Debate and Discussion

Comet provides evidence that origin life started in space.
Aurora Moon at 7:16PM, Aug. 18, 2007
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Cardiff, UK (SPX) Aug 17, 2007
Recent probes inside comets show it is overwhelmingly likely that life began in space, according to a new paper by Cardiff University scientists. Professor Chandra Wickramasinghe and colleagues at the University's Centre for Astrobiology have long argued the case for panspermia - the theory that life began inside comets and then spread to habitable planets across the galaxy. A recent BBC Horizon documentary traced the development of the theory.
Now the team claims that findings from space probes sent to investigate passing comets reveal how the first organisms could have formed.

The 2005 Deep Impact mission to Comet Tempel 1 discovered a mixture of organic and clay particles inside the comet. One theory for the origins of life proposes that clay particles acted as a catalyst, converting simple organic molecules into more complex structures. The 2004 Stardust Mission to Comet Wild 2 found a range of complex hydrocarbon molecules - potential building blocks for life.

The Cardiff team suggests that radioactive elements can keep water in liquid form in comet interiors for millions of years, making them potentially ideal “incubators” for early life. They also point out that the billions of comets in our solar system and across the galaxy contain far more clay than the early Earth did. The researchers calculate the odds of life starting on Earth rather than inside a comet at one trillion trillion (10 to the power of 24) to one against.

Professor Wickramasinghe said: “The findings of the comet missions, which surprised many, strengthen the argument for panspermia. We now have a mechanism for how it could have happened. All the necessary elements - clay, organic molecules and water - are there. The longer time scale and the greater mass of comets make it overwhelmingly more likely that life began in space than on earth.”

Comet Probes Reveal Evidence Of Origin Of Life
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last edited on July 14, 2011 11:10AM
Aurora Moon at 7:18PM, Aug. 18, 2007
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The search for life elsewhere in the solar system and beyond should include efforts to detect what scientists sometimes refer to as “weird” life – that is, life with an alternative biochemistry to that of life on Earth – says a new report from the National Research Council. The committee that wrote the report found that the fundamental requirements for life as we generally know it – a liquid water biosolvent, carbon-based metabolism, molecular system capable of evolution, and the ability to exchange energy with the environment – are not the only ways to support phenomena recognized as life.
“Our investigation made clear that life is possible in forms different than those on Earth,” said committee chair John Baross, professor of oceanography at the University of Washington, Seattle.

The report emphasizes that “no discovery that we can make in our exploration of the solar system would have greater impact on our view of our position in the cosmos, or be more inspiring, than the discovery of an alien life form, even a primitive one. At the same time, it is clear that nothing would be more tragic in the American exploration of space than to encounter alien life without recognizing it.”

The tacit assumption that alien life would utilize the same biochemical architecture as life on Earth does means that scientists have artificially limited the scope of their thinking as to where extraterrestrial life might be found, the report says.

The assumption that life requires water, for example, has limited thinking about likely habitats on Mars to those places where liquid water is thought to be present or have once flowed, such as the deep subsurface. However, according to the committee, liquids such as ammonia or formamide could also work as biosolvents – liquids that dissolve substances within an organism – albeit through a different biochemistry.

The recent evidence that liquid water-ammonia mixtures may exist in the interior of Saturn's moon Titan suggests that increased priority be given to a follow-on mission to probe Titan, a locale the committee considers the solar system's most likely home for weird life.

“It is critical to know what to look for in the search for life in the solar system,” said Baross. “The search so far has focused on Earth-like life because that's all we know, but life that may have originated elsewhere could be unrecognizable compared with life here. Advances throughout the last decade in biology and biochemistry show that the basic requirements for life might not be as concrete as we thought.”

Besides the possibility of alternative biosolvents, studies show that variations on some of the other basic tenets for life also might be able to support weird life. DNA on Earth works through the pairing of four chemical compounds called nucleotides, but experiments in synthetic biology have created structures with six or more nucleotides that can also encode genetic information and, potentially, support Darwinian evolution.

Additionally, studies in chemistry show that an organism could utilize energy from alternative sources, such as through a reaction of sodium hydroxide and hydrochloric acid, meaning that such an organism could have an entirely non-carbon-based metabolism.

Researchers need to further explore variations of the requirements for life with particular emphasis on origin-of-life studies, which will help determine if life can exist without water or in environments where water is only present under extreme conditions, the report says. Most planets and moons in this solar system fall into one of these categories. Research should also focus on how organisms break down key elements, as even non-carbon-based life would need elements for energy, structure, and chemical reactions.

The report also stresses that the future search for alien life should not exclude additional research into terrestrial life. Through examination of extreme environments, such as deserts and deep under the oceans, studies have determined that life exists essentially anywhere water and a source of energy are found together on Earth.

Field researchers should therefore seek out organisms with novel biochemistries and those that exist in areas where vital resources are scarce to better understand how life on Earth truly operates, the committee said. This improved understanding will contribute greatly toward seeking Earth-like life where the conditions necessary for its existence might be met, as in the case of subsurface Mars.

