We're all, like, cosmic children, man!

August 18, 2009 5:49 PM

In 2004, the Stardust mission passed through the tail of comet 81P/Wild (aka Wild 2); in 2006, that captured comet dust was returned to Earth. Now, researchers have found glycine, one of the amino acids in proteins, in that cometary material.

The glycine found is definitely extraterrestrial in origin, since the isotope of carbon that it's built from isn't found in any great quantity on Earth.

Previously:

• The aerogel used to capture the comet dust
• The Stardust@Home distributed computing project to search for dust specks in the aerogel (and earlier)
• News of the jettisoning of the comet dust capture capsule
• Early post about the mission itself with links to comet photos

posted by nonspecialist (34 comments total)

in 2006, that captured comet dust was returned to Earth

Jesus fuck, is NASA trying to bring on the pockyclipse?
posted by dersins at 5:55 PM on August 18, 2009

isn't found in any quantity on Earth.

This shocked an eyebrow; I'm not a chemist, but wikipedia says Carbon 13 is present in 1% quantity compared to Carbon 12. Good thing it wasn't C-14, 'cuz we don't need NASA bringing back isotopes that are deadly for 12,000 years back to Earth, that's for sure.
posted by @troy at 5:59 PM on August 18, 2009

Um, a couple of corrections. Glycine is a building block of proteins, not DNA, and 13-C is definitely found on Earth; it's natural isotopic abundance is about 1.1%, meaning that 1.1% of all carbon atoms on Earth are 13-C (12-C is the more common isotope).

Moving along, why would NASA expect cometary carbon to have a different isotopic abundance that terrestrial carbon? Didn't see that in a quick scan of the links.
posted by Quietgal at 6:03 PM on August 18, 2009

<silly_mistakes>proteins, not DNA, sorry; "any quantity" -> "any great quantity"; link to missed Daily Telegraph story that mentions the isotopic abundance</silly_mistakes>
posted by nonspecialist at 6:12 PM on August 18, 2009

Moving along, why would NASA expect cometary carbon to have a different isotopic abundance that terrestrial carbon?

Photosynthesis preferentially selects C-12 over C-13 (because of the weight difference) so the isotope ratio in organic carbon is different than in inorganic carbon. (Using "organic" to mean "living or derived from the living", not "things based on carbon".)
posted by Chocolate Pickle at 6:12 PM on August 18, 2009

And, quoted from the fourth link:

A glycine molecule from space will tend to have more of the heavier Carbon 13 atoms in it than glycine that's from Earth. That is what the team found.
posted by nonspecialist at 6:13 PM on August 18, 2009

Gah: its ... than ...

On preview: I understand the isotopic selection effects in organic (meaning plant-derived) samples, but it sounded like they mean comets have a higher abundance of 13-C than Earth. Or maybe I misinterpreted and they're only talking about "living" molecules. It would be cool if isotopic abundances were really different in comets vs planets.

@troy, I'm pretty sure you're kidding but Wikipedia sez there's already 300 million Curies of 14-C in Earth's biosphere. A few more picograms won't make any difference.
posted by Quietgal at 6:19 PM on August 18, 2009

nonspecialist

Certainly appears that way!

I think that the basic building blocks for life are out there in space is pretty indicative that this is a universe in which life is inevitable. Life seeks opportunity everywhere.
posted by five fresh fish at 6:46 PM on August 18, 2009

That's really neat. It would be cool to discover that simple life is the rule rather than the exception.
posted by Dr. Send at 6:46 PM on August 18, 2009

Comets are spooge.
posted by Burhanistan at 6:49 PM on August 18, 2009

Godspooge!
posted by five fresh fish at 6:52 PM on August 18, 2009 [2 favorites]

How would the millions of years of plant life on Earth affect the quantities of the different sorts of Carbon? Is it the kind of thing where we could start out with a different mix of the various sorts and have those percentages change over time through the chemical actions within living matter? Or am I completely off base with wondering that at all?
posted by hippybear at 6:53 PM on August 18, 2009

I have the good fortune of having been personally connected to a portion of the Stardust program. I supervised the guy who made part of the reefing line (parachute system) for the recovery module. We used to track the progress of the craft, back in the day, before I got fired . . . . anyway, nice to see this.

Where's the "overlords" comment thread?
posted by yesster at 7:09 PM on August 18, 2009

Godspooge!

