TBIRD: Two Years Demonstrating 200 Gbps Optical Downlink

The TeraByte InfraRed Delivery (TBIRD) payload launched in May 2022 on a 6U CubeSat and operated for just over two years before deorbiting in September 2024. During that time, TBIRD demonstrated 200 Gbps optical downlink from low Earth orbit (LEO) to ground and transferred terabytes of data in brief <5-minute passes. To achieve high downlink rates, TBIRD leveraged fiber-coupled coherent transceivers that are routinely used in terrestrial fiber-based telecommunications. To effectively use fiber-based transceivers in the presence of fading due to atmospheric turbulence, an automatic repeat request (ARQ) protocol on a low-rate optical uplink was used to ensure error-free data transmission from space to ground. With precision pointing feedback from the lasercom payload, spacecraft tracking accuracy of 3 and 7 μrad RMS in the cross boresight axes was achieved. Two NASA optical ground stations (OGS) supported the TBIRD mission: OGS-1 located on Table Mountain in California and OGS-2 located on Haleakala in ¯ Hawaii. In total, 110 laser communications passes were conducted over three test campaigns. This paper provides an overview of the system architecture, operations campaigns, and key results from the mission. The data volume transfer and downlink rates demonstrated by TBIRD are the fastest ever achieved from space.