April 21, 2009

How to Detect Left-Handed Aliens!

Recently, I have been thinking about other ways of detecting biosignatures from Alien Worlds. Suddenly Wired Magazine came up with a very interesting article that is worth looking into.
The key is that "Circular polarization has the potential to be a signature of life", according to astrobiologist Neill Reid.
It turns out that some photons adopt a corkscrewed rather than up-and-down wavelength after bouncing off photosynthesizing cells.
Therefore, all we need is to put a spectrometer calibrated to detect life-specific circular polarized light on a telescope, and viola we have a powerful remote sensing technique for generic life searches.
Critical to their system is the tendency of all living creatures to be made from groups of so-called homochiral molecules. Chirality refers to the "handedness" of molecules, which often contain the same constituent atoms arranged in mirror-image forms. Organisms on Earth happen to contain only left-handed amino acids, and that property produced the circular polarization wavelengths identified in the species of photosynthesizing bacteria studied by Reid's team.
When you think about it, although most people on Earth are right-handed, other planets may host "left-handed" and "right-handed" organisms that may coexist together in equal numbers. And assuming that photosynthesis is common across the universe, then you have a larger and more diverse set of biosignatures. That truly increases the possibility of detecting Life even more.
It is indeed an ingenious idea that ties together the Circular Polarization of light and Chirality to detect Life in other worlds.

Building A Better Alien-Detection System
Left-handed Amino Acids Prevail in Early Meteorites