> Additional members of the Google team are expected to arrive in Sri Lanka later this week to test flight controls on the balloon, A probably stupid question:

> Additional members of the Google team are expected to arrive in Sri Lanka later this week to test flight controls on the balloon, A probably stupid question: how do they use "flight controls" to control the location of the balloon? I don't think they use any propulsion so it must be just a matter of changing altitude. If so what if all winds go in one direction?