Chiral molecule detected in space for first time

Scientists on Tuesday reported the first detection of a chiral molecule in space, a finding that may help understand one of the most puzzling mysteries of the early origins of life.

Like a pair of human hands, chiral molecules have two forms that are identical in structure, but are mirror images of one another.

Life on Earth uses one, and only one, handedness of many types of chiral molecules, a phenomenon known as homochirality.

The amino acids that make up the proteins in our bodies, for example, are all left-handed.

Chiral molecules are of particular significance in pharmaceutical development: one form, or enantiomer, may have a therapeutic effect while the other is toxic.

To date, the source of this chiral bias on Earth has been a mystery, though some suggested insights might be found in space since it's thought that interstellar clouds contain the raw ingredients for the formation of our solar system.

In the new study, a team of scientists used highly sensitive radio telescopes to detect a chiral molecule called propylene oxide, or CH3CHOCH2, in Sagittarius B2, a cloud of gas and dust which is roughly 3 million times the mass of the Sun and located in the center of our Milky Way galaxy.

"It's the first molecule detected in space that has the property of chirality, making it a pioneering leap forward in our understanding of how prebiotic molecules are made in space and the effects they may have on the origins of life," co-first author Brandon Carrol, a chemistry graduate student at the California Institute of Technology, said in a statement.

The research was undertaken primarily with the U.S. National Science Foundation's Green Bank Telescope in West Virginia as part of the Prebiotic Interstellar Molecular Survey, with supporting observations from the Parkes radio telescope in Australia.

Propylene oxide was detected in the cold, outer area of Sagittarius B2 North, rather than the hot cores within the gas cloud. Other organic compounds have also been detected in this region.

Though propylene oxide is not utilized in living organisms, its presence in space is a signpost for the existence of other chiral molecules.

The current data, however, did not distinguish between the left- and right-handed versions of the molecule.

"The next step is to detect an excess of one enantiomer over the other," said Brett McGuire, a chemist with the U.S. National Radio Astronomy Observatory, who shared the first authorship on the work with Carrol.

"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."

The finding was published in the U.S. journal Science and also presented at the American Astronomical Society meeting in San Diego, California.