Comets may have brought life to Earth: new study

Sep 13, 2010
Computer simulations show that long chains containing carbon-nitrogen bonds can form during shock compression of a cometary ice. Upon expansion, the long chains break apart to form complexes containing the protein building amino acid glycine.

(PhysOrg.com) -- Life on Earth as we know it really could be from out of this world. New research from Lawrence Livermore National Laboratory scientists shows that comets that crashed into Earth millions of years ago could have produced amino acids - the building blocks of life.

Amino acids are critical to life and serve as the building blocks of proteins, which are linear chains of amino acids.

In the Sept. 12 online edition of the journal , LLNL’s Nir Goldman and colleagues found that simple molecules found within comets (such as water, ammonia, methylene and carbon dioxide) just might have been instigators of life on Earth. His team discovered that the sudden compression and heating of cometary ices crashing into Earth can produce complexes resembling the amino acid, glycine.

research initially focused on the production of amino acids from organic materials already present on the planet. However, further research showed that Earth’s atmospheric conditions consisted mainly of carbon dioxide, nitrogen and water. Shock-heating experiments and calculations eventually proved that synthesis of necessary for amino acid production will not occur in this type of environment.

“There’s a possibility that the production or delivery of prebiotic molecules came from extraterrestrial sources,” Goldman said. “On early Earth, we know that there was a heavy bombardment of comets and asteroids delivering up to several orders of magnitude greater mass of organics than what likely was already here.”

This video is not supported by your browser at this time.
A video clip of Nir Goldman narrating the carbon nitrogen interaction computer simulation

Comets range in size from 1.6 kilometers up to 56 kilometers. Comets of these sizes passing through the Earth’s atmosphere are heated externally but remain cool internally. Upon impact with the planetary surface, a shock wave is generated due to the sudden compression.

can create sudden, intense pressures and temperatures, which could affect chemical reactions within a comet before it interacts with the ambient planetary environment. The previous general consensus was that the delivery or production of amino acids from these impact events was improbable because the extensive heating (1000s of Kelvin degrees) from the impact would destroy any potential life-building molecules. (One Kelvin equals 1.8 degrees Fahrenheit).

However, Goldman and his colleagues studied how a collision, where an extraterrestrial ice impacts a planet with a glancing blow, could generate much lower temperatures.

“Under this situation, organic materials could potentially be synthesized within the comet’s interior during shock compression and survive the high pressures and temperatures,” Goldman said. “Once the compressed material expands, stable amino acids could survive interactions with the planet’s atmosphere or ocean. These processes could result in concentrations of prebiotic organic species ’shock-synthesized’ on Earth from materials that originated in the outer regions of space.”

Using molecular dynamic simulations, the LLNL team studied shock compression in a prototypical astrophysical ice mixture (similar to a comet crashing into Earth) to extremely high pressures and temperatures. They found that as the material decompresses, protein-building are likely to form.

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Provided by Lawrence Livermore National Laboratory

4.5 /5 (21 votes)

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skand1nsky
2.1 / 5 (9) Sep 13, 2010
This postulate reverberates with truth. This reminds me of Tim Leary's claim of a communique sent by an alien intelligence, using meditation and astral projection techniques. A snippet as below:

"It is time for life on Earth to leave the planetary womb and learn to walk through the stars.
Life was seeded on your planet billions of years ago by nucleotide templates which contained the blueprint for gradual evolution through a sequence of biomechanical stages.
The goal of evolution is to produce nervous systems capable of communicating with and returning to the Galactic Network where we, your interstellar parents, await you.
At this time the voyage home is possible. Mutate! Come home in glory!"

Is the universe a breeding ground for similar life, seeded by higher powers?
Amazing to think of comets as far-flung cosmic nurseries of life.

random
Sep 13, 2010
This comment has been removed by a moderator.
cosmic_chris
4 / 5 (2) Sep 13, 2010
With the discoveries of new solar systems that could possibly contain life sustaining atmospheres, would it be too far fetched for us to "seed" a comet and guide it to a planet? Yes, it would take billions of years for it to evolve like the Earth, but we would at least be doing our part to try and extend life as we know it. Life may not come out exactly as it did here, but at least we tried.
Arkaleus
1 / 5 (5) Sep 13, 2010
That's a great Leary quote. Interesting pre-internet bit of connectedness. If the average distribution of this pre-biotic material is divided over the number of liquid water-stable worlds then we may have a galaxy (universe?) teeming with DNA based life.

The also poses a problem for those of us who think interstellar expansion is going to be a land rush - there is every reason to expect life-stable worlds to already be populated. I can only hope that the nearby star systems that bear life-stable worlds are still in their early animal development or plant development phases. Every galactic colonization simulation I've run has shown that an early interstellar expansion expands fastest and most efficiently when there are no other intelligent species immediately nearby, but close enough to interact with us after we have established a large enough network of stars.
gwrede
3.4 / 5 (5) Sep 13, 2010
"Bringing life to Earth" should be properly specified. In my opinion, for example, even if _all_ prebiotic molecules came from space, that still wouldn't count. -- Since _every_atom_ here came from space, I think "life came from space" needs to mean that living organisms (or pores) came from space. Which I think is less likely than life arising here.

