Tricorder Could ID Alien Gems and Minerals
Downs and Denton have developed a Raman spectrometer about the size of a tabletop.
by Staff Writers
Pittsburgh PA (SPX) Mar 12, 2006
A geoscientist is developing an instrument using a sensing technique called Raman spectroscopy, which he said could help spacecraft or robotic surface rovers identify thousands of types of minerals on other planets.
"We're developing a tricorder," said Robert Downs of the University of Arizona in Tucson, referring to the instrument used by crew members of the Starship Enterprise on the "Star Trek" television series to identify chemical compositions by simply holding the device near a target material.
Downs and colleague M. Bonner Denton presented an update on their work Sunday at the 57th Annual Pittsburgh Conference on Analytical Chemistry and Applied Spectroscopy.
Downs and Denton have developed a Raman spectrometer about the size of a tabletop, but they are working on miniaturizing the device to pocket size, so it could be used on the Mars Science Laboratory, the next generation of rover due to land on the red planet in 2010.
Unlike other methods of identifying minerals, the spectrometer does not require destructive sampling. Instead, it shoots a laser beam at the sample, which excites the material's atoms and produces a very weak light emission in a wavelength pattern revealing the unique signature of the material.
"It's like a fingerprint," Downs said.
The technique is named after Sir C.V. Raman, who won a 1930 Nobel Prize for discovering the underlying physics.
The spectrograph produced by the Raman spectrometer cannot conclusively identify Mars rocks or any other kinds of minerals, however, because the spectrographs of many minerals have not yet been obtained and cataloged. So Downs and his team are compiling a comprehensive database to complete the identification.
So far, the team has cataloged about 1,500 of the approximately 4,000 known minerals with the device as part of an effort known as the RRUFF Project. The project is so named because it has been supported by gemstone connoisseur and collector Michael Scott, the founding president of Apple Computer. RRUFF is the name of Scott's cat.
Downs also is collaborating with George Rossman of the California Institute of Technology in Pasadena to develop the minerals database. He said the technology could help create handheld instruments for use on Earth as well.
He said the Raman spectrometer is superior to other mineral identification techniques, such as X-ray diffraction and electron microprobes, because they require grinding a bit of the sample to powder or polishing the sample in a specific manner. Such rough treatment might not be the method of choice to determine whether a glittering gemstone is truly a diamond, for example.
Downs said a group of his undergraduate students has assisted him in completing the RRUFF project. When completed, it will comprise the first comprehensive database containing the Raman spectra of all of Earth's minerals.
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