Ingredients of Life Found Around Sun-Like Star

smooth wombat writes "NASAs Spitzer Space Telescope has detected the basic organic building blocks of life in a ring orbiting in the 'habitable zone', that area where Earth orbits the Sun and where water exists on the borderline between gas and liquid, in a nearby stellar nursery. When acetylene and hydrogen cyanide combine with water they form adenine, one of the four bases of DNA. The detection supports the widely held theory that many of the molecular building blocks of life were present in the solar system even before planets formed, thus assisting the initial formation of complex organic molecules and the start of life itself." Though it was a little shakier than this observation, we've discussed the possibility of life elsewhere in the galaxy before.

Comments

Re:"the borderline between gas and liquid"

[Red Flayer]

" Shouldn't it be where water exists on the borderline between gas and solid?"

No. Liquid water doesn't exist at the temp and pressure where there is a borderline between gas and solid, you get direct sublimation from solid to gas under those conditions -- unless you happen to be at exactly the triple point.

Conversion between gas and liquid would help in the formation of life precursors, since the phase changes could help concentrate compounds in acqueous solution, resulting in greater rates of reaction. I'm sure there are other reasons why acqueous phase changes would help formation of complex organic molecules.

Re:DNA in space?

[Hiro Antagonist]

Well, radiation is the first problem; there's a hell of a lot of organic-molecule-shattering 'waves of doom' in space, way more than on the surface of a planet that has the shielding of both an atmosphere and a magenetosphere[1].

Second, tidal pools on a planet keep everything nicely together in the same general area, courtesey of Our Friend Gravity. Tidal pools, at least on Earth, also provide a very necessary solvent for the whole organic chemistry process -- water. No water, and pretty much all of the organic processes that we know about stop working; in fact, when you look at the chemistry, it almost seems that an oxygen atmosphere is optional, but that water is a base requiremet for life because of its properties as a solvent.

So, no, it's doubtful that complex molecules like Keith Richards will form outside of a suitable gravity well, and doubly doubtful that complex organic molecules (e.g., DNA) will form without liquid water.

[1] That's a magnetic field around a planet, not a hamster ball for Sir Ian McKellen.

Carbon Dating

[qeveren]

Carbon-14 (the radioactive isotope of carbon used in carbon dating) is continuously generated on Earth at a fairly constant rate, by the interaction of neutrons (from cosmic rays) with nitrogen (and occasionally oxygen and carbon) atoms. So, 'new' carbon-14 atoms are being made all the time.

Because it has a relatively constant abundance in nature, living things should also maintain the same ratio of carbon-12 to carbon-14 in their tissues... until they die, at which point they're no longer taking in new carbon from the environment. Then the carbon-14 starts to decay (with a half-life of ~5700 years), but the carbon-12, which is stable, remains. Measuring this ratio can give an approximation of the length of time since the creature died.

The carbon-12 in your body is stable, and could very well pre-date the solar system. Carbon-14 doesn't hang around very long, in astronomical timescales. :)