Scientists give a hand(edness) to the search for ...( Visiting aliens may be the stuff of ...)

Visiting aliens may be the stuff of legend, but if a scientific team working at the National Institute of Standards and Technology (NIST) is right, we may be able to find extraterrestrial life even before it leaves its home planetby looking for left- (or right-) handed light.

The technique the team has developed* for detecting life elsewhere in the universe will not spot aliens directly. Rather, it could allow spaceborne instruments to see a telltale sign that life may have influenced a landscape: a preponderance of molecules that have a certain chirality, or handedness. A right-handed molecule has the same composition as its left-handed cousin, but their chemical behavior differs. Because many substances critical to life favor a particular handedness, Thom Germer and his colleagues think chirality might reveal lifes presence at great distances, and have built a device to detect it.

You dont want to limit yourself to looking for specific materials like oxygen that Earth creatures use, because that makes assumptions about what life is, says Germer, a physicist at NIST. But amino acids, sugars, DNAeach of these substances is either right- or left-handed in every living thing.

Many molecules not associated with life exhibit handedness as well. But when organisms reproduce, their offspring possess chiral molecules that have the same handedness as those in their parents bodies. As life spreads, the team theorizes, the landscape will eventually have a large amount of molecules that favor one handedness.

If the surface had just a collection of random chiral molecules, half would go left, half right, Germer says. But lifes self-assembly means they all would go one way. Its hard to imagine a planets surface exhibiting handedness without the presence of self assembly, which is an essential component of life.

Because chiral molecules reflect light in a way that indicates their handedness, the research team built a device to
'/>"/>