If we think life actually came from space, then we should study whether life can arise in space, or only on planets. So far we only have seen life on a planet, not space, which would indicate another planet (not necessarily in the Solar system) as the origin of said life, not space.

What makes it so much less likely for life to arise here, that it is _more_likely_ that it arose somewhere else, and then managed to travel and then even survive the voyage here?

Now, wouldn't that be a severe belittlement of Earth as a womb?
skand1nsky
2.3 / 5 (3) Sep 13, 2010
The plausibility of 'Earth as a womb' is undeniable, in that it has facilitated and harboured life for millions of years, as evidenced by our fossil record. More pertinent, however, is the question of whether Life can be perceived as an interstellar communication network, disseminated through the galaxies in the form of nucleotide templates. These "seeds" could potentially land on planets, become activated through high temperature and pressure bond formation, and evolve nervous systems over the course of time.

I think the truth might be right under our very noses, in the form of chemical imprints in our structural DNA. We just don't know how to identify them as yet.
JMDragonWake
not rated yet Sep 13, 2010
"The previous general consensus was that the delivery or production of amino acids from these impact events was improbable because the extensive heating (1000s of Kelvin degrees) from the impact would destroy any potential life-building molecules. (One Kelvin equals 457 degrees Fahrenheit)."

That's incorrect and misleading, right? It makes it sound like thousands of Kelvin is like millions of degrees Fahrenheit. Actually, 1 K = -457.87° F, and an increase of +1 K is an increase of only +1.8° F. So in general, thousands of Kelvin corresponds to less than twice as many thousands of degrees Fahrenheit.
JMDragonWake
not rated yet Sep 13, 2010
"The previous general consensus was that the delivery or production of amino acids from these impact events was improbable because the extensive heating (1000s of Kelvin degrees) from the impact would destroy any potential life-building molecules. (One Kelvin equals 457 degrees Fahrenheit)."

That's incorrect and misleading, right? It makes it sound like thousands of Kelvin is like millions of degrees Fahrenheit. Actually, 1 K = -457.87° F, and an increase of +1 K is an increase of only +1.8° F. So in general, thousands of Kelvin corresponds to less than twice as many thousands of degrees Fahrenheit.
ArcainOne
3.7 / 5 (3) Sep 13, 2010
It seems to many people want to stand on one side of the line or the other. To me it seems improbable that life started in outer space, just as it seems improbable that life sprang up completely just from the planet earth. It seems more probable that it was a combined effort. Organic compounds are known to form in space. This study has shown the shock waves, heat, and pressure generated from a commit impact can produce other complex organic compounds, and we know that other organic compounds are produced through various geological activities on the earth. Given that the environment of earth was vastly different 4.6 billion years ago and given the incredible amount of time the earth had to start life, about 1.1 billion years, the universe had plenty of time to get it right by hurling large chunks of rocky ice and other materials toward the little planet.
yttrium
3.7 / 5 (3) Sep 13, 2010
Incredible work by a talented group of scientists!
mrlewish
4 / 5 (4) Sep 14, 2010
What are you all talking about? All this indicates is that the environments in which the conditions for "prelife" can exist are greatly variable. No one is talking about a preplanned seeding of the cosmos. For one it is a huge leap of logic (and wrongly so) to go from a "we can find organic molecules in comet stuff" to "our galactic overlords must be out there" by expressing such sentiments and attaching yourself to the scientific part of it as to make if your own makes legitimate research in this field suspect in the eyes of uneducated laymen when they hear such silly talk. In other words you are devaluing the work you are fawning over. And two I am pretty sure if there is panspermia it does not need intelligent life to spread it around. Life can spread itself around without "intelligent" help after all. Example.. Earth.
kevinrtrs
1.7 / 5 (6) Sep 14, 2010
Hang onto your hats, people!

This article is specifically about a simulation. There's nothing in it that says such an glycine amino generating process has been discovered when comets hit a planetary[earth] atmosphere. This is all still very much a mathematical construct that doesn't have any reality attached yet.

Don't jump the gun.

Furthermore, even if such a reality [glycine formed in comet shockwaves] gets confirmed it's still lightyears away from having life come from that comet. One little amino acid does not a living cell make. To even begin speculating as to the origins of life is way premature.

Skeptic_Heretic
5 / 5 (1) Sep 14, 2010
There's nothing in it that says such an glycine amino generating process has been discovered when comets hit a planetary[earth] atmosphere. This is all still very much a mathematical construct that doesn't have any reality attached yet.

Don't jump the gun.

Funny you say gun. We used the LLL "Really Big Gun" to prove that cometary impact, primarily glancing blows, would create complex amino acids, including glycine derivatives. As for how we decided what the composition of said pseudo comet should be, we used the data retrieved by the Stardust mission.

Sorry Kev, this is well beyond simple modeling.
chaman
not rated yet Sep 14, 2010
The Leary quote reminds me of the short story "The Fermi Paradox Is Our Business Model", by Charlie Jane Anders.
http://www.tor.co...s-model.