Comets are small icy bodies composed of a mixture of mineral grains and frozen volatiles that inhabit the outermost regions of our System System, extending from the Kuiper Belt to the Oort Cloud. They formed over 4.5 billion years ago from accretion of dust and gas during the collapse of the giant molecular cloud, the progenitor of the Solar System. Consequently, their physical structure and chemical composition provide a unique record our presolar history, the initial stages of planet formation and the prebiotic chemical evolution of the terrestrial planets. To decode this record, however, requires the direct analysis of prisitine cometary materials in laboratories around the world.<br/><br/>Here we describe a next generation mission, the Comet Astrobiology Exploration Sample Return (CAESAR) mission, designed to take the next major scientific leap in the acquisition and study of comet samples. CAESAR will acquire and return to Earth, for laboratory analysis, a minimum of 80g of surface material from the nucleus of comet 67P/Churyumov-Gerasimenko (67P). It will characterize the surface region sampled, preserve the collected sample in a pristine state, and return evolved volatiles by capturing them in a separate gas reservoir. CAESAR’s sample analysis objectives address questions regarding the nature of Solar System starting materials and how these fundamental components came together to form planets and give rise to life. To this end, CAESAR will determine the nature and abundances of interstellar dust grains and molecular cloud materials, and characterize the origins and ages of refractory solar nebula condensates. It will trace the history of volatile reservoirs, delineate the chemical pathways that led from simple interstellar species to complex and prebiotic molecules, and constrain the geological and dynamic evolution of cometary bodies. It will also evaluate the potential role of comets in delivering water and organics to the early Earth. CAESAR will achieve these goals by carrying out coordinated sample analyses that will link macroscopic properties of the comet with microscale mineralogy, chemistry, and isotopic studies of volatiles and solids.

To see a world in a grain of sand: CAESAR comet sample return mission

2019 Fall National Meeting

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