites I wouldn't characterize this as a function of having more satellites, but rather having fewer users per satellite (an admittedly subtle difference). But, related to the above post(s), the smaller geographical area each satellite covers is a problem for coverage (you need more satellites in orbit), but is a benefit for speed -- you have less users vying for the full bandwidth of the satellite. And, because the geographical areas are smaller, instead of having one base station/uplink, you now have geographically distributed base stations, so you have multiple points to access the Internet. This also helps with bandwidth (instead of X total uplink capacity, you need X/n capacity for each site, where n is the number of sites). Once you get around the logistics of managing a fleet of satellites, many, many benefits flow from having lower orbits.
Groxx 6y ago
To grab a couple bits of info from that page + google, to give people a good idea of the distances involved at a glance: Starlink orbit: 550km Geosynchronous orbit: 35,786km Earth's circumference: 40,075km Geosynchronous orbits are quite a way out. Latency at terrestrial distances can be painful already, bouncing through geosynchronous satellites will be multiples worse at a minimum. Meanwhile, Starlink's are at "normal" distances for networking - you probably connect to things further away all the time already.
nereye 6y ago
The low latency is also a requirement to receive FCC subsidies related to rural broadband, e.g. see https://www.reddit.com/r/spacex/comments/h04on0/fcc_just_voted_to_allow_starlink_to_bid_on_low/ https://www.reddit.com/r/spacex/comments/h04on0/fcc_just_vot.... Have heard (IIRC in https://theamphour.com/518-satellites-and-evs-with-joris-aerts/ https://theamphour.com/518-satellites-and-evs-with-joris-aer...) that this could have been part of the reason for Starlink's decision to have their satellites in a lower orbit. The subsidy angle is also of course a familiar playbook across SolarCity/Tesla/SpaceX etc.

tachyonbeam 6y ago

Bandwidth as well. Starlink can reach 100Mbps, and they're talking about 200Mbps. They can do that in part because they have more satellites.

mbreese 6y ago
> because they have more satellites I wouldn't characterize this as a function of having more satellites, but rather having fewer users per satellite (an admittedly subtle difference). But, related to the above post(s), the smaller geographical area each satellite covers is a problem for coverage (you need more satellites in orbit), but is a benefit for speed -- you have less users vying for the full bandwidth of the satellite. And, because the geographical areas are smaller, instead of having one base station/uplink, you now have geographically distributed base stations, so you have multiple points to access the Internet. This also helps with bandwidth (instead of X total uplink capacity, you need X/n capacity for each site, where n is the number of sites). Once you get around the logistics of managing a fleet of satellites, many, many benefits flow from having lower orbits.

Groxx 6y ago

To grab a couple bits of info from that page + google, to give people a good idea of the distances involved at a glance: Starlink orbit: 550km Geosynchronous orbit: 35,786km Earth's circumference: 40,075km Geosynchronous orbits are quite a way out. Latency at terrestrial distances can be painful already, bouncing through geosynchronous satellites will be multiples worse at a minimum. Meanwhile, Starlink's are at "normal" distances for networking - you probably connect to things further away all the time already.

nereye 6y ago

The low latency is also a requirement to receive FCC subsidies related to rural broadband, e.g. see https://www.reddit.com/r/spacex/comments/h04on0/fcc_just_voted_to_allow_starlink_to_bid_on_low/ https://www.reddit.com/r/spacex/comments/h04on0/fcc_just_vot.... Have heard (IIRC in https://theamphour.com/518-satellites-and-evs-with-joris-aerts/ https://theamphour.com/518-satellites-and-evs-with-joris-aer...) that this could have been part of the reason for Starlink's decision to have their satellites in a lower orbit. The subsidy angle is also of course a familiar playbook across SolarCity/Tesla/SpaceX etc.