  The origin of organic compounds detected in meteorites and comets, some of
which could serve as precursors of life on Earth, still remains an open
question. The aim of the present study is to make one more step in revealing
the nature and composition of organic materials of extraterrestrial particles
by comparing infrared spectra of laboratory-made refractory organic residues to
the spectra of cometary particles returned by the Stardust mission,
interplanetary dust particles, and meteorites. Our results reinforce the idea
of a pathway for the formation of refractory organics through energetic and
thermal processing of molecular ices in the solar nebula. There is also the
possibility that some of the organic material formed already in the parental
molecular cloud before it entered the solar nebula. The majority of the IR
"organic" bands of the studied extraterrestrial particles can be reproduced in
the spectra of the laboratory organic residues. We confirm the detection of
water, nitriles, hydrocarbons, and carbonates in extraterrestrial particles and
link it to the formation location of the particles in the outer regions of the
solar nebula. To clarify the genesis of the species, high-sensitivity
observations in combination with laboratory measurements like those presented
in this paper are needed. Thus, this study presents one more piece of the
puzzle of the origin of water and organic compounds on Earth and motivation for
future collaborative laboratory and observational projects.
