High Altitude Balloons in STK
Between Google’s Loon Project which is delivering internet to Puerto Rico after Hurricane Maria or World View’s progress to provide stationary data acquisition and scenic passenger trips in the stratosphere, there has been a lot of recent research and development in the field of high altitude balloons. The stratosphere offers many unique scientific opportunities, and balloons offer the means to provide the high altitude data acquisition of a satellite while remaining relatively stationary.
The balloons manage to keep their position over an area of interest by using the winds aloft as a propulsion system. In order to change directions, the balloons use air as ballast to change their altitude until they intercept an advantageous wind direction. This guidance system can keep the balloon within a 50-100 nautical mile radius of an area of interest. The behavioral characteristics of such a balloon propagation can be modelled in STK using a standard aircraft object with a great arc propagator.
The attached MATLAB code provides the basic setup for modelling such a guidance system and can be run without any user manipulation. The code assumes that no wind data is currently available and instead uses random number generators to create wind speeds and wind directions at random altitudes. The balloon is configured to stay within a certain radius of the point of interest and only vary its altitude within defined limits. All of the balloon characteristics can easily be redefined to create a customized high altitude balloon route profile.
The distance away from the point of interest that the balloons can stray is based on Latitude and Longitude. It is recommended that the distance between two degrees of Longitude be determined for the Latitude region of the mission that is being modelled, if this variance value is modified. The NOAA Lat/Lon Distance calculator is a great resource to determine this metric.
NOAA Lat/Lon Distance Calculator: http://www.nhc.noaa.gov/gccalc.shtml