Tracing measured compositions of comets to their origins continues to be of keen interest to cometary scientists and to dynamical
modelers of Solar System formation and evolution. This requires building a taxonomy of comets from both present-day dynamical
reservoirs: the Kuiper Belt (hereafter KB), sampled through observation of ecliptic comets (primarily Jupiter Family comets,
or JFCs), and the Oort cloud (OC), represented observationally by the long-period comets and by Halley Family comets (HFCs).
Because of their short orbital periods, JFCs are subjected to more frequent exposure to solar radiation compared with OC comets.
The recent apparitions of the JFCs 9P/Tempel 1 and 73P/Schwassmann-Wachmann 3 permitted detailed observations of material
issuing from below their surfaces—these comets added significantly to the compositional database on this dynamical class,
which is under-represented in studies of cometary parent volatiles. This chapter reviews the latest techniques developed for
analysis of high-resolution spectral observations from ∼2–5 μm, and compares measured abundances of native ices among comets.
While no clear compositional delineation can be drawn along dynamical lines, interesting comparisons can be made. The sub-surface
composition of comet 9P, as revealed by the Deep Impact ejecta, was similar to the majority of OC comets studied. Meanwhile,
73P was depleted in all native ices except HCN, similar to the disintegrated OC comet C/1999 S4 (LINEAR). These results suggest
that 73P may have formed in the inner giant planets’ region while 9P formed farther out or, alternatively, that both JFCs
formed farther from the Sun but with 73P forming later in time.
Keywords Comets - Ices - Composition - Parent volatiles - Molecular spectroscopy - Infrared spectroscopy
ISSI Workshop on the Origin and Evolution of Cometary Nuclei, Bern, Switzerland, October 16-20, 2006.