Ubergoo! [NOT TF2-IST]
posted by stavrosthewonderchicken at 7:15 PM on August 18, 2009

Just started reading Here Be Dragons which devotes part of a chapter to the exogenesis theory. This finding doesn't prove anything new about that theory, but does make mention of the left vs. right-handedness of the amino acids. There are reports that only glycine is not left-handed of the amino acids discovered thus far in meteorite samples. Anyone know if there is any significance to this?
posted by RobotVoodooPower at 7:21 PM on August 18, 2009

Said, I'm going down to Yasgur's farm
Gonna join in a rock and roll band
Got to get back to the land
And set my soul free

We are stardust, we are golden
We are billion-year-old carbon
And we got to get ourselves back to the garden
posted by euphorb at 7:28 PM on August 18, 2009 [4 favorites]

In 1989, America staged the Big Space Fuck, which was a serious effort to make sure that human life would continue to exist somewhere in the Universe, since it certainly couldn’t continue much longer on Earth. Everything had turned to shit and beer cans and old automobiles and Clorox bottles. An interesting thing happened in the Hawaiian Islands, where they had been throwing trash down extinct volcanoes for years: a couple of the volcanoes all of a sudden spit it all back up. And so on.

This was a period of great permissiveness in matters of language, so even the President was saying shit and fuck and so on, without anybody’s feeling threatened or taking offense. It was perfectly OK. He called the Space Fuck a Space Fuck and so did everybody else. It was a rocket ship with eight-hundred pounds of freeze dried jizzum in its nose. It was going to fired at the Andromeda Galazy, two-million light years away. The ship was named the Arthur C. Clarke, in honor of a famous space pioneer.

Personal note: this was the first I ever read of Vonnegut; I was twelve at the time!
posted by funkbrain at 7:28 PM on August 18, 2009 [4 favorites]

There are reports that only glycine is not left-handed of the amino acids discovered thus far in meteorite samples. Anyone know if there is any significance to this?

Like ethanol, glycine doesn't come in mirror image versions.
posted by Chocolate Pickle at 7:36 PM on August 18, 2009

There are reports that only glycine is not left-handed of the amino acids discovered thus far in meteorite samples. Anyone know if there is any significance to this?

Carbon, by its nature is able to form atomic bonds to four atoms. If each of the four atoms is different the structure is said to be chiral, meaning it exits in two separate mirror image forms, like left and right gloves. These two structures, called enantiomers, have the same molecular formula but are not equivalent. Glycine, as the simplest amino acid is unique in that two of its bonds are with hydrogen so it doesn't have left and right-handed forms (also called steroisomers).

Life on Earth, and almost certainly, elsewhere will only generate and use one set of steroisomers because it is prohibitively difficult to reliably form complex structures and enzymes composed of a mixture of left and right handed building blocks. Since almost all known natural processes here on earth produce equal amounts of left handed and right handed building blocks (called Racemic mistures), a large difference in the relative amounts of enantiomers could be indicative of life.

However it's commonly thought, though not yet proven, that polarized light from certain stars can produce excess of one enantiomer over another.
posted by euphorb at 7:55 PM on August 18, 2009 [7 favorites]

euphorb- thank you. very much.
posted by yesster at 8:00 PM on August 18, 2009

There is a STAAAAARMAN WAITIN' IN THE SKKKKY.
posted by The Whelk at 8:25 PM on August 18, 2009

This isn't much of a surprise. Radio astronomers have discovered many organic substances in nebulae including most if not all of the amino acids.

The 129 reported interstellar and circumstellar molecules, updated 2005

Interstellar Molecules as Probes of Prebiotic Chemistry
posted by neuron at 8:47 PM on August 18, 2009

I don't think photosynthesis will impact the amount of c-13 total on earth, but only the amount of c-13 that you'd see in organic compounds like glycene. If the glycene were from a non-living source, it would have more c-13 that glycene built in a plant.
posted by empath at 9:04 PM on August 18, 2009

You guys can babble science stuff all you want, I'm gonna just get ready for the amino acid comet gunk man.
posted by Astro Zombie at 9:34 PM on August 18, 2009 [1 favorite]

You guys can babble science stuff all you want, I'm gonna just get ready for the amino acid comet gunk man.
posted by Astro Zombie at 9:34 PM on August 18

eponyhysterical?
posted by yesster at 9:36 PM on August 18, 2009

I dunno - this is really neat... or but not so much.

Neat: earth had nucleic acids rained down upon it from which primitive life could use (very very very long shot).

