Optical Inter-Satellite Links

Optical inter-satellite links (OISLs) use laser terminals to transmit data between satellites at rates exceeding 100 Gbps, creating a mesh network in space that routes traffic without touching ground stations. SpaceX has deployed laser crosslinks on all Starlink satellites since mid-2022, enabling global coverage including over oceans and poles where ground infrastructure is absent. The U.S. Space Development Agency (SDA) is building a parallel military mesh — the Proliferated Warfighter Space Architecture — with optical crosslinks as the backbone of its Transport Layer.

OISLs solve a fundamental constraint of satellite communications: ground station dependency. By routing data satellite-to-satellite, latency can actually beat fiber optic paths for long-distance routes (light travels ~47% faster in vacuum than in glass). For military applications, OISLs enable jam-resistant, low-latency communications that don't require ground stations in contested territory. The technology also supports real-time sensor-to-shooter links, connecting space-based sensors directly to weapons platforms.

The U.S. leads globally in deployed OISL technology, with SpaceX operating the largest laser-linked satellite mesh ever built and multiple defense contractors (Mynaric, SA Photonics, CACI) producing terminals for military programs. This creates a significant capability gap — no other nation has deployed OISLs at comparable scale. The technology is increasingly considered as critical to space-domain sovereignty as the satellites themselves, representing the nervous system of next-generation space architectures.