Planetary Science

Organic Delivery Device

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Science  11 Apr 2014:
Vol. 344, Issue 6180, pp. 129
DOI: 10.1126/science.344.6180.129-a
CREDIT: K. L. THOMAS-KEPRTA ET AL., GEOCHIMICA ET COSMOCHIMICA ACTA (15 MARCH 2014) © 2014 ELSEVIER B.V.

Several plausible mechanisms could produce complex organic molecules on the Moon, including synthesis by energetic UV radiation or impact shocks, delivery from meteorites, and even decay of biotic matter. However, Apollo samples have shown surprisingly low levels of carbon. Thomas-Keprta et al. have now detected complex organics larger than methane within lunar samples from Shorty Crater. They probed glassy beads tens of micrometers in diameter for fluorescence, revealing some with thin layers of carbonaceous material that were apparently embedded while the silicate surface was still molten. Chemical characterization with micro-Raman spectroscopy indicated the presence of macromolecular matter similar to kerogen, a compound that composes the bulk of stony meteorites. The authors favor a production scenario in which these abiotic organics were delivered via micrometeorites around the time that the volcanic glass beads formed. More substantial meteoritic accretion from cometary and asteroidal fragments also is thought to have occurred on the early Earth. The specific quantity and nature of these organics remain under investigation in the context of possible precursors for life in the solar system.

Geochim. Cosmochim. Acta 10.1016/j.gca.2014.02.047 (2014).

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