Spectral Features for Reentry Breakup Event Identification

Abstract

The fragmentation of two aerospace aluminum alloys is investigated in a ground testing facility including mechanical loads as occurring due to aerodynamic forces in a real atmospheric entry event at three trajectory points. The emission spectroscopic analysis shows that these materials fail after distinct alkali metal features are observed in the spectra. The two alloys feature characteristic emissions of the different alkali metals. The presence of lithium lines that have previously been exclusively attributed to battery failure in observation campaigns may be considered as a marker for aluminum breakup. This is particularly interesting for future entry observations because it allows a new insight into the structural failure processes of the demising spacecraft. The lack of emissions of alloying elements points to these spectra being candidates for the determination of spacecraft demise. The identification of such features in ground testing will allow a more certain identification of specific breakup events.