TechnicalISL
Inter-Satellite Link
A direct communications link between satellites, allowing data to be relayed across a constellation without routing through the ground.
An inter-satellite link connects spacecraft directly, using radio frequency or optical (laser) links. ISLs let constellations route traffic in orbit, reducing dependence on a dense network of ground stations and lowering latency for global coverage.
Optical inter-satellite links offer very high bandwidth and are harder to intercept, but require precise pointing. ISLs raise spectrum, security, and interoperability considerations distinct from ground links.