The link between neighboring satellites in a 22-satellite-per-plane constellation at 550km altitude comes at its closest 480km above the ground. The link betwe

The link between neighboring satellites in a 22-satellite-per-plane constellation at 550km altitude comes at its closest 480km above the ground. The link between next-farthest-neighbors comes at its closest 270km from the ground. The link to the second-farthest-neighbor is not in line of sight. Optical effects at 270km or 480km altitude are negligible; 99% of the atmosphere's mass is below 30km altitude. In theory you could go all the way down to an 8-satellite plane at 550km and still maintain line of sight and freedom from most of the atmosphere's interference. Satellite-to-ground optical laser links are another matter, but you can always route a few hops around weather systems.