I really don't understand the first paragraph, > Researchers in Switzerland have transmitted and received optical data at rates of more than 10 Tbit/s between

I really don't understand the first paragraph, > Researchers in Switzerland have transmitted and received optical data at rates of more than 10 Tbit/s between an Alpine peak and an observatory at the University of Bern – a distance of 53 kilometres. This is more than five times further than would be needed to set up a satellite-to-ground communication link Google says Starlink satellites are 550km in altitude... Is this to do with turbulence below 10km?