Scientists develop technique to trace alien lifeApril 24th, 2009 - 5:39 pm ICT by IANS
Washington, April 24 (IANS) Researchers may be able to find extraterrestrial life even before it leaves its home planet — by looking for left or right-handed light.
The technique they have developed at the National Institute of Standards and Technology (NIST) for detecting life elsewhere in the universe will not spot aliens directly.
Rather, it could allow spaceborne instruments to see a tell-tale 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 behaviour differs.
Because many substances critical to life favour a particular handedness, Thom Germer physicist and his colleagues at NIST 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,” said Germer. “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.
“If the surface had just a collection of random chiral molecules, half would go left, half right,” Germer said. “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.”
Because chiral molecules reflect light in a way that indicates their handedness, the research team built a device to shine light on plant leaves and bacteria, and then detect the polarized reflections from the organisms’ chlorophyll from a short distance away. The device detected chirality from both sources, said a NIST release.
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