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Fraser
2009-Aug-17, 08:00 PM
NASA scientists studying the comet samples returned by the Stardust spacecraft have discovered glycine, a fundamental building block of life. Stardust captured the samples from comet Wild 2 in 2004 and returned them to Earth in 2006. "Glycine is an amino acid used by living organisms to make proteins, and this is the [...]

More... (http://www.universetoday.com/2009/08/17/amino-acid-found-in-stardust-comet-sample/)

A.DIM
2009-Aug-17, 09:18 PM
Neato, the first direct evidence for amino-acid-carrying-comets!

More evidence for the seeds of life being everywhere.

Thanks!

transreality
2009-Aug-17, 11:54 PM
Actually, it provides insights into the abiogenic formation of glycine and atmospheric conditions of early life on Earth. The comet condensed from the pre-solar nebula, where highly reducing conditions made the formation of this and a number of other cometary ingredients possible, freezing this primordial glycine. Subsequently to planetary formation, glycine forms in large quanties of Earth, but not on Mars. This is because mars lacks mass onto to retain the Hydrogen required to form a reducing atmosphere, this does happen on Earth allowing the organic molecules to accumulate to the levels that permit life to arise.

A.DIM
2009-Aug-18, 02:40 PM
Thanks.
A question, if I may, arising from this statement:
"Our discovery supports the theory that some of life's ingredients formed in space and were delivered to Earth long ago by meteorite and comet impacts."

Is there a name for this theory?

agingjb
2009-Aug-18, 03:04 PM
Or we could say that it is evidence that at least relatively simple organic chemicals form readily wherever their components are available - including, for instance, the early Earth.

(Glycine is NH2CH2COOH.)

matthewota
2009-Aug-18, 04:44 PM
Is there a name for this theory?

It is called panspermia.

Do not get too excited. Amino acids have been found in interstellar gas clouds, too.

But they are simple organic molecules, not full blown proteins.

transreality
2009-Aug-19, 02:31 AM
Thanks.
A question, if I may, arising from this statement:
"Our discovery supports the theory that some of life's ingredients formed in space and were delivered to Earth long ago by meteorite and comet impacts."

Is there a name for this theory?

I'm not sure, but it obviously includes the tacit assumption that local life originates on Earth.

Weakly Interacting MP
2009-Aug-19, 05:20 PM
I'm not sure, but it obviously includes the tacit assumption that local life originates on Earth.


I don't agree. It includes the tacit assumption that life could originate on Earth, or more precisely in its vicinity.

transreality
2009-Aug-19, 08:56 PM
As I see , there are three theories, that statement that A.DIM quotes would be #2

theory #1 panspermia

life originates elsewhere and spreads via spores around the universe, and here.

theory #2 A.Dims latest theory?

lifes essentials ingredients originate in space and trigger separate 'genesis' events on planets.

theory #3 abiogenesis

lifes essential ingredients arise independently on planets as a matter of course, with inevitable independent genesis events.

Weakly Interacting MP
2009-Aug-20, 04:21 PM
theory #1 panspermia

life originates elsewhere and spreads via spores around the universe, and here.

Even if this theory were true, it fails to asnwer the basic question--how does life arise? If passpermia occurred in this solar system, the question begged is "how did it arise to begin with?"


theory #2 A.Dims latest theory?

lifes essentials ingredients originate in space and trigger separate 'genesis' events on planets.

theory #3 abiogenesis

lifes essential ingredients arise independently on planets as a matter of course, with inevitable independent genesis events.

Not to take away from A.Dims, but I don't think these are 'his" theories.

Regardless, these two appear to be the same side of the coin. Until we have more than one example of a planet supporting life, the rise of life remains (mostly) conjecture.

timb
2009-Aug-20, 11:07 PM
It is called panspermia.


No it's not. Panspermia is the theory that life is propagated throughout the universe. Simple organic molecules arriving from space is not panspermia.