Aerothermal Measurements from the ExoMars Schiaparelli Capsule Entry

The instrumentation package COMARS+ was developed to measure aerothermal parameters on the back cover of the ExoMars Schiaparelli lander during Martian entry. The aerothermal sensors called Combined Aerothermal and Radiometer Sensor (COMARS) combine four discrete sensors, measuring static pressure, total heat flux, temperature, and radiative heat flux. After passing all acceptance tests, the Schiaparelli capsule was launched on top of the Proton launcher on March 14, 2016. All COMARS+ sensors operated nominally during the complete entry phase. But the complete data package is not available due to an anomaly that led to the failure of Schiaparelli shortly before landing. Nevertheless, a subset of the COMARS+ flight data was transmitted real-time during the entry and was received by the ExoMars 2016 orbiter, with the exception of the plasma blackout phase. The radiative heat flux on the back cover close to the vehicle shoulder was measured successfully for the first time on a Mars entry vehicle. The measured maximum radiative contribution was 61% of the total heat flux at the first measurement point after the blackout phase and 33% for the next measured trajectory point 10 s later. These measurements confirm recent findings that radiative heating can be a significant portion of total heating on the back cover during Mars entry. The maximum back cover total heat flux rate was measured at approximately 9% of the calculated stagnation point heat flux on the front cover. All measured heat fluxes on the back cover were below the levels that were used to design the thermal protection system.