DIX Planetary Science Seminar

The importance of studying water and organic molecules in comets is related to their biological relevance. The origin of water oceans and pre-biotic organic molecules on Earth is still unsolved. The terrestrial planets formed in a dry region of the proto-planetary disk by aggregation of rocky planetesimals; icy aggregates could form only beyond the frost lines. Even today the bulk Earth is cosmically dry (poor in H, relative to the protoplanetary disk). About 60 Ma after Earth-accretion, the moon-forming impact probably removed any water that may have outgassed after core formation, leaving the Hadean Earth probably water-poor at its surface. How did Earth acquire its water?

Bombardments of Earth and inner planets by icy and rocky planetesimals (represented today by comet nuclei and asteroids) were common from their formation through the Late Heavy Bombardment. Because water is the most abundant native ice in cometary nuclei, with the aggregate CHON ices comprising a close second, we want to understand the role primitive bodies played in delivering water and pre-biotic organics to the young inner planets.

High resolution spectroscopy with long-slit echelle spectrometers is powerful method for ground- based IR surveys. In the infrared spectral region of about (3 – 5 um), trace volatiles are sampled simultaneously with H2O. The inter-comparison of cosmogonic indicators in comets and in planetary atmospheres through high-resolution spectroscopic studies might address these unresolved questions.