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Analyzing chemical samples from space.

A new test case that could be used for evaluating extraterrestrial samples for evidence of life has been identified by chemical engineers at the Georgia Institute of Technology, Atlanta. It ultimately may allow the use of simpler analytical instrumentation on future space missions.

In the search for life on other planets, astrobiologists regard liquid water and chiral biomolecules to be critical components. "Yet, because chiral molecules can be made synthetically as well as biologically, it's not enough to just find them on other planets. We need to show a change of chirality over time," states Tracey Thaler, a graduate student at the School of Chemistry and Biochemistry.

Thaler has investigated racemization--the conversion of an optically active compound to a racemic form, which has no optical rotation--as a new approach for analyzing samples in outer space. "Because this type of reaction is found only in biological systems, it could serve as a marker for extraterrestrial life," Thaler explains.

Chromatography, the current method used to evaluate extraterrestrial samples on space missions, is a tedious process. Another drawback is that researchers must know in advance the specific compounds they are looking for, which is not always possible.

In contrast, polarimetry, a method for measuring optical activity, does not require knowledge of the structure being analyzed. Because existing polarimeters have performance limitations, Georgia Tech researchers are working to develop a more sensitive polarimeter that has the ability to detect smaller concentrations of optically active compounds. Thaler's work serves as a test bed for such an instrument.

"[Thaler's] study is significant because it marks the first time that racemization has been looked on as a sign of life on other planets," emphasizes Andreas Bommarius, professor of biomolecular engineering. "What's more, she has identified two new media in which the enzyme mandelate racemase is active."

An important part of the study determined that mandelate racemase reactivity could occur at subzero temperatures found on planets such as Mars or moons like Titan, Europa, or Enceladus, where recent data show water is likely to exist.
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Publication:USA Today (Magazine)
Geographic Code:1USA
Date:Jun 1, 2006
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