In-orbit test results of a free space optical satellite link between a CubeSat-compatible laser communication terminal and MeO ground station

Optical links with a duration of five minutes have been established between CubeCAT, an in-orbit CubeSat-compatible laser terminal and MeO, the Metrology and Optics Telescope in Grasse, Côte d’Azure. In total three links have been established between CubeCAT and the MeO optical ground station (OGS) in the span of two consecutive days. Both a daytime and a nighttime link covered most of the overpass, starting at less than 24 degrees elevation angle and ranging up to eight degrees elevation at the opposite horizon. This publication presents the (preliminary) experimental results which provide insight in attained link performance during these overpasses. The interoperability of ground and space laser communication terminals (LCTs) from different suppliers is important for adoption of DTE terminals. The satellite terminal CubeCAT was developed by TNO, AAC Hyperion and partners for Gb/s direct-to-earth (DTE) optical communication. CubeCAT supports the CCSDS O3K standard and recently, the MeO optical ground station (OGS), which is part of the Observatoire de Côte d’Azure - Laberatoire GéoAzur in Grasse, was refitted with an optical bench to comply with the same standard. In a joint test campaign, three links between MeO and CubeCAT were established on December 5th and 6th of 2024. This paper presents the link losses for both up- and downlink based on the measured received irradiance by respectively CubeCAT and the MeO OGS. Subsequently the resulting link losses are compared with the geometrical losses for both up- and downlink, which aims to provide insight in the composition of the encountered link loss.