  Buckminsterfullerene, C60 , is the largest molecule observed to date in
interstellar and circumstellar environments. The mechanism of formation of this
molecule is actively debated. Despite targeted searches in primitive
carbonaceous chondrites, no unambiguous detection of C60 in a meteorite has
been reported to date. Here we report the first firm detection of fullerenes,
from C30 to at least C100 , in the Almahata Sitta (AhS) polymict ureilite
meteorite. This detection was achieved using highly sensitive laser desorption
laser ionization mass spectrometry. Fullerenes have been unambiguously detected
in seven clasts of AhS ureilites. Molecular family analysis shows that
fullerenes are from a different reservoir compared to the polycyclic aromatic
hydrocarbons detected in the same samples. The fullerene family correlates best
with carbon clusters, some of which may have been formed by the destruction of
solid carbon phases by the impacting laser. We show that the detected
fullerenes are not formed in this way. We suggest that fullerenes are an
intrinsic component of a specific carbon phase that has yet to be identified.
The nondetection of fullerenes in the Murchison and Allende bulk samples, while
using the same experimental conditions, suggests that this phase is absent or
less abundant in these primitive chondrites. The former case would support the
formation of fullerenes by shock-wave processing of carbonaceous phases in the
ureilite parent body. However, there are no experimental data to support this
scenario. This leaves open the possibility that fullerenes are an interstellar
heritage and a messenger of interstellar processes.
