5.625 Gbps bidirectional laser communications measurements between the NFIRE satellite and an Optical Ground Station

5.625 Gbps bidirectional laser communication at 1064 nm has been demonstrated on a repeatable basis between a Tesat coherent laser communication terminal with a 6.5 cm diameter ground aperture mounted inside the European Space Agency Optical Ground Station dome at Izana, Tenerife and a similar space based terminal (12.4 cm diameter aperture) on the Near Field Infrared Experiment low earth orbiting spacecraft. Both night and day bidirectional links were demonstrated with the longest being 177 seconds in duration. Correlation with atmospheric models and preliminary atmospheric r <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> and scintillation measurements have been made for the conditions tested, suggesting that such coherent systems can be deployed successfully at still lower altitudes without resorting to the use of adaptive optics for compensation.