Results of SDA-standard-compatible optical inter-satellite link testing between Kepler Communications LEO satellites (Invited Paper)

Kepler presents the results of its on-orbit Space Development Agency (SDA)-compatible optical inter-satellite link (OISL) testing, between two TESAT SCOT80 optical terminals onboard Kepler Communications low Earth orbit (LEO) satellites, compatible with v2.1.2 of the SDA Optical Communications Standard. Since June 2024, Kepler has closed OISLs across thousands of kilometers lasting several hours and is continually shortening link acquisition times. We describe optical communications terminal (OCT) commissioning, self-test procedures, validation of the OCT / star tracker interface, Moon calibration, and successful link acquisition. We show example OCT telemetry including the pointing, acquisition, and tracking state machine, dynamic attitude knowledge error, the corrections by the fine-steering mirror to maintain the link, and received power on the tracking sensors. Kepler plans further demonstrations of SDA-compatible links including space-to-ground and space-to-air. Kepler’s SDA-compatible optical space data relay constellation is launching in 2025, providing gigabit, sub-second connectivity anywhere in LEO.