Abstract: Example methods and systems for determining a distribution of balloons based on population densities is provided. A method may include receiving information indicating a region divided into a plurality of horizontal bands of latitudes and a population density for one or more areas of the region. The method may also include associating the population density for a given area with a corresponding horizontal band of latitude in which the given area resides, and based on the population density associated with each horizontal band of latitude, determining a distribution of a plurality of balloons per horizontal band of latitude. The method may also include providing instructions to control the distribution of the plurality of balloons per horizontal band of latitude to remain in a trajectory substantially within a respective horizontal band of latitude.

Abstract: Methods and systems for determining altitudes for a vehicle to travel are provided. In one example, a method comprises receiving information indicating a desired location for a balloon and a time period for traveling to the desired location. A region may include the desired location, and the region can be divided into a plurality of cells. The method may include determining estimated cell locations that can be reached by the balloon over a time interval by following a wind at a given altitude. The method may also include assigning a cost value to each cell based on a proximity of the estimated cell locations to a cell including the desired location. The method may further include determining for each cell an altitude for the balloon to travel based on the assigned cost value, and storing information indicating the cost value and the altitude for the balloon to travel.