Finding Answers to Life’s Big Questions… In Comets

August 19th, 2009

I am fascinated by the recent news regarding comets in our solar system.

Most recently a team from NASA reported finding the simple amino acid glycine in materials returned from the Stardust mission.

The Stardust mission sent a craft from Earth on a trajectory that, like a boomerang, flew it through the tail of comet Wild 2 and then back to Earth. Comet Wild 2 originates from the outer reaches of our solar system, and as such is thought to be about as old as our solar system itself. Scientists have been analyzing the collected comet bits since Stardust’s return hoping to discover what the early solar system was made of.

And, now, it seems the early solar system contained the building blocks for life.

Sure, we’ve found glycine in bits of asteroids before, but those are from the warmer, inner parts of the solar system. Finding that an amino acid can come from the cold reaches of space indicates that these molecules don’t need a more temperate climate to form. The necessary chemical reactions can occur far from the sun.

Take that conclusion a bit further, and it means these molecules could be forming all over the universe, which makes the likelihood for carbon-based life in other stellar neighborhoods a bit more plausible. This realization makes our observations of glycine in distant nebulae substantially more interesting.

Now, consider that even though glycine doesn’t need a comfortable place to live, we do. How on Earth (pun intended) did the building blocks get here and evolve into what we know as life?

Glycine could have naturally come about as a result of chemical interactions on the early planetary surface. Or, it could have come from asteroids and comets.

Well, an insightful piece of computational research our of the Niels Bohr Institute in Denmark tried to answer this question by looking at iridium in 3.8 billion year old rocks from Greenland and in rocks returned from the moon during the Apollo missions.

Iridium is a metal that while naturally present on the Earth is found in much higher concentrations in asteroids and comets. Additionally, asteroids are estimated to have more iridium than comets, and leave more behind when they impact with the planet; some 18,000 parts per trillion versus 130 parts per trillion were expected in the impact sites.

The analysis found that the amount of iridium contained in the ancient rocks was more in line with comet impacts than with asteroids. They also found that their cometary calculations jived with concentrations of iridium found in the moon rocks.

The researchers, concluding that comets were the most likely culprits during the Late Heavy Bombardment (taking place after the Earth’s young molten-hot phase), estimated that the amount of water that would remain on the Earth as a result was right on par with the amount of water in all the Earth’s oceans.

So, did comets create our oceans? Maybe. The calculations are based on lots of assumptions as to the amount of iridium that should be found in rocks formed during asteroid or comet impacts. Regardless, it is still a fascinating train of thought.

I love this quote from the research paper:

“We may sip a piece of the impactors every time we drink a glass of water.”

And, the final question, is whether comets, in addition to bringing water, brought life’s building blocks as well.

It’s not too far of a reach to consider it a possibility, especially with the recent impact on Jupiter, and work that suggests comet showers make their way through the solar system every 500 million years or so.

Just like April showers bring May flowers, what do comet showers bring?


5 Responses to “Finding Answers to Life’s Big Questions… In Comets”

  1. Andreas Næsby Rasmussen on August 20, 2009 1:41 am

    Nice write up and fascinating thoughts. But I never understood the need for the building blocks of life coming from space. How would this make understanding the process easier, as you then have to explain how the building blocks collected in the asteroids?

    I also thought I read recently that the basic process had finally been realized in a lab.

  2. David on August 20, 2009 10:33 am

    Oh my head is light with excitement (I know, I should get a life). I live in good ol’ Kansas and I deal with creationist on a daily basis. When I mention this to them next time, they will cover their ears and go “la la la…”
    Last, and not detracting one bit from this post, are there degrees of plausibility?

  3. Darryl Rabon on August 20, 2009 9:05 pm

    I find your podcasts fascinating. Leo sometimes doesn’t seem to let you get a word in, though. Just jump in, he won’t mind.

    Anyway I’m thinking there’s so much more we’ll learn about the “seeds of creation” that we’ll look back on this age as our infancy.

    My dad was a civil engineer and “scientist” at USGS in water resources, so I got it from the cradle – keep up the good work; I know Americans can be illiterate sometimes in science and expert in celebrity matters, but hang in there, you may be both popular with the masses and respected given time.

    Information is a science too. I’ve found so many fields “cross wires” (as Joseph Campbell might have said) and that interdisciplinary approaches seem to work best, IMO.

    But I’m just an amateur. I know the sky on a clear night brings me solace. There are benefits to being stuck in the country without big city lights.

    I just hope civilization has a real chance if the comets brought get a little close. Do you think activity was more dangerous in the early days of the universe/galaxy/solar system? Are we protected more now by the odds given “lesser activity”? I’m thinking the moon may be a false indication of nearby strikes.
    (I aspire to be a glass “half-full” person).

    Have you seen the movie “Stardust”? We humans do have our art. Kubrick’s 2001 is my favorite, though. Intelligence to me is the cream rising to the top. I think the internet may be earth’s salvation.

    I find it difficult to believe that ALL the elements other than basic ones come from comets and/or other projectiles, but the time scales are so enormous – who knows? We must take our first baby steps to get to understandings that let us know how much we don’t know.

    Keep appealing to the “intelligent laity” – we don’t need to get lost in jargon. I love the down to earth approach.

    What do they say, 100 billion earth-like planets in our galaxy and an “infinite” number of galaxies? Life must be out there, but it really might be “out there”. I hope the new administration finds the money to help out SETI and NASA to find out what we can. We owe it to ourselves.

    A wag might say Comet Showers bring “Mayflowers” i.e. time to move off earth with a “moving van”.

    [heretic in chat]

  4. Jon on August 21, 2009 3:25 pm

    I hope this means we will find tasty new life forms to snack on in our solar system. It’s another good reason to get to Europa quickly. Seriously, it is interesting news. Glycine is the smallest of the amino acids and probably a durable molecule, so it’s a natural first amino acid to find in space. I have to wonder if there is any chance that finding glycine in the sample was due to contamination. It doesn’t take much and there is plenty of glycine in our environment, even in bacteria. I would suggest that we don’t know if the glycine in a comet was formed when the comet was in a temperate phase. After all, a lot can happen to a comet in a few billion years and we don’t have much evidence for our conjectures.

  5. alloycowboy on August 23, 2009 6:10 pm

    I wouldn’t get to excited about finding C2H5NO2 in a comet, it goes to reason that simple chemical compounds are pretty pleantiful in the universe. The Interesting part is how these simple compounds morph into highly complex strands of DNA which generate in to a highly complex organism that is the sum of more then its bio chemistry.

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