Altitude control via rotation of balloon to adjust balloon density

摘要

A balloon that includes an envelope with a gas contained within the envelope, as well as a payload connected to the envelope wherein the envelope has a first portion that has a first absorptive or reflective property with respect to allowing solar energy to be transferred to the gas within the envelope, and a second portion that has a second absorptive or reflective property with respect to allowing solar energy to be transferred to the gas within the envelope where the second absorptive or reflective property is different than the first absorptive or reflective property, and wherein the envelope is rotatable to allow a preferred ratio of the first and second portions of the envelope to be positioned facing the sun.