[The following is an exact transcript of this podcast.]
Many of the key molecules for life have a specific direction, or handedness: DNA twists to the right, amino acids to the left. Now scientists at the National Institute of Standards and Technology (or NIST) aim to take advantage of this so-called chirality to search for signs of extraterrestrial life.
When chemists synthesize organic compounds in the lab, they often wind up with a mix of molecules: half are right-handed, and half are left. But cells are a bit more particular. When life arose, our ancestors made some choices. They went with the right-handed sugars, and the left-handed amino acids, a tradition still in effect.
The scientists at NIST have come up with a gadget that can see the polarized light that bounces off of molecules that show a preferred handedness. And in the Proceedings of the National Academy of Sciences, they report using the device to detect the signature reflection that comes from the chlorophyll in plant leaves. If this handedness meter works well at a distance, they could load it onto a space probe—a preponderance of right- or left-handed biomolecules could mean a planet has at least simple life forms on it. And we might even find out if ET is a southpaw.