Investigation of Re-Entry Break-Up Radiation Markers with a Splitter Probe

Abstract

In the present study a dedicated plasma probe was designed to enhance the understanding of the physical separation of objects during re-entry and their radiative response. The plasma probe was exposed to an air plasma inside the plasma wind tunnel facility PWK4 of the Institute of Space Systems (IRS) of the University of Stuttgart. The chosen plasma condition corresponds to the thermochemical environment of a typical break-up altitude of a low earth orbit entry trajectory. The radiative response during the exposure of the plasma probe to the air plasma flow was observed via spatially and temporally resolved optical emissions spectroscopy. The spatially resolved emissions of the atomic oxygen triplet at 777.34 nm prove to be an excellent indicator for the study of shock layer thickness and location. Additionally, a significant increase in the spectral radiance of N2⁺ bands of the first negative system was observed at the merging point of two shock layers in between the opened plasma probe. Thus, it was concluded that a significant change in radiative markers related to a low-level break-up or break-off event could be the increased radiation of ionized molecular species of the surrounding air plasma.