Neater: the nucleic acids -> amino acids (glycine) is a common occurance - but then, extra-terrestrial glycine can mean that it be synthesized completely outside of the terrestrial DNA->amino acid cycle

Personally cool - "god" is the initial situation where our current universe began ("big bang") and the distribution of energies and their interactions resolved into a system that gave rise to our current observable reality. That glycine could form from a mixture of carbon and nitrogen and hydrogen anywhere in the universe means that the series of events that gave rise to us here-and-now means that it could else where in the universe and so life elsewhere could plausibally form from the same basic parameters.

Then again, in our unimagineably large universe, "life" could... life... must have arisen but that we might not recognize as such.
posted by porpoise at 10:01 PM on August 18, 2009

Wasn't this the one that busted open when it hit the earth? I remember seeing something like that live on CNN. Or maybe that was a few years earlier.

Yeah, I guess that was this thing. But according to Wikipedia this stardust probe had the same design flaw, but it apparently didn't cause the problem.
posted by delmoi at 10:34 PM on August 18, 2009

Then again, in our unimagineably large universe, "life" could... life... must have arisen but that we might not recognize as such.

Funny thing is I'm smitten with the idea that most life in the universe looks kinda like us.

This is driven by the unsupportable surmise that life has a normal distribution, and as far as we know at this point in time we are the median, mean, and mode.

If you really want to blow your mind just remember that there's nothing that we know that says there aren't a complete infinite of universes all slightly different, and life like us can perceive it due to this weak anthtropocentricity.

Athiests like me like to think we have answers, but late at night I can fold my brain with these questions and realize that I really don't know anything. :)
posted by @troy at 1:07 AM on August 19, 2009

Maybe the question is whether the sample has more ¹³C than is in the average American.
posted by fleacircus at 2:16 AM on August 19, 2009

[Fixed the details in the post re: proteins and quantity.]
posted by cortex at 6:51 AM on August 19, 2009

Athiests like me like to think we have answers, but late at night I can fold my brain with these questions and realize that I really don't know anything. :)

See, athiests like me love the fact that there are always more answers to find, and not knowing everything is a great relief. I couldn't imagine the hubris it would take to say "Oh yeah, I have it on good authority that everything in the universe is laid out just like this." Keep on freaking me out, you wild and crazy universe!
posted by FatherDagon at 10:25 AM on August 19, 2009

> How would the millions of years of plant life on Earth affect the quantities of the different sorts of Carbon?

Hippybear, living organisms don't convert one isotope into another - that's outside the realm of ordinary chemical reactions. The bias seen in living/formerly-living samples comes from the kinetic isotope effect (KIE). Basically, lighter atoms like 12-C can move a little faster simply because they're lighter. The chemical reactions of living cells, like photosynthesis, involve grabbing a molecule and shoving it through a series of enzymes which are often extremely close together but still separated by some distance. Molecules made of lighter atoms - those that contain most or all 12-C with little or no 13-C - tend to move faster through this "assembly line".

The KIE is tiny but over zillions of biochemical reactions over millions of years, it shows up as a preferential enrichment for 12-C in biological samples compared to the pool of total carbon on Earth.

I tried to find out where 13-C comes from, with no luck and I'm too lazy to keep looking. (I'm sure somebody else can fill this in.) It's possible that 13-C is formed at a slow but constant rate from radioactive decay of another element. This might slowly shift the ratio of carbon isotopes over millions of years, since 13-C is a stable isotope (i.e., it doesn't decay into anything else, it just sits there).

However, I learned that 14-C, a radioactive isotope, is actually formed continuously in the upper atmosphere! How cool is that? We'll never run out of radioactive carbon!
posted by Quietgal at 11:12 AM on August 19, 2009

Thanks for everyone for answering my silly question about carbon-13 and such. It is my Chemistry professor father's eternal shame that I had to drop high school chemistry because I couldn't balance a chemical equation at all, ever. Thanks for taking up the slack in my education by educating me here!
posted by hippybear at 11:20 AM on August 19, 2009

Quietgal, C13 is also formed in the upper atmosphere, but that may not be the sole source of it.

The KIE effect you describe can be a lot more significant than you let on. The weight difference between C12 and C13 is 8%, which is really quite a lot.

KIE is the reason why D2O is poisonous. Chemically it's water, but water formed from deuterium (H2) instead of protium (H1) and the weight difference is 11%. If you drink a lot of D2O and it gets absorbed, the effect is to foul up chemical processes essential to life -- and you can die as a result.
posted by Chocolate Pickle at 10:10 PM on August 20, 2009