Carbonaceous matter in cometary dust and coma.

The analysis of carbonaceous matter in p/Halley's dust and coma via mass spectrometry of positive ions is reviewed. Dust impact generated ions were analyzed by the PUMA instrument aboard VEGA I, and coma plasma ions by the PICCA instrument aboard GIOTTO. For the organic molecules results an overall C:H:O:N ratio of 1.:1.4:0.6:0.1. Most of this polymer material can formally be understood as an aggregation of monomers C2H2, CH2O, and HCN. Special emphasis is given to possible aromatic, especially heterocyclic, and other unsaturated ions, and their importance for abiotic chemical and prebiotic evolution. Aspects of the potential heterogeneous catalysis in liquid water at the inorganic grain backbone structure found by this analysis, too, are also treated.