How much earth? Quoting https://www.worldscientific.com/doi/abs/10.1142/S0217732312500770 https://www.worldscientific.com/doi/abs/10.1142/S02177323125... from 2

How much earth? Quoting https://www.worldscientific.com/doi/abs/10.1142/S0217732312500770 https://www.worldscientific.com/doi/abs/10.1142/S02177323125... from 2012 > We report on the performance of a low-rate communications link established using the NuMI beam line and the MINERvA detector at Fermilab. The link achieved a decoded data rate of 0.1 bits/sec with a bit error rate of 1% over a distance of 1.035 km, including 240 m of earth. https://arxiv.org/pdf/1601.05022.pdf https://arxiv.org/pdf/1601.05022.pdf from 2016 upped that to 810 km.