a low-earth-orbit satellite network
/ LEE-oh /
Picture wanting Internet in a remote village, a ship at sea, or a research station where no cables reach. Older satellite Internet used a few giant satellites parked very high up, about 36,000 km away in geostationary orbit, so a signal's round trip to space and back added more than half a second of delay — painful for anything interactive. A low-earth-orbit satellite network instead uses a swarm of thousands of small satellites flying low, a few hundred kilometers up. Being close means much less delay; but because they are low, each one races across the sky in minutes, so you need a whole moving constellation to keep at least one always overhead.
Concretely, a LEO network (Starlink is the famous example) places thousands of satellites in low orbits. Your dish on the ground locks onto whichever satellite is currently overhead and hands off to the next one as it sets, much like a phone handing off between cell towers — except here the towers are the ones moving, fast. The satellites can relay your traffic down to a ground station connected to the regular Internet, and modern constellations also link satellites directly to each other with laser links, forming a mesh in the sky. Because the satellites are so close, round-trip delays can be in the tens of milliseconds, competitive with or even better than long terrestrial fiber routes over very long distances.
Why it matters and the hard part: this brings broadband to places fiber cannot economically reach. But the routing problem is genuinely new. The network's nodes are not fixed — every satellite is moving at thousands of kilometers per hour, so the graph of who-can-reach-whom is constantly changing, links appear and vanish on a schedule, and the system must continuously re-plan paths and re-aim antennas. Honest caveats: capacity over any one spot is shared and limited, the sky is getting crowded (raising concerns about collisions and astronomy), and you still cannot beat the speed of light — latency improves over very long links but a satellite hop is not free.
A satellite serving your area is overhead for only a few minutes before it sets below the horizon. Your dish must hand your connection off to the next rising satellite seamlessly — many times an hour — while the network constantly recomputes which satellites and laser links form the current path to a ground station.
The towers move, so the whole topology is a moving target.
Low orbit cuts latency but does not repeal physics: the per-user capacity over a given area is finite and shared, so a LEO network is not an infinite pipe, and in dense areas it can become congested just like any other access network.