Survival of organic phases in porous IDPs during atmospheric entry: A pulse-heating study

In this study, we have performed pulse-heating experiments at different temperatures for three organic molecules (a polycyclic aromatic hydrocarbon [PAH], a ketone, and an amino acid) absorbed into microporous aluminum oxide (Al2O3) in order to imitate the heating of the organic molecules in interplanetary dust particles (IDPs) and micrometeorites (MMs) during atmospheric entry and to investigate their survival. We have shown that modest amounts (a few percent) of these organic molecules survive pulse-heating at temperatures in the 700 to 900 degrees C range. This suggests that the porosity in IDPs and MMs, combined with a sublimable phase (organic material, water), produces an ablative cooling effect, which pen-nits the survival of organic molecules that would otherwise be lost either by thermal degradation or evaporation during atmospheric entry.