  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 emission of alloying elements
points to these spectra being a candidate for the determination of spacecraft
demise. The identification of such features in ground testing will allow a more
certain identification of specific break-up events
