Scientists find first chiral molecule in interstellar space

"By discovering a chiral molecule in space, we finally have a way to study where and how these molecules form," said researcher Brett McGuire.

By Brooks Hays

Propylene oxide is the first chiral molecule discovered in space. Photo by B. Saxton; NRAO/AUI/NSF

Astronomers announced the discovery of the first chiral molecule in interstellar space this week at an American Astronomical Society meeting.

Chirality is a quality of asymmetry. A chiral object is one that has a mirror image that cannot be superimposed on the original object. On the human body, pairs of feet and hands are examples of chiral objects. In chemistry, chirality refers to a molecule's asymmetric atomic structure.

Chiral molecules can be composed of the same basic chemical formula, but can feature two separate chiral structures, sometimes called "left handed" and "right handed." These two differently designed molecules, called enantiomers, can posses all the same chemical properties, but react differently with other molecules.

In nature, many biochemical processes deal exclusively with one of the two types of chiral molecules. The adherence to one-handedness is called homochirality.

Despite the frequency of homochirality in nature, scientists haven't found chiral molecules in space until now.

Researchers Caltech discovered the chiral molecule propylene oxide, CH3CHOCH2, while analyzing data collected by the Green Bank Telescope Prebiotic Interstellar Molecular Survey. Astronomers confirmed the molecule in followup observations using Australia's Parkes radio telescope.

Researchers described the discovery in a new paper, published this week in the journal Science.

"While the technique we used does not tell us about the abundance of each enantiomer, we expect this work to enable future observations that will let us understand a great deal more about chiral molecules, the origins of homochirality, and the origins of life in general," Brandon Carroll, a grad student at Caltech and co-first author of the new study, said in a news release.

Many chiral molecules are large and complex, making them difficult to study. Propylene oxide is relatively small and simple.

"The next step is to detect an excess of one enantiomer over the other," said Brett McGuire, co-first author and a researcher fellow at the National Radio Astronomy Observatory. "By discovering a chiral molecule in space, we finally have a way to study where and how these molecules form before they find their way into meteorites and comets, and to understand the role they play in the origins of homochirality and life."