Fullerenes in an impact crater on the LDEF spacecraft

Abstract

THE fullerenes C₆₀ (ref. 1) and C₇₀ have been found to occur natu-rally on Earth^2,3, and have also been invoked to explain features in the absorption spectra of interstellar clouds^1,4. But no definitive spectroscopic evidence exists for fullerenes in space and attempts to find fullerenes in carbonaceous chondrites have been unsuccessful^5,6. Here we report the observation of fullerenes associ-ated with carbonaceous impact residue in a crater on the Long Duration Exposure Facility (LDEF) spacecraft. Laser ionization mass spectrometry and Raman spectroscopy indicate the presence of fullerenes in the crater and in adjacent ejecta. Man-made fuller-enes survive experimental hyper velocity (∼6.1kms^-1) impacts into aluminium targets, suggesting that space fullerenes contained in a carbonaceous micrometeorite could have survived the LDEF impact at velocities towards the lower end of the natural particle encounter range (<13 km s^-1). We also demonstrate that the full-erenes were unlikely to have formed as instrumental artefacts, nor are they present as contaminants. Although we cannot specify the origin of the fullerenes with certainty, the most plausible source is the chondritic impactor. If, alternatively, the impact produced the fullerenes in situ on LDEF, then this suggests a viable mechanism for fullerene production in space.