As many of you know, NASA has recently launched a satellite into orbit that will be imaging stars in order to detect Earth-like planets.
http://kepler.nasa.gov/about/
The next step after identifying these planets is to do some spectroscopy on them to determine what their atmospheres and surfaces contain. Such spectroscopy could indicate whether or not life is likely to exist on that planet. I recently came across an article that describes one clue scientists could look for through extra-solar planet spectroscopy to indicate if that planet may have life. That clue would be a distintive handedness to the spectrum (a preferred chirality). Here is the article describing the method:
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 planet—by 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 life's presence at great distances, and have built a device to detect it.
"You don't 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, DNA—each 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 life's self-assembly means they all would go one way. It's hard to imagine a planet's surface exhibiting handedness without the presence of self assembly, which is an essential component of life."
Article continues here
The Kepler Mission and the Search for Extraterrestrial Life
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