Rebuilding freestream atmospheric conditions using surface pressure and heat flux data

This paper proposes a technique for the reconstruction of freestream atmospheric quan- tities from Entry, Descent and Landing measurements of both pressure and heat flux in the vehicle forebody surface. The proposed approach is statistical and yields both the freestream values and uncertainty bounds that take into account measurements errors as well as uncertainties in the flow model parameters. It exploits pressure and heat flux mea- surements given by Flush Air Data Systems at the stagnation point of the entry vehicle, as well as Inertial Measurement Unit flight data. This novel technique is compared to more conventional methods for trajectory and atmospheric reconstruction based on Inertial Mea- surement Unit data and stagnation pressure data. This expensive Bayesian reconstruction algorithm is accelerated by a surrogate model for the quantities of interest, namely pressure and heat flux at the stagnation point.