More Proof That Getting Clobbered By Comets Led to Life

Chemistry plus heat can lead to biology—and cometary impacts warm things up nicely

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You don’t find a lot of creationists among planetary biologists. Even scientists who are also people of faith will typically agree that life is a happy accident involving chemistry, randomness and a whole lot of very slow evolution. But that doesn’t mean an outside power may not have had a hand in getting things started. That power is the impact of comets and meteorites.

Water is plentiful in the universe, but in the early days of the solar system, when Earth was a molten ball of flaming goo, it would have been hard for the proto-planet to stay hydrated. Once things had settled down some, incoming comets, which are little more than water ice and rock and were plentiful in what is known as the heavy bombardment phase of the solar system’s past, could have imported all we needed. Under those wet conditions, the right elements could have started coming together to form precursors to amino acids, then the acids themselves and then, a few jillion steps later, butterflies and bunnies and all the rest. And that initial chemistry wouldn’t even have had to have gotten started on Earth. Amino acids and amino acid precursors have been detected in both comets and meteorites, meaning they could have been imported to us ready-made.

(MORE: New Proof That Comets Watered the Earth)

All the same, there’s one more thing that would help get the basic elements to join hands, and that would be energy—typically in the form of heat. That’s something that ought to be hard to come by in a dirty snowball or a fragment of rock flying through space, but very easy to come by when an impact occurs. A watery object striking a dry body like Earth—or, in the alternative, a dry object striking an icy body like Jupiter’s frozen moon Europa or Saturn’s icy Enceladus—could shock-heat complex organic compounds into existence.  Indeed, the Cassini spacecraft has detected those kinds of organics in water plumes that jet out from Enceladus.

Still, you can hardly test your theory by standing on a moon, waiting for a meteor to hit and then sampling the water. So a team of scientists from the U.K.’s Imperial College and the University of Kent came up with another way, one they described in a paper published in this week’s Nature Geoscience.

The researchers first mixed up batches of water with raw chemical signatures matching the various types found in comets—though without any kinds of amino acid precursors. Then they sealed the water in containers and heated it to 932º F (600º C) to ensure that any traces of organic contaminants were destroyed. The water samples were then frozen, and steel projectiles—also heat-sterilized—were fired at them from a gas gun at high speed. Ice plus impact could, in theory, equal organics—and in one sample it did.

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The winning solution was water with a mix of ammonia gas, carbon dioxide and methanol—all carbon, hydrogen, oxygen compounds. That formula produced not just precursors, but amino acids themselves. Give them 4.5 billion years—a longitudinal study if ever there was one—and who knows what they might turn into? The scientists don’t have quite that much time, but lending support to their findings is the fact that computer simulations of the same impact events yield the same chemical results.

“The fact that impacts occur is without question,” the authors wrote. “It is also known that comets contain significant quantities of the compounds used in this study, and that these compounds are found on the impacted surfaces of many of the icy bodies in the outer Solar System.”

Visiting any of those bodies to study the chemistry and confirm the theories is not set to happen anytime soon, but it’s at least on the agenda. NASA is looking at proposals for a robotic mission to Europa, and the European Space Agency has an even more ambitious one planned for launch in 2022. Called JUICE (a somewhat awkward acronym for JUpiter ICy moons Explorer) it will study Europa as well as its sister satellites Ganymede and Callisto. JUICE may not find life, but it will bring us closer to understanding how it got started—on Earth and perhaps on untold other worlds as well.

(MORE: Aliens Among Us)

12 comments
dfiantwolfe
dfiantwolfe

One also has to consider the atmospheric conditions at the time that this would have happened. We have other experiments that confirm quite a few different conditions under which life can occur. You really have to wonder, just how many other planets out in this universe have forms of life, and how different they might be from our own. 

Of course I wouldn't get any high hopes of meeting any other form of *intelligent* life.  Most the stars we see from our own night sky are long dead by the time their light reaches us.  And by the time *our* light reaches those same places. Our own sun will be long gone.

fredlb
fredlb

It's not just the heat that forms the amino acids, but the impact pressure must be considered as the magic sauce forcing less complex molecules into seeking a  more compact (and complex) form.  The heat is just an energy source.

