A new scientific technique developed by a team of University of Hawaii astronomers may help in the search for life in the planetary system closest to ours, and maybe beyond.
Led by Svetlana Berdyugina, a visiting scientist at the UH NASA Astrobiology Institute, the team has found a way to detect life forms through reflected light using polarizing filters -- similar to Polaroid sunglasses or 3-D movie goggles -- even in the glow of a star millions of times brighter than a planet.
Technique life
The findings, published in the International Journal of Astrobiology, were presented last week at the International Astronomical Union General Assembly in Honolulu.
Scientists from the University of Hawaii are Jeff Kuhn, David Harrington and John Messersmith. Berdyugina is from the Institute of Physics of the University of Freiburg and the Freiburg Kiepenheuer Institute for Solar Physics.
In their research, the team developed a method of detecting life as we know it in photosynthetic pigments, which offer a unique signature in the light they reflect.
The scientists measured different biological photosynthetic pigments in the laboratory. These biopigments absorb almost all solar light of specific colors in the visible spectrum and convert it into chemical bonds to store energy. Chlorophyll pigments, for example, absorb blue to red light and reflect a small part of green in the visible, as seen in green plants.
The scientists found that the part of visible light reflected by plants oscillates in certain directions, while other light oscillates in all directions. Due to this phenomenon, the reflected light can be seen remotely using polarizing filters, with each biopigment having its own colored mark seen in polarized light.
"Indeed, we can detect colors as we measure really a spectrum of polarized light," Berdyugina said. "We can distinguish liquid water and (photosynthetic pigments, such as those found in plants).
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