Impact of space-to-ground video transmission constraints on teleoperated final approach and docking

This study investigates the impact of communication link constraints in the transmission of streaming video feedback on spacecraft teleoperation system performance. A final approach and docking scenario with an uncooperative, rotating target was set up, in which operators in three experiment series were presented with different video frame rate levels, compressed image quality levels, and roundtrip time delay levels. The data show that none of the variables has an effect on the maneuver accuracy, efficiency, or safety. However, there were significant effects on subjective perception and task success. Decreasing the compressed image quality has negligible effect on operator perception, and it has no effect on task success. Reducing the frame rate down to 7.5 framed per second also has no effect, but operator perception dropped significantly with further reduction, without effect on task success. An increase in roundtrip time delay causes a decrease in task success rate between low delays below 750 ms and high delays above 1000 ms, as well as a decrease in subjective system controllability index and an increase in task load. This study thus identifies the envelopes of maximum operator performance for frame rate and roundtrip delay, which translate into communication architecture, power, and frequency requirements.