Abstract
Comets are regarded as probably the most primitive of solar system objects, preserving a record of the materials from which the solar system aggregated. Key amongst their components are organic compounds – molecules that may trace their heritage to the interstellar medium from which the protosolar nebula eventually emerged. The most recent cometary space mission, Rosetta, carried instruments designed to characterize, in unprecedented detail, the organic species in comet 67P/Churyumov–Gerasimenko (67P). Rosetta was the first mission to match orbits with a comet and follow its evolution over time, and also the first mission to land scientific instruments on a comet surface. Results from the mission revealed a greater variety of molecules than previously identified and indicated that 67P contained both primitive and processed organic entities.
Highlights
CH, CHN, CHS, CHO2- and CHON- bearing saturated and have a good understanding of the inventory of soluble unsaturated species present
A direct comparison between meteoritic organics and organic molecules detected in comets is difficult because the survival of such materials in meteorites that arrive on Earth is unlikely
Water in carbonaceous chondrites is combined within phyllosilicate minerals and organic molecules, rather than as H2O ice, as is the case in comets
Summary
CH-, CHN-, CHS-, CHO2- and CHON- bearing saturated and have a good understanding of the inventory of soluble unsaturated species present. Goesmann et al (2015) identified a wide variety of organic molecules in low abundance compared to water, including CH3CHO (ethanal, known as acetaldehyde); CH2OHCHO (2-hydroxyethanal) and CH2(OH)CH2(OH) (1,2-ethanediol). The presence of nitrogen-bearing species – including CH3NH2 (methanamine), C2H5NH2 (ethanamine), HCONH2 (methanamide), plus several molecules not identified previously in comets, such as CH3NCO (isocyanatomethane), CH3COCH3 (propanone), C2H5CHO (propanal) and CH3CONH2 (ethanamide) – were inferred from the spectrum.
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