Fusion of In-Flight Aerothermodynamic Heating Sensor Measurements Using Kalman Filtering

Abstract

On February 18th, 2021, the Mars 2020 entry system successfully delivered the Perseverance rover to the surface of Mars at Jezero Crater. The entry capsule carried instrumentation installed on the heatshield and backshell, named “Mars Entry, Descent, and Landing Instrumentation 2.” The instruments were used to measure the aerodynamic and aerothermodynamic performance of the entry vehicle. Five sensors at two locations (three sensors at one location and two sensors at the second location), including a thermocouple plug, heat flux gauge, and a radiometer, were co-located on the backshell. The sensors were exposed to roughly the same aerodynamic heating but measured these environments in different ways, each with its own set of modeling and measurement error complications. This paper develops a method for blending each of these measurements together in a single algorithm to produce estimates of the aerothermodynamic environments at each backshell location. The approach makes use of the Kalman–Schmidt filter/smoother methodology, where systematic measurement error parameters are modeled as multiplicative states that are estimated by the filter along with the aerothermal states. The results of the sensor fusion approach are expected to be used to inform and improve aerothermal modeling for future Mars entry capsules.