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Dashing Hopes that Molecule May be Marker of Life

[img3="Credit: B. Saxton (NRAO/AUI/NSF); NASA/JPL-Caltech/UCLA"]https://cdn.eso.org/images/screen/eso1732a.jpg[/img3][hr][/hr]

Observations made with the Atacama Large Millimeter/submillimeter Array (ALMA) and ESA’s Rosetta mission, have revealed the presence of the organohalogen Freon-40 in gas around both an infant star and a comet. Organohalogens are formed by organic processes on Earth, but this is the first ever detection of them in interstellar space. This discovery suggests that organohalogens may not be as good markers of life as had been hoped, but that they may be significant components of the material from which planets form. This result, which appears in the journal Nature Astronomy, underscores the challenge of finding molecules that could indicate the presence of life beyond Earth.

Using data captured by ALMA in Chile and from the ROSINA instrument on ESA’s Rosetta mission, a team of astronomers has found faint traces of the chemical compound Freon-40 (CH₃Cl), also known as methyl chloride and chloromethane, around both the infant star system IRAS 16293-2422 [1], about 400 light-years away, and the famous comet 67P/Churyumov-Gerasimenko (67P/C-G) in our own Solar System. The new ALMA observation is the first detection ever of a stable organohalogen in interstellar space [2].

Organohalogens consist of halogens, such as chlorine and fluorine, bonded with carbon and sometimes other elements. On Earth, these compounds are created by some biological processes — in organisms ranging from humans to fungi — as well as by industrial processes such as the production of dyes and medical drugs [3].

This new discovery of one of these compounds, Freon-40, in places that must predate the origin of life, can be seen as a disappointment, as earlier research had suggested that these molecules could indicate the presence of life. ...

• Nature Astronomy 1:703 (02 Oct 2017) DOI: 10.1038/s41550-017-0237-7 (preprint)