Space missions will need adjustment to increase the breadth of their search for life. Planned Mars missions, for example, should include instruments that detect components of light elements – especially carbon, hydrogen, oxygen, phosphorous, and sulfur – as well as simple organic functional groups and organic carbon. Recent evidence indicates that another moon of Saturn, Enceladus, has active water geysers, raising the prospect that habitable environments may exist there and greatly increasing the priority of additional studies of this body.

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last edited on July 14, 2011 11:10AM
ozoneocean at 8:27PM, Aug. 18, 2007
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Actually they're sort of related, and then again quite unrelated in a way Aurora. One is a semi scientific article claiming the life MUST have originated in outerspace (a pretty strong position to have), and the other is about the fact that we're far too focused on looking for Earth type life away from Earth, so focused that it's likely that we'll miss real extra terrestrial life if we ever do come into contact with it.

While the first one is sort of straining very hard to convince people of a rather unlikely theory, the other is questioning the assumptions behind looking for the conditions of Earth life at all. Personally I think the second has far more merit, heh, reminds me of that Star Trek episode I saw as a little kid with the Silicone life form they didn't know what to make of, or in the start of the Hicthhicker's guide to the Galaxy (the novel), where various creatures are waiting for the Starship The Heart of Gold to be launched and one of their number includes beings who are light wavelengths “an Interesting shade of blue” trapped in a prism for the event. lol!

A bit way out perhaps, but more imaginative, and perhaps more sensible to?

Although, to go by the first article, if that were actually true you would naturally expect to find earth type life everywhere that it was suitable because of comets seeding planets all the time all over the place, so if that's the case then we should be mostly looking for Earth life since it's the easiest for us to get our heads around! But to go by the other what we should do is re-think what life is and what other forms it could take and perhaps that will allow us to look much closer to home because different forms of life could possibly exist anywhere at all, while Earth life would be very limited and inaccessible to us given out current technology. :(
 
last edited on July 14, 2011 2:27PM
Aurora Moon at 9:01PM, Aug. 18, 2007
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Yeah. I just thought those two topics would be intersting for people to discuss, and think about. After all, if what those people say is true in one of the articles, then it does open up a lot more aspects of stuff to explore.
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last edited on July 14, 2011 11:10AM
Runosonta at 2:37AM, Aug. 19, 2007
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Slightly off topic but…

You know, I'm gonna be SO pissed off if I die before the find something out there. And I mean REALLY find. Like a huge whale made out of energy travelling through space and time. Or a green dude saying things like “bleeb!”

last edited on July 14, 2011 3:12PM
Loud_G at 6:58AM, Aug. 20, 2007
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This just begs the same question. If life didn't start on earth, but started on a comet, asteroid, meteor, whatever. Why and how did it start in that place.

This theory doesn't really address anything. It just moves the start of life to a different place. Why are those key elements on that flying piece of rock?

Is it because they are magical seed pods? or is it because they are remnants or another earthlike world carrying bits of genetic data? or is this flying rock theory just more silliness?



As for the carbon based life forms thing, its about time they widened their scope. I personally believe that all sentient life forms out there in space are human and carbon based, but as a scientific thinking person, I am not about to rule out other fun stuff just because. :D
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last edited on July 14, 2011 1:45PM
TnTComic at 7:29AM, Aug. 20, 2007
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Loud_G
As for the carbon based life forms thing, its about time they widened their scope. I personally believe that all sentient life forms out there in space are human and carbon based, but as a scientific thinking person, I am not about to rule out other fun stuff just because. :D

to paraphrase a smarter dude than me;

Chemosynthetic Hypothesis of Emergence:
Basically in a system where enregy is provided constantly but not consistently, the chemicals in the system naturally over time form more and more complex structures because of how their properties reacte to each other. In our case because of the cocktail of carbon hydrogen oxygen, and various other elements like sodium, nitrogen, phosphorus, iron, etc, life emerged over time.


So no, I don't rule out -based life forms.
last edited on July 14, 2011 4:31PM
StaceyMontgomery at 7:56AM, Aug. 20, 2007
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I find the reasoning in the first article a little weak. They speculate that there's more clay in comets than clay on Earth, and that life formed in clay, therefore, it is more likely that life formed in comets than on Earth.

That's a pretty weak chain of reasoning. I don't think they've really justified the conclusion. It's a fun idea, but they have not established the “more likely” part, not yet.

Still, it would be great to see inside more comets.
last edited on July 14, 2011 3:55PM
mlai at 9:44AM, Aug. 20, 2007
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I think they base their hypothesis more on the fact that there are complex hydrocarbons in the comet. Saying “clay” makes them sound like Creationists.

I'm still astounded how probes land on comets in the first place. How they do that? Aren't those things going at like a million miles per hour?

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last edited on July 14, 2011 2:05PM

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