Passive Method to Measure Reentry Radiation in the Presence of Ablative Products

Reentry radiation is one of the key phenomena to take into account while designing an Entry Descent and Landing (EDL) phase for sample return and some gas/ice giants' missions. In the case of an ablative thermal protective system (TPS), the physicochemical processes involved produce a large amount of dust and phenolic gases that can obstruct the optical path. The QubeSat for Atmospheric Research and Measurement on Ablation mission (5.2 kg CubeSat launched in December 2019) gave a low-cost opportunity to develop a dedicated payload named "Imbedded Nanoplatform-size Emission Spectrometer" (INES) to study the radiation of a reentry plasma in the presence of an ablative heatshield (Cork P50 from Amorim (TM)). The payload is able to measure both radiation and thickness evolution of the TPS at the same location. The paper presents a passive method to prevent any contamination of the optical path from the ablative TPS to be able to measure radiation for a wide range of mission profiles and heatshield locations.