Next, they should fire the steel balls into the amino acid solution.

KevinAdams
KevinAdams

I prefer the theory that the waters of the great deep launched deuterium laden water into outer space along with microbes, diatoms, and plant matter which froze into our present day comets.  All the water in our solar system was from this event, the biblical great flood.  There is water ice on Mercury, our moon, Mars, and moons of Jupiter, all sourced from Earth, where amino acids abound.  The Truth will prevail, stay strong brothers and sisters!

tryingit123
tryingit123

To completely buy an evolutionary only viewpoint you have to wonder why no life exist on the other planets since, theoretically anyway, over a 14 billion year period (remember, that's a pretty long time folks) life of any sort would have had ample time to evolve. 

In other words, why is it only life forms in Earth's unique combination of temps, chemicals, light, etc.  Why no ammonia breathing, 5 eyed, cold temp loving slugs on Jupiter?

Or are all you science types expecting cats, dogs and blue eyed, long-legged blonds as life forms?

Duffman
Duffman

I'm sorry, Bible says no...

downpour
downpour

If you understand how and why elements bond together into molecules, and how these combine into more complex structures, life should not seem so unlikely.

It just turned out that 4 of these molecules could form long chains (thereby encoding information). Each link in the chain could also bond to one other specific molecule (out of the 4) via a weaker bond, so the chains produced mirror images of themselves (thereby copying the encoded information). Not only that, but groups of 3 of these molecules could bond to amino acids, making new chains called proteins, that all life is made from. Over time the information started to become less random and more usefull and evolution began.

Given the vast size of the universe, the countless different environments it contains and it's unimaginable age. Life is no unlikely, it is enevitable.

Nkurtar
Nkurtar

"Even scientists who are also people of faith will typically agree that life is a happy accident involving chemistry, randomness and a whole lot of very slow evolution" 

Very interesting to see someone like Mr. Kluger making an odd definition of life as "happy accident, randomness, etc."in his scientific column. Considering the going in the world there must have been, I think, very unfortunate accident not happy one to have resulted in existence of humankind. I'm very much doubted about the life, maybe one of the most complex things in our universe, can be explained with an accidental event.       




downpour
downpour

The conditions inside Jupiter are insane, so it's unlikely anything would survive under all that pressure and battering from the raging storms, but we haven't even looked, so those slugs may well exist for all we know. The only place we have even started to look is Mars and that is probably just a dead planet, but we need to search far more varied environments before we come to any conclusions.

The universe is indeed unimaginably huge, even if life only exists around 1 in every 100 billion stars, that still means there would be 200 billion star systems that contained life. Now humans are the only species on our planet capable of broadcasting out presence, so it's unlikely that many aliens would have our rare abilities. This means the vast majority would be completely undetectable to us with our current technology.

Our recent discovery that most stars have planets makes alien life even more likely, after all chemistry works the same everywhere, it's only the environmental conditions that can vary.

WilliamR.James
WilliamR.James

@downpour While I share your belief that life is likely fairly common in the universe, I think that, at this point, saying it's inevitable is extremely premature.  We don't yet know enough to come to that conclusion.  We just don't know yet what triggered life even if we'v found that the ingredients are common.  Before we can make even an educated guess, we need wither samples of life elsewhere, or samples showing the absence of life under good conditions for billions of years, or the discovery of exactly what the trigger was. 

We do know that life on Earth started pretty soon after it became possible. That's tantalizing as a clue, but it's not much of a clue in reality.  Because it's only one sample, it's mere testimonial, which is useless in science. 

downpour
downpour

I only mean life is inevitable under the right conditions. Given the size of the universe and the fact that very similar events have occurred in hundreds of billions of star systems simultaneously, it would be very strange if almost identical conditions to our own couldn't be found in a great number of them.

WilliamR.James
WilliamR.James

@downpour I'd say that's likely true, but on the other hand we really don't know yet.  It's possible that something, some extremely rare event or sequence of events were necessary to trigger life, something so extremely rare so extremely unlikely that we are alone in the universe.  I seriously doubt it, but it's possible.