The Composition of Comets

TL;DR

This paper reviews our current understanding of comet composition, focusing on gas and dust analysis from past observations and upcoming insights from the Rosetta mission, highlighting new data on comet 67P/Churyumov-Gerasimenko.

Contribution

It provides a comprehensive overview of comet composition studies and discusses how the Rosetta mission will enhance our knowledge of cometary materials.

Findings

Initial Rosetta findings on comet 67P/Churyumov-Gerasimenko

Comparison of in situ and remote sensing data

Taxonomic classification of comet gases

Abstract

This paper is the result of the International Cometary Workshop, held in Toulouse, France in April 2014, where the participants came together to assess our knowledge of comets prior to the ESA Rosetta Mission. In this paper, we look at the composition of the gas and dust from the comae of comets. With the gas, we cover the various taxonomic studies that have broken comets into groups and compare what is seen at all wavelengths. We also discuss what has been learned from mass spectrometers during flybys. A few caveats for our interpretation are discussed. With dust, much of our information comes from flybys. They include {\it in situ} analyses as well as samples returned to Earth for laboratory measurements. Remote sensing IR observations and polarimetry are also discussed. For both gas and dust, we discuss what instruments the Rosetta spacecraft and Philae lander will bring to bear to improve our understanding of comet 67P/Churyumov-Gerasimenko as "ground-truth" for our previous comprehensive studies. Finally, we summarize some of the initial Rosetta Mission findings.