Effective Approach to Characterization of Prediction Errors for Balloon Ascent Trajectories

Abstract

In order to comply with the objectives of a balloon mission, it is usually necessary to predict, monitor and track the flight trajectory. Within the framework of the Unmanned Space Vehicles program, the Italian Aerospace Research Center has developed several methodologies and tools useful to evaluate balloon mission feasibility, predict balloon flight trajectory and assess trajectory prediction errors. These methodologies are based on weather forecast data for trajectory computation obtained using the Integrated Forecast System model by the European Center for Medium Range Weather Forecast and on the use of a proprietary simulation software for the prediction of flight trajectory and thermal behavior of high altitude zero-pressure balloons. In this paper, we propose an effective approach for the characterization of trajectory prediction error based on: statistical characterization of the forecast error of the Integrated Forecast System atmospheric data (winds, temperature and pressure), statistical characterization of the error on gas mass due to inflation procedures and analytical error propagation of these sources of uncertainties on the balloon’s velocity vector. The proposed approach allows to estimate the actual trajectory dispersion once the predicted trajectory is computed using forecast data. The methodology proposed in this paper is an improvement of the trajectory prediction methodology that has been successfully used during the first Dropped Transonic Flight Test mission accomplished by Italian Aerospace Research Center.