A vast population of primitive, small, icy bodies exists in the outer reaches of the Solar System. The two main regions are the Oort Cloud and the Edgeworth-Kuiper Belt, and are believed to be the main sources of the long period and short period comets respectively. While the Oort Cloud is too distant to study individual objects, the Edgeworth-Kuiper Belt is much closer (35 and 50 AU) and lends itself more readily to investigation. The size of the objects so far detected range from about 200 km up to 1000 km across with probably many more small objects, too faint to detect easily from Earth.
Comets offer an unprecedented opportunity to investigate early solar system processes operating in the outer portions of the accretion disk having been essentially “locked” in cold storage for the 4.5 billion years since they formed. PSSRI (PSS) is actively working on a wide range of activities investigating these important bodies including:
Observational programs to detect and characterize distant objects in the EKB;
In situ investigation using a mass spectrometer experiment (Ptolomy) on board the Philae lander that is part of the ESA Rosetta mission due to encounter comet 67/P Churyumov-Gerasimenko in May 2014
Detailed laboratory analysis of cometary samples such as those of comet Wild2, returned by the NASA Stardust mission in 2006, and stratospheric dust particles collected when the Earth crossed the comet Grigg-Skjellerup dust trail.