Space.com (May 28, 2009)
"Although Captain Kirk and crew could zip over to a planet at warp speed and teleport down to the surface to check if it was inhabited, current-day scientists will generally have to search for life from a distance. New research gives some hope that we could detect a 'handedness' beacon from a planet full of microbes.
"This handedness, or homochirality, is characteristic of life on Earth. The molecules that make proteins and DNA all have either a left-handed or right-handed orientation. Both orientations are made in equal quantities by non-biological processes, but life prefers to have just one type of hand over the other.
" 'Homochirality is a fundamental aspect of self-replication,'...."
The article gives a pretty good introduction to homochirality, with examples. It also touches on other ways that could be used to detect life from light years away. Most of them, like looking for chemically unstable mixtures of gasses in a planet's atmosphere, or reflection spectra (a detailed analysis of what colors are reflected - including colors we can't see), could give false positives. Volcanoes, for example, can add chemicals to an atmosphere that don't last long, and some minerals have an infrared signature that mimics that of plants.
The 'handedness' of chemicals used in living organisms is something that biologists have known about for decades, although the knowledge hasn't seemed to filter into the medical and pharmaceutical population too well. Which is another topic.
What's exciting is that the technology - and a telescope - exists, that could be used to look for asymmetric light from other worlds.
Related posts, at
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