The second flight of CASS•E allowed the collection of stratospheric samples but the post-flight finding of fluorescent beads on the sample collection filters (shown in the image above) demonstrated that a contamination pathway was present. Therefore this feature allowed a clear interpretation of the experiment -i.e. contamination did occur, which would not have been achievable without. Further studies will (i) clarify the specific contamination pathways seen, (ii) develop further the use of positive controls for the presence of microbial contamination pathways and (iii) a 2nd generation of CASS•E incorporating lessons learned and increased sample collection capacity.