Data Assimilation Applied Thermal Analysis of Mars Airplane for High-altitude Flight Test (MABE2)

As a new means of Mars exploration method, Mars airplane has been studied for a long time. The Mars airplane enables to bridge the scale and resolution measurement gaps between rovers and orbiters. However, it is not realized yet due to the severe flight conditions. Now, JAXA advances the development of the Mars airplane and plans to make a high altitude flight test called MABE2 (Mars Airplane Balloon Experiment 2). In order to demonstrate a severe condition: atmospheric temperature and pressure on Mars, the flight model will be launched to 35 km in altitude on Earth by High-Altitude Balloon. There, the Mars airplane is released from the balloon, and the flight test is conducted under the Martian-like atmospheric condition. For the high altitude flight test, a thermal mathematical model of the Mars airplane was built on Thermal Desktop©, and thermal analysis was conducted. In the analysis, we introduced a new thermal analysis method using data assimilation to build a reliable thermal mathematical model. The data assimilation is a statistical method to combine physical simulation and observation data obtained from an actual system, and has been used to solve dynamic inverse problems. We employed the Ensemble Kalman Filter, which is one of the data assimilation techniques, to the thermal mathematical model and estimated uncertain parameters, such as thermal conduct conductance. This paper describes the thermal modeling of the Mars airplane for a high-altitude flight test, firstly. Then, the results of the thermal vacuum test and model-test correlation are described. Finally, the result of the thermal conductance estimation and the availability of the new thermal analysis method using data assimilation is discussed.