Definitely the most interesting part of this project in my opinion.

> This is the first time we have used our new machine learning powered algorithms to keep balloons clustered over Puerto Rico, so we’re still learning how best to do this. As we get more familiar with the constantly shifting winds in this region, we hope to keep the balloons over areas where connectivity is needed for as long as possible.

https://blog.x.company/how-project-loons-smart-software-lear...

Apparently, back in 2016 they launched the balloons from Puerto Pico to do their first test of the autopilot system in Peru. Now they are flying the balloons from Nevada to implement it in Puerto Rico.

> we had figured out how to cluster balloons in teams, dancing in small loops on the stratospheric winds, over a particular region.